Crystal structure refinement with SHELXL

Where Does the Proton Go? Structure and Dynamics of Hydrogen-Bond Switching in Aminophosphine Chalcogenides

Aminophosphates are the focus of research on prebiotic phosphorylation chemistry. Their bifunctional nature also makes them a powerful class of organocatalysts. However, the structural chemistry and dynamics of proton-binding in phosphorylation and organocatalytic mechanisms are still not fully understood. Aminophosphine chalcogenides, preserving the central H2N-P+-Ch- structural motif, represent well-suited molecular models that mimic proton-binding, hydrogen-bond switching and supramolecular self-assembling behavior of catalytically and prebiotically relevant molecules. Through spectroscopic (IR, 1H DOSY, 15N NMR), molecular dynamics, and computational investigations, the dynamic proton switching capability of aminophosphate analogs was demonstrated. It was shown under which conditions the amino (NH2) or chalcogen (Ch) functions in H2N-P+-Ch- structural units are protonated. In fact, all conceivable modes of hydrogen-bonding were identified, revealing substantial differences between the oxygen derivative and the heavier congeners. Using coordinating anions, supramolecular zigzag- and cube-shaped arrangements were found in the solid-state and in solution. After break-up of the cube structure, the sulfides and selenides no longer form stable interactions with HCl molecules. In the absence of coordinating anions, however, protonation of the chalcogen function is preferred. In contrast to the oxygen derivative, the heavier protonated congeners show dynamic intramolecular proton-hopping between the chalcogen and the amino function.

Diorganotin(IV) Complexes of Organoselenolato Ligands with Pyrazole Moieties-Synthesis, Structure and Properties

Diorganotin(IV) compounds of types RR'Sn(SeCH2CH2pz)2 [R = R' = nBu (2), Ph (3); R = 2-(Me2NCH2)C6H4, R' = Me (4), nBu (5), Ph (6)], and RR'SnX(SeCH2CH2pz) [R = 2-(Me2NCH2)C6H4, R' = nBu, X = Cl (7), R' = Me, X = SCN (9)], as well as [2-(Me2NCH2)C6H4](Me)Sn(NCS)2 (8), and the tin(II) Sn(SeCH2CH2pz)2 (10) (pz = pyrazole), were prepared by salt metathesis reactions between the appropriate diorganotin(IV) dichloride or dipseudohalide and Na[SeCH2CH2pz], with the latter freshly prepared from (pzCH2CH2)2Se2 (1). The solution behaviour of these compounds was investigated by multinuclear NMR (1H, 13C, 77Se, 119Sn), and the NMR spectra showed the existence of the Se-Sn bonds in solution. Compounds 4 and 5 showed decomposition in a solution of chlorinated solvents with the formation of selenium bridged dimeric species of type {[2-(Me2NCH2)C6H4](R')Se}2 [R' = Me (4-a), nBu (5-a)], as the single-crystal X-ray diffraction studies revealed, in contrast with compound 9, for which a monomeric structure was observed with the desired composition. The solid state structures of 4-a, 5-a, 8, and 9 revealed N→Sn intramolecular coordination of the nitrogen atom in the pendant CH2NMe2 arm. The NMR spectra suggested such a coordination at room temperature only for compound 7.

59Co Thermal Sensitivity in Co(III) Trisdithiocarbamate Complexes

Understanding temperature sensitivity in magnetic resonance is key to novel molecular probes for noninvasive temperature mapping. Herein, we report an investigation of the effects of heavy-donor-atom dithiocarbamate ligands on the variable-temperature 59Co nuclear magnetic resonance (NMR) properties of six Co(III) complexes: Co(et2-dtc)3 (1), Co(bu2-dtc)3 (2), Co(hex2-dtc)3 (3), Co(pyrr-dtc)3 (4), Co(benzyl2-dtc)3 (5) and Co(2,6-dmpip-dtc)3 (6) (et2-dtc = diethyldithiocarbamate; bu2-dtc = dibutyldithiocarbamate; hex2-dtc = dihexyldithiocarbamate; pyrr-dtc = pyrrolidine-dithiocarbamate; benzyl2-dtc = dibenzyldithiocarbamate; and 2,6-dmpip-dtc = 2,6-dimethylpiperidine-dithiocarbamate). This study reveals 59Co chemical-shift temperature dependences of 1.17(3)-1.73(4) ppm/°C as a function of ligand substituents. Solid-state Raman spectroscopic analyses show that more Raman-active Co-S6 vibrational modes correlate to higher thermal sensitivities for these compounds, in line with our current model for temperature sensitivity. Short spin-lattice relaxation T1 times in solution (ca. 200 μs) were observed, and correlation with T2* times and solid-state 59Co NMR analyses reveal that the solution-phase line widths are attributable to quadrupolar relaxation processes, which ultimately lower temperature-sensing resolution.

Enhanced Antimicrobial Efficacy of Sulfones and Sulfonamides via Cage-Like Silsesquioxane Incorporation

This work introduces a novel class of hybrid antimicrobial agents by integrating sulfone and sulfonamide functionalities with polyhedral oligomeric silsesquioxanes (POSSs). By employing efficient synthetic protocols, we have successfully prepared both sulfone (ethylvinylsulfone-POSS and phenylethylsulfone-POSS) and sulfonamide (benzenesulfonamide-POSS, p-toluenesulfonamide-POSS, 3-fluorobenzenesulfonamide-POSS, and 2-naphthalenesulfonamide-POSS) derivatives with high yields (73-90%). All derivatives were examined using Fourier transform infrared spectroscopy, multinuclear (1H, 13C, 19F, and 29Si) NMR spectroscopy, MALDI-ToF MS spectrometry, and elemental analysis. Additionally, the crystal structure of the p-toluenesulfonamide-POSS hybrid was revealed. The unique cage-like POSS structure not only imparts enhanced thermal and chemical stability, a common feature of silsesquioxane-based hybrids, but also boosts the lipophilic character of these compounds, thereby facilitating their interaction with microbial membranes. This interaction, likely resulting in membrane disruption and cell lysis, translates into potent antimicrobial activity (against Escherichia coli, Pseudomonas aeruginosa, Enterococcus hirae, Staphylococcus aureus, and Candida albicans)─especially against Gram-positive bacteria─at remarkably low minimum inhibitory concentrations in the range from 125 to 3000 μM. In turn, E. hirae and S. aureus were more susceptible compared to Gram-negative bacteria and C. albicans. The strategic incorporation of POSSs into these sulfur-based moieties represents a significant breakthrough, opening new avenues for the development of advanced antimicrobial coatings and therapeutic agents in the fight against antibiotic resistance.

Towards the Stable Chelation of Radioantimony(V) for Targeted Auger Theranostics

Antimony-119 (119Sb) is one of the most attractive Auger-electron emitters identified to date, but it remains practically unexplored for targeted radiotherapy because no chelators have been identified to stably bind this metalloid in vivo. In a departure from current studies focused on chelator development for Sb(III), we explore the chelation chemistry of Sb(V) using the tris-catecholate ligand TREN-CAM. Through a combination of radiolabeling, spectroscopic, solid-state, and computational studies, the radiochemistry and structural chemistry of TREN-CAM with 1XX/natSb(V) were established. The resulting [1XXSb]Sb-TREN-CAM complex remained intact for several days in human serum, signifying high stability under biological conditions. Finally, the first in vivo single photon emission computed tomography and positron emission tomography imaging studies were carried out using 117Sb, the diagnostic analogue of 119Sb. These studies revealed marked differences in the uptake and distribution of activity in mice administered unchelated [117Sb]Sb(OH)6 - versus [117Sb]Sb-TREN-CAM, suggesting that 117Sb is largely retained by TREN-CAM over the time course of the study. Collectively, these findings demonstrate the most physiologically stable complex of no-carrier-added 1XXSb yet reported, offering new promise for the clinical implementation of radioantimony in nuclear medicine. Our results also establish the feasibility of 117Sb as an elementally matched partner to 119Sb for theranostic applications.

