Crystal structure refinement with SHELXL

A difunctional Dy(III) complex exhibiting single-molecule magnet behaviour and fluorescent cellular imaging

A mononuclear Dy(III) complex, with formula [Dy(Dicnq)(TFNB)3] (1), is synthesized through self-assembly with 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (TFNB) and 6,7-dicyanodipyrido [2,2-d:2',3'-f] quinoxaline (Dicnq) ligands. Single-crystal structure determination reveals that the Dy(III) ion in complex 1 features an N2O6 octacoordinated environment with distorted square-antiprism (D4d) geometry. Magnetic data analysis shows that 1 behaves as a single-molecule magnet, with an energy barrier of 192 K under a zero dc field. With an external field of 1200 Oe, the quantum tunneling of magnetization is suppressed in 1, resulting in an enhanced energy barrier of 261 K. Additionally, 1 displays room-temperature photoluminescence. Leveraging its optical properties and minimal cytotoxic effects, we assess its suitability for cellular-imaging applications. Subsequent laser confocal microscopy analysis revealed that 1 is capable of efficiently traversing the plasma membrane and nuclear membrane of HeLa cells, an observation that is not commonly reported in dysprosium-based complexes.

Synthesis, electronic and photophysical investigations of ruthenium(II)-centred heterometallic Kuratowski complexes which feature redox-active metal centres

We present the synthesis and comprehensive characterization of a series of complexes belonging to the Kuratowski (K3,3) family. These are pentanuclear {RuIIM4} complexes (M = Co2+, Ni2+, Zn2+) which were prepared by employing a directed two-step synthesis facilitated by the recently published [RuII(Me2bta)2(Me2btaH)4] precursor complex (Me2btaH = 5,6-dimethyl-1,2,3-benzotriazole). The pentanuclear Kuratowski complexes showcase a unique combination of photo-active ruthenium with redox-active metal centres. The μ3-bridging 1,2,3-triazolate ligands in these complexes facilitate electronic coupling between the metal centers, as revealed through electrochemical and photophysical studies. Comparisons with {RuIIZn4} and {RuIICu4} Kuratowski compounds reveal that Co(II) significantly influences both the Ru(II/III) redox step and the position of the MLCT (metal-to-ligand charge transfer) band, whereas Cu(II) and Ni(II) exhibit minimal influence. Photophysical investigations reveal the {RuIIZn4} compound as the only phosphorescent species, displaying an emission band extending into the near-infrared region. This emission originates from a triplet 3MLCT state and features an exceptionally large Stokes shift, with a long lifetime of the excited-state of about 3.3 μs in powdered form at room temperature.

Ionic-Liquid-Based Synthesis of U24 Uranyl Peroxide Cage Clusters with Encapsulated Hexanuclear Lanthanide Oxide/Hydroxide Clusters

Six lanthanide-containing (Pr-Tb, excluding Pm) uranyl peroxide cage clusters (UPCs) formed following the dissolution of studtite, [(UO2)(O2)(H2O)2](H2O)2, and lanthanide nitrates in the ionic liquid 1-ethyl-3-methylimidazolium diethyl phosphate (EMIm-DEP). Crystals of the compounds were isolated and characterized using single crystal X-ray diffraction, Raman and infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The six structures are composed of U24, [(UO2)24(O2)24(OH)24]24-, cage clusters with the sodalite topology encapsulating [Ln6O(OH)8]8+ hexanuclear units. The crystal packing of the cage clusters produces a highly porous crystal structure and nonlocalized EMIm-DEP ions reside in pores within the crystal structure, providing charge-balance to the anionic cage clusters. Adjacent U24 cages are directly linked through hydrogen bonds donated by hydroxy groups of one cluster and accepted by uranyl ion oxygen atoms of another. The typical UPC synthesis involves decomposition of studtite in alkaline aqueous conditions, making the formation of Ln-containing UPCs impractical owing to the precipitation of insoluble lanthanide compounds under such conditions. This is the first report of studtite dissolving in an ionic liquid and subsequently forming UPCs, as well as the first report of the formation of U24 containing lanthanide cations.

Solvent-directed assembly in MOFs with linear trinuclear cobalt(II) nodes: formation of inverted Figaro chains

Four new cobalt(II) coordination networks based on the nitrilotribenzoic acid ligand (H3ntb) with the formula [Co3(ntb)2(solv)2]n (where solv = dmf, def, dma, and EtOH), denoted as JUMP-4(solv), are reported. The trinuclear cobalt(II) clusters that constitute the three-dimensional network are coordinated by the six carboxylate groups of two bridging, deprotonated ntb3- ligands. These clusters have two flexible coordination sites on the two terminal cobalt ions, which are partially saturated by the condensation of these clusters, leading to unprecedented inverted Figaro chains. Three of the frameworks were synthesized by combining cobalt(II) chloride and the ligand in a mixture of acetonitrile and the corresponding amide (dmf, def, and dma) in a 9 : 1 ratio, while the ethanol analogue could only be obtained by single-crystal-to-single-crystal transformation starting from the dmf and dma derivatives. The difference in the size of the solvents coordinated to the terminal cobalt(II) ions results in a pore-partitioning effect, as reflected in the argon sorption behavior of the networks. Magnetic measurements reveal antiferromagnetic interactions between the anisotropic cobalt(II) ions along the alternating inverted Figaro chains.

Penta- and Hexacoordinated Copper(II) Complexes with Azido and 4-amino-3,5-di-2-pyridyl-4H-1,2,4-triazole Ligands with Field-Induced Slow Magnetic Relaxation

Two new Cu(II) complexes with abpt (4-amino-3,5-di-2-pyridyl-4H-1,2,4-triazole) and azido ligands, [Cu(abpt)2(N3)]NO3 (1) and [Cu(abpt)2(N3)2]⋅2H2O (2), have been prepared and characterized by crystal structure analysis, spectral and magnetic measurements. The presence of neutral abpt, as well as azido ligands was proved by IR spectroscopy and the composition of the complexes confirmed an elemental analysis. Monocrystal X-ray structure analysis revealed that 1 is an ionic pentacoordinated Cu(II) complex, exhibiting a distorted tetragonal pyramidal geometry of the coordination polyhedron, while 2 is a neutral molecular complex with a distorted octahedral environment of the Cu(II) atom. The structures are stabilized by π-π stacking interactions between the aromatic rings of abpt, as well as various intra- and intermolecular hydrogen bonds involving nitrate ions and molecules of solvated water in 1 and 2, respectively. A field-induced slow magnetic relaxation was observed at low temperatures in 1, described by the direct and Raman process involving low-energy intramolecular vibrational modes, which were predicted by the DFT calculations.

Facile N═N Bond Cleavage of Cis-Azobenzene with Bis-silylenes

The very different features of cooperative disilicon(II)-mediated N═N bond activation of trans- vs. cis-azobenzene are reported, employing two bis-silylenes with distinct intramolecular Si···Si distances, PhN(LSi:)₂ 1 (L = PhC(tBuN)₂, Si···Si: 2.9 Å) and XT(LSi:)₂ 2 (XT = 9,9-dimethyl-xanthene-4,5-diyl, Si···Si: 4.3 Å). While trans-azobenzene reacts with both bis-silylenes to form C─H and N═N π bond activation products, the cis-isomer undergoes only N═N bond scission. Thus, the reaction of 1 with cis-azobenzene at room temperature affords the unprecedented N═N bond cleavage product 4, featuring a bis-silaimine with terminal and bridging Si═N moieties. In contrast, the reaction of 2 with cis-azobenzene at -30 °C in THF allows for the isolation of the [1+2] cycloaddition intermediate 6, containing a three-membered SiN₂ ring (siladiazirane), which rearranges to the N═N bond cleavage product 8 at room temperature. Compound 6 reacts with one additional equivalent of cis-azobenzene to form bis-silaazirane 7 with two SiN₂ rings. Density functional theory (DFT) calculations support stepwise Si(II)···Si(II) cooperative activation mechanisms and provide insights into the role of bis-silylenes for selective N═N cleavage reactions.

