The utility of Hibiscus sabdariffa L. to prepare metal oxides NPs for clinical application on osteoporosis supported by theoretical study.

Green synthesis of metal oxides as a treatment for bone diseases is still exploring. Herein, MgO and Fe2O3 NPs were prepared from the extract of Hibiscus sabdariffa L. to study their effect on vit D3, Ca+2, and alkaline phosphatase enzyme ALP associated with osteoporosis. Computational chemistry was utilized to gain insight into the possible interactions. These oxides were characterized by X-ray diffraction, SEM, FTIR, and AFM. Results revealed that green synthesis of MgO and Fe2O3 NPs was successful with abundant. MgO NPs were in vitro applied on osteoporosis patients (n = 35) and showed a significant elevation of vit D3 and Ca+2 (0.0001 > p < 0.001) levels, compared to healthy volunteers (n = 25). Thus, Hibiscus sabdariffa L. is a good candidate to prepare MgO NPs, with a promising enhancing effect on vit D3 and Ca+2 in osteoporosis. In addition, interactions of Fe2O3 and MgO NPs with ALP were determined by molecular docking study.

Experimental and density functional theory studies on some metal oxides and the derived nanoclusters: a comparative effects on human ferritin.

A comprehensive investigation into the green synthesis of metal oxide nanoparticles (NPs) has garnered significant attention due to its commendable reliability, sustainability, and environmentally friendly attributes. Green synthesis methods play a crucial role in mitigating the adverse effects associated with conventional approaches employed for nanostructure preparation. This research endeavors to examine the impact of ginger plant extract-assisted green synthesis of metal oxides NPs on the serum ferritin levels of anemic diabetic patients in vitro, focusing specifically on α-Fe2O3 and ZnO NPs. Sixty diabetic volunteers with anemia (35-50 years) and thirty healthy volunteers were enrolled as controls. The assessment was conducted using the VIDAS Ferritin (FER) assay. Photoluminescence (PL) spectroscopy measurements were performed to elucidate the intrinsic and extrinsic transitions of these NPs, affirming the successful formation of α-structured iron oxide. Density functional theory (DFT) calculations were carried out at the B3LYP/6-311++G(d,2p) level of theory to investigate the geometry optimization and molecular electrostatic potential maps of the NPs. Furthermore, TD-DFT calculations were employed to explore their frontier molecular orbitals and various quantum chemical parameters. The binding affinity and interaction types of ZnO and α-Fe2O3 NPs to the active site of the human H-Chain Ferritin (PDB ID: 2FHA) target were determined with the help of molecular docking. Results unveiled the crystalline structure of ZnO and the α-structure of α-Fe2O3. Analysis of the frontier molecular orbitals and dipole moment values demonstrated that ZnO (total dipole moment (D) = 5.80 µ) exhibited superior chemical reactivity, biological activity, and stronger molecular interactions with diverse force fields compared to α-Fe2O3 (D = 2.65 µ). Molecular docking of the metal oxides NPs with human H-chain ferritin provided evidence of robust hydrogen bond interactions and metal-acceptor bonds between the metal oxides and the target protein. This finding could have a great impact on using metal oxides NPs-ferritin as a therapeutic protein, however, further studies on their toxicity are required.

Synthesis, crystal structure, potential drug properties for Coronavirus of Co(II) and Zn(II) 2-chlorobenzoate with 3-cyanopyridine complexes.

