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As part of our ongoing investigation on the chemical and biological properties of piperazinium salts, we synthesized three novel compounds: 1-ethyl­piperazinium 3,5-di­nitro­benzoate (I), 1-methyl­piperazinium 3,5-di­nitro­benzoate (II) and 1-methyl­piperazinium 4-iodo­benzoate (III). The crystal structures of these compounds are built up of organic layers formed by the strong connection between the mol­ecules by hydrogen bonds of type N—H...O. These layers are linked through N—H...O hydrogen bonds and C—H...O inter­actions or C—I...N halogen bonding, leading to the formation of a three-dimensional network., Funding for this research was provided by: Spanish Ministerio de Ciencia e Innovacion (grant No. PID2020-113558RB-C41 to Santiago Garcia-Granda); Gobierno del Principado de Asturias (grant No. GRUPIN-ID2018-170 to Santiago GarciaGranda); University of Mysore (grant to Sriramapura D. Archana); Darmstadt University of Technology (studentship to Hemmige S. Yathirajan).

New NZP-type solid solutions, Na1+2xZr2–xNix(PO4)3 and Ca0.5+xZr2–xNix(PO4)3 with x = 0.10, 0.25, and 0.50, have been prepared by solid-state reactions. The synthesized samples have been characterized by X-ray diffraction and IR spectroscopy. Crystal structure of the compound CaZr1.5Ni0.5(PO4)3 has been refined by full-profile X-ray diffraction analysis method, reliability factors is Rp = 4.78% and Rwp = 6.45%, respectively. Thermal expansion of the phosphates has been studied by high-temperature X-ray diffraction in the temperature range 25–700°C. The synthesized compounds have been shown to be intermediate- and low-thermal-expansion materials. Using SPS method we have produced ceramic samples with a high relative density (ρrel > 97%), based on phosphate powders. Strength characteristics (microhardness and fracture toughness) of the ceramics have been determined.

In spite of the enormous promise that polymeric carbon nitride (PCN) materials hold for various applications, the fabrication of high-quality, binder-free PCN films and electrodes has been a largely elusive goal to date. Here, we tackle this challenge by devising, for the first time, a water-based sol−gel approach that enables facile preparation of thin films based on poly(heptazine imide) (PHI), a polymer belonging to the PCN family. The sol−gel process capitalizes on the use of a water-soluble PHI precursor that allows formation of a non-covalent hydrogel. The hydrogel can be deposited on conductive substrates, resulting in formation of mechanically stable polymeric thin layers. The resulting photoanodes exhibit unprecedented photoelectrochemical (PEC) performance in alcohol reforming and highly selective (∼100 %) conversions with very high photocurrents (>0.25 mA cm−2 under 2 sun) down to, This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–Projektnummer 364549901–TRR 234 [Projects B6, B7, C2, C4 and Z2] and BE 5102/5-1. C.N and A.T. acknowledge financial support of the DFG through the project TU 149/8-2 “Towards photo-active membranes for artificial photosynthesis” as well as the DFG through a research infrastructure grant INST 275/257-1 FUGG. S.G.G. acknowledges support by Spanish MINECO (MAT2016-78155-C2-1-R) and Gobierno del Principado de Asturias (GRUPIN-ID2018-170). L.d.S.G. acknowledges Juan de la Cierva Formación scholarship. I.K. acknowledges the support of the Alexander von Humboldt Foundation through the Humboldt Research Fellowship. Open access funding enabled and organized by Projekt DEAL.

Thermal analysis confirmed the presence of the phase transition at T = 320 K in the Cs2SeO4·H6TeO6 (CsSeTe) material. The structural study carried out at T = 360 K shows that this compound passes from the monoclinic system with the space group P21/c at room temperature, to the trigonal system with the space group R3¯m. At room temperature, the anionic groups are well ordered and stable, whereas after the transition at T = 320 K, the selenate groups change their orientation and the tellurate polyhedra change their positions. The high-temperature vibrational studies, carried out in a temperature range of 289–353 K, confirm the presence and nature of the transition detected by thermal analysis. The conductivity evolution versus temperature shows the presence of an ionic–protonic conduction phase transition at T = 490 K., This work is supported by the Ministry of the Higher Education and Research of Tunisia.

