Syntheses,characterization, antimicrobial and cytotoxic activities of pyridine-2,5-dicarboxylate complexes with 1,10-phenanthroline

In this study, four mononuclear M(II)-pyridine-2,5-dicarboxylate (M = Co(II), Ni(II), Cu(II) and Zn(II) complexes with pyridine-2,5-dicarboxylic acid or isocinchomeronic acid, 1,10-phenanthroline (phen), [Co(Hpydc)₂(phen)]·H₂O (1), [Ni(pydc)(phen)₂]·6.5H₂O (2) [Cu(pydc)(phen)(H₂O)₂] (3) and [Zn(pydc)(phen)(H₂O)₂]·H₂O (4) have been synthesized. Elemental, thermal and mass analyses, molar conductance, magnetic susceptibilities, IR and UV/vis spectroscopic studies have been performed to characterize the complexes. Subsequently, these ligands and complexes were tested for antimicrobial activity by disc diffusion method on Gram positive, negative bacteria and yeast. In addition, cytotoxic activity tests were performed on rat glioma (C6) cells by MTT viability assay for 24 and 48 h. Antimicrobial activity results demonstrated that when compared to the standard antibiotics, phen displayed the most effective antimicrobial effect. The effect of synthesized complexes was close to phen or less. Cytotoxic activity results showed that IC₅₀ value of phen was determined as 31 μM for 48 h. (1) and (2) compared to the alone ligand had less toxic activity. IC₅₀ values of (3) for 24 and 48 h treatments were 2.5 and 0.6 μM, respectively. IC₅₀ value of (4) for 48 h was 15 μM. In conclusion, phen, (3) and (4) may be useful as antibacterial and antiproliferative agents in the future.     

Syntheses, crystal structures and magnetic properties of two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes

Two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes [Co₂(H₂O)₂(phen)₂(adc)₂]·(C₂H₇N)·2H₂O (1) and [Co(H₂O)(phen)(adc)]·H₂O (2) were synthesized in a mixed solvent under 45 °C (H₂adc = adamantane-1,3-dicarboxylic acid). Compound 1 consists of dinuclear [Co₂(H₂O)₂(phen)₂(adc)₂] complex molecules, dimethylamine (C₂H₇N) molecules and hydrogen-bonded water molecules. The dinuclear molecules, via intermolecular hydrogen bonds, are interconnected into hydrogen-bonded chains along [1 0 0] and interdigitation of phen ligands due to interchain π?π stacking interactions assembles the hydrogen-bonded chains into 2D supramolecular layers parallel to (0 0 1). In compound 2, the Co(II) ions are bridged by adamantane-1,3-dicarboxylate anions to form 1D chains along [0 0 1], and the resulting chains are assembled into double-chains based on interchain π?π interactions. The double-chains are further held together via hydrogen bonds into 2D supramolecular layers parallel to (1 0 0). The variable temperature magnetic measurements show an overall weak antiferromagnetic behavior for 1, and an weak ferromagnetic behavior over 300-75 K followed by antiferromagnetic behavior below 75 K for 2.     

Crystal structures, DNA interaction and antiproliferative activities of the cobalt(II) and zinc(II) complexes of 2-amino-1,3,4-thiadiazole with demethylcantharate

Two new mixed-ligand complexes [M(atdz)(DCA)(H₂O)₂]·2H₂O, (M = Co(II), Zn(II); atdz = 2-amino-1,3,4-thiadiazole, C₂H₃N₃S; DCA = demethylcantharate, 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C₈H₈O₅) were prepared and characterized by elemental analysis. The structures of the complexes were determined by X-ray diffraction. The crystals have empirical formulas CoC₁₀H₁₉N₃O₉S (1) and ZnC₁₀H₁₉N₃O₉S (2), respectively. Complex 1 and 2 are monoclinic systems with space group P2₁/m. The structures of the complexes assume severely distorted octahedral geometries. The DNA binding properties of the complexes were investigated by electronic absorption spectra, thermal denaturation studies, fluorescence quenching studies and viscosity measurements. All the results showed the interaction modes between the complexes and DNA were partial intercalation. The results of agarose gel electrophoresis indicated the complexes could cleave supercoiled DNA. The antiproliferative activities testing revealed that all the complexes showed weak to moderate activities against human hepatoma cells (SMMC7721) and human breast cells (MCF-7) in vitro.     