Two new complexes of Co(II) and Zn(II) 2-chlorobenzoate (2-ClBA) with 3-cyanopyridine (CNP) of the general formula [Co(2-ClBA)2(CNP)2(H2O)2] and [Zn(2-ClBA)2(CNP)2(H2O)2] were synthesized. The structures of the complexes were characterized by single crystal XRD and FT-IR and NMR spectroscopy and Mass Spectrometry (MALDI-TOF MS) methods. Mononuclear complexes exhibit octahedral coordination. In addition, Hirshfeld surface analysis was performed to determine non-covalent interactions in crystal packing. The geometry optimization of the molecules was carried out using the LANL2DZ level of theory of the DFT method and the obtained findings were confirmed by comparing with the data obtained from the single crystal X-ray diffraction method. The theoretical and experimental bond angles and lengths are very close to each other. The effectiveness of the complexes against SARS-CoV-2 enzymes was investigated in silico using the molecular docking method, and a binding score of -8.0 kcal/mol on NSP16 of complex 1 as an inhibitor was obtained. To investigate the drug potential of the complexes, their pharmacokinetic and toxicokinetic properties were estimated by ADMET calculations.

Synthesis and Crystallographic, Absorption and Emission Studies of 4-Pyridine Carboxamide of Zn(II) 4-Chlorophenylacetate.

A new zinc(II) complex, [Zn(CB)2(INA)2] (where CB is 4-chlorophenylacetate and INA is 4-pyridine carboxamide) was synthesized. The structure of the complex was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction technique. Besides, the thermal stability of the complex was investigated by TGA/DTA analysis method. Moreover, the optical absorption and the emission features of the complex were examined by using UV-Vis and fluorescence spectrophotometers, respectively. Furthermore, Density Functional Theory (DFT) calculations were carried out to support the experimental results. Accordingly, it was determined that the complex crystallized in a monoclinic system with space group Pc, a = 8.3329 (2) Å, b = 25.6530 (4) Å, c = 13.5048 (3) Å, α = 90°, ß = 91.703 (3)° and γ = 90°. The complex consists two crystallographically independent molecules. In each molecule, the ZnII ion adopts a distorted trigonal pyramidal coordination formed by two O atoms from the two 4 chlorophenylacetate ligand and two N atoms of the two 4-pyridine carboxamide ligands. It was observed that the linear absorption spectra of the complex were similar to linear absorption spectra of the semiconductors. In addition, two emission peaks were observed in the fluorescence spectra which could be due to the formation of excimer and the interactions of the benzene and pyridine rings. The energy gap (ΔEgap = ELUMO - EHOMO) of the complex has been calculated as 3.712 eV and this value is very close to the experimentally measured value (3.86 eV). Therefore, because of higher fluorescence intensity of emission peak that was observed between 309 and 556 nm wavelength besides other traits, the complex could potentially be used in the blue light OLED application by filtering of the emission peak around 710 nm wavelength. Graphical Abstract It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. The fluorescence measurements showed that these materials are much suitable for application area of the detection of nitroaromatic explosives. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results. It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results.

Crystal structure and Hirshfeld surface analysis of aqua-bis-(nicotinamide-κN1)bis-(2,4,6-tri-methyl-benzoato-κ2O,O')cadmium(II).

The asymmetric unit of the title complex, [Cd(C10H11O2)2(C6H6N2O)2(H2O)], contains one half of the complex mol-ecule, with the CdII cation and the coordinated water O atom residing on a twofold rotation axis. The CdII cation is coordinated in a bidentate manner to the carboxyl-ate O atoms of the two symmetry-related 2,4,6-tri-methyl-benzoate (TMB) anions and to the water O atom at distances of 2.297 (2), 2.527 (2) and 2.306 (3) Što form a distorted penta-gonal arrangement, while the distorted penta-gonal-bipyramidal coordin-ation sphere is completed by the two pyridine N atoms of the two symmetry-related monodentate nicotinamide (NA) ligands at distances of 2.371 (3) Šin the axial positions. In the crystal, mol-ecules are linked via inter-molecular N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds with R22(12), R33(8), R33(14), R33(16), R33(20), R33(22), R44(22), R55(16), R66(16) and R66(18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are H⋯H (56.9%), H⋯C/C⋯H (21.3%) and H⋯O/O⋯H (19.0%) inter-actions.