Near-Infrared Ytterbium Complexes Based on Polycyclic Aromatic Dicarboxylate Ligands and the Solution-Processed NIR OLED with Irradiance up to 110,284 μW/m2

Since the O-H and N-H oscillators of solvent molecules attached to ytterbium ion (Yb3+) and C-H oscillators existing in the inner coordination sphere of Yb3+ would quench the excited energy of Yb(III), which leads to low quantum yields (QYs) of Yb(III) complexes, we aimed to design a ligand that could block solvent molecules and C-H oscillators out of the first coordination sphere of Yb3+. Herein, a series of novel polycyclic aromatic dicarboxylate ligands are designed and synthesized to effectively protect Yb3+ from solvent molecules and efficiently sensitize Yb3+ luminescence, while the cost and sophistication of the synthesis are satisfactory. Therein, [Yb(MO-DPyPDA)2](DIEA) exhibited a considerable QY of 5.20% and a long luminescent lifetime of 102 μs in CD3OD. The single-crystal structure demonstrates that there are no solvent molecules and C-H oscillators existing in the inner coordination sphere of Yb3+, which is conducive to alleviating the quenching effect. Meanwhile, we also carried out experiments to verify that it was thermodynamically feasible for ligands to sensitize the luminescence of center ion through internal redox processes. Moreover, several groups of near-infrared organic light-emitting diodes based on [Yb(DTFM-DPyPDA)2](DIEA) were fabricated based on the solution-processing method, and the highest irradiance of 110,284 μW/m2 was realized by optimizing the device structure.

A new supramolecular tecton: the crucial impact of the polycation charge and geometry of H-bonds on the structure and properties of halometallates in the solid state

A new tricationic organic supramolecular tecton has been designed and synthesized. Contrary to known mono- and dicationic species, this new molecule, being a "three-way connector", allows assembling infinite supramolecular sheets and nets upon interaction with appropriate inorganic counterpart complex anions. In this work, triprotonated 6-amino-5,7-dimethyl-1,3-diazaadamantane, comprising two secondary and one primary nitrogen atoms, is used as a trication to form hybrid compounds with iodometallate anions by forming five hydrogen bonds at a time. It is shown that the bulky cation works simultaneously as a spacer and a connector, such that the positions of inorganic [MI6]3- anions (M = Sb or Bi) in the crystal structures are defined by five hydrogen bonds and are well-separated from each other. The latter is considered as a prerequisite for the hybrid compounds to exhibit optical properties originating from the undisturbed electronic structure of individual inorganic anions.

Expanding the Family of Monosubstituted 15-Membered Pyridine-Based Macrocyclic Ligands for Mn(II) Complexation in the Context of MRI

As Mn(II) complexes attract continuous interest as alternatives to Gd-based contrast agents (CAs) in clinical magnetic resonance imaging (MRI), we synthesized two monosubstituted derivatives of the 15-membered pyridine-based macrocycle 15-pyN3O2 bearing either a 2-pyridylmethyl (L2) or a 2-benzimidazolylmethyl pendant arm (L3) and characterized their Mn(II) complexes MnL2 and MnL3 in the context of MRI contrast agent development. Their X-ray molecular structures confirmed a coordination number of seven and a pentagonal bipyramidal geometry with one coordination site available for inner-sphere water. Protonation constants of L2 and L3, and stability constants with selected divalent metal ions were determined using potentiometry. MnL2 and MnL3 complexes are fully formed at pH 7.4; however, they both display low kinetic inertness due to a significant spontaneous dissociation of the nonprotonated complex. The presence of one inner-sphere water molecule in the Mn(II) complexes was confirmed by 17O NMR and 1H NMRD measurements. The water exchange rate constants are very low (kex298 = 0.46 × 107 and 0.23 × 107 s-1 for MnL2 and MnL3, respectively), but typical for Mn(II) complexes of 15-pyN3O2 derivatives. The relaxivities are in good agreement with monohydrated small-molecular-weight Mn(II) chelates (r1 = 2.49 and 2.77 mM-1 s-1 at 20 MHz, 25 °C, for MnL2 and MnL3, respectively).

Robust and High Temperature Spin Crossover Controlled via the Self-Assembly of Chiral and Racemic Polymorphs in Triazolylimine [Fe2L3](BF4)4 Helicates

Three new chiral spin crossover (SCO) dinuclear triple helicates of type [Fe2L3](BF4)4 are reported exhibiting a robust magnetic behavior that is resistant to rapid changes in temperature, moisture and light. The selective formation of racemic aggregates upon crystallization of a solution of the respective racemic complexes was found to be associated with the helical torsion, intermetallic distance as well as the spatial arrangement of the enantiomers and anions. Torsional stress and particular hydrogen bonding interactions were related to the potential coiling and uncoiling mechanisms inherent to some helically chiral systems as well as to the efficacy of cooperativity transmission within the crystal lattice. These unique structural dynamics were correlated with the display of a chirality-dependent semiabrupt SCO profile observed for each enantiopure aggregate. This study highlights how the molecular shape as well as the crystal packing of helically chiral compounds can be altered to modulate the magnetic behavior toward a robust and high temperature SCO system.

Donor and Geometry Optimization: Fresh Perspectives for the Design of Polyoxometalate Charge Transfer Chromophores

Three linear, dipolar arylimido-polyoxometalate (POM) and one 2-dimensional bis-functionalized arylimido-polyoxometalate charge transfer chromophore, with diphenylacetylene bridges, have been synthesized and studied by spectroelectrochemistry, hyper-Rayleigh scattering (HRS), and DFT/TD-DFT calculations. The linear systems show that with julolidinyl (Jd) and -NTol2 donor groups, the alkyne bridge yields high second-order nonlinear optical (NLO) coefficients β (Jd, β0,zzz = 318 × 10-30 esu; -NTol2, β0,zzz = 222 × 10-30 esu), indeed the Jd compound gives the highest NLO activity of any organoimido-POM to date with minimal decrease in transparency. The bis-functionalized 2D (C2v) POM derivative showed increased activity over its monofunctionalized analogue with no decrease in transparency, although the NLO response was only minimally two dimensional. Spectroelectrochemistry and TD-DFT calculations showed switchable linear optical responses for the monofunctionalized derivatives due to the weakened charge transfer character of the electronic transitions in the reduced state, while TD-DFT also indicated potential for switched NLO responses. These have been demonstrated by electrochemistry-HRS for the Jd compound, but cyclability is limited by relatively poor stability in the reduced state. IR and CV studies for these sterically protected arylimido polyoxometalates indicate that decomposition proceeds via a breakdown of the {Mo6} cluster in the reduced state, rather than simple solvolysis of the Mo≡N bond.

Synthetic and structural investigation of new Au(I) complexes featuring bidentate imidazole-2-thione ligands

Gold(I) imidazole-2-thione (IMT) complexes [Au(IMT)2]+, [Au(diIMT)]+ and [Au2(diIMT)2]2+ were synthesized by reacting Au(SMe2)Cl with ligands containing one or two IMT groups. These AuI-IMT complexes were characterized by X-ray diffraction, NMR spectroscopy, and mass spectrometry. The IMT ligands provided a linear coordination array around the AuI center, with IMT CS bonds orthogonal to the S-Au-S axis. In some cases for complexes of form [Au(IMT)2]+ or [Au(diIMT)]+, the cations aggregate to create dimeric or trimeric units in the solid state, and exhibit inter-cation Au⋯Au distances in the range of ∼3.03-3.07 Å, indicative of aurophilic interactions. The new AuI-IMT complexes exhibit NMR and mass spectra that are generally consistent with the structures of cations of the form [Au(IMT)2]+, [Au(diIMT)]+ or [Au2(diIMT)2]2+ as seen in the solid state. In two cases, however, 1H NMR spectra suggested that mononuclear and dinuclear complexes [Au(diIMT)]+ and [Au2(diIMT)2]2+ existed in equilibrium, undergoing exchange reactions rapidly on the NMR timescale. Density functional theory (DFT) analysis supported the experimental conformations, showing agreement between the energetically favorable conformers and experimental structures. Photochemical and electrochemical properties were reported, with only one complex being strongly luminescent. The luminescence, at least in solution, did not appear to result from aurophilic interactions.

