Crystal structure refinement with SHELXL

Discovery of novel 1,2,3-Triazole hybrids derivatives as vasorelaxant agents: Molecular structure, Hirshfeld surface, in-vivo and in-silico investigation by molecular docking simulation

In this study, we have developed a new category of antihypertensive agents using copper-catalysed "click chemistry". This series of six hybrid compounds (HRa-f) consists of quinazoline-(3H)-one-1,2,3-triazole-acetamide derivatives. In order to confirm their structures, they were characterised by a number of techniques including infrared spectroscopy, proton and carbon nuclear magnetic resonance, heteronuclear multiple bond correlation, heteronuclear single quantum coherence and correlation spectroscopy. X-ray diffraction analysis and interactions, including hydrogen bonding which stabilises the crystal lattice, have been studied. Analyses of the Hirshfeld surface mapped to di, de, dnorm and shape index were used to detect intermolecular interactions. The histogram of the fingerprints shows that the H⋯H (48.2 %) and O⋯H (12.6 %) contacts are the dominant interactions in the crystal stacking. The vasorelaxant activity of the synthesised compounds was evaluated using aortic rings from precontracted rats exposed to epinephrine (10 μM). Dose-response studies indicated that the vasorelaxant efficacy varied depending on the structural modifications of the drugs. Molecular docking studies were also performed to predict binding affinity and identify the most likely binding interactions between the hybrid molecules and the calcium channel. Cav 1.2, the alpha-subunit containing key binding sites (EEE locus: GLU 363, GLU 706, GLU 1135, GLU 1464), was compared with the drug verapamil. Docking results confirmed that verapamil (-8.22 kcal/mol) was the most potent compound, followed by the HRa-f compounds.

Effect of stereochemistry at position C20 on the antiproliferative activity and selectivity of N-acylated derivatives of salinomycin

Salinomycin (SAL), a natural polyether ionophore, exhibits a broad spectrum of pharmacological activities, including potent anticancer activity. Over the past decade, much effort has been put into developing methods for rational chemical modification of SAL to obtain semisynthetic analogs with higher anticancer activity than the native structure. In this paper, we describe an optimized procedure for synthesizing C20-aminosalinomycin 2 with native stereochemistry at position C20, which was confirmed by single-crystal X-ray diffraction analysis. We further transformed amine precursor 2 into a series of 48 C20-N-(thio)acylated products, including N-(sulfon)amides, N-(thio)ureas, and N-carbamates (urethanes), along with their sulfur analogs, i.e., S-substituted thiocarbamates and dithiocarbamates. This previously unreported class of derivatives showed superior cytotoxicity mostly in the nano- and subnanomolar concentration range and improved selectivity toward human cancer cells compared to those of chemically unmodified SAL and a commonly used oncological drug cisplatin. Of note, the obtained products inhibited the proliferation of reference cancer cells more effectively than their C20-epi-N-acylated counterparts, pointing out the pivotal role of stereochemistry at position C20. Our findings support the premise that the modification of SAL is a fruitful strategy for products with promising biological activity profiles. Moreover, the straightforward protocols should be of significant value for more elaborate modifications of SAL in the future.

Hyperhelianthemones A-D: Polycyclic polyprenylated benzoylphloroglucinols from Hypericum helianthemoides

Phytochemical investigation of the n-hexane-soluble fraction of the aqueous ethanol extract of the aerial parts of Hypericum helianthemoides (Spach) Boiss. (Hypericaceae), furnished four undescribed polycylic polyprenylated benzoylphloroglucinols (PPBPs) 1-4, together with phytyl formate (5) and thirteen previously reported prenylated phloroglucinol derivatives, including yezo'otogirin C (6), hyperibrins A (7) and F (8), hyperibones G (9), J (10), La (11a)/Lb (11b), 7-epi-clusianone a (12a)/7-epi-clusianone b (12b), and hypermongones A (13), C (14), E (15), G (16), H (17), and sampsonione L (18). The structures of 1-4 were established by extensive 1D and 2D NMR spectral analysis as well as HREI-MS. The absolute configurations of the stereogenic carbons in 1 were established by X-ray crystallographic analysis, while the stereochemistry of 2 was assigned by quantum chemical calculation of its 1H and 13C NMR chemical shift values using DP4+ probability analysis. The isolated compounds were assayed for antileishmanial activity on Leishmania tropica and L. major parasites. Compounds 9 and 16 displayed activities against L. tropica, with IC50 values of 17.7 and 31.5 μM, respectively. Moreover, 9 was only active against L. major, with IC50 value of 34.2 μM.

Chemical modification of monensin as a source of potent antiplasmodial agents

Malaria remains a significant public health issue and one of the leading causes of child mortality worldwide. Due to the growing problem of drug resistance, new modes of fighting the disease are searched for. In this context, ionophore antibiotics, natural compounds with high potential for combating parasitic diseases, deserve special attention. The primary representative of such compounds, monensin (MON), demonstrates exceptionally high antiplasmodial activity. In this work, the C26-amino derivative of MON was used as a convenient substrate for the synthesis of its acyl analogues, such as amides and urea. All derivatives exhibited strong activity against the hepatic stage of Plasmodium berghei infection in vitro, which exceeded that shown by the reference drug primaquine. The IC50 value for MONO-phenyl urethane (8) was less than 1 nM.

Phyllanfranins A-F, anti-inflammatory ent-cleistanthane diterpenoids from Phyllanthus franchetianus

A comprehensive chemical investigation of the EtOAc extract derived from the dried branches and leaves of Phyllanthus franchetianus H. Lév had successfully resulted to the isolation of six undescribed cleistanthane diterpenoids phyllanfranins A-F (1-6), along with three known compounds phyllarheophol C (7), phyacioid C (8), and spruceanol (9). The chemical structures of these compounds were elucidated by combined means of HRESIMS, 1D and 2D NMR spectra, together with ECD calculations. The absolute configuration of phyllanfranin A (1) was established by single crystal X-ray diffraction analysis. Notably, phyllanfranin F (6) represents the first ent-cleistanthane diterpenoid with the unique 6/6/6/6 tetracyclic system occurring in nature. Additionally, all the isolates were evaluated for anti-inflammatory activities. As a result, compounds 4 and 8 showed notable inhibitory activity against NO production in LPS-stimulated macrophages RAW264.7 cells, with IC50 values of 19.03 and 18.14 μM, respectively.

Synthesis, NMR and X-ray characterization of dibenzoannulated dimeric steroid spiroketals. Evaluation of cytotoxicity and anti-inflammatory activity

Two dibenzoannulated dimeric steroid spiroketals were obtained from cholesterol and 1,4-phenylenedimethanol. The key step in synthetic protocol is a Pd-catalyzed double spiroketalization in an adduct obtained from the double Sonogashira coupling of the 5α and 5β diastereomers of 4,5-secocholestan-5-ol. A detailed NMR characterization supported by Single Crystal X-ray Diffraction studies corroborated the obtained structures. While no cytotoxic effect was observed, the obtained compounds produced a significant reduction in the production of nitric oxide in macrophages stimulated with Lipopolysaccharide (LPS), indicating a potential anti-inflammatory activity.

Novel p-terphenyls with anti-neuroinflammatory activity from fruiting bodies of the Chinese edible mushroom Thelephora ganbajun Zang

The detailed mycochemical exploration of the EtOAc extract of a famous edible mushroom Thelephora ganbajun, resulted in the isolation of six new p-terphenyl derivatives, named theleganbanins A - F (1-6), together with five known ones, namely atromentin (7), fendleryl B (8), 2-O-methylatromentin (9), vialinin B (10), and ganbajunin B (11). Their structures were precisely determined through comprehensive spectroscopic analyses, especially 1D and 2D NMR data and HRMS measurement. Single crystal X-ray diffraction and comparison of calculated and experimental ECD spectra were conducted to further confirm the absolute configurations of compounds 1-6. Theleganbanins A (1) and B (2) featuring a rare α, β-unsaturated-γ-butyrolactone core were proposed to be biosynthesized through aldol condensation for the first time in naturally occurring p-terphenyl derivatives. Theleganbanin C (3) was identified as a pair of p-terphenyl enantiomers with a novel 1', 6'-dyhydro-2', 5'-pyridinedione ring. Theleganbanin D (4) was the first example of p-terphenyl derivatives with a hemiacetal furanone moiety. The anti-neuroinflammatory activities of compounds 1-2 and 4-10 were screened. As a result, these compounds showed inhibitory activity on the production of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β in lipopolysaccharide (LPS)-induced BV-2 microglial cells. Further investigation showed that compound 2 could inhibit the phosphorylation of JAK2/STAT3 signaling pathway. These finding indicated that p-terphenyl derivatives from edible mushroom Thelephora ganbajun Zang would be promising drug candidates in treatment of neuroinflammatory related diseases.