A new triazolic compound 4,5-diamino-3-methyl-4H-1,2,4-triazol-1-ium nitrate (DAMT·HNO3) is synthesized and characterized by elemental analysis, FTIR, 1H NMR spectroscopy, and single crystal X-ray diffraction along with thermal analyses (TGA/DSC). The X-ray analysis of the compound reveals triazolium nitrate salt with a new tautomeric form. Among different N-H…X bonds (X = C, N, O), the N-H…O ones form R 22(4), R 42(8), R 44(18), R 24(14), and R 21(4) hydrogen bond motifs. The crystal network of DAMT·HNO3 is also stabilized by π-π stacking interactions between triazole rings. Thermal studies reveal that this compound has a good thermal stability and can release a considerable amount of heat at the first decomposition step. Further, the thermal properties of this compound are compared with its chloride salt analogue DAMT·HCl. The thermodynamic stability of DAMT·HNO3 is studied by DFT calculations and compared with those of DAMT·HCl and DAMT. The ability of these compounds to interact with a DNA molecule is investigated by docking studies., We acknowledge the financial support from Spanish Ministerio de Economía y Competitividad (MAT2016-78155-C2-1-R and FPI grant BES-2011-046948 to MSM.A.) and FEDER funding.

A new bis(benzamidinium)tetrachloridomercurate(II) monohydrate, (C7H9N2)2[HgCl4]·H2O, was synthesized by slow evaporation at room temperature and characterized by powder XRD, IR, Raman, UV-vis spectroscopy and thermal analysis. Single-crystal X-ray diffraction analysis indicates that the asymmetric unit of the title compound is formed by tetrachloridomercurate [HgCl4]2− anion, a protonated organic cation (C7H9N2)2+ and one free water crystallization molecule. The cohesion of the structure is insured by N–H···Cl, O–H···Cl and N–H ···O hydrogen bonds and π-π stacking interactions. The density functional theory (DFT)-optimized structure at the B3LYP/6-311++G(2d,2p) level is compared with the experimentally determined molecular structure. Comprehensive experimental and theoretical structural studies on the compound are carried out through IR and UV-vis spectroscopies. The compound was characterized by thermal analysis to determine its thermal behavior with respect to the temperature. The in vitro antibacterial activity of the compound against different bacterial strains was evaluated. The three-dimensional Hirshfeld surface (3 D-HS) and the two-dimensional fingerprint plots (2 D-FP) reveal that the structure is dominated by H···Cl/Cl···H (51.0%) and H···H (32.3%) contacts., Financial support from the Ministry of Higher Education, Scientific Research and Technology of Tunisia, Spanish Ministerio de Economía y Competitividad (MAT2016-78155-C2-1-R) and Gobierno del Principado de Asturias (GRUPIN-IDI/2018/170) is gratefully acknowledged.

A novel organic–inorganic hybrid compound based on iron fluoride, formulated as (H2Piper)4 [(FeF6)2FeF5(H2O)(H2O)4] (Piper = Piperazine), C1, has been synthesized through hydrothermal method and characterized by X-ray single-crystal diffraction, thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) and dielectric measurements. Single-crystal X-ray study demonstrated that C1 crystallizes in P̅1 space group with lattice parameters: a = 12.5535(5) Å, b = 12.8715(4) Å, c = 22.2774(8) Å, α = 92.321(3)°, β = 95.957 (3)°, γ = 91.946(3)°, V = 3574.6 Å3 and Z = 4. In the molecular arrangement, [FeF6]3- and [FeF5(H2O)]2- anions are connected to [H2Piper]2+ cations and free water molecules through hydrogen bonds (O–H⋅⋅⋅F and N–H⋅⋅⋅F) generating 3D network. Thermal analysis (DSC and TG) of C1 confirmed the presence of two phase transitions as well as the temperature of the decomposition of the hybrid material. The complex impedance of C1 was investigated in the temperature range 410–530 K and in the frequency range 200–2.106 Hz. Additionally, an electrical equivalent circuit was reported to explain the impedance results. The variation of the dc and ac conductivity corroborated two phase transitions of the title compound. Furthermore, the frequency dependence of alternative current (ac) conductivity was interpreted in terms of Jonscher's law. The alternative current (ac) electrical conduction in C1 material was accounted for in terms of two processes that can be assigned to the hopping transport mechanism (CBH and NSPT model). The temperature dependences of dielectric permittivity indicated a relaxation process and highlighted the good protonic conduction of this material., The Minister of Superior Education and Research of Tunisia and Spanish Ministerio de Ciencia e Innovación (PID2020-113558RB-C41) and Red CrysFact (Red2018-102574-T (AEI/MCI)) are acknowledged.