Manipulation of Solvent Donor Effects to Overcome the Calcium Schlenk Equilibrium

Synthetic access toward well-defined, monomeric s-block metal complexes is mired with chemical challenges, primarily attributed to the formation of homoleptic complexes promoted by the Schlenk equilibrium. Ligand redistribution is significantly pronounced for the heavier s-block metals, such as calcium, which form bischelate complexes readily through traditional synthetic routes such as transmetalation, amination, and ligand exchange. Mechanistic investigation of each of these routes with phenoxyimine (ONN) ligands was explored to ascertain the fundamental parameters promote bischelate formation. Donor effects from coordinated solvent proved to be deleterious, and in an effort to circumvent bischelation, a new calcium bisamide, {Ca[N(SiMe3)2]2(diox)2}∞, was synthesized and characterized as a coordination polymer with a unique square planar geometry, rarely seen for group 2 complexes. Amination with {Ca[N(SiMe3)2]2(diox)2}∞ was found to significantly shift the Schlenk equilibrium to favor heteroleptic species, allowing for the characterization of new phenoxyimine calcium-amido complexes: [ONN1Ca-N(SiMe3)2]2(diox) and [ONN3Ca-N(SiMe3)2(diox)]∞. Subsequent studies showed that solvent exchange from the isolated dioxane complexes with THF notably shortened the stability of the complex in solution. Although steric parameters have previously been regarded as the key to the stabilization of heteroleptic calcium complexes, it is equally important to consider the donor ability of coordinated solvent ligands to achieve longer-lived heavy s-block complexes.

Self-assembled nickel(II)-centered metal-organic square grid complexes for CO2 sensing

Detection and monitoring of hazardous CO2 gas are essential for ensuring human health and environmental safety, which form part of Goal 13 of the United Nations Sustainable Development Goals (SDGs). Metal-organic square complexes in thin-film forms are explored in this work for the first time as CO2 gas sensors. Two new Ni(II) metal-organic square grid complexes [Ni(HL)]4Cl4·26H2O (1) and [Ni(HL)]4 (BF4)4·20H2O (2) were achieved by self-assembly, utilizing 1,5-bis(2-benzoylpyridine) thiocarbohydrazone (H2L) as building blocks. The formation of a molecular square [NiHL]44+ unit containing four octahedrally coordinated Ni(II) centers in complex 1 was confirmed by single crystal X-ray diffraction (SCXRD). Complex 2, conversely, yielded single crystals of a new complex, [NiL]4 (2a), from its DMF and ethanol mixture. The MALDI mass spectral study indicates that the metallosupramolecular square grid units are stable in solution, while the thermogravimetric study reveals the rigidity of the cationic grid structures in their solid states. The solvent accessible pore volume of 1952 Å3 (≈18.2%) for complex 1 was in accordance with the TG result of 18.1% weight loss up to 272 °C. Hirshfeld surface study was used for void surface analysis. The BET surface areas of complexes 1 and 2 were observed to be 2.390 and 4.803 m2 g-1, respectively. The experimentally observed solid-state band gap energy for complexes 1 and 2 was ∼1.45 eV, revealing semiconductor characteristics. Thin films of both these complexes were then developed using a drop casting process and were employed for CO2 sensing, as these metallosupramolecular hosts consist of many secondary amine groups. Both complexes 1 and 2 demonstrated sensing capability towards hazardous CO2 gas, which was found to improve further under white light illumination. The responses to CO2 gas were found to be 31% and 59% for the sensors engineered using complexes 1 and 2, respectively. The limit of detection for reliable CO2 gas sensing with complex 2 was found to be 500 ppm. The thin film gas sensor working in the chemiresistive mode using complex 2 outperformed its counterpart when operated as a CO2 sensor.

Diverging Reactivity in Anilidophosphine Supported Group III Complexes

We report the synthesis of scandium and yttrium halide complexes with bidentate, monoanionic anilidophosphine (PN) ligands and the general formula (PN)2MX (M = Sc (1-X), Y (2-X); X = Cl (1-Cl/2-Cl), X = I (1-I/2-I). Attempts to functionalize these complexes by salt metathesis reaction revealed that the chlorido complexes are quite unreactive precursors, whereas the iodo complexes readily engage in a broad variety of reactions. We report the azide complexes (1-N3 and 2-N3) as well as the heavy cyanate complexes with the general formula (PN)2M(OCPn) (M = Sc; Pn = P (1-OCP), Pn = As (1-OCAs) and M = Y; Pn = P (2-OCP), Pn = As (2-OCAs)). Furthermore, the amido and phosphanido complexes of the general formula (PN)2M(PnHMesityl) with Pn = N (1-NHMes, 2-NHMes) and Pn = P (1-PHMes, 2-PHMes) are reported. Attempts to synthesize benzyl complexes of the general type (PN)2M(Benzyl) with M = Sc, Y, La revealed drastic differences in the reactivity of the group III metal ions. While the scandium and yttrium complexes displayed elimination of KPN without the formation of defined metal complexes, for lanthanum, defined C-H activation chemistry has been observed, yielding -ate complex 3-CH.

Pyrazine-Functionalized Ru(II)-Complexes as Visible-Light Activated Photobases

Excited-state proton transfer (ESPT) roots in significantly increased acidities or basicities of up to ca. 10 pKa units in the excited state compared to the ground state. While organic photobases are either of "single use" in the case of photobase generators or are limited functionally by their UV absorption, metal complex-based photobases offer intriguing properties. By exciting the characteristic metal-to-ligand charge transfer (MLCT) transitions in the visible range, multiple and reversible ESPT processes can be triggered. In this contribution we present the synthesis of two novel Ruthenium(II)-complexes with pyrazine-functionalized polypyridyl ligands and study their photobasic properties by ultrafast spectroscopy. We find that MLCT excitation in aqueous solution leads to a ΔpKa of 9 units and that the involved ESPT process takes place within ca. 300 picoseconds. Our investigations combine experimental spectroscopy with theoretical calculations.

Influence of the charge of 1,3,5-triaza-7-phosphaadamantane-based ligands on the anticancer activity of organopalladium complexes

In this study, we report the synthesis and characterization of novel organopalladium complexes featuring 1,3,5-triaza-7-phosphaadamantane (PTA)-based ligands, including several cationic derivatives prepared as hexafluorophosphate salts to prevent halide exchange reactions. The complexes incorporate diverse organopalladium fragments-Pd(ii)-vinyl, Pd(ii)-butadienyl, Pd(ii)-allyl, Pd(ii)-imidoyl, Pd(ii)-aryl, and Pd(0)-alkene-many of which have recently shown promising antitumor activity. Most reactions proceeded rapidly at room temperature under aerobic conditions using non-anhydrous solvents. Biological evaluation against ovarian cancer (A2780), cisplatin-resistant ovarian cancer (A2780cis), triple-negative breast cancer (MDA-MB-231), glioblastoma (U87), and non-cancerous fibroblasts (MRC-5) revealed the remarkable cytotoxicity of the complexes, particularly those with Pd(ii)-butadienyl, Pd(ii)-aryl, and Pd(0)-alkene fragments. These compounds demonstrated activity comparable to or exceeding cisplatin, with some showing up to two orders of magnitude greater efficacy. Importantly, the complexes were highly selective for cancer cells, exhibiting minimal toxicity toward MRC-5 fibroblasts, unlike cisplatin. Complex 14b, that contains a Pd(0)-alkene fragment and two MePTA+ ligands, was the only one that exhibited excellent cytotoxicity across all cancer cell lines, including glioblastoma. These findings underscore the potential of PTA-based organopalladium complexes as selective anticancer agents, warranting further in vitro and in vivo studies, as well as mechanistic investigations.

Beyond Barriers, Big Crystallization Hurdles: Atropisomerism in Beyond Rule of Five Compounds Explored by Computational and NMR Studies

Stereochemical purity, stability, and selection of a suitable solid-state form are pivotal factors in pharmaceutical development, particularly for complex beyond Rule of 5 (bRo5) compounds. In this study, we explore the intricate interplay between atropisomerism and crystallization using two model bRo5 compounds, namely, ACBI1 and BI201335, both violating three of four Lipinski's rules. One of the tool compounds exhibits Class 2 atropisomeric behavior, and the other is devoid of it. A diverse array of crystallization methods, including solution-phase crystallization, cocrystallization, and salt formation, were applied, revealing the critical role of atropisomerism-induced stereochemistry in polymorphism and nucleation outcomes. In silico torsion profile calculations and NMR studies were employed to elucidate the rotational energy barriers and confirm the presence or absence of atropisomerism. This comprehensive analysis highlights the significance of understanding stereochemical phenomena such as atropisomerism in designing and developing bRo5 compounds. By integrating advanced analytical techniques and crystallization strategies, this work provides novel insights into tailoring pharmaceutical properties for next-generation therapeutics.