Novel flucytosine salt: Structure, Hirshfild surface analysis, morphology, FIMs, and computational studies

5-Flucytosine (FC) exhibits an advanced solid-state structure, which presents challenges for its pharmaceutical development. This paper presents experimental, and theoretical studies of a novel pharmaceutical salt, fluorocytosinium chloride, HFC+.Cl-. Single crystal X-ray diffraction (SCXRD) investigation indicates that HFC+.Cl- forms crystals in the monoclinic system and P21/c space group. The structure is maintained by a series of hydrogen bonding interactions, comprising N-H···Cl, N-H···O, and C-H···F. In addition, noncovalent anion···π interactions between chloride anions and HFC+ cations play a role in establishing a three-dimensional network. Hirshfeld surface analysis (HS) and two-dimensional fingerprinting were used to enumerate the intermolecular interactions within the crystal. The results demonstrate that the H···Cl/Cl···H, O···H/H···O, and F···H/H···F interactions are the most significant. Full Interaction Maps (FIMs) analysis predicts the positions of hydrogen bond acceptors and donors, confirming the supramolecular arrangement observed in HFC+.Cl-. Computational modeling studies using the Bravais-Friedel, Donnay-Harker (BFDH), and Growth Morphology (GM) methods predict the morphology of the HFC+.Cl- crystal. Both approaches estimate a comparable crystal shape characterized by six principal facets. Density functional theory (DFT) calculations were conducted utilizing the DMol3 software to investigate the electronic structure and comprehensive reactivity features of HFC+.Cl-. The low HOMO energy suggests significant stability against electrophilic attacks, while the high HOMO-LUMO band gap indicates high chemical hardness. Fukui functions were also calculated to identify atomic sites susceptible to nucleophilic and electrophilic attacks. This study offers a comprehensive insight into the structural and electronic properties of HFC+.Cl-, offering valuable information for the development of new pharmaceutical compositions.

Biomimics of [FeFe]‑hydrogenases: Diiron aza- versus oxadiphenylpropanedithiolate complexes with mono- versus diphosphines

To extensively devolep the bioinspired chemistry of [FeFe]‑hydrogenases, this study performs an insigt into the selective substitution of all‑carbonyl diiron aza- versus oxadiphenylpropanedithiolate precursors Fe2(μ-Ph2xdt)(CO)6 (Ph2xdt = Ph2odt = (SCHPh)2O for 1 and Ph2adtNH = (SCHPh)2NH for 2) by mono- versus diphosphines P(C6H4R-p)3 (R = Me and Cl) and (Ph2P)2R' (R' = cis-CH=CH- for dppv and -CH2CH2- for dppe). With monophosphines, their monosubstituted diiron Ph2odt complexes Fe2(μ-Ph2odt)(CO)5){κ1-P(C6H4R-p)3} (R = Me for 1a and Cl for 1b) were obtained through the oxidative decarbonylating of 1 at room temperature in MeCN with Me3NO·2H2O; in contrast, analogous diiron Ph2adtNH complexes Fe2(μ-Ph2adtNH)(CO)5){κ1-P(C6H4R-p)3} (R = Me for 2a and Cl for 2b) were afforded via the photolytic decarbonlating of 2 under UV irradiation (365 nm) in toluene. With diphosphines, the dppv-chelated diiron Ph2xdt complexes Fe2(μ-Ph2xdt)(CO)4(κ2-dppv) (Ph2xdt = Ph2odt for 1c and Ph2adtNH for 2c) were prepared from the UV-irradiated decarbonylation of 1 or 2 in toluene; by contrast, the dppe-chelated diiron similar complexes Fe2(μ-Ph2xdt)(CO)4(κ2-dppe) (Ph2xdt = Ph2odt for 1d and Ph2adtNH for 2d) were synthesized from the Me3NO-assisted decarbonylation of 1 in room-temperature MeCN and that of 2 at refluxing toluene, respectively. The elemental analysis, FT-IR and NMR (1H, 31P) spectroscopy are used for the full elucidation of the molecular structures of these new diiron complexes and X-ray crystallography is applied for further confirmation of 1, 2 and 1a, 2b. The electrochemical properties of representative complexes 1, 1a, 1c and 2, 2a, 2c have been explored and compared with and without acetic acid (AcOH).

Redox-driven photoselective self-assembly

Self-assembly via non-covalent interactions is key to constructing complex architectures with advanced functionalities. A noncovalent synthetic chemistry approach, akin to organic chemistry, allows stepwise construction with enhanced control. Here, we explore this by coupling Pt(II) complex self-assembly with a redox reaction. Oxidation to Pt(IV) creates a non-emissive monomer that, upon reduction to Pt(II), forms luminescent gels with unique kinetic and thermodynamic pathways. UV irradiation induces Pt(IV) reduction, generating supramolecular fibers with Pt∙∙∙Pt interactions, enhancing photophysical properties and enabling visible light absorption up to 550 nm. This allows photoselective growth, where fibers convert surrounding Pt(IV) to Pt(II), promoting growth over nucleation, as observed via real-time fluorescence microscopy.

Exploring the energetic potential of 2,5-disubstituted tetrazoles: a case of 2,5-bis(oxadiazolyl)tetrazoles

Exploration of new possible molecular combinations for the preparation of energetic materials remains a challenging task. Herein, the construction of new azole assemblies incorporating the poorly studied 2,5-disubstituted tetrazole motif in combination with oxadiazole moieties is presented. A complete set of experimentally defined properties including thermal stability and mechanical sensitivity, as well as the calculated detonation performance, was evaluated. All target energetic substances have high densities (1.72-1.74 g cm-3) and high combined nitrogen-oxygen content (55-73%). Azo-bridged hexaheterocyclic entities showed high friction sensitivity (on the level of primary explosives), while the introduction of two amino groups improved the sensitivity up to a nitro ester's level, considered as the lowest acceptable level for manufacturing.

Modulation of Optical and Electrochemical Properties of Cu(I) Alkynyl Clusters by Carboxylic Acid Ligands

Surface ligands play a pivotal role in the functional design of atomically precise Cu(I) nanoclusters. They act as protective agents, ensuring the stability of the Cu(I) clusters, while also influencing their structure and properties. This study delves into the synthesis, structure, and properties of innovative Cu(I) nanoclusters co-stabilized by carboxylic acid and alkynyl ligands. The findings reveal that these surface ligands wield a significant impact on the cluster's structure and can even modulate the luminescent characteristics of the Cu(I) alkynyl clusters. Moreover, density-functional theory (DFT) calculations shed light on how different carboxylic acid ligands affect the UV-visible absorptivity of paired Cu(I) clusters. In addition, ferrocene carboxylic acids were employed as protective ligands to impart electrochemical properties to the Cu(I) clusters. This research presents an effective methodology for synthesizing atomically precise Cu(I) clusters shielded by carboxylic acid ligands.

Intramolecular Electron Transfer in Unsymmetric Azohetero-aromatic Radical Bridged Diruthenium(III) Set Up

The article demonstrated the stabilization of MLCT excited state in structurally characterized unsymmetric N,N/N,O- donating azoheteroaromatic radical bridged (acac)2RuIII(μ-L3•-)RuIII(acac)2 (2, S=1/2) [L3= deprotonated 5-(diethylamino)-2-(6-methybenzo[d] thiazol-2-yl)diazenylphenol, acac= electron rich acetylacetonate, N-N(azo) distance: 1.379(4) Å] via intramolecular electron transfer (IET) at the metal-azo interface. On the contrary, similar IET driven stabilization of MLCT excited state was failed to take place in N,N donating HL3 derived mononuclear counterpart (acac)2RuII(HL3) (1, S=0) with unperturbed azo function (N=N distance: 1.3361(18) Å) in spite of the fact of facile RuII/RuIII oxidation (0.28 V versus SCE) and azo reduction (-1.05 V versus SCE), presumably due to the influence of hydrogen bonding interaction at the back face of coordinated HL3. On the other hand, the use of electron poor bpy (2,2'-bipyridine) as a co-ligand facilitated exclusive generation of the mononuclear [(bpy)2RuIIL3]ClO4 ([3]ClO4, S=0) encompassing N,O--donating L3 with neutral azo group (N=N distance: 1.317(6) Å), unlike N,N donating HL3 in 1 due to the impact of σ-donating acac versus π-accepting bpy, which also devoided of IET step. DFT calculations further suggested the origin of multiple redox steps and absorption profiles of 1, 2, 3+.