Synthesis and Photophysics of the Doubly Cyclometalated Pd(II) Complexes [Pd(C∧N∧C)(L)], L = PPh3, AsPh3, and SbPh3

While Pt(II) complexes containing doubly cyclometalated ligands as tridentate luminophores are well studied, the synthetic accessibility of their Pd(II) counterparts was lacking for a long time. Inspired by a recent report on the synthesis of [Pd(dpp)(PPh3)] involving the C∧N∧C coordination mode (with dpp2- = 2,6-di(phenid-2-yl)pyridine) and following our own work on closely related Pt(II)-based compounds, we produced the series of complexes [Pd(dpp)(PnPh3)] (Pn = P, As, Sb) by optimizing the synthetic procedure and exploring their reactivity in the process. Our study of the electrochemical (cyclic voltammetry) and photophysical (UV-vis absorption and emission, transient absorption (TA) spectroscopy) properties of the Pd(C∧N∧C) complexes represents the first report on their characterization. We observed UV-vis absorption bands down to 450 nm and electrochemical HOMO-LUMO gaps around 3.2 V, which show minimal variation with different PnPh3 coligands. A more pronounced influence of the coligand was observed in time-resolved emission and TA spectroscopy. The highest photoluminescence quantum yield (ΦL) in the series was found for [Pd(dpp)(AsPh3)], reaching 0.06. The interpretation of the spectroscopic data is supported by (TD-)DFT calculations. Additionally, we report structural and spectroscopic data for several dinuclear Pd(II) complexes, including the precursor {[Pd(dppH)(μ-Cl)]}2 and multiple decomposition products of the sensitive compounds [Pd(dpp)(PnPh3)].

Tuning the Electronic Properties of Tetravalent Cerium Complexes via Ligand Derivatization

Molecular cerium complexes are of interest due to their remarkable redox and photophysical properties. We have investigated the ligand tunability of the electronic structure and properties of cerium(IV) complexes with functionalized tetradentate N2O2-donor ligands: [CeIV(LtBu)2] (1), [CeIV(LH)2] (2) and [CeIV(LNO2)2] (3), where H2LtBu = bis(2-hydroxy-3,5-di-tert-butylbenzyl)(2-pyridylmethyl)amine, H2LH = bis(2-hydroxybenzyl)(2-pyridylmethyl)amine and H2LNO2 = bis(2-hydroxy-5-nitrobenzyl)(2-pyridylmethyl)amine. These compounds all exhibit a quasi-reversible one-electron reduction to cerium(III), with the redox potential correlating with the electron donor-acceptor characteristics of the ligand substituents. This correlation is rationalized by energy stabilization of the HOMO, as determined by density functional theory calculations, and is consistent with arene π → Ce 4f* ligand-to-metal charge transfer bands. The L3-edge XANES exhibits minimal variation in Ce 4f occupation for the three compounds, which suggests that the 4f covalent character and composition of the ground-state character do not vary significantly across the series. However, M4,5-edge XAS shows charge transfer satellites that subtly differ in shape and energy, indicating small distinctions in ligand-to-metal charge transfer for the compounds, consistent with small differences in temperature-independent magnetism. The ability to modulate the redox and optical properties of cerium complexes through ligand derivatization highlights the potential for customizable molecular cerium catalysts and photocatalysts.

Continuous Flow Synthesis of Nitrofuran Pharmaceuticals Using Acetyl Nitrate

Nitrofurfural is a key building block for the synthesis of antimicrobial nitrofurans as active pharmaceutical ingredients. Its synthesis involves the nitration of furfural, a substrate derived from biobased resources. However, furfural has a delicate heteroaromatic backbone. Typical nitrations involve harsh reaction conditions, which often compromise this structure, resulting in poor reproducibility and low yields. Although acetyl nitrate, a mild nitrating agent, is suitable for this task, major deterrents remain. First, its conventional preparation method involves conditions that are not compatible with furfural. Second, significant safety concerns are associated with the unstable and explosive nature of acetyl nitrate. These critical issues are addressed herein. A safe and robust continuous flow platform featuring in situ generation of acetyl nitrate for the nitration of furfural to nitrofurfural is reported. The high level of integration and automation enables remote process operation by a single operator. Key furfural-based pharmaceutical intermediates were synthesized with favorable metrics and high reproducibility. The efficiency of this flow platform is demonstrated using a selection of best-selling nitrofuran pharmaceuticals (nifuroxazide, nifurtimox, nitrofurantoin, and nitrofural), which were obtained with excellent isolated yields in under five minutes.

Anti-Cancer Stem Cell Properties of Square Planar Copper(II) Complexes with Vanillin Schiff Base Ligands

Current breast cancer therapies are unable to positively impact the lives of a significant proportion of diagnosed patients (24% based on 10-year survival rate). Breast cancer relapse and metastasis, the leading cause of breast cancer-associated deaths, is linked to the existence of breast cancer stem cells (CSCs). Redox-modulating metal complexes have been used to perturb the redox balance in breast CSCs and effect cell death. Here, we sought to expand this promising class of anti-breast CSC agents. Specifically, we report the synthesis, and anti-breast CSC properties of a series of copper(II) complexes bearing regioisomeric vanillin Schiff base ligands (1-4). X-ray crystallography studies show that the copper(II) complexes 1-4 adopt square planar geometries with the copper(II) centre coordinated to two vanillin Schiff base ligands. The most effective copper(II) complex within the series 4 displays low micromolar potency towards breast CSCs, up to 4.6-fold higher than salinomycin and cisplatin. Mechanistic studies indicate that copper(II) complex 4 elevates reactive oxygen species levels in breast CSCs, leading to activation of the JNK/p38 pathway and caspase-dependent apoptosis. Overall, this work expands the library of anti-breast CSC copper(II) complexes and provides insight into their mode of action.

Synthesis and X-ray evaluation of 7 N-1S thiabendazole based 1,2,3-triazole as a dual metal sensing probe: Molecular logic gate construction, DFT analysis, real water sample analysis and catalytic activity investigation of its metal complexes

The research aimed to develop of a thiabendazole-derived dual metal sensing probe (TBZT) for the selective detection of metal ions and to explore its metal complexes in reducing environmental pollutants like nitro-phenol and dyes. Absorption and emission based studies predicted the selectivity and sensitivity of TBZT towards Ni(II) and Co(II) ions which was further validated by 1HNMR, Mass, FT-IR, DFT, Docking, electrochemical, TGA studies and vibrating sample magnetometer analysis techniques. Limit of detection (LOD) values were calculated as 2 × 10-10 M and 4.17 × 10-8 M for Ni(II) metal ion in emission and absorption based techniques respectively and 2.8 × 10-9 M and 4.5 × 10-6 M for Co(II). EDTA based Reversible binding behaviour suggested its potential for constructing molecular logic gates. Catalytic studies of metal complexes of TBZT with these metals demonstrated TBZT-Co(II) superior activity in reducing nitro-phenol, rhodamine B and methyl red. Real sample analysis validated its capability for the environmental monitoring of these metal ions. This emphasized its potential application in metal ion detection and catalysis.