Crystal structure and Hirshfeld surface analysis of di-aqua-bis-(N,N-di-ethyl-nicotinamide-κN1)bis-(2,4,6-tri-methyl-benzoato-κO)manganese(II).

In the title centrosymmetric complex, [Mn(C10H11O2)2(C10H14N2O)2(H2O)2], the MnII cation is located on an inversion centre. The four O atoms form a slightly distorted square-planar arrangement around the MnII cation, and the distorted octa-hedral coordination is completed by two pyridine N atoms at distances of 2.3289 (15) Å. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 87.73 (16)°, while the benzene and pyridine rings are oriented at a dihedral angle of 43.03 (8)°. In the crystal, the water mol-ecules are involved in both intra-molecular (to the non-coordinating carboxyl-ate O atom) and inter-molecular (to the amide carbonyl O atom) O-H⋯O hydrogen bonds. The latter lead to the formation of layers parallel to (100). These layers are further linked via weak C-H⋯O hydrogen bonds, resulting in a three-dimensional supra-molecular network. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (70.0%), H⋯O/O⋯H (15.5%) and H⋯C/C⋯H (14.0%) inter-actions. One of the ethyl groups of the di-ethyl-nicotinamide ligand is disordered over two sets of sites, with an occupancy ratio of 0.282 (10):0.718 (10).

Crystal structure and Hirshfeld surface analysis of aqua-bis-(nicotinamide-κN)bis-(4-sulfamoylbenzoato-κO1)copper(II).

In the crystal of the title complex, [Cu(C7H6NO4S)2(C6H6N2O)2(H2O)], the CuII cation and the O atom of the coordinated water mol-ecule reside on a twofold rotation axis. The CuII ion is coordinated by two carboxyl-ate O atoms of the two symmetry-related 4-sulfamoylbenzoate (SB) anions and by two N atoms of the two symmetry-related nicotinamide (NA) mol-ecules at distances of 1.978 (2) and 2.025 (3) Å, respectively, forming a slightly distorted square-planar arrangement. The distorted square-pyramidal coordination environment is completed by the water O atom in the axial position at a distance of 2.147 (4) Å. In the crystal, the mol-ecules are linked via O-H⋯O and N-H⋯O hydrogen bonds with R22(8) and R22(18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (42.2%), H⋯H (25.7%) and H⋯C/C⋯H (20.0%) inter-actions.

Crystal structure and Hirshfeld surface analysis of hexa-kis-(µ-benzoato-κ2O:O')bis-(pyridine-3-carbo-nitrile-κN1)trizinc(II).

The asymmetric unit of the title complex, [Zn3(C7H5O2)6(C6H4N2)2], contains one half of the complex mol-ecule, i.e. one and a half ZnII cations, three benzoate (Bnz) and one pyridine-3-carbo-nitrile (Cpy) mol-ecule; the Bnz anions act as bidentate ligands through the carboxyl-ate O atoms, while the Cpy ligand acts as a monodentate N(pyridine)-bonding ligand. The complete centrosymmetric trinuclear complex thus comprises a linear array of three ZnII cations. The central ZnII cation shows an octa-hedral coordination and is bridged to each of the terminal ZnII cations by three Bnz anions. By additional coordination of the CPy ligand, the terminal ZnII cations adopt a trigonal-pyramidal coordination environment. In the crystal, the Bnz anions link to the Cpy N atoms via weak C-H⋯N hydrogen bonds, forming a two-dimensional network. C-H⋯π and π-π inter-actions [between the benzene and pyridine rings of adjacent mol-ecules with an inter-centroid distance of 3.850 (4) Å] help to consolidate a three-dimensional architecture. The Hirshfeld surface analysis confirms the role of H-atom contacts in establishing the packing.

Crystal structure and Hirshfeld surface analysis of di-aqua-bis-(isonicotinamide-κN)bis-(2,4,6-tri-methyl-benzoato-κO1)nickel(II) dihydrate.