Low-/High-Spin Cobaltaboratranes Stabilized by Cis-/Trans-Isomeric Bisphosphines

Electronic spin isomerism in low-valent cobalt complexes can potentially be achieved through the rational design of ligand fields, but such instances have rarely been reported up to now. Herein, we crystallized two cobaltaboratrane complexes featuring CoI → B dative covalent bonds by leveraging the rigidity of the C═C bond from cis-/trans-isomeric bisphosphine ligands. The CoI cores in CoIB-cis/CoIB-trans are stabilized in six- and five-coordinate octahedral and trigonal bipyramidal geometries, respectively, resulting in low- and high-spin ground states, as demonstrated by magnetic measurements. Ab initio ligand field analysis revealed that both the ligand field and the CoI → B dative bond play crucial roles in the disparities in the energies of the d orbitals and their spin configurations.

Circularly Polarized Luminescence From Spontaneous Symmetry Breaking in a Bimetallic Eu-Al Complex

The emergence of optically active functional compounds through spontaneous chiral symmetry breaking is a rare but intriguing phenomenon with relevance of both practical and fundamental interest. Here we show that a racemic Eu-Al compound, bearing only non-chiral ligands, forms a conglomerate upon crystallization. Single crystals of the compound are electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) active. Moreover, we found that a significant enantiomeric excess (50%) of either enantiomer is present in each crystallization batch (non-racemic conglomerate). Such spontaneous symmetry breaking leads not only to optically active single enantiomorph crystals but to an overall solid bulk with significant ECD and CPL.

Halogen Bond-Driven Ligand Displacement: Co-Crystal Lattice Versus Coordination Bonds

Coordination bonds are generally stronger than halogen bonds; however, the Jahn-Teller effect in d⁹ Cu(II) and the trans influence of the oxo-ligand in vanadyl (V═O) acetylacetonates can weaken N→Cu/V bonds, bringing them closer to the upper range of halogen bond strength. The study investigates the interactions between transition metal acetylacetonate complexes, M(acac)2(L) (M─Cu(II), V(IV) = O; L = amine ligands), and halogen bond (XB)-donor co-formers, particularly 1,4-diiodotetrafluorobenzene (1,4-DITFB). The co-crystallization experiments reveal an unusual ligand displacement phenomenon wherein the expected M(acac)2(L)·1,4-DITFB complexes fail to form, instead yielding separate M(acac)2·1,4-DITFB and L·1,4-DITFB co-crystals. Computational studies reveal that while XB interactions alone may be insufficient to disrupt the M─N coordination bond, they can induce ligand displacement when amplified by the lattice stabilization of the resulting halogen-bonded co-crystals, particularly in Jahn-Teller distorted d⁹ Cu(II) and trans-influenced V(IV) = O complexes interacting with halogen bond donors.

Oxidation-Deformylation Cascade Catalyzed By a Mononuclear Copper Complex

In this study, two copper complexes were synthesized using N3 (arising from two pyridines and one amide group) containing ligands N-(2-picolyl)picolinamide (L1H) and bis(2-pyridylcarbonyl)amine (L2H), forming [(L1)CuII(OH2)(NO3)] (1) and [(L2)CuII(OH2)2](NO3) (2). The reaction of complex 1 with hydrogen peroxide in alcoholic solvents yielded a formate-bound complex. Studies with isotopically labeled 13C ethanol indicated that formate originates from the C1 of ethanol after C-C bond cleavage. Complex 1 was found to catalytically convert primary alcohols into formic acid probably following a two-step process: (i) alcohol oxidation to aldehyde and (ii) aldehyde deformylation. Further experiments with 2-phenylpropionaldehyde (2-PPA) confirm the ability of complex 1 to catalyze aldehyde deformylation. Both steps of the reaction are associated with significant kinetic deuterium isotope effects (KDIE), suggesting that hydrogen atom abstractions (HAA) occur during the rate-determining steps of both conversions. Overall, this system proposes a clean catalytic process for alcohol-to-formic acid conversion, operating under mild conditions, and offering potential synthetic applications.

Thermoresponsive Behaviors of Poly(N-methacryloyl glycinamide) and Poly(N-acryloyl glycinamide): Effect of Methacrylation

Poly(N-acryloyl glycinamide) (PNAGA) proves to be an interesting and useful polymer with an upper critical solution temperature (UCST) behavior in water due to intra- and intermolecular hydrogen bonding. Its methacrylamide counterpart, poly(N-methylacryloyl glycinamide) (PNMAGA), has a different UCST behavior, which is easier to dissolve in water. In this work, PNMAGA and PNAGA were synthesized by RAFT polymerization and free radical polymerization, and their solution properties in dilute aqueous media have been studied and compared in detail to elucidate the effects of temperature, polymer concentration, molecular weight, and chain end. The direct comparison provides a better understanding of the UCST behaviors. The presence of an extra methyl group on the repeating unit helps the polymer to dissolve better and eliminates the need for special thermal treatment to obtain a complete dissolution. Infrared spectroscopy and X-ray diffraction analysis show variation in hydrogen bonds between the two polymers and their respective monomers, providing insights into the structural origin of their different solution properties.

An Anthracene Derivative with a Highly Vertical Molecular Orientation

Controlling the orientation of the transition dipole moment (TDM) is very important in the field of optoelectronics. In particular, the horizontal orientation of emissive TDMs in organic materials has been extensively studied because it can improve the out-coupling efficiency of organic light-emitting diodes (OLEDs). Conversely, the vertical orientation of emissive TDMs remains virtually unexplored. Using angle-dependent photoluminescence measurements, we discovered that 9,10-bis(3,5-dimethoxyphenyl) anthracene (DMA) shows an extremely high vertical emissive TDM orientation (ΘV) of 82% in an evaporated neat film. To the best of our knowledge, this is the highest value reported so far for organic molecules. To investigate the origin of the high ΘV value, we conducted two-dimensional grazing-incidence wide-angle X-ray scattering measurements (2D GIWAXS) on a DMA film and observed distinct periodic peaks in the out-of-plane direction. By combination of these measurements with single-crystal X-ray diffraction analysis, the periodic peaks were identified as lamellar structures in which DMA molecules are stacked with their long molecular axes oriented vertically on a quartz substrate. Moreover, by virtue of the exceptionally high vertical TDM orientation, the DMA film exhibits highly polarized emission from the substrate edge. We also investigated the TDM orientation of other 9,10-diphenylanthracene derivatives and observed random or horizontal TDM orientations in all cases, which highlights the uniqueness of the vertical orientation of DMA.

Advantages of Novel Anti-cancer Selenosemicarbazones: Preferential Reactivity of Their Fe(III), Cu(II), and Zn(II) Complexes with Key Physiological Reductants/Ligands Versus Isosteric Thiosemicarbazones

Fe(III) complexes of clinically trialed thiosemicarbazones demonstrate deleterious oxy-myoglobin and oxy-hemoglobin oxidation. Therefore, the PPP4pSe selenosemicarbazone analogues were designed with several PPP4pSe Fe(III) complexes completely preventing deleterious oxy-myoglobin oxidation. This was ascribed to the decreased potentials of their Fe(III) complexes and steric hindrance effects. The Fe(III), Cu(II), and Zn(II) complexes of PPP4pSe demonstrated greater reactivity with physiological reductants/ligands (glutathione, l-cysteine, or l-ascorbate), than respective complexes of the isosteric thiosemicarbazone, PPP4pT. Considering this: (1) [Fe(PPP4pSe)2]+ demonstrated increased reduction relative to [Fe(PPP4pT)2]+ with glutathione and l-cysteine, while l-ascorbate led to comparable reduction; (2) glutathione led to complete dissociation of [Zn(PPP4pSe)2], while incomplete dissociation of [Zn(PPP4pT)2] occurred; and (3) [Cu(PPP4pSe)Cl] demonstrated complete coordinate sphere substitution with glutathione, l-cysteine, and l-ascorbate, whereas [Cu(PPP4pT)Cl] demonstrated partial substitution. The role of glutathione in all three latter reactions is significant, given the greater reactivity of the selenosemicarbazone, and glutathione's key role in selenosemicarbazone and thiosemicarbazone anticancer activity.