Anticancer activity promoted by ligand diversity in diiron thiocarbyne complexes

Mononuclear iron (II) complexes have been intensively investigated with the aim of developing efficacious anticancer drugs that can overcome the serious limitations associated with the platinum complexes currently employed in chemotherapy. Combining a promising antitumor potential with appropriate physicochemical properties, such as aqueous stability and a balanced hydrophilic/lipophilic character, is essential for clinical progression. We prepared six highly functionalized diiron(I) complexes from the μ-thiocarbyne precursor [Fe2Cp2(CO)2(μ-CO)(μ-CSMe)]CF3SO3, 1 (Cp = η5-C5H5), through the substitution of one carbonyl ligand with isocyanides (2-4) and the subsequent substitution of a second CO with N- or P-ligands (5-7). All products 2-7 were structurally characterized using IR and multinuclear NMR spectroscopy. One compound from series (7) was also characterized by single crystal X-ray diffraction. Complexes 2-7 exhibit outstanding stability in physiological-like solutions, with 92-97 % of the compounds unchanged after storing in DMEM at 37 °C for 24 h, and substantial amphiphilicity, with most of Log Pow values falling in the range -1 to +1. Complexes 3, 4, 5 and 7 exhibited cytotoxic activity against human (HCT 116, MCF-7, A2780) and murine (CT26, 4T1, B16-F1, B16-F10) cancer cell lines with IC50 values up to the nanomolar range, along with moderate selectivity toward the malignant phenotype. The induction of cell differentiation, senescence, and apoptotic cell death with cell-specific redox response were in the background of cytotoxic activity. However, limited tumor volume reduction and observed systemic toxicity in vivo indicated the need for additional structure-activity relationship studies to optimize the compounds anticancer profile.

Ba2BP7N14 - A Quaternary Alkaline Earth Nitridoborophosphate with a Mixed 3D Network Structure

Highly condensed alkaline earth nitridophosphates have attracted increasing scientific interest, due to their high thermal and chemical stability, as well as their promising luminescence behavior upon doping with Eu2+ for pc-LED applications. In particular, the barely explored mixed tetrahedra-based nitridophosphates offer a wide range of structural and compositional diversity, enabling new insights into structure-property relationships. Herein, we report on the first quaternary alkaline earth nitridoborophosphate Ba2BP7N14, synthesized at 8 GPa and 1600 °C in a multianvil press, starting from Ba(N3)2, h-BN and P3N5. Ba2BP7N14 crystallizes in the barylite-1O polytype and features a highly condensed mixed (B,P)-N anionic 3D network (κ≈0.57) built up of PN4 and mixed occupied (P0.75B0.25)N4 tetrahedra. The structure was characterized by a multi-step process involving single-crystal and powder X-ray diffraction (SCXRD, PXRD), elemental analysis, electron microscopy (STEM, EELS), and solid-state 31P and 11B MAS NMR spectroscopy. The plausibility of the structural model was corroborated by low-cost crystallographic calculations. The optical band gap and the thermal behavior of an undoped sample of Ba2BP7N14, were determined from diffuse reflectance spectroscopy and temperature-dependent powder X-ray diffraction, respectively. Irradiation of a Eu2+-doped sample with near-UV light results in a blue emission peaking at λem=422 nm.

Reaction of a Potassium Aluminyl with Sn[N(SiMe3)2]2 - Isolation of a Stable, Trimetallic Sn(I) Radical Anion

The reaction of the potassium aluminyl K[Al(NON)] ([NON]2-=[O(SiMe2NDipp)2]2-, Dipp=2,6-iPr2C6H3) with the stannylene Sn[N(SiMe3)2]2 in benzene afforded K3[(Sn4){Al(NON)}2{N(SiMe3)2}], containing a distorted tetrahedral Sn4-cluster. Computational analysis indicates that four of the edges in this unit are composed of Sn-Sn bonds, with the remaining two that are spanned by aluminium involved in three centre two electron (3c2e) Sn-Al-Sn bonds. The formation of Al(II) species during this reaction is indicated by the isolation of the dialuminated cyclohexadiene 1,4-[Al(NON)]2(μ-C6H6). Repeating the reaction in methylcyclohexane generated a thermally stable, trimetallic Sn(I) radical anion in K[Sn{Al(NON)}2]. Compared to all other reported Sn(I) radicals, its EPR spectrum is unique; the main turning points of its spectrum appear at g values above 2 and the Sn hyperfine coupling is substantially smaller in magnitude. These data, together with ENDOR measurements and DFT calculations show that the SOMO is entirely localised in an unhybridised 5p orbital, such that spin-orbit contributions to the g and Sn hyperfine tensors are quenched.

Selective adsorption of CO2 in TAMOF-1 for the separation of CO2/CH4 gas mixtures

TAMOF-1 is a robust, highly porous metal-organic framework built from Cu2+ centers linked by a L-histidine derivative. Thanks to its high porosity and homochirality, TAMOF-1 has shown interesting molecular recognition properties, being able to resolve racemic mixtures of small organic molecules in gas and liquid phases. Now, we have discovered that TAMOF-1 also offers a competitive performance as solid adsorbent for CO2 physisorption, offering promising CO2 adsorption capacity ( > 3.8 mmol g-1) and CO2/CH4 Ideal Adsorbed Solution Theory (IAST) selectivity ( > 40) at ambient conditions. Moreover, the material exhibits favorable adsorption kinetics under dynamic conditions, demonstrating good stability in high-humidity environments and minimal degradation in strongly acidic media. We have identified the key interactions of CO2 within the TAMOF-1 framework by a combination of structural (neutron diffraction), spectroscopic and theoretical analyses which conclude a dual-site adsorption mechanism with the majority of adsorbed CO2 molecules occupying the empty voids in the TAMOF-1 channels without strong, directional supramolecular interactions. This very weak dominant binding opens the possibility of a low energy regeneration process for convenient CO2 purification. These features identify TAMOF-1 as a viable solid-state adsorbent for the realization of affordable biogas upgrading.

Molecular and Immobilized Tripodal Phosphine Ligands and Their Trinuclear Palladium Complexes

The synthesis and characterization of the tripodal phosphines RSi(CH2CH2PPh2)3 (R = Me, OMe, OEt) (1-3) is described. The 1H NMR spectra of all phosphines display virtual coupling patterns. The ligands form the corresponding trinuclear Pd complexes [RSi(CH2CH2PPh2)3]2(PdCl2)3 (4-6) with three PdCl2 moieties sandwiched between two tripodal ligands. The complexes 4, 5, and 7 (R = OH) have been analyzed by single crystal X-ray diffraction. The coordination at the Pd center is square planar with the phosphine groups occupying trans positions. The 31P{1H} MAS NMR spectra of polycrystalline 1 are in accordance with the packing motif of the molecules in the unit cell. The tripodal ligand 3 has successfully been immobilized on silica as 3i. It coordinates PdCl2 on the surface, as demonstrated by 31P{1H} MAS NMR. Hereby, the cis coordination is prevalent when 3i has maximal surface coverage. At low surface coverage, one tripodal linker can accommodate trans coordination at the metal center. A surface-bound trinuclear Pd complex has been generated, as well as a heterobimetallic Pd/Cu complex. All surface species have been characterized by 31P{1H} MAS NMR.

Asymmetric Catalytic Aziridination to Synthesize Spiro-aziridine Oxindoles

Asymmetric catalytic aza-Michael-initiated ring closure of methyleneindolinones with N-tosyloxycarbamates has been established. The reaction using a chiral nickel complex catalyst enabled the formation of a series of spiro-aziridine oxindoles in good yields (up to 99 %) with high stereoselectivity (up to 97 % ee, >19 : 1 dr) under mild reaction conditions. Ring-opening of spiro-aziridine oxindole leads to formation of glycinate-bearing oxindoles with retention of configuration.