In the title NiII complex, [Ni(C10H11O2)2(C6H6N2O)2(H2O)2]·2H2O, the divalent Ni ion occupies a crystallographically imposed centre of symmetry and is coordinated by two O atoms from the carboxyl-ate groups of two 2,4,6-tri-methyl-benzoate (TMB) ligands [Ni-O = 2.0438 (12) Å], two N atoms from the pyridyl groups of two isonicotinamide (INA) ligands [Ni-N = 2.1506 (15) Å] and two water mol-ecules [Ni-O = 2.0438 (12) Å] in a slightly distorted octa-hedral geometry. The coordinating water mol-ecules are hydrogen bonded to the non-coordinating carboxyl-ate O atom of the TMB ligand [O⋯O = 2.593 (3) Å], enclosing an S(6) hydrogen-bonding motif. Two solvent water mol-ecules are also present in the formula unit. In the crystal, a network of inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the complexes into a three-dimensional array. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (59.8%), O⋯H/H⋯O (20.2%) and C⋯H/H⋯C (13.7%) inter-actions.

Crystal structure and Hirshfeld surface analysis of aqua-bis-(nicotinamide-κN1)bis-(2,4,6-tri-methyl-benzoato-κO)zinc.

The asymmetric unit of the title complex, [Zn(C10H11O2)2(C6H6N2O)2(H2O)], contains one half of the complex mol-ecule, and the ZnII cation and the water O atom lie on a twofold rotation axis. The ZnII cation is coordinated by two carboxyl-ate O atoms of the two symmetry-related 2,4,6-tri-methyl-benzoate (TMB) anions and by the water O atom at distances of 2.0311 (16) and 2.076 (2) Što form a slightly distorted trigonal-planar arrangement, while the distorted trigonal-bipyramidal coordination sphere is completed by the two pyridine N atoms of the two symmetry-related monodentate nicotinamide (NA) ligands at distances of 2.2066 (19) Šin the axial positions. In the crystal, mol-ecules are linked via inter-molecular N-H⋯O and O-H⋯O hydrogen bonds with R22(12), R33(10) and R33(16) ring motifs, forming a double-column structure running along the c-axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (58.4%), H⋯C/C⋯H (20.3%) and H⋯O/O⋯H (18.3%) inter-actions.

Crystal structure of catena-poly[[[di-aqua-bis-(2,4,6-tri-methyl-benzoato-κO)cobalt(II)]-µ-aqua-κ2O:O] dihydrate].

The asymmetric unit of the title one-dimensional polymeric compound, {[Co(C10H11O2)2(H2O)3]·2H2O} n , contains one CoII cation situated on a centre of inversion, one-half of a coordinating water mol-ecule, one 2,4,6-tri-methyl-benzoate (TMB) anion together with one coordinating and one non-coordinating water mol-ecule; the TMB anion acts as a monodentate ligand. In the anion, the carboxyl-ate group is twisted away from the attached benzene ring by 84.9 (2)°. The CoII atom is coordinated by two TMB anions and two water mol-ecules in the basal plane, while another water mol-ecule bridges the CoII atoms in the axial directions, forming polymeric chains running along [001]. The coordination environment for the CoII cation is a slightly distorted octa-hedron. The coordinating and bridging water mol-ecules link to the carboxyl-ate groups via intra- and inter-molecular O-H⋯O hydrogen bonds, enclosing S(6) ring motifs, while the coordinating, bridging and non-coordinating water mol-ecules link to the carboxyl-ate groups and the coordinating water mol-ecules link to the non-coordinating water mol-ecules via O-H⋯O hydrogen bonds, enclosing R22(8) and R33(8) ring motifs. Weak C-H⋯O and C-H⋯π inter-actions may further stabilize the crystal structure.

Crystal structure of bis-(µ-3-nitro-benzoato)-κ3O,O':O;κ3O:O,O'-bis-[bis-(3-cyano-pyridine-κN1)(3-nitro-benzoato-κ2O,O')cadmium].