Diverse redox-mediated transformations to realize the para-quinoid, σ-bond, and ortho-diphenoquinoid forms

π-Electron systems with multiple redox-active units have attracted attention in various fields due to their potential applications. However, the design strategy remains elusive to selectively synthesize the diverse molecular structures of redox-convertible species. In this study, covalently linked quinodimethane derivatives with a sulfur bridge [(Ar4QD)2S] were designed as redox-active motifs that can be converted into three different geometries via redox reaction. Here we show that the favored geometry of the corresponding redox states of (Ar4QD)2S can be precisely controlled by adjusting the steric bulk of the substituents on the aryl group to change the proximity of the quinodimethane units. Notably, this redox-mediated strategy also leads to the isolation and structural determination of the missing link with an o-diphenoquinoid structure, a diphenoquinoid isomer whose isolation had remained elusive for almost a century. Thus, this study provides a method that allows the modulation/control of electronically and/or thermodynamically stable structures, as well as their electronic and spectroscopic properties.

Synthesis and characterization of a novel copper carboxylate complex and a copper complex-coated polyether sulfone membrane for the efficient degradation of methylene blue dye under UV irradiation: single crystal X-ray structure of the copper carboxylate complex

This study presents the synthesis of a novel binuclear Cu(II) carboxylate complex under ambient laboratory conditions. The complex possesses a paddle wheel structure in which the axial positions are occupied by bromide/nitrate ligands. The synthesized complex was characterized using single-crystal X-ray crystallography, FT-IR, X-ray diffraction, and UV-Visible spectroscopic techniques. The thermal stability of the metal complex was studied through thermogravimetric analysis. The synthesized metal complex was employed for the synthesis of metal complex-coated polyether sulfone (PES) membranes, which were characterized before and after filtration using the FESEM technique. The photocatalytic efficiency of the metal complex for the degradation of methylene blue dye under UV irradiation in the presence of H2O2was studied and compared with the photodegradation efficiency of the metal complex-coated polyether sulfone (PES) membrane.

Zero- to One-Dimensional Transformation in a Highly Porous Metal-Organic Framework to Enhance Physicochemical Properties

The dynamic behaviors of metal-organic frameworks (MOFs) continue to expand the accessible architectures and properties within this material class. However, the dynamic behaviors that can be studied in MOFs are limited to the transitions, preserving their high crystallinity. For this reason, their significant structural changes involving coordination bond breakage and rearrangement remain largely underexplored. Herein, we report a three-step single-crystal-to-single-crystal (SCSC) phase transition in a new cerium-based MOF, HKU-9 [Ce2PET(DMF)2(H2O)2], transforming zero-dimensional (0D) secondary building units (SBUs) into one-dimensional (1D) chain SBUs in HKU-90 [Ce2(μ-H2O)PET(H2O)2]. Single-crystal X-ray diffraction studies unambiguously delineate the structural evolution at each stage of this multistep transition, revealing multiple coordination bond dissociations/associations and a significant lattice contraction─all while preserving single-crystal integrity. This dimensional transformation endows HKU-90 with enhanced chemical stability (pH 1-10) and a record-high Brunauer-Emmett-Teller (BET) surface area of 2660 m2 g-1 among reported Ce-based MOFs. Further, HKU-90 exhibits exceptional gas sorption performance, with one of the highest reported C2H2 storage capacities (184 cc g-1 at 273 K, 1 bar) and outstanding C2H2/CO2 selectivity (2.16) under these conditions. Notably, the formation of 1D chain SBUs, a structural motif found in many high-performance MOFs, highlights the potential of using the solid-state fusion of multinuclear metal clusters to tailor the properties of the framework.

Dual magnetic behavior of an Fe(III)-dioxolene complex with tri-substituted catechol

Magnetically bistable compounds attract considerable attention due to their possible applications in molecular electronics and spintronics devices. Of special interest are spin-crossover (SCO) systems that can interconvert between the low-spin and high-spin states leading to switching of the magnetic properties. Synthesis and comprehensive characterization of a family of ionic ferric-dioxolene complexes [(TPA)Fe(HO-DBCat)]ClO4 (1), [(TPA)Fe(NO2-DBCat)]ClO4 (2) and [(TPA)Fe(MeOCH2-DBCat)]ClO4 (3) (TPA = tris(2-pyridylmethyl)amine; HO-DBCat = dianion of 4,6-di-tert-butyl-1,2,3-trihydroxybenzene, NO2-DBCat = dianion of 4,6-di-tert-butyl-3-nitro-1,2-dihydroxybenzene and MeOCH2-DBCat = dianion of 4,6-di-tert-butyl-3-methoxymethyl-1,2-dihydroxybenzene) are reported. Variable temperature structural, magnetic and spectral analyses revealed that compounds 1-3 undergo a thermally induced SCO in the solid state between the high-spin (S = 5/2) and low-spin (S = 1/2) states. Alternating current magnetic susceptibility measurements indicated that the nitro-substituted complex 2 shows a field supported slow magnetic relaxation in the low-spin state at 5000 Oe. Such duality of magnetic properties makes complex 2 the first ferric compound which demonstrates a complete S = 5/2 → S = 1/2 SCO with a single molecule magnet behavior (SMM, S = 1/2). Electronic structures and magnetic properties of 1, 2 and 3 were investigated with the aid of DFT and SA-CASSCF/NEVPT2 calculations.

Tungsten oxide as a universal source for the synthesis of complexes with different nuclearities in WO3/chalcogen/NaCN systems

Tungsten trioxide can be used as a readily available source in the one-step preparation of a variety of cyanide and chalcocyanide mononuclear and cluster complexes of tungsten. In our study of phase formation in the system 6WO3 + 8Q + 32NaCN (Q = S, Se or Te) in the temperature range of 250-700 °C, we determined which soluble complex compounds are formed, the temperature limits of their existence and the influence of synthesis time on the composition of the products. As the temperature increases, the process begins with the formation of mononuclear and then cluster complexes and ends with the formation of tungsten dichalcogenides: [W(CN)8]4- → [WS4]2-/[WS3O]2- → [{W3Q4}(CN)9]5- (Q = S or Se), [{W3S3O}(CN)9]5- → [{W4Q4}(CN)12]6- (Q = S, Se or Te) → WQ2 (Q = S or Se). Depending on the synthesis conditions, these complexes can either coexist in a mixture or one of them becomes the main product of the reaction. The obtained trinuclear and tetranuclear cluster complexes were studied by 13C, 77Se and 183W NMR spectroscopy using DFT calculations to assign the spectral signals. The crystal structures of the salts Cs5Na3[W(CN)8]2·2H2O (1), Cs2.8Na2.2[{W3S4}(CN)9]·2.2H2O (2), Cs5[{W3S3O}(CN)9]·2H2O·0.5CsCl (3) and Cs3.5Na1.5[{W3Se4}(CN)9]·6.5H2O (4) were determined by single-crystal X-ray diffraction analysis. It was also revealed that the quantitative ratio of trinuclear complexes [{W3S3O}(CN)9]5- and [{W3S4}(CN)9]5- with different cluster core compositions formed in the 6WO3 + 8S + 32NaCN system at 300 °C depends on the synthesis time. Dynamics of the observed transformation of the initially dominant complex with a heteroleptic cluster core {W3(μ3-S)(μ-S)2μ-O} into the complex with a homoleptic core {W3(μ3-S)(μ-S)3} was studied using 13C NMR spectroscopy.