Probing the subtle differences between promethium and curium

Curium and promethium share similar chemical and physical properties thereby complicating their separation. Co-located processing at Oak Ridge National Laboratory results in curium contamination of the fission product stream containing promethium. To gain insight into the difficulty of this separation, the fundamental properties of these elements are experimentally and computationally probed in a 2,2':6',2"-terpyridine crystal system. Analysis of the isostructural compounds via single crystal X-ray diffraction and quantum theory of atoms in molecules reveals that bonding between promethium and curium is quite similar in this particular structure type. The small differences in the analysis of these two elements in this isostructural series sheds light on the difficulty required to separate the elements from each other. More so, this study develops the fundamental chemistries of two rare elements in the solid state and experimentally portrays the often-omitted position of promethium within the lanthanide series.

Insights into topochemical versus stress-induced high-pressure reactivity of azobenzene by single crystal X-ray diffraction

This study addresses azobenzene's structural compression and reactivity under hydrostatic high-pressure conditions. Synchrotron X-ray diffraction data of single crystals compressed with neon as the pressure-transmitting medium allowed the refinement of the crystal structure up to 28 GPa, at which the onset of the reaction was observed. Analysis of the pressure-dependent lattice parameters reveals a first-order isostructural phase transition at 13 GPa. We have solved the crystal structure of the high-pressure phase of azobenzene offering a key insight into the strong contribution of stress on the structural compression mechanism and crystal's reaction chemistry at elevated pressures. While the collapse of the b cell parameter, previously observed under non-hydrostatic conditions, was identified as the crucial step toward the formation of azobenzene-derived double-core nanothreads, under quasi-hydrostatic conditions the compression of the cell parameters up to 33 GPa followed a different route. The evolution of the cell parameters and the refinement of the crystal structure close to the onset of the reaction identified a topochemical polymerization path, corroborated by reaction kinetics data by infrared spectroscopy and by computed polymer structures, suggesting a complex growth process, resulting in a distinctly different material compared to that formed upon non-hydrostatic compression. These findings underscore the pivotal role of compression conditions in determining the reaction pathways of azobenzene, providing novel insights for its application in nanomaterial synthesis.

Isolation of a Rare Terminal Zr(IV) Peroxide and Insight into Polyoxovanadate Support Impact on Thioether Oxidation

Substitutional lability of the terminal methoxide ligand on a Zr(IV) substituted polyoxovanadate-alkoxide (POV-alkoxide) via protonolysis is presented. Addition of excess water or stoichiometric 2,2,2-trifluoroethanol results in the exchange of the terminal methoxide ligand for a hydroxide or 2,2,2-trifluoroethoxide ligand, respectively. The lability of the terminal methoxide ligand at zirconium is leveraged to access a relatively stable terminal peroxide bound to a POV-alkoxide supported Zr(IV) center, via addition of hydrogen peroxide adducts compatible with organic solvent. Isolation of the terminal peroxide complex allows for investigation into the impact of the sterically protected, electron-rich POV-alkoxide support on the activation of hydrogen peroxide at Zr(IV). While the isolated peroxide complex is inactive towards the oxidation of thioethers, the methoxy terminated Zr(IV) functions as a precatalyst for the reaction. Mechanistic analysis reveals electrophilic oxidation conditions with hydrogen peroxide substrates, with a nucleophilic parameter (χ N u ${{{{\bf\chi}}}_{{\bf N u}}}$ ) of 0.09±0.02. In thioether oxidation reactions, selectivity for sulfoxide products (95-99 %) in acetonitrile is observed, suggesting the use of a reduced POV-alkoxide prevents over-oxidation of substrate.

A lanthanide MOF with nanostructured node disorder

Structural disorder can be used to tune the properties of functional materials and is an important tool that can be employed for the development of complex framework materials, such as metal-organic frameworks. Here we show the synthesis and structural characterization of a metal-organic framework, UoB-100(Dy). Average structure refinements indicate that the node is disordered between two orientations of the nonanuclear secondary building unit (SBU). By performing 3D diffuse scattering (DS) analysis and Monte Carlo (MC) simulations, we confirm the presence of strong correlations between the metal clusters of UoB-100(Dy). These nodes assemble into a complex nanodomain structure. Quantum mechanical calculations identify linker strain as the driving force behind the nanodomain structure. The implications of such a nanodomain structure for the magnetic, gas storage, and mechanical properties of lanthanide MOFs are discussed.

Metal-Assisted Synthesis of Diverse Porphyrinoids by Cyclization of an N-Confused Thia-Pentapyrrane

Oxidation of thia-pentapyrrane S-P4 with terminal β-linked pyrrole and thiophene units in the presence of various metal ions has been found to afford distinct porphyrinoids. Specifically, N-confused thiasapphyrin (1), Cu(III) norrole (2), neo-confused phlorin (3), and p-benzinorrole (4) were obtained, when S-P4 was oxidized with p-chloranil in acetonitrile in the presence of Ni2+, Cu2+, Cd2+, and Co2+, respectively. The structures of 1-4 have been clearly elucidated by NMR spectroscopy, HRMS, and X-ray crystal diffraction (for 2-4). This work indicates that the oxidative cyclization by linking highly reactive β-linked pyrrole unit with less reactive thiophene unit assisted by various metal ions shows great potential in the construction of various novel porphyrinoids.

High-Pressure Synthesis of Ultra-Incompressible Beryllium Tungsten Nitride Pernitride BeW10N14(N2)

For the activation of nitrogen and its reduction to ammonia, transition metals are crucial in biological as well as industrial processes. So far, only a few binary transition metal compounds with nitrogen dimer anions are known, whereas a ternary compound has remained undiscovered as yet. Here, we report on the synthesis and properties of the first ternary transition metal compound, namely, BeW10N14(N2), which exhibits dinitrogen anions. It was synthesized in a high-temperature high-pressure approach from W2Be4N5. The crystal structure, elucidated with synchrotron radiation, unites WN7 capped trigonal prisms with intriguing BeN6 octahedra and (N2)-anions. Elastic and electronic properties of the title compound were corroborated by DFT calculations, revealing simultaneous ultra-incompressible and metallic behavior. The synthesis and investigation of the first ternary transition metal nitride with dinitrogen units opens the door to a new field of research on nitride and pernitride chemistry.

[natY/90Y]Yttrium and [natLu/177Lu]Lutetium Complexation by Rigid H4OCTAPA Derivatives. Effect of Ligand Topology

We present a detailed investigation on the coordination chemistry of [nat/90Y]Y3+ and [nat/177Lu]Lu3+ with the new acyclic chelator H4CHXOITAPA. This octadentate chelator forms nine-coordinated Y3+ and Lu3+ complexes thanks to the coordination of a water molecule, as demonstrated by the X-ray structure of [Y(HCHXOITAPA)(H2O)] and 1H, 13C, and 89Y NMR studies in solution. These complexes display slightly higher thermodynamic stabilities compared with those of the known H4CHXOCTAPA and H4OCTAPA chelators, reaching log KYL and log KLuL values of 21.24(5) and 21.96(1), respectively. Kinetic studies indicate that these complexes dissociate mainly through the spontaneous and proton-assisted pathways at pH 7.4. The chelator can be readily radiolabeled with [90Y]Y3+ and [177Lu]Lu3+ at room temperature in 10 min. The radio-complexes are stable in human serum at 37 °C, in contrast with the analogues of the known H4CHXOCTAPA and H4OCTAPA chelators, which experience significant dissociation under these conditions. Thus, the H4CHXOITAPA chelator represents the most promising candidate among the H4OCTAPA family for the development of 90Y- and 177Lu-based radiopharmaceuticals.