Semisynthetic Derivatives of Perovskone: Development of a Promising Class of Antiprotozoal Lead Compounds

Perovskones, intricate triterpenoids with potent antiplasmodial activity, predominantly derive from Salvia hydrangea DC. ex Benth. In this study, ample quantities of the parent compound, perovskone (1), were isolated from the plant. Using perovskone (1) as a feedstock, seven semisynthetic analogues (2-8) were generated via reactions like hydroxylation, elimination, and esterification. Structural characterization was performed by using 1D and 2D NMR, HRMS, and X-ray diffraction experiments. The compounds underwent in vitro antiparasitic testing against Leishmania donovani, Trypanosoma brucei rhodesiense, Plasmodium falciparum, and Trypanosoma cruzi. Cytotoxicity evaluation was performed using rat myoblast (L6) cells. Perovskone (1) demonstrated excellent activity against T. cruzi, showing an IC50 value of 0.89 μM and a selectivity index (SI) of 14.9. Perovskone I (4) and perovskone G (2) exhibited potent activity against P. falciparum (IC50 values of 0.03 and 0.08 μM, respectively), with favorable SIs of 843.0 and 80.0, comparable to those of chloroquine and artemisinin. Perovskone M (8) displayed promising antileishmanial activity (IC50 = 0.44 μM, SI = 22), comparable to the efficacy of miltefosine against L. donovani (IC50 = 0.51 μM). We believe that the current study holds immense potential for the development of promising leads in antiplasmodial drug discovery.

Studies Related to the Proposed Biotransformation of Bohemamine D into the Co-occurring Marine Natural Product Spinoxazine B

The 1,3-oxazin-6-one-containing spinoxazines A and B (2 and 3, respectively) have been isolated from the marine-derived Streptomyces spinoverrucosus strain SNB-048 and, by another group, from the Solar Saltern-derived Streptomyces sp. KMF-004. Two distinct pathways have been proposed for the conversion of the co-occurring pyrrolizidine alkaloid bohemamine D (1) into compound 3. Here, we report that the readily prepared compound 10, which embodies the 2-hydroxy-1,2-dihydro-3H-pyrrol-3-one core of bohemamine D (1) and is the bis-O-methyl ether of the alkaloid discoipyrrole C, is converted into 1,3-oxazin-6-one 11 on heating at elevated temperatures in air. The mechanism of this conversion was studied using density functional theory and the biosynthetic implications of it are discussed. The photochemical reaction of compound 10 in the presence of oxygen is also detailed and, again, the possible biosynthetic implications of the resulting conversion are considered.

Integration of Through-Space Conjugation of an Adjacent Arene with a Nitrogen/Carbonyl Framework for Narrowband Emission

Organic luminescent materials featuring noncovalent through-space conjugation (TSC) have attracted considerable attention. However, the presence of multiple vibrational energy levels and weak spatial electron delocalization typically results in broad emission peaks for TSC-based emitters, significantly impeding their extensive application in optoelectronic technologies. Herein, two TSC emitters, TSFQ-TRZ and TSFQ-Ph, were synthesized by integrating a fused nitrogen/carbonyl skeleton with various adjacent arene 2,4,6-triphenyl-1,3,5-triazine (TPTRZ) and phenyl group segments through a rigid spiro spacer. These emitters exhibited narrow emissions, with full widths at half-maximum of 19 nm and 25 nm, respectively. Experimental and theoretical investigations unveiled that the TPTRZ segment introduces steric hindrance, while simultaneously suppressing molecular vibrations through intramolecular interactions-a key factor in achieving narrow emissions. Leveraging this narrow blue emission, electroluminescent devices employing TSFQ-TRZ as the emitter achieved an impressive maximum external quantum efficiency of 26.7 %, which further increased to 28.3 % when sensitized by phosphorescent emitter. This work demonstrates highly efficient, narrowband emissions from TSC-based emitters, thereby expanding their potential applications in the electroluminescence field.

Physical properties and cytotoxicity of Cu(II) and Zn(II) complexes with a TMS-substituted indolo[2,3-c]quinoline-derived Schiff base

The incorporation of non-native chemical elements, such as silicon, into drug molecules has gained significant attention as a strategy to broaden the chemical space in medicinal chemistry and develop novel drug candidates. Traditionally, research has focused on the isosteric replacement of a carbon atom with silicon ("silicon switch") in known drug structures or the attachment of a trimethylsilyl (TMS) group to biologically active scaffolds. In this study, a TMS-substituted indoloquinoline-based Schiff base (HLTMS) and its corresponding metal complexes, Cu(HLTMS)Cl2 (1) and Zn(HLTMS)Cl2 (2), were synthesized and comprehensively characterized using elemental analysis, spectroscopic techniques (IR, UV-vis, 1H and 13C NMR for HLTMS and 2), ESI mass spectrometry and single-crystal X-ray diffraction (SC-XRD) for 1 and electron diffraction (ED) for 2. The attachment of the TMS group enhanced the lipophilicity of HLTMS, while complex formation with Cu(II) substantially improved the antiproliferative activity. Exploitation of their intrinsic fluorescence to investigate cellular uptake and intracellular localization in cancer cells was impeded by limited solubility. Both HLTMS and 2 were found to generate reactive oxygen species under cell-free conditions in accord with their redox activity established by cyclic voltammetry. The photochemical activity of the indolo[2,3-c]quinoline-based proligand HLTMS and its complexes 1 and 2 has been disclosed. The compounds exhibited significant toxicity on various human cancer cells and disrupted the mitochondrial membrane potential, suggesting the contribution of mitochondrial dysfunction, triggered by HLTMS and its metal complexes, to their toxic effects. These findings highlight the potential of TMS-substituted Schiff bases as promising anticancer drug candidates.

β-Lactam Ylidenes: An Overlooked Class of N-Heterocyclic Carbenes

In this study, the underappreciated class of β-lactam carbenes (BLCs) is revisited and systematically explored. The required precursors are available in a highly modular synthetic approach from simple starting materials. Two routes may be followed for the generation of the free BLCs: thermal fragmentation of spiro-fused oxadiazoles (110 °C, toluene), or deprotonation of carbene HCl-adducts at -80 °C with a strong base. TEP values (2065-2072 cm-1), 77Se NMR shifts of selenium-adducts (812-995 ppm), as well as DFT calculations reveal moderate σ-donor and strong π-acceptor character of BLCs, leading to a pronounced ambiphilic reactivity. The formation of a wide variety of products under thermal conditions in the cause of oxadiazole fragmentation (110 °C, toluene) is rationalized by a combination of computational reaction discovery and experimental validation. Products include olefinic dimers as well as unprecedented N2-bridged dimers arising from bimolecular reactions, while sterically more demanding precursors are converted in a monomolecular fragmentation reaction via CO release to form ketenimines as intermediates, which finally form amides. With substituents providing appropriate steric protection, a persistent BLC is available via the low temperature route, characterized by its 13C NMR shift of 287 ppm at -20 °C.

Steroidal saponins from the bulbs of Lilium lancifolium Thunb. and their antioxidant effects

Nine previously undescribed compounds (1-9) and one known compound (10) are isolated from the bulbs of Lilium lancifolium Thunb. Of these compounds 1 and 2 feature unique structures based on the known polyoxypregnane skeleton. All the compounds are characterized via nuclear magnetic resonance and high-resolution mass spectrometry, and their cytotoxicity on rat adrenal pheochromocytoma cells (PC12 cells) and their antioxidant effects against hydrogen peroxide (H2O2)-induced oxidative damage in PC12 cells are evaluated. The results indicate that none of the compounds (1-10) exhibit significant cytotoxicity on PC12 cells at a concentration of 50 μM. Moreover, compounds 5 and 6 significantly protect the apoptosis of PC12 cells stimulated with H2O2, suggesting their potential as antioxidants; in addition, 1-4 and 7 exhibit varying degrees of antioxidant activity.