Different mechanisms for lanthanide(III) sensitization and Yb-field-induced single-molecule magnet behaviour in a series of pentagonal bipyramidal and octahedral lanthanide complexes with axial phosphine oxide ligands

Seven mononuclear lanthanide complexes have been isolated and structurally characterised. Four of them are cationic, whose charges are balanced by chloride counteranions, and exhibit pentagonal bipyramidal coordination geometry, whereas the rest of them are neutral and display octahedral coordination environment. In all cases, the coordination sphere of the LnIII ions consists of two di(1-adamantyl)benzylphosphine oxide ligands in axial positions, whereas in the equatorial plane the former contains a chloride and four water molecules and the latter a solvent molecule and three chloride ligands. We report a detailed photophysical investigation, including time-dependent density functional theory (TD-DFT) calculations and intramolecular energy transfer (IET) analysis, which reveals two distinct lanthanide sensitization mechanisms. Compound-specific energy transfer pathways occur through either the S1 or T1 states, as supported by calculated IET rates and resonance with lanthanide acceptor transitions. In addition, dc and ac magnetic properties were measured on complexes 1 and 2, showing that compound 1 behaves as a bi-functional compound, exhibiting field-induced single molecule magnet behaviour together with YbIII-centred NIR luminescence. The relaxation of the magnetization in this pentagonal bipyramidal complex takes place through Raman and direct processes, as supported by ab initio calculations.

Highly tenebrescent hackmanites from natural nepheline

Photochromic hackmanites, (Na,K)8Al6Si6O24(Cl,S)2, were synthesized with a solid state reaction route using natural nepheline, (Na,K)AlSiO4, as a starting material together with NaCl, KCl and Na2SO4. The hackmanite was obtained using NaCl, whereas with KCl the nepheline reacted only partially. In particular, materials synthesized with NaCl showed a deep photochromic color under UV irradiation and good sensitivity to even low solar UV index values. This suggests that the material is well suited for personal solar UV exposure monitoring.

Chemical and Electrochemical Investigation of the Oxidation of a Highly Reduced Fe6C Iron Carbide Carbonyl Cluster: A Synthetic Route to Heteroleptic Fe6C and Fe5C Clusters

A chemical and electrochemical investigation of the redox chemistry of [Fe6C(CO)15]4- is reported and supported by computational studies. Depending on the experimental conditions, the original Fe6C cage is retained or partially degraded to Fe5C. Chemical oxidation of [Fe6C(CO)15]4- with [Cp2Fe][PF6], [C7H7][BF4], or Me3NO affords the previously reported [Fe6C(CO)16]2-, whereas oxidation in the presence of a base (Na2CO3 or NaOH) results in the new carbonate-carbide cluster [Fe6C(CO)14(CO3)]4-. Oxidation of [Fe6C(CO)15]4- in the presence of a phosphine ligand produces the heteroleptic species [Fe6C(CO)15(PTA)]2- and [Fe5C(CO)13(PPh3)]2-. Reaction of [Fe6C(CO)15]4- with alkylating or acylating agents (MeI, CF3SO3Me, and MeCOCl) affords the acetyl-carbide cluster [Fe5C(CO)13(COMe)]3-, with partial oxidative degradation of the original Fe6C cage. The new clusters have been spectroscopically and structurally characterized. The redox chemistry of [Fe6C(CO)15]4- was further investigated by electrochemical and spectroelectrochemical methods. According to computational outcomes, the spectroelectrochemical oxidation of [Fe6C(CO)15]4- follows an EEC mechanism, leading to the formation of [Fe6C(CO)16]2-. The [Fe6C(CO)15]3- intermediate can accumulate and be spectroscopically detected. These new chemical and electrochemical findings have been supported and corroborated by computational methods. DFT calculations suggest an EEC pathway also for the reverse electrochemical process, i.e., reduction of [Fe6C(CO)16]2- to [Fe6C(CO)15]4-.

Crystal Structure and Low-Dimensional Magnetism in CsNiV2O6Cl

Single crystals of CsNiV2O6Cl were grown hydrothermally. Its crystal structure (space group I2̅/a) is based on vertex-sharing twisted chains of Ni2+O4Cl2 octahedra and edge-sharing chains of V5+O5 tetragonal pyramids. These chains running along the c- and a-axes, respectively, link, forming an open framework with Cs ions in the voids. At elevated temperatures, the temperature dependence of dc magnetic susceptibility evidences a Haldane-type behavior with estimated intrachain exchange interaction J = 267 ± 16.5 K followed by the strong upturn at lower temperatures. Both dc and ac magnetic susceptibilities exhibit a sharp peak at low temperatures; the latter is independent of frequency. The position of the peak in Fisher's specific heat d(χT)/dT coincides with that in specific heat Cp, which defines the Neel temperature TN = 5.6 ± 0.2 K. While the values of the calculated interchain exchange interaction J' and single-ion anisotropy D place this system into the Haldane sector of the Sakai-Takahashi phase diagram, the long-range antiferromagnetic order at low temperatures is induced by the defects/impurities.

Facile synthesis of acridine-based nickel(II) complexes via metal-mediated rearrangement of diphenylamine derivative and application in H2 evolution reaction

In this study, the formation of acridine-based metal complexes from rearrangement of diphenylamine-2,2'-dicarboxaldehyde (2,2'-dpadc) in the presence of transition metal ions was investigated. As a result, two novel isomorphic nickel(II) complexes bearing acridine-based Schiff-base ligand [NiLACR](X)2·CH3CN (X = BF4 (1), ClO4 (2), LACR = (E)-N1-(2-((acridin-4-ylmethylene)amino)ethyl)-N1-(2-aminoethyl)ethane-1,2-diamine) were successfully synthesized via a one-pot condensation of 2,2'-dpadc and tris(2-aminoethyl)amine (TREN) with a satisfactory yield of approximately 60%. These complexes were fully characterized by X-ray crystallography, UV-vis spectroscopy and CHN elemental analysis. Additionally, their thermal stability (thermogravimetric analysis) and electrochemical properties were also determined. A plausible mechanism for the nickel(II)-mediated rearrangement of 2,2'-dpadc to form the acridine-based nickel(II) complex was proposed. To demonstrate their potential applications, complex 1 was explored in the realm of electrocatalysis. It exhibited moderate activity towards hydrogen evolution reaction (HER). During 1-h controlled-potential electrolysis (CPE) experiments, H2 production (16 micromole) was observed with faradaic efficiency of 40% when the reaction was conducted in a TBAPF6/DMF solution at -2.1 V vs. Fc/Fc+ in the presence of acetic acid as a proton source. The facile synthesis of these acridine-based nickel(II) complexes reported herein may stimulate further development of novel acridine-based ligands and their corresponding metal complexes for a wide range of applications.

A Study on the [3+2] Cycloaddition Reaction of Square Planar Ni(II) Azido Complexes: Structure, Properties, and Catalytic Applications of the Products

Two square planar Ni(II) azido complexes [Ni(N3)(L1)] and [Ni(N3)(L2)] (where L1 = N-phenyl-2-(pyridin-2-ylmethylene)hydrazine-1-carbothioamide; L2 = (E)-1-(((2-(diethylamino)ethyl)imino)methyl)naphthalen-2-olato) were used to study the effect of auxiliary ligands on the [3+2] cycloaddition reactions with different dipolarophiles. The reactivity of the complex [Ni(N3)(L1)] was greater than that of the complex [Ni(N3)(L2)]. [Ni(N3)(L1)] gives an N2-triazolato product with an electron-deficient alkyne R1─C≡C─R2 with R1 = R2 = COOCH3, COOEt, or R1 = CF3, R2 = COOEt while [Ni(N3)(L2)] gives a homobimetallic bis(μ-NN'-triazolato) bridged product only with F3C─C≡C─COOEt. The complex [Ni(N3)(L2)] reacts with dialkyl acetylene-dicarboxylate alkyne, yielding N1-triazolato products under strictly anhydrous conditions, whereas the same reaction under ambient conditions yielded a new unexpected octahedral complex in which the alkyne is converted into a novel O, O donor bidentate ligand. The nature of the predominant triazolato isomer (N1/N2) was experimentally confirmed by single-crystal X-ray diffraction analysis and also verified by DFT calculations. [Ni(N3)(L1)] gives a homobimetallic bis(μ-tetrazolato) bridged product by the [3+2] cycloaddition reaction of 2-cyanopyridine and 2-cyanopyrimidine. [Ni(N3)(L1)] also underwent a 1,3-dipolar cycloaddition with phenyl isothiocyanate at room temperature, giving the corresponding tetrazolato-thione complex, while the same reaction with [Ni(N3)(L2)] does not proceed. Both complexes give Ni(II) isothiocyanate complexes by the reaction of carbon disulfide. The catalytic activities of all the Ni(II) complexes were evaluated for the synthesis of 2-amino-3-cyano-4H-pyran derivatives. [Ni(triazolateCOOMe,COOMe-N2)(L1)] (complex 3) emerged as a highly efficient catalyst, demonstrating performance significantly superior to previously reported catalysts at room temperature. 0.0001 mol % catalyst loading is sufficient to obtain the product, and the highest turnover number (680000) and turnover frequency (34000 min-1) were achieved.