Hydrogen Oxidation by Bioinspired Models of [FeFe]-Hydrogenase

Synthetic azadithiolate-bridged diiron clusters serve as structural analogues of the active site of [FeFe]-hydrogenases. Recently, an o-alkyl substitution of aniline-based azadithiolate bridge allowed these synthetic models to both oxidize H2 and reduce H+, i.e., bidirectional catalysis. Hydrogen oxidation by synthetic analogues of hydrogenases is rare, and even rarer is the ability of diiron hexacarbonyls to oxidize H2. A series of synthetic azadithiolate-bridged biomimetic diiron hexacarbonyl complexes are synthesized where the substitution in the para position of the ortho-methyl aniline in the azadithiolate bridge is systematically varied between electron-withdrawing and electron-donating groups to understand factors that control H2 oxidation by diiron hexacarbonyl analogues of [FeFe]-hydrogenases. The results show that the substituents in the para position of the ortho-ethyl aniline affect the electronic structure of the azadithiolate bridge as well as that of the diiron cluster. The electron-withdrawing -NO2 substituent results in faster H2 oxidation relative to that of a -OCH3 substituent.

Aluminum Photosensitizers on Trial: Synthesis, Crystal Structures, Photophysical and Photobiological Properties of Tris(Dipyrrinato)Aluminum(III) Complexes with Long-Lived Triplet States

Metal coordination compounds are currently a focus of research in developing new photosensitizers for materials and medicinal applications. As an abundant element in the earth's crust aluminum is a suitable target element. However, only limited studies are available on its use in photoactive systems. We now report the facile preparation of a library of homoleptic tris(dipyrrinato)aluminum(III) [AL(DIPY)3] complexes. The majority of complexes was characterized by single crystal X-ray analysis and their photophysical properties upon photoexcitation and their tendency to react with the molecular oxygen of the microenvironment and generate singlet oxygen - in polar and non-polar environment was investigated. These studies are complemented by density functional theory (DFT) calculations to assess the possible electronic distribution on the frontier molecular orbitals within the complexes. As a result of charge transfer states, long-lived triplet excited states were formed and allowed for singlet oxygen generation. An initial screening of the AL(DIPY)3 complexes via in vitro phototoxicity studies against a mouse colon carcinoma cell line (CT26) was promising as these complexes were able to trigger cell death upon irradiation at nanomolar and micromolar concentrations. The results highlight the potential of aluminum dipyrrin complexes as a broadly applicable class of photosensitizers.

Transmetalation From Boron to Beryllium in Phosphorus-Based Scorpionate Complexes

Investigation of tris(di-iso-propylphosphanylmethyl)phenylborate ([TP(iPr)]-) organo-beryllium complexes [TP(iPr)]BeR with R = Ph, nBu, Cp, Cp* revealed transmetalation of [CH2P(iPr)2]- groups from boron onto beryllium. This reaction is caused by partial dissociation of the scorpionate, which can be triggered through steric overcrowding of the beryllium atom or reducing the ligand beryllium bond strength through oxidation of the phosphorus atoms with selenium. Oxidation with oxygen or sulfur results in the formation of stable phosphine oxide and sulfide scorpionates.

Anti-Inflammatory Activity of Two Labdane Enantiomers from Gymnosperma glutinosum: An In Vivo, In Vitro, and In Silico Study

Background/Objectives: Diseases associated with inflammatory processes continue to grow steadily throughout the world. Unfortunately, prolonged use of drugs induces adverse effects ranging from hypersensitivity reactions to damage to the digestive system. These negative effects open the possibility of continuing the search for anti-inflammatory compounds with less toxicity. The aim of this research was to isolate and evaluate the anti-inflammatory activity of a mixture of two enantiomeric labdanes isolated from Gymnosperma glutinosum by in vivo, in vitro, and in silico methods. Methods: A brief description of the main methods or treatments applied. This can include any relevant preregistration or specimen information. The structure of the labdanes enantiomers was elucidated by X-ray crystallography and spectroscopies methods. The anti-inflammatory effect was evaluated on a mouse model of ear edema induced with 12-O-tetradecanoyl phorbol-13-acetate; the pro-inflammatory mediators, nitric oxide (NO) and interleukin (IL-6), were quantified on macrophages stimulated with lipopolysaccharide, and the interaction between labdanes and diana was studied by molecular docking. Results: We identified the chemical structures of two new labdane enantiomers: a-gymglu acid and b-ent-gymglu acid. The enantiomer mixture, named gymglu acid, diminished ear edema at doses of 1 and 2 mg/ear by 36.07% and 41.99%, respectively. A concentration of 155.16 µM of gymglu acid inhibited the production of NO by 78.06% and IL-6 by 71.04%. The in silico results suggest two routes by which these labdanes reduce inflammation: partial agonism toward the corticosteroid receptors and inhibition of nitric oxide synthases. Conclusions: These results show that the gymglu acid enantiomers have promising anti-inflammatory activity.

CaCu1.424Fe0.576Si2

A CaCu1.424Fe0.576Si2 phase was obtained during high-pressure sinter-ing of an Si-rich quasicrystal composition prealloy with the nominal chemical com-position Si61Cu30Ca7Fe2. The obtained phase crystallizes in the space group I4/mmm (No. 139), with a = b = 4.041 Å and c = 10.010 Å. It is isotypic with CaCu2Si2 (a = b = 4.06 Å and c = 9.91 Å) [Palenzona et al. (1986 ▸). J. Less-Common Met. 119, 199-209] and CaFe2Si2 (a = b = 3.94 Å and c = 10.19 Å) [Hlukhyy et al. (2012 ▸). Z. Anorg. Allg. Chem. 638, 1619-1619]. It features a co-occupancy of Cu and Fe atoms with a ratio of the refined site-occupancy factors of 0.71 (15):0.29 (15).

4,4-Dimethyl-2-phenyl-4,5-di-hydro-pyrrolo-[2,3,4-kl]acridin-1(2H)-one

In the title compound, C22H18N2O, the pendant phenyl ring is twisted by 43.85 (1)° with respect to the acridine moiety, which has almost coplanar atoms apart from the sp 3 carbon atoms. The extended structure features aromatic π-π stacking with a centroid-to-centroid distance of 3.489 (2) Å and weak C-H⋯O hydrogen bonds.

(5,6-Dimethyl-1,10-phenanthroline)(2-{[2-(di-phenyl-phosphan-yl)benzyl-idene]amino}-ethan-1-amine)-platinum(II) dinitrate methanol disolvate

The title compound, [Pt(C14H12N2)(C21H21N2P)](NO3)2·2CH3OH, is a platinum(II) complex, which crystallizes in a monoclinic (P21/c) space group. The complex exhibits a distorted square-planar geometry, which includes a monodentate 5,6-dimethyl-1,10-phenanthroline ligand and a tridentate 2-{[2-(di-phenyl-phosphan-yl)benzyl-idene]amino}-ethan-1-amine ligand. The structure reveals both intra- and inter-molecular π-stacking inter-actions between the phenanthroline and phosphine rings. Hydrogen bonding is observed between the complex ion, nitrate counter-ions and solvent mol-ecules.