The asymmetric unit of the title compound, [Cd2(C7H4NO4)4(C6H4N2)4], contains one CdII atom, two 3-nitro-benzoate (NB) anions and two 3-cyano-pyridine (CPy) ligands. The two CPy ligands act as monodentate N(pyridine)-bonding ligands, while the two NB anions act as bidentate ligands through the carboxyl-ate O atoms. The centrosymmetric dinuclear complex is generated by application of inversion symmetry, whereby the CdII atoms are bridged by the carboxyl-ate O atoms of two symmetry-related NB anions, thus completing the distorted N2O5 penta-gonal-bipyramidal coordination sphere of each CdII atom. The benzene and pyridine rings are oriented at dihedral angles of 10.02 (7) and 5.76 (9)°, respectively. In the crystal, C-H⋯N hydrogen bonds link the mol-ecules, enclosing R22(26) ring motifs, in which they are further linked via C-H⋯O hydrogen bonds, resulting in a three-dimensional network. In addition, π-π stacking inter-actions between parallel benzene rings and between parallel pyridine rings of adjacent mol-ecules [shortest centroid-to-centroid distances = 3.885 (1) and 3.712 (1) Å, respectively], as well as a weak C-H⋯π inter-action, may further stabilize the crystal structure.

Crystal structure of trans-di-aqua-bis-(4-cyano-benzoato-κO)bis-(N,N-di-ethyl-nicotinamide-κN)cadmium.

The mononuclear title cadmium complex, [Cd(C10H14N2O)2(C8H4NO2)2(H2O)2], is centrosymmetric and contains two water mol-ecules, two 4-cyanobenzoate (CB) ligands and two di-ethyl-nicotinamide (DENA) ligands. All the ligands are coordinated to the CdII atom in a monodentate mode. The four nearest O atoms around the CdII atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination sphere being completed by the two pyridine N atoms of the DENA ligands at distances of 2.3336 (13) Å. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 8.75 (16)°, while the benzene and pyridine rings are oriented at a dihedral angle of 57.83 (5)°. The water mol-ecules exhibit both intra-molecular [to the non-coordinating carboxyl-ate O atom, enclosing an S(6) hydrogen-bonding motif, where O⋯O = 2.670 (2) Å] and inter-molecular [to the amide carbonyl O atom, enclosing an R22(16) ring motif, where O⋯O = 2.781 (2) Å] O-H⋯O hydrogen bonds. The latter lead to the formation of supra-molecular chains propagating along [110].

Crystal structure of trans-di-aqua-bis-(4-cyano-benzoato-κO)bis-(N,N-di-ethyl-nicotinamide-κN)zinc(II).

In the title complex, [Zn(C8H4NO2)2(C10H14N2O)2(H2O)2], the ZnII cation, located on an inversion centre, is coordinated by two water mol-ecules, two 4-cyano-benzoate (CB) anions and two di-ethyl-nicotinamide (DENA) ligands in a distorted N2O4 octa-hedral geometry. In the mol-ecule, the dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 9.50 (14)°, while the benzene and pyridine rings are oriented at a dihedral angle of 56.99 (5)°. The water mol-ecules exhibit both an intra-molecular hydrogen bond [to the non-coordinating carboxyl-ate O atom, enclosing an S(6) hydrogen-bonding motif, where O⋯O = 2.6419 (19) Å] and an inter-molecular hydrogen bond [to the amide carbonyl O atom, enclosing an R22(16) ring motif, where O⋯O = 2.827 (2) Å]; the latter lead to the formation of supra-molecular chains propagating along the [110] direction.

Crystal structure of di-aqua-bis-(4-tert-butyl-benzoato-κO)bis-(nicotinamide-κN (1))cobalt(II) dihydrate.