Expanding the Toolbox: Synthesis of Zintl Salts Containing Anions of the In/Sb and Tl/Sb Elemental Combinations

Binary Zintl anions comprising atoms of two p-block elements, and ternary Zintl clusters, in which the latter are combined with d-/f-block metal ions, are being studied with great activity. However, although an impressive variety of elemental compositions have been realized, some combinations of the p-block (semi)metals are lacking in corresponding substructures. The In/Sb combination is extremely rare, and Tl/Sb has not yet been realized at all, although the existence of pseudo-tetrahedral species, for instance, was predicted by quantum chemical studies. Extraction of the novel ternary phase K6InSb3 and of K6Tl2Sb3 with ethane-1,2-diamine (en) yielded binary Zintl anions of these elemental combinations as salts comprising pseudo-tetrahedral anions (InSb3)2- and (TlSb3)2- or nine-vertex cages (In4Sb5)3- and (Tl4Sb5)3-, respectively. To establish efficient synthesis routes, the extractions were monitored using electrospray-ionization mass spectrometry and fractionated crystallization. We thereby isolated salts of two further anions that might represent intermediates on the way to larger species, namely, a novel salt of the Sb73- anion, and a salt of the new binary anion (TlSb7)2-. We describe the experimental approach, the process of its optimization, the geometric structures of the new compounds as well as their electronic structures that were established by DFT calculations.

pH-Dependent Structural Engineering of Sulfonate-Carboxylate Cu-MOFs for High Proton Conductivity

Metal-organic frameworks (MOFs) with free carboxylic acid (COOH) groups are promising for solid-state proton-conducting materials, owing to the Brønsted acidity, polarity, and the hydrogen-bonding ability of COOH groups. In this work, two Cu-MOFs with different dimensions were synthesized by adjusting the pH of the reaction solution using disodium-2,2'-disulfonate-4,4'-oxidibenzoic acid (Na2H2DSOA) and 4,4'-bipyridine (4,4'-bpy) as ligands to coordinate with Cu(II). The resulting compounds, CuDSOA-1 (([Cu(4,4'-bpy)2(H2O)2][Cu(H2DSOA)2(4,4'-bpy)(H2O)2]·12H2O)) and CuDSOA-2 ([Cu2(DSOA)(4,4'-bpy)2(H2O)2]·4H2O), have distinct dimensionalities and structures, mainly due to the pH's effect on carboxylic acid deprotonation. Notably, CuDSOA-1 with abundant COOH groups, uncoordinated sulfonate groups, and water molecules shows a significantly enhanced proton conductivity of 2.46 × 10-2 S cm-1 at 95 °C and 98% RH, surpassing CuDSOA-2 (3.40 × 10-5 S cm-1 at 85 °C and 98% RH). The conductivity mechanism was found to be a Grotthuss mechanism, confirmed by deuterium-hydrogen isotopic effects. This study offers a method to control the coordination of sulfonic-carboxylic acid ligands with Cu(II) by pH adjustment, aiming to create MOFs with ultrahigh proton conductivity.

Mechanistic Insight into Water Oxidation Catalysis by a Mononuclear Ruthenium Complex

A reaction mechanism of water oxidation involving a mononuclear RuIV-oxo complex (1) as an intermediate with use of (NH4)2[CeIV(NO3)6] (CAN) as an oxidant has been scrutinized to provide a clear view of O-O bond formation and O2 release. This work includes the spectroscopic and theoretical characterization of an end-on RuIII-superoxo complex (3), together with the crystallographic characterization of a side-on RuIV-peroxo complex (4) which should be in equilibrium with 3 in an aqueous solution. The formation of the RuV-oxo intermediate as a responsible species for the water oxidation was supported by a square wave voltammogram of 1 in an aqueous solution, showing an oxidation wave at +1.52 V (vs NHE) which is accessible with use of excess CAN through an electron-transfer equilibrium. Kinetic analysis and isotope labeling experiments supported a water nucleophilic attack (WNA) mechanism in the water oxidation. The stability of 3 as a product of WNA allowed us to detect it in aqueous solution. The diamagnetic character of 3 enabled the detailed kinetic investigation of O2-releasing from the intermediate to determine activation parameters. Herein, a new insight was gained into the O2 release from 3 as the final step of water oxidation by the mononuclear Ru catalyst.

Broad Orange Emission from Piperazine-Based Layered Halide Perovskites

The excellent optoelectronic properties of layered halide perovskites make them ideal for devices such as solar cells, light-emitting diodes, and photodetectors. In this study, we report five two-dimensional (2D) halide perovskites: (C6H14N2)PbBr4, (C8H18N2)PbBr4·H2O, (C6H14N2)PbI4, 1-(C8H18N2)PbI4, and 2-(C8H18N2)PbI4, (C6H14N2 = N-Ethylpiperazine, C8H18N2 = 1-Butylpiperazine). The optical band gaps of these compounds range from 2.63 to 3.35 eV. (C6H14N2)PbBr4 exhibits broad orange emission with a peak at 624 nm, a full width at half-maximum (fwhm) of 246.8 nm, and a Stokes shift of 237 nm. In contrast, (C8H18N2)PbBr4·H2O shows a peak at 640 nm, fwhm of 262.8 nm, and a larger Stokes shift of 286 nm, attributed to exciton self-trapping induced by strong electron-phonon coupling and structural distortions. This significant Stokes shift is a notable feature of 2D materials. Our findings expand the database of layered halide perovskites, providing valuable insights for the development of next-generation optoelectronic technologies.

Gold Acyclic Diaminocarbene Complexes as Selective and Potent Agents for Multitarget Cancer Therapy

Gold acyclic diaminocarbene (ADC) complexes represent a promising, yet underexplored, class of chemotherapeutics. ADCs offer superior flexibility and stronger sigma donation compared with traditional N-heterocyclic carbenes, making them ideal ligands for stable gold-based drugs. In this study, a series of gold ADC complexes were synthesized via the nucleophilic addition of amines to [AuCl(CNCy)], yielding three structural families: gold-chloride-ADC (chiral and achiral), bis(carbene), and thiolate-gold-ADC complexes. Extensive characterization, including X-ray diffraction, revealed noncovalent interactions, such as hydrogen bonding and aurophilic contacts, that significantly shape their molecular architecture. These complexes exhibit potent cytotoxicity (IC50 in submicromolar) against drug-resistant cancer cell lines (A549, HCT116 WT, Jurkat, MiaPaca2), with some showing high selectivity toward cancer cells over healthy lymphocytes (selectivity index up to 74). Mechanistic investigations indicate that they disrupt mitochondrial function, elevate reactive oxygen species (ROS), and, in the case of bis(carbene) species, bind DNA. Apoptosis is induced at low concentrations, while higher doses trigger alternative death pathways. Notably, they also strongly inhibit thioredoxin reductase (TrxR), comparable in potency to auranofin. The combination of ROS induction, DNA interaction, mitochondrial disruption, and TrxR inhibition highlights the multitargeted anticancer potential of gold-ADC complexes and supports their further development as selective and effective chemotherapeutic agents.

Ferroelectricity, Piezoelectricity, and Unprecedented Starry Ferroelastic Patterns in Organic-Inorganic (CH3C(NH2)2)3[Sb2X9] (X = Cl/Br/I) Hybrids

In this study, we present a novel class of lead-free hybrid antimony halides incorporating the acetamidinium cation, with the chemical compositions: (CH3C(NH2)2)3[Sb2Cl9] (ACA), (CH3C(NH2)2)3[Sb2Br9] (ABA), and (CH3C(NH2)2)3[Sb2I9] (AIA) . Despite their seemingly analogous chemical formulations, these compounds exhibit diverse physical characteristics, predominantly dictated by the differences in their metal-halide architectures. Indeed, the anionic frameworks of ACA and AIA are reminiscent of well-known ferroelectric materials, with ACA distinguished by its piezoelectric and ferroelastic characteristics, underpinned by a buckled honeycomb two-dimensional (2D) layers of antimony chloride. Conversely, AIA is characterized by its ferroelectric attribute, with discrete bioctahedral units forming a zero-dimensional (0D) structure. A surprising structural deviation constitutes the anionic sublattice of ABA, which amalgamates features from both ACA and AIA, yielding an unprecedented hybrid two-component (0D + 2D) anionic architecture. The ferroelectric properties of AIA have been demonstrated through pyroelectric current measurements and hysteresis loop analyses. Additionally, the noncentrosymmetric nature of ACA and AIA has been corroborated by second harmonic generation experiments. The piezoelectricity of ACA was confirmed using piezoresponse force microscopy (PFM). Furthermore, observations under a polarizing microscope revealed distinct ferroelastic properties in both ACA and ABA, characterized by well-defined and abundant star patterns previously observed only in simple oxides and alloys.