Borate Salts of Aluminum-Alkyl Cations Stabilized by P-, O-, and C-Donors: Synthesis, Characterization and Application as Cocatalysts

Well-defined Al-alkyl borate (AAB) salts {[iBu2(L)Al]2(μ-H)}+[B(C6F5)4]- (AlHAl_L) with L = N-donor ligands have been recently reported as promising "complete" cocatalysts for olefin polymerization. Herein, we explore structural variations of AlHAl_L going beyond the class of N-donors like the prototypical N,N-dimethyl aniline (DMA). Thirteen P-, O-, and C-donor ligands were screened, allowing isolation of AAB salts with mono- and bidentate phosphines, alkyl-, aryl-, and silyl-ethers, and a N-heterocyclic carbene. Except for the diphosphine with the longest spacer between the P atoms [bis(diphenylphosphino)hexane, DPPH], all donors gave well-defined tetracoordinate or tricoordinate molecular species, which were characterized in solution (NMR) and solid state (XRD), and tested as cocatalyst in ethylene/1-hexene copolymerization with an ansa-zirconocene catalyst [rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2]. The vast majority of novel AAB salts provided active catalytic systems, further demonstrating the broad tunability of these species. Consistent with previous studies, variability in productivity upon L variation is primarily related to the efficiency of precatalyst activation, determining the fraction of Zr active sites. Variations in polymer molecular weight and comonomer incorporation observed with some P-, O- and C-donor ligands indicate that also interactions between the L donors and the Zr active species might be relevant in determining catalytic performance in some cases.

Enhanced Drug Loading Capacity Using the Dual Metformine-Dexketoprofren Salt on Nanoapatite Materials

Both apatite nanoparticles and multicomponent pharmaceutical materials have proved the ability to significantly improve the bioavailability of different drugs using different strategies. Herein, the use of nanoapatite is proposed as a promising vehicle for advanced drug delivery of multicomponent pharmaceutical materials. To this purpose, the full synthesis and comprehensive characterization of apatite nanoparticles and the molecular pharmaceutical salt metformin-dexketoprofen are reported, paying special attention to the improvements regarding solubility and stability of the novel materials compared to the parent active pharmaceutical ingredients, as well as the drug loading capacity enhancement achieved in nanoapatites. Our results evidence the potential of the presented novel strategy, enhancing the dexketoprofen-loading a remarkable 50-fold when compared to native drug, thanks to the improvement of solubility achieved via salt-formation (567 and 168 mg/mL at pH 6.8 and 1.2, respectively), thus expecting improved therapeutic outcomes.

Mononuclear Copper(II) Phosphinates Bearing Mono-, Bi-, and Tridentate N-Donor Ligands: DNA Binding and Cleavage, Cytotoxicity, and Nanoencapsulation

Mononuclear Cu(II) phosphinate-based compounds, [Cu(H2L1)2(Py)2] (1), [Cu(OAc)(H2L1)(Cl-tpy)] (2), and [Cu(H2L1)(Phen)2]H2L1 (3) (Py = pyridine, Cl-tpy = 4'-chloro-2,2':6',2''-terpyridine, Phen = 1,10-phenanthroline monohydrate) were synthesized by reacting Cu(OAc)2·2H2O with N-donor ligands in the presence of bis(2-hydroxy-5-methylphenyl) phosphinic acid (H3L1). The compounds were isolated as single crystals and characterized by spectroscopic and microanalytical techniques. Owing to the bioavailability and biocompatibility of copper, the oxidative DNA cleavage ability of 1-3 was studied by incubating supercoiled (SC) pUC19 DNA (40 µM). The highest cleavage efficiency of complex 3 is attributed to the strong partial intercalation of 1, 10-phenanthroline rings, which enhances reactive oxygen species (ROS) generation. Encapsulation of 3 in a polydiacetylene-supported liposome nanocarrier (Lip-(3)) improves biocompatibility and anticancer activity while addressing solubility and toxicity concerns. The spherical nanoparticles (∼93 nm), characterized by UV-vis, TEM, DLS, and EDX studies exhibit stability, efficient encapsulation, and suitability for targeted drug delivery.

Lanthanide-nickel molecular intermetallic complexes featuring a ligand-free Ni2- anion in endohedral fullerenes

Transition metals (TMs) typically exhibit rich redox chemistry and can be found in various oxidation states. In most cases, TMs are positively charged. Strong π-accepting ligands have been shown to stabilize molecular complexes with TMs in formal negative oxidation states. By contrast, organic-ligand-free TM anions remain rare, limited to intermetallic compounds based on third-row TMs such as gold or platinum. Here we report the synthesis of air-stable lanthanide-nickel molecular intermetallic complexes featuring a ligand-free Ni2- confined within fullerenes, namely, Tb2Ni@C82. The charged Tb2Ni lanthanide nickelide cluster forms metal-only Lewis pairs, featuring strongly polarized Tb-Ni covalent bonds with short bond lengths in the range of 2.50-2.57 Å. X-ray absorption spectroscopy supports the -2 oxidation state of Ni with 3d104s2 electron count, in line with the spectroscopic and magnetic measurements, and theoretical study. This finding opens up an efficient way to stabilize intermetallic clusters with elusive nucleophilic TM anions by confining them inside molecular carbon cages.

4,5-Diazafluorene derivatives and their silver(I) complexes: Synthesis and biological evaluation as antiproliferative agents

This work is focused on the synthesis and biological evaluation of 4,5-diazafluorene bipyridines and their silver(I) complexes. These 4,5-diazafluorene derivatives have two aromatic R groups at the C9 position (R = 4-C6H4X, X = H, 3; Me, 4; NH2, 5; OH, 6; OMe, 7; Br, 8; F, 11; Cl, 12; I, 13; R = 3-Me-4-NH2-C6H3, 9; 3,5-Me2-4-NH2-C6H2, 10). Their synthesis was carried out from a direct SEAr from 4,5-diazafluoren-9-one and the corresponding aryl compound or via the diazonium salt strategy. These compounds were used as ligands to synthesize [Ag(N-N)2]NO3 complexes (3Ag-13Ag). The stability of these complexes in DMSO solution was studied showing that no dissociation was observed over 48 h. All compounds were characterized by NMR (1H and 13C) and MS. The crystal structures of three complexes were determined by single-crystal X-ray diffraction revealing different coordination geometries in solid state. The cytotoxicity study of the compounds was analyzed in lung carcinoma (A-549), cervical carcinoma (HeLa), melanoma (HBT70) cancerous cell lines and in non-malignant lung fibroblasts (MRC-5) and normal human dermal fibroblasts (HDFn) cell lines. Only ligands 3, 7, 11, and 13 exhibited antiproliferative activity. On the other hand, most of the complexes were active suggesting a positive impact when silver is incorporated into the molecule. The selectivity index towards cancerous cells was calculated. Values from 3 to more than 16 were obtained suggesting that these silver complexes are promising molecules for future anticancer treatments. Drug-likeness and ADME properties were in silico calculated for the ligands. The P-gp interaction and Papp were experimentally evaluated. Regarding their action, ROS production does not appear to be the main mechanism by which these complexes exert their cytotoxicity, nor do they appear to be DNA intercalators or DNA covalent binders.

Structural diversity of photoluminescent lanthanide(III) coordination compounds with an isothiazole derivative

Two different series of europium(III), terbium(III) and gadolinium(III) complexes with 4,5-dichloroisothiazole-3-carboxylic acid (HL) were obtained. According to the data obtained from various analysis methods, the first type of coordination compounds with the general formula of [Ln(H2O)L2(OAc)]n was polymer chains, and the second type with the general formula of [Ln6(H2O)10L18] was hexanuclear complexes, with central atoms arranged similar to octahedrons. DFT calculations were used to determine the location of the electron density in HOMO/LUMO and the value of the triplet state energy of the ligand molecule. The highest luminescence quantum yield was observed in the case of the hexanuclear terbium(III) complex (24%) with a millisecond luminescence lifetime, while the hexanuclear europium(III) compound (96%) exhibited the highest value of color purity.

Phenylalanine-Based Amphiphilic Self-Assembled Materials: Gels or Crystals?