This article belongs to the Special Issue Molecular Simulations Applications in Biochemistry and Molecular Biology., The solid-state structural analysis and docking studies of three adamantane-linked 1,2,4-triazole derivatives are presented. Crystal structure analyses revealed that compound 2 crystallizes in the triclinic P-1 space group, while compounds 1 and 3 crystallize in the same monoclinic P21/c space group. Since the only difference between them is the para substitution on the aryl group, the electronic nature of these NO2 and halogen groups seems to have no influence over the formation of the solid. However, a probable correlation with the size of the groups is not discarded due to the similar intermolecular disposition between the NO2/Cl substituted molecules. Despite the similarities, CE-B3LYP energy model calculations show that pairwise interaction energies vary between them, and therefore the total packing energy is affected. HOMO-LUMO calculated energies show that the NO2 group influences the reactivity properties characterizing the molecule as soft and with the best disposition to accept electrons. Further, in silico studies predicted that the compounds might be able to inhibit the 11β-HSD1 enzyme, which is implicated in obesity and diabetes. Self- and cross-docking experiments revealed that a number of non-native 11β-HSD1 inhibitors were able to accurately dock within the 11β-HSD1 X-ray structure 4C7J. The molecular docking of the adamantane-linked 1,2,4-triazoles have similar predicted binding affinity scores compared to the 4C7J native ligand 4YQ. However, they were unable to form interactions with key active site residues. Based on these docking results, a series of potentially improved compounds were designed using computer aided drug design tools. The docking results of the new compounds showed similar predicted 11β-HSD1 binding affinity scores as well as interactions to a known potent 11β-HSD1 inhibitor., This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Research Groups Program (Grant No. RGP-1442-0010-4).

A novel hybrid material, [C10H22N2]3·PbCl5·3Cl·3H2O, has been synthesized and its structure was determined by single-crystal X-ray diffraction. In the atomic arrangement, the different entities are held together through NH⋯Cl, OH⋯Cl and OH⋯O hydrogen bonds to form a three-dimensional network. Intermolecular interactions were investigated by Hirshfeld surfaces. The powder XRD data confirms the phase purity of the crystalline sample. The resulting IR spectrum calculated by the DFT/B3LYP/LanL2DZ method, is similar to the experimental spectrum allowing a good correlation between the experimental and theoretical wavenumbers. The optical properties in the UV–visible region have been explored by the UV–visible absorption. The photoluminescence (PL) spectroscopy, which was investigated at room temperature, exhibited one emission at 426 nm. Thermal analysis discloses a phase transition at 435 K and the decomposition of the sample starts from 554 K., Financial support from Spanish MINECO (MAT2016-78155-C2-1-R, MAT2013-40950-R, and FPI grant BES-2011-046948 to MSM.A.), Gobierno del Principado de Asturias (GRUPIN14-060), FEDER, and the Secretary of State for Scientific Research and Technology of Tunisia, are acknowledged.

Anion complexes of the cryptand built with the tripodal amine tris(2-aminoethyl)amine, known as tren, with water and several oxoanions of biological and environmental interest (nitrate, sulfate, phosphate, perchlorate and arsenate) have been crystallized from aqueous solution and resolved with single-crystal X-ray diffraction. All crystals show guest species encapsulated in the interior of the cavity as well as, in some cases, sitting in the grooves defined by the arms of the macrocycle. Hydrogen bonding and electrostatic interactions play a major role in anion binding to the host. The macrocycle is able to encapsulate anions in a wide range of protonation degrees. Solution studies have been carried out to show that those interactions happen also in solution in addition to the solid state. The results show that the receptor binds consistently to the ligand in a wide range protonation degrees., Financial support by the Spanish Ministerio de Economía y Competitividad (projects CTQ2016-78499-C6-1-R, Unidad de Excelencia MDM 2015-0038 and CTQ2017-90852-REDC) and Generalitat Valenciana (Project PROMETEOII2015-002) is gratefully acknowledged. S. B. thanks MINECO for a Juan de la Cierva postdoctoral grant.