The asymmetric unit of the mononuclear cobalt complex, [Co(C11H13O2)2(C6H6N2O)2(H2O)2]·2H2O, contains one half of the complex mol-ecule, one coordinating and one non-coordinating water mol-ecule, one 4-tert-butyl-benzoate (TBB) ligand and one nicotinamide (NA) ligand; the Co atom lies on an inversion centre. All ligands coordinating to the Co atom are monodentate. The four nearest O atoms around the Co atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination completed by the two pyridine N atoms of the NA ligands at distances of 2.1638 (11) Å. The coordinating water mol-ecules are hydrogen bonded to the carboxyl O atoms [O ⋯ O = 2.6230 (17) Å], enclosing an S(6) hydrogen-bonding motif, while inter-molecular O-H⋯O hydrogen bonds link two of the non-coordinating water mol-ecules to the coordinating water mol-ecules and NA anions. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 29.09 (10)°, while the benzene and pyridine rings are oriented at a dihedral angle of 88.53 (4)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, enclosing R 2 (2)(8), R 2 (2)(10) and R 4 (4)(12) ring motifs, forming layers parallel to (001). The C and H atoms of the tert-butyl group of the TBB ligand are disordered over two sets of sites with an occupancy ratio of 0.631 (5):0.369 (5).

Crystal structure of catena-poly[[aqua-bis-(4-cyano-benzoato-κO)copper(II)]-µ-N,N-di-ethyl-nicotinamide-κ(2) N (1):O].

The asymmetric unit of the title polymeric compound, [Cu(C8H4NO2)2(C10H14N2O)(H2O)] n , contains one Cu(II) atom, one coordinating water mol-ecule, two 4-cyano-benzoate (CB) ligands and one coordinating N,N-di-ethyl-nicotinamide (DENA) mol-ecule. The DENA ligand acts as a bis-monodentate ligand, while the CB anions are monodentate. Two O atoms of the CB ligands, one O atom of the water mol-ecule and the pyridine N atom of the DENA ligand form a slightly distorted square-planar arrangement around the Cu(II) atom which is completed to a square-pyramidal coordination by the apically placed O atom of the DENA ligand, with a Cu-O distance of 2.4303 (15) Å. In the two CB anions, the carboxyl-ate groups are twisted relative to the attached benzene rings by 2.19 (12) and 3.87 (15)°, while the benzene rings are oriented at a dihedral angle of 5.52 (8)°. The DENA ligands bridge adjacent Cu(2+) ions, forming polymeric coordination chains running along the b axis. In the crystal, strong water-carboxyl-ate O-H⋯O hydrogen bonds link adjacent chains into layers parallel to (10-1) and weak C-H⋯O hydrogen bonds further stabilize the crystal structure. The cyano group C and N atoms of one of the CB ligands are disordered over two sets of sites with equal occupancies.

Crystal structure of di-aqua-bis-(N,N-di-ethyl-nicotinamide-κN (1))bis-(2,4,6-tri-methyl-benzoato-κO (1))cobalt(II).

The centrosymmetric mol-ecule in the monomeric title cobalt complex, [Co(C10H11O2)2(C10H14N2O)2(H2O)2], contains two water mol-ecules, two 2,4,6-tri-methyl-benzoate (TMB) ligands and two di-ethyl-nicotinamide (DENA) ligands. All ligands coordinate to the Co(II) atom in a monodentate fashion. The four O atoms around the Co(II) atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination sphere completed by two pyridine N atoms of the DENA ligands. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 84.2 (4)°, while the benzene and pyridine rings are oriented at a dihedral angle of 38.87 (10)°. The water mol-ecules exhibit both intra-molecular (to the non-coordinating carboxyl-ate O atom) and inter-molecular (to the amide carbonyl O atom) O-H⋯O hydrogen bonds. The latter lead to the formation of layers parallel to (100), enclosing R 4 (4)(32) ring motifs. These layers are further linked via weak C-H⋯O hydrogen bonds, resulting in a three-dimensional network. One of the two ethyl groups of the DENA ligand is disordered over two sets of sites with an occupancy ratio of 0.490 (13):0.510 (13).