A comparison of microcrystal electron diffraction and X-ray powder diffraction for the structural analysis of metal-organic frameworks

This study successfully implemented microcrystal electron diffraction (microED) and X-ray powder diffraction (XRPD) for the crystal structure determination of a new phase, TAF-CNU-1, Ni(C8H4O4)·3H2O, solved by microED from single microcrystals in the powder and refined at the kinematic and dynamic electron diffraction theory levels. This nickel metal-organic framework (MOF), together with its cobalt and manganese analogues with formula M(C8H4O4)·2H2O with M = MnII or CoII, were synthesized in aqueous media as one-pot preparations from the corresponding hydrated metal chlorides and sodium terephthalate, as a promising 'green' synthetic route to moisture-stable MOFs. The crystal structures of the two latter materials have been previously determined ab initio from X-ray powder diffraction. The advantages and disadvantages of both structural characterization techniques are briefly summarized. Additional solid-state property characterization was carried out using thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectroscopy.

Triple-chromic (photo-, thermo-, and mechano-chromic) metal complexes containing N-salicylideneaminopyridine ligands

N-Salicylideneaminopyridine (SAP) is a well-known organic chromic compound that shows a reversible colour change upon UV light irradiation (photochromism) and upon cooling (thermochromism). Herein, we report novel multi-chromic metal complexes containing SAP derivatives as ligands, viz. [Ni(NCS)2(3,5-t-Bu-SAP)4] (Ni1) and [Co(NCS)2(3,5-t-Bu-SAP)4] (Co1). The Ni1 crystals exhibited both photo- and thermochromism with new colour variations, which were due to the light absorption of the Ni(II) ions and chromic properties of the SAP ligands. The Co1 crystal also exhibited photo- and thermochromism originating from the SAP ligands. Furthermore, the Co1 crystal exhibited mechanochromism induced by grinding with a mortar, which was considered to be attributable to the change of the Co1 coordination structure. Such a triple-chromic material is rare and very fascinating for the applications of multiple sensors, memory devices, and functional inks.

Design, synthesis and molecular modeling of new Pyrazolyl-Benzimidazolone hybrids targeting breast Cancer

Methyl-piperidino-pyrazole (MPP) is a pyrazole derivative acting as a lead estrogen receptor (ER) antagonist and has an anti-breast cancer effect. Since some benzimidazole derivatives were reported for their inhibitory activity against breast cancer, hybrids from these reported compounds (5a-c, 6a-c, 7a-c and 8a-c) were designed to develop anti-breast cancer agents. The synthesis involved 1,3-dipolar cycloaddition of nitrilimines on the benzimidazolone derivatives 2a-b and 3a-b which occurred with chemo- and regioselectivity depending on the dipole and was confirmed by an X-ray structure of 6b. In vitro biological testing of the newly prepared compounds against the 60-cell line panel showed that 5a-c and 6a-c with a partially unsaturated pyrazole ring possessed a high GI% in the T-47D breast cancer cell line with a selectivity margin against different cell lines. Five compounds were selected for apoptotic studies in T-47D cells, of which 6a arrested cells in G1 phase and caused more apoptosis than MPP. The MTT assay revealed that compound 6a has an IC50 = 6.77 ± 0.03 μM against T-47D cells. Furthermore, 6a reduced the estrogen receptor 1 gene expression levels 3-fold in T-47D cells. Molecular dynamics simulations indicated that the complex of the active compound 6a remained stable over the last 150 ns. An analysis of the binding mode revealed that compound 6a exhibited a similar conformation compared to MPP and the co-ligand in the active site of via a specific pose involving noncovalent interactions.

A novel type of heteroleptic Cu(I) complexes featuring nitrogen-rich tetrazine ligands: syntheses, crystal structures, spectral properties, cyclic voltammetry, and theoretical calculations

Heteroleptic copper(I) complexes with the general formula [Cu(N^N)(P^P)]X constitute one of the most studied categories of 3d metal photosensitizers. Here, we examine using 1,2,4,5-tetrazine-based ligands to synthesize photoactive Cu(I) complexes. The newly prepared complexes were characterized by single-crystal X-ray analysis, which revealed the formation of dinuclear complexes [Cu2(μ-L1)(xantphos)2](ClO4)2 (1) and [Cu2(μ-L2)(xantphos)2](ClO4)2 (2), and mononuclear complexes [Cu(L3)(xantphos)]ClO4 (3) and [Cu(L4)(xantphos)]ClO4 (4), where L1 = 3,6-di(2'-pyridyl)-1,2,4,5-tetrazine (bptz), L2 = 3,6-bis-(3,5-dimethyl-pyrazol-1-yl)-1,2,4,5-tetrazine, L3 = 3-(2-pyridyl)-1,2,4,5-tetrazine, L4 = 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine and xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene. Solution stability assays were addressed by NMR spectroscopy showing that complexes are stable in dichloromethane over several days. The electronic excited states were investigated by UV-Vis and luminiscence spectroscopy and interpreted with the help of TD-DFT calculations. In the case of all the newly prepared complexes 1-4, the absorptions in the visible region were assigned to non-emissive MLCT transitions between the Cu(I) and the respective tetrazine ligand. Redox properties were probed by cyclic voltammetry and also supplemented by DFT calculations. Interestingly, tetrazine ligands L1-L4 show a shift of reduction potential to less negative values upon the formation of Cu(I) complexes 1-4. Moreover, the two complexes 3-4 represent the first reported case of mononuclear heteroleptic Cu(I)-tetrazine complexes.

Crystal structure of 1-amino-3-(4-chloro-phen-yl)-2-cyano-3H-benzo[4,5]thia-zolo[3,2-a]pyridine-4-carboxamide

In the structure of the title compound, C19H13ClN4OS, the four atoms of the pyridinic ring that are not fused with the thia-zole, including the sp 3 C atom, lie significantly outside the benzo-thia-zole plane. A short intra-molecular S⋯O contact of 2.5992 (4) Å is observed. The amide NH2 group is planar, whereas the amine NH2 group is pyramidalized. The three-dimensional packing involves two inter-connected layer structures. The first, parallel to the bc plane, involves three classical hydrogen bonds N-Hamine⋯O (one of two), N-Hamine⋯Cl and one N-Hamide ⋯Ncyano; the second, parallel to the ab plane, involves two hydrogen bonds, N-Hamide⋯O and the second N-Hamine⋯O, together with the short and linear contact Ncyano⋯Cl-C, which may be regarded as a halogen bond.

Polymorphism and Hirshfeld surface analysis of tetra-oxa[2]perfluoro-arene[2]triazine

The title compound, tetra-oxa[2]perfluoro-arene[2]triazine (C20H6F8N6O6), composed of two tetra-fluoro-phenyl-ene and two triazine moieties connected by four oxygen atoms, was crystallized via slow evaporation of a di-chloro-methane solution, yielding two polymorphs: block- (I) and plate-shaped (II) crystals. Polymorph I (triclinic, P1, V = 516 Å3 at 173 K) was previously reported by Yang et al. [(2015. Org. Lett. 15, 4414-4417] whereas the newly identified polymorph II (triclinic, P1, V = 1085 Å3 at 100 K) shares the same space group but has a unit-cell volume twice as large, accommodating two symmetrically distinct mol-ecules, Mol-ecule-1 and Mol-ecule-2, with a different mol-ecular arrangement. Since these crystals are expected to exhibit the characteristics of non-porous adaptive crystals, detailed analyses of inter-molecular inter-actions were conducted, revealing that C-F⋯π-hole inter-actions are more pronounced in II than in I. Hirshfeld surface analysis at 100 K revealed that the primary contributions to the crystal packing in polymorph I were F⋯F (17.1%), F⋯H/H⋯F (21.5%), C⋯H/H⋯C (6.3%), C⋯F/F⋯C (4.5%) and C⋯O/O⋯C (9.2%) inter-actions, whereas in polymorph II, these inter-actions were F⋯F (9.9% and 10.0%), F⋯H/H⋯F (20.9% and 26.5%), C⋯H/H⋯C (6.3% and 2.9%), C⋯F/F⋯C (8.5% and 10.0%) and C⋯O/O⋯C (4.9% and 4.6%) for Mol-ecule-1 and Mol-ecule-2, respectively. Powder X-ray diffraction analysis indicates that polymorph I is the more stable crystalline form, predominantly obtained through rapid precipitation or by grinding the crystals.