A selective triazole-based COX-2 inhibitor, 4-(4-chlorophenyl)-3-[(4-fluorobenzyl)sulfanyl]-5-(thiophen-2-yl)-4H-1,2,4-triazole, C19H13ClFN3S2, has been synthesized, and its crystal structure was determined at 150 K. Single-crystal X-ray diffraction analysis revealed that the thiophene ring was disordered over two orientations. The crystal structure is stabilized by weak hydrogen and chalcogen bonds and unorthodox F···π and S···C(π) contacts. These noncovalent interactions cooperatively generate the supramolecular self-assembly in the crystalline state. The Hirshfeld surface and its associated two-dimensional (2D)-fingerprint plots were obtained to analyze the role of different noncovalent interactions in the crystal packing. Further, the enrichment ratio was obtained from different atom···atom pairs to calculate the propensity of these pairs to form noncovalent interactions. The strength of different dimeric motifs formed in the crystal structure and lattice energies was calculated by the PIXEL method. Furthermore, the topological analysis of the charge density of intermolecular interactions was described. A CSD survey of C–H···F hydrogen bond, C–S···Cl chalcogen bond, and unorthodox nonbonded contacts (F···π and S···C(π)) is presented. The title compound possesses selective inhibitory activity against human COX-2 enzyme rather than COX-1. The quantum mechanics (QM) polarized ligand docking analysis was used to predict the binding pose and study the title compound’s selectivity against COX-1/2 enzymes., This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Research Groups Program (grant no. RGP-1442-0010-4). S.T. and M.J.P. thank Laboratorio Nacional de Supercomputo del Sureste (LNS-BUAP) for computational resources.

A novel pyrazole-based Co(II) complex, namely dichloro-tetrakis(1H-pyrazole)-cobalt(II), was synthesized and characterized. Its X-ray crystal structure showed that it crystallizes in the monoclinic C2/c space group with discrete [CoPz4Cl2] units held together via intra- and intermolecular hydrogen bonds. The non-covalent interactions were explicitly analyzed by means of the topological and Hirshfeld surface analyses, revealing the presence of 0-periodic binodal 1,6-connected 1,6M7–1 and 14-connected uninodal bcu–x topologies built up through N—H…Cl and C—H…Cl hydrogen-bonding networks in addition to weak non-classical H…H, Nsingle bondH…C, Csingle bondH…N, N—H…π, π…lp/lp…π and lp…lp interactions. Additionally, interactions energy and energy frameworks analyses were performed in order to compute the total energies of the possible intermolecular interactions. The empty space in the crystal lattice was analyzed using void mapping which lead to the presence of small cavities. The structure was furthermore optimized showing a very good agreement with the experimental results, the molecular electrostatic potential (MEP) maps were obtained with their active regions and the non-linear optical properties estimated. Additionally, the optical properties of the title complex were investigated at room temperature using optical UV-visible absorption and photoluminescence spectroscopy, exhibiting π → π*, n → π*, d → d and ligand-field transitions which result in a large variety of emission bands predominant by a bright red photoluminescence. An in silico study was carried out and the binding ability of the title complex with Staphylococcus aureus tyrosyl-tRNA synthetase and Pyrococcus kodakaraensis aspartyl-tRNA synthetase was evaluated displaying a good inhibition activity towards the last one., Funding was provided by the General Direction of research and development technologies/Ministry of Higher Education and Research Sciences DGRSDT/MESRS, Algeria. The financial support from Abbes Laghrour University of Khenchela (Algeria), TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure), Spanish MINECO (MAT2016–78155-C2–1-R), Gobierno del Principado de Asturias (GRUPIN-IDI/2018/000170) are acknowledged. This work is supported by the Scientific Research Project Fund of Sivas Cumhuriyet University under the project number RGD-020.

CoxNi3-xP2O8 (0 ≤ x ≤ 3) solid solutions were synthesized via the chemical co-precipitation method. Variation of unit cell parameters and interatomic distances indicated that these solid solutions with the Ni3P2O8 structure are stable between 800 and 1200 °C in compositions with 0 ≤ x ≤ 1.5 and between 800 and 1000 °C when (0 ≤ x ≤ 3). When (2.5 ≤ x ≤ 3.0), the solid solutions lead to the Co3P2O8 structure, being stable between 800 and 1000 °C. The yellow colour of the Ni3P2O8 compound changes to pink or red when Co(II) ions are incorporated in the structure as Ni3P2O8 solid solutions are formed. Bands corresponding to second and third electronic transitions of the Co(II) ions in octahedral coordination appear in the 450–600 nm in the UV-V spectra, and they are responsible of the observed changes in the colour. Absorbance in the visible spectra was also obtained from enamelled samples but a new band at 650 nm with considerable absorbance when x > 1.0 increased the blue amount, and colour of the enamelled samples was yellowish brown, brown, green and blue., We gratefully acknowledge the financial support provided by Spain's Ministerio de Ciencia, Innovación y Universidades, project MAT2016-78155-C2-1-R.