We prepared three simple molecules, that we chose as representative examples of amphiphilic and bolamphiphilic amino acid derivatives: N-lauroyl-L-phenylalanine (Lau-Phe-OH), N-palmitoyl-L-phenylalanine (Pal-Phe-OH), N,N-azeloyl-L-diphenylalanine Az-(Phe-OH)2, to study the influence of the aliphatic side chain on the formation of supramolecular materials. We found that Pal-Phe-OH is a very efficient gelator in contrast with Az-(Phe-OH)2 that efficiently forms crystals, while Lau-Phe-OH forms metastable hydrogels that slowly become crystals. We demonstrated by X-ray diffraction that Lau-Phe-OH and Pal-Phe-OH easily form hetero-intermolecular hydrogen bonds between the carboxylic and amidic groups, while Az-(Phe-OH)2 forms homo-intermolecular hydrogen bonds, i. e., the typical carboxylic ring dimer and chains between the amidic functions, which leads to an extended and robust 2D hydrogen bonding network. Moreover, Lau-Phe-OH is more ordered than Pal-Phe-OH and the comparison of these results clearly indicates that the reduced order of Pal-L-Phe-OH is the main reason for the efficiency of this molecule as supergelator.

Copper-Based Metal-Organic Framework as Photoelectric Material

Photo-stimulated Polymers have garnered significant attention for their potential applications ranging from optical memory to sensing. Herein, by changing coordination metal and the position of nitrogen atom in pyridine-based photo-stimulated ligand, we successfully synthesised a novel photo-stimulated copper-based MOF (Cu-MOF) using 9,10-bis(di(pyridine-3-yl)methylene)-9,10-dihydroanthracene as the photo-stimulated ligand. Structural analysis revealed a 3D porous architecture, offering a distinct advantage over previously reported 1D coordination polymer using similar photo-stimulated ligand. The Cu-MOF exhibited exceptional photoelectric properties, demonstrating potential as an anode material for lithium-ion batteries and a luminescent MnO₄- sensor. Its electrochemical performance revealed high reversibility, with discharge capacities retaining stability under varying current densities. Additionally, the Cu-MOF displayed notable photo-stimulated behavior under UV light irradiation, enhancing its optical properties. Although the structure changes from 1D coordination polymer to 3D MOF, the photocyclized form (c-Cu MOF) still exhibited superior fluorescence quenching efficiency and sensitivity for MnO₄- detection with Ksv (quenching constant) 5.24×105 M-1. This work highlights the utility of Cu-MOF as a multifunctional material for energy storage and environmental sensing applications.

Mimicking the CuD Site of pMMO via a Copper Cage-Complex

The mechanism of action of particulate monooxygenase (pMMO) has yet to be determined. The CuD site with two histidines and an asparagine coordinating to copper has been identified as a potential active site of pMMO. Here, we present a copper cage complex, that assembles this coordination sphere, being a structural mimic of the pMMO. The cage is capable to catalyze aerobic oxidations of organic substrates such as benzylic alcohols to aldehydes and hydroquinones to quinones. This is inspired by the reactivity that is observed for enzymatic active sites possessing copper.

Ruthenocenoporphyrinoids─π-Conjugation Transmitted across 1,3-Substituted Ruthenocene

Synthesis of ruthenocenoporphyrinoids, wherein the [RuCp*]+ moiety coordinates to the cyclopentadienyl π-surface of the 21-carba-23-selenaporphyrin macrocyclic platform, has been developed. The specific electronic ruthenocene-macrocycle communication is observed. The macrocyclic ring current is maintained despite the strong π-conjugation in the cyclopentadienyl ring of the ruthenocene fragment. The theoretical data are consistent with the magnetic properties reflected by 1H NMR spectra. DFT-optimized molecular models were used to evaluate the NICS 2D maps and EDDB plots. These data gave an insight into the aromaticity and effectiveness of π-conjugation across 1,3-substituted ruthenocene in the obtained hybrid molecules.

Pressure-Induced Hydrogen Bond Symmetrization in Babingtonite

Hydrogen bond symmetrization and electronic spin transition of iron under pressure are key factors in understanding the physical properties and behaviors of Fe- and H-bearing minerals. However, the coexistence of these two effects may often result in inconsistent interpretations. Babingtonite is characterized by prominent hydrogen bonds and diverse iron oxidation states within its crystal structure. These features make it an ideal subject for studying the interactions between hydrogen bond symmetrization and spin transitions of iron. Here, we conducted high-pressure infrared absorption spectroscopy, single-crystal X-ray diffraction, and Mössbauer spectroscopy experiments on babingtonite to investigate the behaviors of hydrogen bonds and spin states of iron. Pressure-induced hydrogen bond symmetrization occurs at approximately 22 GPa in babingtonite, while no spin transition of iron is detected up to 40 GPa. Our results show that the notable deformation of the unit cell and the kink in the trend of the hydrogen-bonded O-O distance with increasing pressure provide insightful evidence for hydrogen bond symmetrization. The symmetrical rigid configuration of the hydrogen bond leads to increased distortion in the neighboring Fe3+-O octahedron. These findings will contribute to the determination of hydrogen bond symmetrization through crystallographic structural analysis, partly overcoming the challenge of accurately locating hydrogen positions using X-ray diffraction.

Addition of Lithium Silylamides to 1,2-Dicyanobenzene: Isoindoline-1,3-diimine Derivatives Investigated by NMR/XRD/DFT Approach

Phthalocyanines and their building blocks, isoindoline-1,3-diimines (diiminoisoindoles, DIIs), represent a structurally diverse class of compounds with the ability to make metal complexes and perform in various fields from medicine to photovoltaics and homogeneous catalysis. According to the present study, monosubstituted diiminoisoindoles, their higher homologues, and complexes can be effectively prepared by addition of silylated lithium amides to 1,2-dicyanobenzene followed by mild protonolysis or a condensation. An addition of DII to carbodiimides or reactions of lithiated DIIs with acyl chlorides give DII-guanidines and amido derivatives. The imino group of the amido derivatives is preferentially and quantitatively reduced by sodium borohydride. Dynamic behavior and structure of all studied classes of compounds were investigated from the stereochemical point of view─possible E/Z-isomerization and dimerization (DIIs and amido derivatives), tautomerism (guanidines), and stability both in solution and in solid state. The resonance-assisted hydrogen bonds are present in all species except reduced amides, predetermining them to be exceptional ligands in coordination chemistry.

Structural Diversity and Stability of Organic-Inorganic Hybrid Quinuclidine-Based Metal Bromides

Organic-inorganic hybrid compounds based on quinuclidinium and metal bromides, (C7H14N)2MBr4 (M = Co, Mn, Cd), have been synthesized. Differential scanning calorimetry measurements indicate that all compounds undergo a reversible phase transition at 251 K (Co), 205 K (Mn), and 363 K (Cd) upon heating. The respective temperature dependences of the dielectric permittivity reveal anomalies, confirming the occurrence of phase transitions. Although the crystals are isostructural at room temperature, as confirmed by X-ray diffraction data, the mechanism of the phase transitions varies in each compound. The main driving force is the reorientation of quinuclidinium, resulting in the rearrangement of hydrogen bonds. Satisfactory dielectric and thermal stability properties of these materials have been demonstrated, highlighting their potential for applications in temperature sensors and switch devices.

Product Variation in Reactions of MI3(thf)4 with Bis(Mesitoyl)Phosphide Across the M = U, Np, Pu Series

A series of reactions using sodium bis(mesitoyl)phosphide (MesBAP-) with the actinide starting material AnI3(thf)4 (An = U, Np, Pu) as well as the analogous reaction with CeI3(thf)4 was performed. Similar U and Np An(MesBAP)4 (An = U, Np) products were obtained in the +4-oxidation state. The thorium homologue was synthesized using ThI4(dme)2 to generate Th(MesBAP)4, which was employed as a diamagnetic and predominantly redox inert metal center for comparison. The resulting product isolated from the analogous reaction with PuI3(thf)4 was [Na(thf)][Pu(MesBAP)4], where the metal coordinated four ligands and retained the +3-oxidation state. This result is distinct from that obtained from the reaction with CeI3(thf)4, where the Ce3+ product was Ce(MesBAP)3(thf)2. The compounds were isolated and characterized by X-ray diffraction, ultraviolet-visible (UV-vis)-nIR and NMR spectroscopies, and cyclic voltammetry. The synthetic results reveal how different redox stabilities across the 5f series can result in divergent reactivity of Pu. Electrochemical experiments produced redox features that suggest the potential to form reduced complexes supported by the MesBAP ligand framework.