Diaryl Diimidazopyrimidine Derivatives as Potent Inhibitors of Influenza A Virus: Synthesis, Evaluation and Docking Studies

In this report, we present a new series of diaryl diimidazopyrimidine derivatives 3a-m, that have been synthesized and assessed for their in vitro antiviral activity. The derivatives were prepared through a one-step reaction involving commercially available 2,4-diamino-6-chloropyrimidine and various phenacyl bromides 2a-m, leading to the formation of the desired diaryl diimidazo- pyrimidines 3a-m with good yields. In vitro evaluations against the Influenza A H1N1 strain identified compounds 3m (SI = 73) and 3b (SI = 23) as the most potent candidates. Additionally, antimicrobial screening indicated that compounds 3d and 3j, which contain methyl and methoxy substitutions, exhibited moderate activity against Streptococcus mutans, Salmonella typhi, and Candida albicans. Molecular Docking studies of the promising compounds 3b and 3m demonstrated significant binding interactions with the M1 matrix protein (PDB ID: 5CQE) in comparison to M2 proton channel of Influenza A (PDB: 6US9), suggesting that these derivatives may be effectively targeting the M1 protein. Additionally, molecular dynamics (MD) simulations were conducted to evaluate the stability, dynamic behaviour, and binding affinity of the most potent compounds 3b and 3m. The in vitro antiviral studies, molecular docking and MD simulations data highlight the promising pharmacological potential of these analogues, paving the way for further structural optimization and development as potential antiviral agents.

Synthesis and structure of tris-(2-methyl-1H-imidazol-3-ium) 5-carb-oxy-benzene-1,3-di-carboxyl-ate 3,5-di-carb-oxy-benzoate

The structure of the title salt, 3C4H7N2 +·C9H5O6 -·C9H4O6 2-, 1, consists of three 2-methyl-imidazolium cations and both a single and a doubly deprotonated form of trimesic acid as anions. A detailed analysis of the bond lengths and angles reveals both differences and similarities between compound 1 and the previously reported 2-methyl-1H-imidazol-3-ium 3,5-di-carb-oxy-benzoate structure [Baletska et al. (2023). Acta Cryst. E79, 1088-109], as well as the neutral counterpart of the ions. Examination of the crystal packing shows the formation of infinite chains by the anions, which, along with the cations, form zigzag planes parallel to the ab plane. The packing inter-actions are primarily driven by π-π inter-actions and hydrogen bonding between anions.

3-Chloro-propio-phenone

The title compound, 3-chloro-propio-phenone (or 3-chloro-1-phenyl-propan-1-one), C9H9ClO, consists of an almost planar mol-ecule that is charaterized by very small torsion angles within the alkyl side chain (torsion angles < 6.3°). No hydrogen bonds are observed in the crystal packing. The compound exhibits a melting point of 54°C.

Charge transfer between a metal-bound halide and a quinone through π-hole interactions leads to bulk conductivity

π-Hole interactions between a metal-bound halide and a quinoid ring are described in four novel isostructural co-crystals with the formula [Cu(terpy)ClX]·X'4Q (terpy = 2,2':6',2''-terpyridine; Q = quinone; X = Br, I; X' = Cl, Br). An unusually strong π-hole interaction between Cu-X and the quinoid ring is noted. Periodic DFT computations estimate the energy of the X⋯quinone interaction to be -20.79 kcal mol-1, indicating a very strong non-covalent interaction attributed to a higher degree of polarization along the bonding path. The black colour of the crystals originates from a cooperative intermolecular charge transfer between the [Cu(terpy)ClX] complex and the quinone π-system, with iodine playing a dominant role in this process by facilitating the π-hole interaction that enhances the charge transfer mechanism. All the compounds are considered to be weak semiconductors with the σDC magnitude ranging between 10-11 and 10-9 S cm-1. It is anticipated that by a smart choice of electron donors and electron acceptors, one can substantially enhance the effect and engineer more efficient conductive materials.

Syntheses and crystal structures of three tri-phenyl-sulfonium halometallate salts of zinc, cadmium and mercury

Bis(tri-phenyl-sulfonium) tetra-chlorido-zinc(II), (C18H15S)2[ZnCl4] (I), bis-(tri-phenyl-sulfonium) tetra-chlorido-cadmium(II), (C18H15S)2[CdCl4] (II), and bis-(tri-phenyl-sulfonium) tetra-chlorido-mercury(II) methanol monosolvate, (C18H15S)2[HgCl4]·CH3OH (III), each crystallize in the monoclinic space group P21/n. In all three structures, there are two crystallographically independent tri-phenyl-sulfonium (TPS) cations per asymmetric unit, each adopting a distorted trigonal-pyramidal geometry about the S atom (S-C bond lengths in the 1.77-1.80 Å range and C-S-C angles of 100-107°). The [MCl4]2- anions (M = Zn2+, Cd2+, Hg2+) are tetra-hedral; their M-Cl bond lengths systematically increase from Zn2+ to Hg2+, consistent with the larger ionic radius of the heavier metal. Hirshfeld surface analyses show that H⋯H and H⋯C contacts dominate the TPS cation environments, whereas H⋯Cl and S⋯M inter-actions anchor each [MCl4]2- anion to two surrounding TPS cations. Weak C-H⋯Cl hydrogen bonds, as well as inversion-centered π-π stacking, generate layers in (I) and (II) and dimeric [(TPS)2-HgCl4]2 assemblies in (III).

Derivatives of Pyrazole-Based Compounds as Prospective Cancer Agents

Five pyrazole-based compounds, 3,5-dimethyl-1H-pyrazole, L1; 3,5-diphenyl-1H-pyrazole, L2; 3-(trifluoromethyl)-5-phenyl-1H-pyrazole, L3; 3-(trifluoromethyl)-5-methyl-1H-pyrazole, L4; and 3,5-ditert-butyl-1H-pyrazole, L5 were synthesized from a typical condensation reaction of β-diketone derivatives with hydrazine hydrate reagent and characterized using various spectroscopic techniques such as FT-IR, UV-vis, 1H and 13C NMR, and LC-MS spectroscopy. L1 was further analyzed by single-crystal X-ray diffraction, and the N1-N1' bond distance was found to be 1.361(3) Å and correlated well with other pyrazole-based compounds. The short-term cytotoxicity of 10 μM pyrazole compounds (L1-L5) was evaluated against pancreatic (CFPAC-1 and PANC-1), breast (MDA-MB-231 and MCF-7), and cervical (CaSki and HeLa) cancer cell lines using the MTT cell viability assay. Cisplatin and gemcitabine were included as positive control drugs followed by the determination of the half-maximal effective concentrations of prospective compounds. L2 and L3, respectively, displayed moderate cytotoxicity against CFPAC-1 (61.7 ± 4.9 μM) and MCF-7 (81.48 ± 0.89 μM) cell lines.