Novel Sulfonamide-Sydnone Hybrids: Complementary Insight into Anti-Inflammatory Action, Anti-SARS-CoV-2 Activity, Human Serum Albumin Interaction, and in silico Analysis

Acute lung injury (ALI) is a severe condition often seen in intensive care unit patients. Due to limited treatment options, ALI is linked to high rates of mortality and morbidity. Bacterial and viral infections are significant contributors to ALI. For instance, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can lead to a strong inflammatory response that may progress to ALI, a leading cause of death in COVID-19 cases. Prior research has demonstrated that sulfonamides and sydnones exhibit anti-inflammatory and antiviral properties, which has led us to develop compounds containing both scaffolds. Most of the new sulfonamide-sydnone hybrids are expected to be orally bioavailable based on in silico ADME predictions. They effectively suppressed the development of ALI in lipopolysaccharide (LPS)-challenged mice and inhibited viral replication in Calu-3 cells, with minimal cytotoxicity in non-infected Calu-3 and Vero E6 cells. Molecular docking investigations indicated some possible viral targets for the action of the sydnones, highlighting the possible interaction with non-structural proteins of SARS-CoV-2. Additionally, combined experimental and theoretical studies indicated that the new compounds can strongly interact with human serum albumin, suggesting a possible extended residence time in the human bloodstream.

Bis-alkynylphosphine Oxide Pt(II) Complexes: Aggregation-Induced Phosphorescence Enhancement and Mechanochromic Luminescence Properties

Four bis-alkynyl Pt(II) complexes [Pt(dtbpy)(C2-L-P(O)Ph2)2] with dtbpy = 4,4'-ditertbutyl-2,2'-bipyridine and alkynylphosphine oxide ligands (L = no linker, Pt0; phenyl, Pt1; biphenyl, Pt2; naphthyl, Pt3) have been synthesized and fully characterized by spectroscopic methods and single crystal XRD analysis. It has been found that the nature of the π-conjugated linker is a key factor in fine-tuning the emission energy of the complexes in solution and in achieving the aggregation-induced phosphorescence enhancement (AIPE) effect for complex Pt0 with the most compact linker. Phosphine oxide fragment, which can be involved in weak intermolecular interactions, promotes the existence of two solid forms with different luminescence properties. These two forms can be switched from one to another upon grinding, thus featuring distinct mechanochromic luminescence properties. TDDFT calculations are consistent with the experimental results and assign mixed 3MLCT and 3LL'CT solution emission character and 3MMLCT and 3LL'CT emission nature in supramolecular dimeric structures.

Anti-thermal quenching in NdIII molecular near-infrared thermometers operating at physiological temperatures

Examples of molecular complexes acting as thermometers operating at room temperature in near infrared region are scarce, therefore this work showcases the anti-thermal quenching effect on neodymium(III) molecular thermometers working in biological windows within the physiological temperature range. A mononuclear complex, [Nd(L)(NO3)3] (1Nd), where L is a macrocyclic ligand, was synthesized and used as a precursor to develop two novel species: a dinuclear, [(Nd(L)(NO3))2(µ-BDC)](NO3)2·H2O (2Nd), linked by 1,4-benzenedicarboxylate (BDC), and a hexameric, [(Nd(L))(µ-BTC)(H2O)]6·35H2O (6Nd), linked with 1,3,5-benzenetricarboxylate (BTC). Thermometric properties were studied in the physiological temperature range (292-332 K), utilizing 804 nm laser excitation (first biological window) and monitoring emissions in the second biological window (908, 1065, and 1340 nm) associated with the 4F3/2 → 4I9/2, 4I11/2, 4I13/2 transitions, respectively. Among the complexes, the hexamer 6Nd exhibited exceptional performance, with Sr of 2.4%K-1 at 293 K, when luminescence intensity ratio (LIR) of two Stark components of the 4F3/2 → 4I11/2 emission was used, positioning it as a high-performance NdIII-based thermometer. All complexes displayed anti-thermal quenching behavior, surpassing the current molecular-based thermometers in the near-infrared region. Theoretical calculations using complete active space self consistent field (CASSCF) and Boltzmann population models between Kramers doublets of the 4F3/2 level were performed to rationalize the anti-thermal behavior.

Oxidation-Condensation Tandem Catalysis via a Multifunctional Cu-Based Metal-Organic Framework

The development of heterogeneous catalysts for tandem reactions remains a significant challenge for practical applications, primarily due to the need for multiple isolated catalytic sites. This study presents a novel metal-organic framework (MOF), Cu-AIPA, formulated as Cu(AIPA)(DMF)2 (AIPA: 2-amino isophthalic acid, DMF: N, N-dimethylformamide). The Cu-AIPA framework integrates three distinct catalytic mechanisms: redox activity, Brønsted basicity, and Lewis acidity. The structure of Cu-AIPA features redox-active Cu(II) centers and Brønsted basic sites, enabling the sequential transformation of alcohols to aldehydes and their subsequent condensation into imines. The close spatial arrangement of these redox-active/Lewis acidic and basic sites within the confined pores of Cu-AIPA facilitates efficient tandem catalysis. This process involves oxidizing benzyl alcohol to benzaldehyde using TEMPO without requiring an external base, followed by amine condensation. Compared with HKUST-1, another Cu-based MOF with a high surface area, Cu-AIPA demonstrated superior catalytic performance at room temperature. Recyclability tests revealed that Cu-AIPA retained over 90 % conversion efficiency across at least three catalytic cycles. This study highlights the potential of MOFs incorporating multiple catalytic sites and confined pore structures for tandem reactions, emphasizing their potential for scalable and sustainable industrial applications.

Photo-Induced Cracking in a Bi-Component Molecular Solid: Capturing Structural Intermediates

A photo-responsive bi-component solid is designed based on robust large synthons. The study not only provides a template-based approach for a system that was difficult to photo-dimerize, but the designed solid also leads to photo-induced cracking upon photodimerization. The delicate structural design helps in capturing the structural intermediates, which reveals a possible reorientation of the photodimer within the crystal to maintain structural integrity.

Benzo[1,3]oxathiol-2-one Motif-Based a New Chromogenic Copillar[5]arene: Synthesis, Solid-State Assembly, Photophysical Studies, and Colorimetric Recognition of S2

Herein, for the first time, we have reported a route to the introduction of benzo[1,3]oxathiol-2-one group onto pillar[5]arene to synthesize a new copillar[5]arene, which gives a new pillar[5]arene derivative 1 upon further functionalization. The well-defined cavity of this new copillar[5]arene exhibits solvent inclusion properties as characterized by single-crystal X-ray structures. The present study explores the inclusion of ethyl acetate (EtOAc) and acetonitrile (CH3CN) and the supramolecular assemblies with different features in the solid state. Copillar[5]arene 1 shows inclination to form dimers in both EtOAc and CH3CN. While ethyl acetate-occupied macrocycles give 2D arrangement involving π-π interaction, acetonitrile-occupied macrocycles follow π-π, C-H⋅⋅⋅π, and H-bond interactions in 2D arrangement and create a rhombus-shaped molecular channel with a diameter of ~5.5 Å in 3D packing. Compound 1 shows good photophysical behavior and aggregation. It acts as a chromogenic sensor for the selective recognition of sulfide (S2-) over a series of other anions in both organic and aqueous-organic solvents. The detection limit for S2- is determined to be 3.81×10-7 M.