Influence of Magnetic Anisotropy on the Ground State of [CH3NH3]Fe(HCOO)3: Insights into the Improper Modulated Magnetic Structure

The hybrid perovskites [CH3NH3]CoxNix-1(HCOO)3 with x = 0, 0.25, 0.5, 0.75, and 1.0 possess multiple phase transitions, including incommensurate structures. Notably, [CH3NH3]Ni(HCOO)3 features a proper magnetically incommensurate structure ground state. To explore similar behavior, we investigated the isomorphous [CH3NH3]Fe(HCOO)3 (1). A combination of magnetometry measurements, single crystal and powder neutron diffraction, and density functional theory calculations have been used to accurately determine and understand the sequence of nuclear and magnetic phases present in compound 1. At room temperature, it crystallizes in the Pnma space group with a perovskite structure. Below 170 K, new satellite reflections indicate a transition to a modulated structure, refined in the Pnma(00γ)0s0 with q1 = 0.1662(2)c*. At 75 K, the satellite reflections become closer to the main reflections, indicating a second transition, which maintains the superspace group symmetry but decreases the modulation wave vector to q2 = 0.1425(2)c*, i.e., with a longer modulation period. This modulation persists to 2 K, overlapping with the onset of 3D antiferromagnetic order at 17 K, offering a unique opportunity to study magneto-structural coupling. Our results point to an improper magnetic modulated structure where, interestingly, the spins are perpendicular to those of previously reported compounds.

Sb2(TeO4)(SO4): An Anhydrous Tellurite Sulfate with Large Birefringence and Enhanced Thermal Stability

The birefringence of birefringent materials is positively correlated with structural anisotropy. By introducing 5s2-electron-containing Sb3+ and Te4+ cations into a sulfate system, the anhydrous antimony tellurite sulfate Sb2(TeO4)(SO4) was obtained. Due to the stereochemically active lone pairs (SCALPs), both Sb3+ and Te4+ cations are four-coordinated with O atoms to form the distorted seesaw-shaped units. Benefiting from the strong polarizability anisotropy of the distorted polyhedra, Sb2(TeO4)(SO4) exhibits a large birefringence, as well as wide transparency range and high thermal stability, making the compound a potential UV birefringent material. Structural and theoretical calculations indicate that the optical properties mainly originate from the highly distorted SO4 and TeO4 units and their uniform alignment. This work will provide some useful insights into the development of SCALP-cation-based birefringent crystals.

In vitro cellular and molecular plus in silico studies of a substituted bipyridine-coordinated Zn(II) ion: cytotoxicity, ROS-induced apoptosis, anti-metastasis, and BAX/BCL2 genes expression

A new dimethyl-substituted bipyridine-Zn(II) complex (2Mebpy-Zn) was synthesized and structurally characterized. Single-crystalline structure of the complex was elucidated as [Zn(2Mebpy)3](ClO4)2∙1.5(dioxane) by X-ray diffraction, where 2Mebpy is 4,4'-dimethyl-2,2'-bipyridine. The three-dimensional electrostatic potential maps (3D ESP) were plotted for [Zn(2Mebpy)3]2+ cation and [Zn(2Mebpy)3](ClO4)2 molecule. In vitro cytotoxicity studies indicated significant cytotoxicity of 2Mebpy-Zn against both breast (MCF-7) and glioblastoma (U-87) cancer cells relative to normal murine embryo cells (NIH/3T3). The results are indicative of a superior selectivity toward MCF-7 over the other cell lines as confirmed by IC50 value of 5.1 ± 0.5 µM after 48 h. Interestingly, MCF-7 and U-87 cells death induced by 2Mebpy-Zn mostly proceed through an apoptotic pathway which probably associates with the overproduction of reactive oxygen species (ROS). The Zn(II) complex suppressed the metastatic affinity of MCF-7 cells by blocking migration as well as formation of colonies. Also, the expression of two opponent apoptosis-relevant genes (BAX and BCL2) measured by real-time polymerase chain reaction (qPCR) experiments indicated that 2Mebpy-Zn could potentially trigger apoptotic cell death. Moreover, 2Mebpy-Zn could cleave hydrolytically the pUC19 DNA without the need to add any external agent. Finally, the binding affinity of two enantiomers of 2Mebpy-Zn toward cancer therapeutic targets, such as anti-apoptotic proteins, estrogen receptor α, tubulin, and topoisomerase II, was studied by in silico molecular docking. In conclusion, 2Mebpy-Zn can be introduced as a potential therapeutic agent in breast cancer and indicates that other metal complexes with bipyridine derivatives can also exhibit promising anticancer effects.

Tuning 2,3-Bis(arylimino)butane-nickel Precatalysts for High-Molecular-Weight Polyethylene Elastomers

The catalytic performance of α-diiminonickel complexes is highly sensitive to structural modifications in their ligand frameworks. In this study, a series of unsymmetrical 2,3-bis(arylimino)butane-nickel complexes featuring ortho-2,6-dibenzhydryl groups as sterically demanding motifs and para-methyl groups as electron-donating enhancers were proposed and synthesized. These nickel complexes were thoroughly characterized using FTIR, elemental analysis, and single-crystal X-ray diffraction (for Ni4 and Ni5), revealing deviations from ideal tetrahedral geometry. Upon activation with Et2AlCl, these complexes demonstrated exceptional ethylene polymerization activity, achieving a remarkable value of 13.67 × 106 g PE mol-1 (Ni) h-1 at 20 °C. Notably, even at 80 °C, the nickel complexes maintained a high activity of 1.97 × 106 g PE mol-1 (Ni) h-1, showcasing superiority compared to previously reported unsymmetrical 2,3-bis(arylimino)butane-nickel complexes. The resulting polyethylenes exhibited ultra-high molecular weights (Mw: 3.33-19.47 × 105 g mol-1) and tunable branching densities (84-217/1000C), which were effectively controlled by polymerization temperature. Moreover, the mechanical properties of the polyethylenes, including tensile strength (σb = 0.74-16.83 MPa), elongation at break (εb = 271-475%), and elastic recovery (SR = 42-74%), were finely tailored by optimizing molecular weight, crystallinity, and branching degree. The prepared polyethylenes displayed outstanding elastic recovery, a hallmark of high-performance thermoplastic elastomers, making them promising candidates for advanced material applications.

A quantum crystallographic protocol for general use

Quantum crystallography has become ever more important in recent years for the accurate determination of molecular and crystal structures. The results of quantum crystallographic refinements of X-ray data are as accurate and precise as from neutron diffraction and they give access to the complete electronic structure of the compound under investigation. Is the method now mature enough and easy enough to use to extend and ultimately supersede standard X-ray crystal structure determination routines? We utilize the world's most common crystal structure-the YLID test crystal that every owner of an X-ray diffractometer receives with their machine-to show under which circumstances routine, low-resolution, and even room-temperature measurements can be subjected to quantum crystallographic refinement. Based on this, we describe a quantum crystallographic protocol step by step that makes application of quantum crystallographic refinement easy to use and reproducible. We encourage that valuable YLID test measurements are not discarded but made available for method development, increasing the availability of repeated measurements from a handful to tens of thousands.

Zero-field Hall effect emerging from a non-Fermi liquid in a collinear antiferromagnet V1/3NbS2

Magnetically intercalated transition metal dichalcogenides (TMDs) provide a versatile three-dimensional (3D) material platform to explore quantum phenomena and functionalities that emerge from an intricate interplay among magnetism, band structure, and electronic correlations. Here, we report the observation of a nearly magnetization-free anomalous Hall effect (AHE) accompanied by non-Fermi liquid (NFL) behavior and collinear antiferromagnetism (AFM) in V1/3NbS2. Our single-crystal neutron diffraction measurements identify a commensurate, collinear AFM order formed by intercalated V moments. In the magnetically ordered state, the spontaneous AHE is tenfold greater than expected from empirical scaling with magnetization, and this strongly enhanced AHE arises in the NFL regime that violates the quasiparticle picture. V1/3NbS2 challenges the existing single-particle framework for understanding AHEs based on one-body Berry curvature and highlights the potential of magnetically intercalated TMDs to unveil new electronic functionalities where many-body correlations play a critical role.