Single-Step Synthesis of a Heterometallic [Cu2PdL4]2+ Hybrid Metal-Organic Coordination Cage

Traditional methods of assembling low-symmetry heterometallic cage architectures are limited to stepwise construction and combinations of inert and labile metal ions, affording complex, anisotropic cage structures by sacrificing synthetic ease. Herein, a heterometallic [Cu2PdL4]2+ lantern-type cage has been assembled in a single self-assembly step through the use of a heteroditopic ligand with two different metal-binding groups. The resultant cage complex is a fusion of two common lantern-type cage motifs-carboxylate-based metal-organic Cu4L4 cages and pyridyl-based Pd2L4 coordination cages. Evidence for heterometallic cage formation in solution was provided by 1H and diffusion-ordered NMR spectroscopy and electrospray ionization mass spectrometry (ESIMS) data, whereas circular dichroism (CD) spectra confirmed the helical nature of the assembly. The heterometallic cage was then exploited in binding heterotopic guests. It is envisioned that the simple design strategy presented herein will ease the assembly of other structurally complex, low-symmetry cage architectures.

Novel Derivatives of Nicotinic Acid: Synthesis, Crystal Structure, Antimicrobial Activity and Cytotoxicity

The overuse of antibiotics is one of the reasons which has led to the development of drug-resistant bacteria, which is a huge challenge for modern medicine. As well as the incidences of cancer, which are increasing every year, currently known cytostatics do not provide satisfactory therapeutic effects with many side effects. Bearing in mind these problems of modern medicine, we have synthesized new acylhydrazones with potential antibacterial and anticancer activities. The compounds were created as a result of condensation of commercially available nicotinic acid hydrazide with appropriate aldehydes. Additionally, some of them were obtained using mechanochemistry. The chemical structure of the obtained compounds was confirmed by spectral methods IR, 1H NMR and 13C NMR, and the crystal structure of selected compounds was determined by single-crystal X-ray diffraction analysis. Phase purity tests were performed for each compound. The tested compounds had very significant activity against Gram-positive bacteria and slightly worse activity against fungi from the genus Candida. The least antibacterial activity of obtained acylhydrazones was shown against Gram-negative bacterial strains. In addition to these, the compounds described did not have a toxic effect on normal cell lines.

Synthesis and Reactivity of Six-Membered Cyclic Diaryl λ3-Bromanes and λ3-Chloranes

Despite the remarkable advancements in hypervalent iodine chemistry, exploration of bromine and chlorine analogues remains in its infancy due to their difficult synthesis. Herein, we introduce six-membered cyclic λ3-bromanes and λ3-chloranes. Through single-crystal X-ray structural analyses and conformational studies, we delineate the crucial bonding patterns pivotal for the thermodynamic stability of these compounds. Notably, these investigations reveal pronounced π-π stacking phenomena within the crystal lattice of hypercoordinated bromine(III) and chlorine(III) species. Their reactivity profile is explored as they are radical precursors or electrophilic reagents in metal-free intermolecular biaryl couplings, O- and S-arylations, and Cu(I)-promoted intramolecular biaryl couplings which is complementary to the known reactivity of five-membered bromanes and chloranes. Mechanistic insights are provided, elucidating the pathways governing their reactivity and underscoring the potential in organic synthesis.

Solid-State Photoconversion of a Discrete Mixed Iodine(I) System to a 1D Polymer

The first example of a mixed halogen(I) complex (2), containing three distinct iodine(I) moieties ([N-I-N]+, O-I-N, and [O-I-O]-) within the same structure, was synthesized with 4-styrylpyridine (4-stypy) and 3,4,5,6-tetrafluorophthalate as the stabilizing Lewis bases. This complex was observed to be in equilibrium with its respective bis(OIN) complex (1a), with isolated samples of 2 also being found to convert to 1a in solution. Upon UV irradiation of 2, a single-crystal-to-single-crystal [2 + 2] cycloaddition reaction was observed, converting the discrete salt 2 to the 1D polymer 5. Complex 5 retained all the iodine(I) moieties from prior to photoconversion and represents the first example of nondestructive photoconversion of a halogen(I) complex. To facilitate comparisons to 2 and 5, several additional closely related iodine(I) complexes were synthesized, with the iodine(I) complexes characterized by NMR (1H, 1H-15N HMBC) and SCXRD, as well as by Raman and IR spectroscopy for 2, 5, and their close structural analogue 1a.

Crystal structure and Hirshfeld surface analyses, inter-molecular inter-action energies and energy frameworks of methyl 6-amino-5-cyano-2-(2-meth-oxy-2-oxoeth-yl)-4-(4-nitro-phen-yl)-4H-pyran-3-carboxyl-ate

The title compound, C17H15N3O7, contains pyran and phenyl rings, with the pyran ring exhibiting a flattened-boat conformation. In the crystal, inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into centrosymmetric dimers, forming R 2 2(12) ring motifs. These dimers are linked through N-H⋯O hydrogen bonds into a three-dimensional architecture. A Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (29.7%), H⋯H (28.7%), H⋯C/C⋯H (16.0%) and H⋯N/N⋯H (12.9%) inter-actions. In addition to van der Waals inter-actions and N-H⋯N and N-H⋯O hydrogen bonds, halogen bonds, tetrel bonds and pnictogen bonds also play an important role in the cohesion of the crystal structure.

Synthesis, crystal structure and Hirshfeld surface analysis of a propyl 4-{[1-(2-methyl-4-nitro-phen-yl)-1H-1,2,3-triazol-4-yl]meth-oxy}benzoate copper(II) chloride complex

The core of the title complex, di-chlorido-bis-(propyl 4-{[1-(2-methyl-4-nitro-phen-yl)-1H-1,2,3-triazol-4-yl]meth-oxy}benzoate)copper(II), [CuCl2(C20H20N4O5)2], which belongs to the copper(II) complex family, consists of two C20H20N4O5 ligands and two chloride ligands arranged around the metal, forming a trans-di-chlorido square-planar complex. In the crystal, the mol-ecules are linked by C-H⋯Cl and C-H⋯O hydrogen bonds as well as by aromatic π-π stacking inter-actions into a three-dimensional network. To further analyse the inter-molecular inter-actions, a Hirshfeld surface analysis was performed.

Fluorine-hydrogen inter-actions observed in a helix structure having an orn-free gramicidin S sequence incorporating 4-trans-fluoro-proline

The deca-peptide Boc-(d-Phe-tFPro-Val-Leu-Leu)2-OMe (1) (Boc is tert-but-oxy-carbonyl, tFPro is 4-trans-fluoro-l-proline d-Phe is d-phenyl-alanine, Val is valine and Leu is leucine) crystallized in a methanol-solvated form (C68H104F2N10O13·CH4O). Peptide 1 has a sequence similar to gramicidin S (GS) incorporating tFPro. GS is a cyclic peptide, with the d-Phe-Pro unit known as a strong β-turn inducer in previous studies. Thus, it was initially assumed that 1 would bend at the d-Phe6-tFPro7 position, potentially forming a sheet-like structure. However, the structure of 1 was a helix, a surprising finding in GS-related structural studies. A factor enabling this helical formation could be the fluorine-H inter-actions between tFPro and the aromatic rings of d-Phe residues.

Synthesis and crystal structure of dipotassium nickel polyphosphate

Single crystals of K2Ni(PO3)4 were obtained by solid-state reaction. The structure consists of infinite zigzag polyphosphate chains, running along the c-axis direction, linked by Ni2+ ions and delimiting large tunnels in which the K+ ions are located. Ni2+ ions form slightly distorted NiO6 octa-hedra and the coordination numbers of the independent potassium cations are 8 and 10.