Crystal structure of trans-di-aqua-bis-(nicotinamide-κN (1))bis-(4-nitro-benzoato-κO)manganese(II).

The asymmetric unit of the title compound, [Mn(C7H4NO4)2(C6H6N2O)2(H2O)2], contains one Mn(II) atom, one 4-nitro-benzoate (NB) anion, one nicotinamide (NA) ligand and one water mol-ecule; NA and NB each act as a monodentate ligand. The Mn(II) atom, lying on an inversion centre, is coordinated by four O atoms and two pyridine N atoms in a distorted octa-hedral geometry. The water mol-ecules are hydrogen bonded to the carboxyl-ate O atoms. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 24.4 (3)°, while the benzene and pyridine rings are oriented at a dihedral angle of 86.63 (11)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, forming a layer parallel to the ab plane. The layers are further linked via weak C-H⋯O hydrogen bonds, a π-π stacking inter-action [centroid-centroid distance = 3.868 (2) Å] and a weak C-H⋯π inter-action, resulting in a three-dimensional network.

Crystal structure of tetra-kis-(µ-2,4,6-tri-methyl-benzoato-κ(2) O:O')bis-[(nicotinamide-κN (1))copper(II)].

In the title binuclear Cu(II) complex, [Cu2(C10H11O2)4(C6H6N2O)2], the two Cu(II) cations [Cu⋯Cu = 2.5990 (5) Å] are bridged by four 2,4,6-tri-methyl-benzoate (TMB) anions. The four nearest O atoms around each Cu(II) cation form distorted square-planar arrangements and the distorted square-pyramidal coordinations are completed by the pyridine N atoms of nicotinamide mol-ecules at distances of 2.164 (2) and 2.165 (2) Å, respectively. The Cu(II) cations are displaced by -0.2045 (3) and 0.2029 (3) Šfrom the corresponding planes formed by the nearest four O atoms. In the mol-ecule, the dihedral angles between the planes of the benzene rings and the adjacent carboxyl-ate groups are 80.6 (2), 51.4 (2), 24.4 (2) and 32.5 (2)°, while the planes of the pyridine rings are oriented at a dihedral angle of 11.28 (10)°. In the crystal, bifurcated N-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules, enclosing R 2 (2)(8) and R 4 (4)(8) ring motifs, into a three-dimensional network. The structure contains a solvent-accessible void of 72 Å(3), but there is no solvent mol-ecule located within this void. The crystal studied was an inversion twin refined with a minor component of 0.488 (8).

Crystal structure of catena-poly[[di-aqua-bis-(4-formyl-benzoato-κO (1))cobalt(II)]-µ-pyrazine-κ(2) N:N'].

In the title polymeric compound, [Co(C8H5O3)2(C4H4N2)(H2O)2] n , the Co(II) atom is located on a twofold rotation axis and has a slightly distorted octa-hedral coordination sphere. In the equatorial plane, it is coordinated by two carboxyl-ate O atoms of two symmetry-related monodentate formyl-benzoate anions and by two N atoms of two bridging pyrazine ligands. The latter are bis-ected by the twofold rotation axis. The axial positions are occupied by two O atoms of the coordinating water mol-ecules. In the formyl-benzoate anion, the carboxyl-ate group is twisted away from the attached benzene ring by 7.50 (8)°, while the benzene and pyrazine rings are oriented at a dihedral angle of 64.90 (4)°. The pyrazine ligands bridge the Co(II) cations, forming linear chains running along the b-axis direction. Strong intra-molecular O-H⋯O hydrogen bonds link the water mol-ecules to the carboxyl-ate O atoms. In the crystal, weak O-Hwater⋯Owater hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via C-Hpyrazine⋯Oform-yl hydrogen bonds, forming a three-dimensional network. There are also weak C-H⋯π inter-actions present.