Calcium coordination polymer containing dimethylphosphate ligands and exhibiting nucleating properties towards α and Β crystal polymorphs of isotactic polypropylene

The synthesis, structure and thermal properties of a one-dimensional coordination polymer based on calcium bis(dimethylphosphate) (CaDMP) are reported. The rod-like particles of CaDMP crystallized from water in a monoclinic space group P21/c, and contained Ca[O2P(OCH3)2]2 polymeric chains consisting of the octahedrally coordinated Ca2+ ions bridged by the tridentate dimethylphosphate ligands. The variable temperature powder X-ray diffraction measurements showed that this structure undergoes anisotropic thermal expansion upon heating, with no polymorphic transitions occurring up to 190 °C. Thermolysis of CaDMP began around 260 °C leading to the formation of calcium condensed phosphates and volatile oxophosphorus species. A detailed differential scanning calorimetry (DSC) analysis, combined with a fitting of the experimental data to the Avrami or Liu-Mo kinetic models, revealed that CaDMP accelerates isothermal and non-isothermal crystallization of isotactic polypropylene (iPP). DSC and wide-angle X-ray scattering measurements confirmed the presence of α-iPP and β-iPP crystal domains in the systems loaded with CaDMP particles. The crystallographic analysis indicated that β-iPP polymorph formed via epitaxial crystallization on the surface of CaDMP crystals. Mechanical tests proved that the CaDMP-containing composites exhibited better ductility and impact strength than neat iPP.

Tuning of Guest Uptake/Release Kinetics of a Dinuclear Cobalt(III) Metallohost by Auxiliary Amine Ligands

A series of dicobalt(III) metallohosts, [LCo2A4](OTf)2, which have different auxiliary amine ligands A (=EtNH2, PhCH2NH2, PhC2H4NH2, PhC3H6NH2), were synthesized in order to investigate the tuning of the guest uptake/release kinetics without significantly affecting the guest binding affinity. The metallohosts were characterized by spectroscopic methods and X-ray crystallography. All the metallohosts showed a Na+ selectivity among the investigated alkali meal ions with a clear selectivity trend of Na+>K+>Rb+>Cs+. The difference in the auxiliary amine ligands A had a more significant influence on the guest uptake rates than on the release rates. This can be mainly explained by the structural features of the guest-free form, [LCo2A4]2+, in which the phenyl C-H groups in the auxiliary amine ligands A interacted with the oxygen atoms of the O6 binding cavity via the C-H⋅⋅⋅O interactions.

Crystal structure and Hirshfeld surface analysis of the fungicide metconazole

Metconazole is a systemic triazole fungicide that inhibits the ergosterol bio-synthesis pathway. It is widely used in agriculture to control fungal infections, including rusts, fusarium and septoria diseases. The mol-ecular structure is a three-ring system, namely, 5-(4-chlorobenz-yl)-2,2-dimethyl-1-(1H-1,2,4-triazol-1-ylmeth-yl)cyclo-pentan-1-ol, C17H22ClN3O, consisting of a cyclo-pentan-1-ol with 1,2,4-triazol-1-ylmethyl, gem-dimethyl and 4-chloro-benzyl groups attached at the 1-, 2- and 5-positions of the cyclo-penta-nol ring. It has two stereocentres (cyclo-penta-nol positions 1 and 5) leading to four stereoisomers, with the (1S,5R) form being the most bioactive. Despite its agricultural significance, detailed crystallographic data remain scarce. This study reports the crystal structure and Hirshfeld surface analysis of racemic cis-metconazole [(1S,5R)/(1R,5S)], determined in the monoclinic space group P21/c with two independent mol-ecules in the asymmetric unit (Z' = 2). Both exhibit similar conformations, with minor differences in the cyclo-penta-nol ring puckering and the torsion angles between the three rings. The crystal packing consists of 21-screw-related hy-dro-gen-bonded chains parallel to the b axis, with additional weak C-H⋯N and C-H⋯Cl contacts linking adjacent mol-ecules. Hirshfeld surface analysis indicates that inter-molecular inter-actions are dominated by contacts involving hy-dro-gen (96.1 and 96.7% for the two mol-ecules).

Crystal structure and Hirshfeld surface analysis of ketorolac tromethamine

Ketorolac tromethamine or 1,3-dihy-droxy-2-(hy-droxy-meth-yl)propan-2-am-inium 5-benzoyl-2,3-di-hydro-1H-pyrrolizine-1-carboxyl-ate, C15H12NO3 +·C4H12NO3 -, was studied by single-crystal and powder X-ray diffraction methods. One cation and one anion are present in the asymmetric unit. In the crystal, N-H⋯O and O-H⋯O hy-dro-gen bonds link the cation and anion. All the hy-dro-gen-bond inter-actions result in the formation of a di-periodic layer in the (100) crystallographic plane.

Crystal structures of two pyrrolidin-1-yl derivatives of cathinone: α-PVP and α-D2PV

Two cathinones found on the market for legal highs have been characterized using X-ray crystallography. These are 1-(1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride monohydrate, C15H22NO+·Cl-·H2O (α-PVP·HCl·H2O), with erythritol [(2R,3S)-butane-1,2,3,4-tetrol, C4H10O4] as diluent in the sample, and 1-(2-oxo-1,2-diphenylethyl)pyrrolidin-1-ium chloride, C18H18NO+·Cl- (α-D2PV·HCl or A-D2PV·HCl). The intermolecular interactions occurring in the various crystal structures of these compounds have been described. The two arene rings of α-D2PV participate in the formation of π-π bonds (with parallel-displaced geometries of the π-π interactions). In addition, one of the rings forms a C-H...π interaction with an arene ring participating in an adjacent π-π bond, resulting in a linear arrangement of the molecules in the crystal. In the hydrated α-PVP salt, the molecules form a structure, the so-called `corral', in which two water molecules and two chloride ions are confined. The whole is held together by intermolecular hydrogen bonds. The structure of the chloride salt of α-D2PV described here lacks water molecules, which automatically allows for the formation of other types of intermolecular interactions. This structure was compared with the previously published hydrated form.

Effect of Coordination Environment and Electronic Coupling on Redox Entropy in a Family of Dinuclear Complexes

The elucidation of factors that govern the temperature sensitivity of the electrochemical potential is essential to the development of electrochemical systems with target properties. Toward this end, we report a series of isostructural homo- and heterometallic M2 (M = FeII, FeIII, ZnII) complexes supported by a phenoxo-centered tetrapyridyl ligand and ancillary carboxylate ligands that enables independent change in (i) charge, (ii) coordination environment of the redox-active center(s), and (iii) electronic coupling strength between redox centers. Variable-temperature electrochemical analysis of the series reveals the temperature coefficient for Fe-based redox couples to be highly dependent on the coordination environment of the redox-active center(s), with Fe centers in a pseudo-octahedral [FeN3O3] coordination environment affording a 2-fold greater temperature coefficient for the FeIII/FeII redox couple than those in ancillary ferrocenyl groups. In contrast, identical temperature coefficients for the FeIII/FeII redox event in Fe2 and FeZn complexes establish electronic coupling strength to have a minimal impact on the temperature dependence of the Fe-based redox couple. Taken together, these results provide important insights for the design of molecular compounds with target redox properties, and they provide the first examination of how electronic coupling influences the temperature dependence of the redox potential and the associated redox entropy in molecular compounds.

Additive-driven microwave crystallization of tyramine polymorphs and salts: a quantum crystallography perspective

Polymorphism - the ability of a compound to exist in multiple crystalline forms - needs to be carefully considered in the design of functional materials, particularly in the context of cocrystallization. Tyramine, a biogenic amine, is a promising candidate for polymorph exploration due to its conformational flexibility and ability to form salts. In this study, we investigate the crystallization of tyramine polymorphs using additives and microwave-assisted techniques. Our findings reveal the formation of a new tyramine polymorph and two distinct salts, highlighting the impact of microwave radiation and additive-driven crystallization on polymorph stability and molecular encapsulation. The study demonstrates that the triclinic tyramine polymorph (T2) is thermodynamically more stable due to its lower electronic energy, whereas the monoclinic form (T1) features slightly stronger intermolecular interactions. Over time, in solution, crystals of barbital-tyramine salts (C1 and C2) begin to form, providing an opportunity to assess structural evolution. Optical properties calculations show significant maximum linear birefringence values (0.164 and 0.255) for two polymorphs of tyramine, whereas for C1, this value decreases to 0.095.