Enhancing the activity of γ-hydroxy lactone derivatives as innovative peroxisome proliferator-activated receptor γ non-agonists inhibiting cyclin-dependent kinase 5-mediated phosphorylation

Insulin resistance (IR) is a pathological condition in which tissues exhibit a reduced response to normal or elevated levels of insulin. Type 2 diabetes mellitus (T2DM) and Metabolic Syndrome are the most prevalent disorders associated with IR. Most of the glitazones, traditional anti-diabetic drugs acting as Peroxisome Proliferator-Activated Receptor γ (PPARγ) agonists, have been withdrawn from the market. To mitigate the serious adverse effects associated with PPARγ agonism, a new opportunity is represented by the inhibitors of PPARγ phosphorylation by the Cyclin-Dependent Kinase 5 (CDK5). Their mechanism of action is mediated by the stabilization of the PPARγ β-sheet containing Ser245. Recently, we identified 4-(4-bromophenyl)-3-hydroxy-5-(3-hydroxyphenyl)furan-2(5H)-one (I) as a PPARγ non-agonist, capable of blocking the phosphorylation of the enzyme without direct effects on either CDK5 or PPARγ. Here, we isolated the two enantiomers of I, unambiguously defined their absolute configuration through single crystal X-ray diffraction and demonstrated by Grating-Coupled Interferometry binding assays that both (S)-I and (R)-I exhibited comparable affinity for PPARγ. Then, a library of 12 analogs was designed through structure-based modifications, optimizing the interactions within the ligand-binding domain. GCI analysis identified derivative 11, featuring an oxyacetic group in place of the initial hydroxyl function of the reference compound I, as the most promising candidate (KD = 186 nM). The crystal structure of the PPARγ-LBD/11 complex revealed a hydrogen bond interaction with Arg280, further stabilizing the binding conformation. These findings highlight the potential of γ-hydroxy lactone derivatives as PPARγ modulators and provide a foundation for future drug development targeting IR.

Application of modular isoxazoline-β2,2-amino acid-based peptidomimetics as chemical model systems for studying the tau misfolding

Tau is a microtubule-associated protein essential for regulating microtubule dynamics and axonal transport in neurons. In tauopathies, the transition of tau from a physiological to a pathological form remains unclear, though the hexapeptides PHF6 and PHF6∗ are key in triggering aggregation. These sequences are shielded by a β-hairpin structure in the native state but expose hydrophobic residues during misfolding, promoting self-assembly. This study employs a non-natural β2-amino acid to induce PHF6 and PHF6∗ into either extended or β-hairpin conformations. The extended form triggers tau aggregation without additives, acting as a seed-competent monomer model system. Conversely, the β-hairpin preserves tau in a soluble monomeric state. Additionally, a β-hairpin mimic inspired by Hsp90 showed potential as a chaperone mimic and inhibitor of tau aggregation, offering insights into corrective folding and aggregation modulation in neuronal environments.

Saarvienin A-A Novel Glycopeptide with Potent Activity against Drug-Resistant Bacteria

A member of a new family of glycopeptides, named saarvienin A, was isolated from a rare actinomycete Amycolatopsis sp. YIM10. Extensive NMR and MS analyses revealed a halogenated peptide core comprising four amino acids cyclized via a ureido linkage with an exocyclic 2-hydroxy-3-(4-hydroxyphenyl)propyl residue connected to a five-sugar/aminosugar chain. Two of the three aminosugars constitute the N-methylated and N,O-dimethylated derivatives of eremosamine (4-epi-vancosamine) that have not been reported in any natural product. Saarvienin A exhibits potent activity against a range of Gram-positive bacteria, effectively overcoming resistance to several frontline antibiotics in clinical isolates. It demonstrates an eight-fold reduction in minimum inhibitory concentrations (MICs) against methicillin-resistant, vancomycin-intermediate, and daptomycin-resistant Staphylococcus aureus compared to vancomycin.

4-Substituted Pyridine-3-Sulfonamides as Carbonic Anhydrase Inhibitors Modified by Click Tailing: Synthesis, Activity, and Docking Studies

In the search for new selective inhibitors of human carbonic anhydrase (hCA), particularly the cancer-associated isoforms hCA IX and hCA XII, a series of 4-substituted pyridine-3-sulfonamides was synthesized using the "click" CuAAC reaction, proven by X-ray crystallography, and evaluated for their inhibitory activity against hCA I, hCA II, hCA IX, and hCA XII. Additional molecular docking studies and cytostatic activity assays on three cancer cell lines were conducted. The compounds exhibited a broad range of inhibitory activity, with KI reaching 271 nM for hCA II, 137 nM for hCA IX, and 91 nM for hCA XII. Notably, compound 4 demonstrated up to 5.9-fold selectivity toward the cancer-associated hCA IX over the ubiquitous hCA II, while compound 6 exhibited a remarkable 23.3-fold selectivity between transmembrane isoforms hCA IX and hCA XII. Molecular docking studies have shown the possibility of selective interaction with the hydrophilic or lipophilic half of the active site, what results from the adjacent (3,4) position of the "tail" in relation to the sulfonamide group.

Tunable Dual-emission of Mixed-lanthanide MOFs with no Antenna Effect

Heteronuclear zinc(II):mixed-lanthanide(III) metal organic frameworks (MOFs) bearing the formula [L n x A L n y B ${{{\rm L}{\rm n}}_{{\rm x}}^{{\rm A}}{{\rm L}{\rm n}}_{{\rm y}}^{{\rm B}}}$ Zn3(oda)6(H2O)6]⋅nH2O (Ln = lanthanide(III) ion,L n B ${{{\rm L}{\rm n}}^{{\rm B}}}$ is smaller thanL n A ${{{\rm L}{\rm n}}^{{\rm A}}}$ , x+y=2, n=13 or 14) were obtained by direct reaction of the corresponding metal ion salts and oxydiacetate (-OOC-CH2-O-CH2-COO-) in aqueous solution, followed by slow solvent diffusion. This strategy led to the isolation of thirteen pure crystalline samples of isostructural hexagonal compounds (space group P6/mcc). Characterization by single-crystal X-ray diffraction was complemented by the analytical determination of the finalL n B / L n A ${{{\rm L}{\rm n}}^{{\rm B}}/{{\rm L}{\rm n}}^{{\rm A}}}$ molar ratio by microwave induced plasma atomic emission spectrometry. Results show that the experimentally determinedL n B / L n A ${{{\rm L}{\rm n}}^{{\rm B}}/{{\rm L}{\rm n}}^{{\rm A}}}$ molar ratio is systematically higher than that set out in the synthesis, especially for combinations of Ln that have larger size differences. Dual emission luminescence is observed for the compounds containing a combination of the more efficient visible-emitting Ln (Sm, Eu, Tb, Dy). The selected aliphatic ligand does not promote antenna effect. Thus, tunable color luminescence can be achieved by selectively targeting each Ln preferential excitation wavelength. Dual emission is also observed for CeEu mixed-MOF since the simultaneous excitation of both Ln is possible. Interestingly, GdEu mixed-MOF also shows dual emission when only Gd is directly excited.

Zinc(II)-Enhanced Excimer Probe for Recognition of MDMB-CA Synthetic Cannabinoids

Specific recognition with optical responses towards the analytes which are structurally diverse and weak chemical-active remains a big challenge but is of great significance. Here, a zinc(II) enhanced fluorescent emission probe was developed by conjugated modulating and metal bridging to specifically recognize synthetic cannabinoids (SCs). The transformed luminescence mechanism from excimer emission to fluorescence resonance energy transfer was demonstrated upon the integration of coordination and non-covalent interactions towards target SCs. As a result, the specific and instant detection of the certain type SCs (MDMB-CA series) was achieved in complicated sample medium. Hence, we envisage that this work would not only offer a novel recognition strategy for SCs, but also advance the development of the optical sensing probe especially for analyzing the substances with diverse structures and weak chemical-activity, as well as for fighting against the illicit drugs.