Synthesis, crystal structures, antimicrobial properties and enzyme inhibition studies of zinc(II) complexes of thiones

Zinc(II) complexes of thiones having the general formula [ZnL₂Cl₂] where L = N-methylthiourea (Metu), N,N′-dimethylthiourea (Dmtu), tetramethylthiourea (Tmtu), N,N′-diethylthiourea (Detu), and diazinane-2-thione (Diaz), were prepared by reacting ZnCl₂ with the corresponding thiones. They were characterized by elemental analysis, IR and NMR spectroscopy and two of them {[(Tmtu)₂ZnCl₂] (1) and [(Diaz)₂ZnCl₂] (2)} using X-ray crystallography. The spectral data suggests that the coordination of thiones to zinc(II) occurs through the sulfur atom as indicated by an up field shift in the CS resonance of thiones in ¹³C NMR and downfield shift in N-H resonance in ¹H NMR. The crystal structures of the complexes show a tetrahedral coordination environment around the zinc atoms with the bond angles ranging from 99.33(5)° to 116.81(7)°. Antimicrobial activities of the complexes were evaluated by minimum inhibitory concentration and the results showed that the complexes exhibited significant activities against gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and yeasts (Candida albicans, Saccharomyces cerevisiae). However, moderate activity was observed against molds (Aspergillus niger, Penicillium citrinum). The complexes were also tested for inhibition activity against an enzyme, Alkaline Phosphatase EC 3.1.3.1 and were found to be active inhibitors.     

Syntheses, thermal analyses, crystal structures and antimicrobial properties of silver(I)-saccharinate complexes with diverse diamine ligands

Five new silver(I)-saccharinate complexes [Ag₂(sac)₂(tmen)₂] (1), [Ag₂(sac)₂(deten)₂] (2), [Ag₂(sac)₂(dmen)₂] (3), [Ag(sac)(N,N-eten)] (4), and [Ag(sac)(dmpen)]_n (5); (sac = saccharinate, tmen = N,N,N′,N′-tetramethylethylenediamine, deten = N,N′-diethylethylenediamine, dmen = N,N′-dimethylethylenediamine, N,N-eten = N,N-diethylethylenediamine and dmpen = 1,3-diamino-2,2-dimethylpropan) have been synthesized and characterized by elemental analyses, IR, thermal analyses, single crystal X-ray diffraction and antimicrobial activities. The crystallographic analyses show that all the complexes crystallize in monoclinic space group P2₁/c. In 1, the sac ligand acts as a bridge to connect the silver centres through its imino N and carbonyl O atoms forming an eight-membered bimetallic ring in a chair conformation. Complex 2 has also a dimeric structure in which the monomeric [Ag(sac)(deten)] units are linked by Ag?Ag interactions. In 3, saccharinate ligand acts as a bridging bidentate ligand between two silver(I) centres through sulfonyl group and imino N atom, forming an alternating polymeric chain through the direction [0 1 0]. In 4, the inter-molecular N-H?O hydrogen bonds form one-dimensional polymeric chains through the a axis, and these linear chains are inter-connected to each other by N-H?O hydrogen bonds, which produce a chain of edge-fused and rings along [1 0 0]. Complex 5 is a coordination polymer in which the monomeric [Ag(dmpen)(sac)]_n units are linked by Ag?Ag interactions, and the dmpen ligand acts as a bridge between the silver(I) ions, forming a two-dimensional network parallel to the (1 0 0) plane.     

Cytotoxic activity, X-ray crystal structures and spectroscopic characterization of cobalt(II), copper(II) and zinc(II) coordination compounds with 2-substituted benzimidazoles

Herein we present the synthesis, structural and spectroscopic characterization of coordination compounds of cobalt(II), copper(II) and zinc(II) with 2-methylbenzimidazole (2mbz), 2-phenylbenzimidazole (2phbz), 2-chlorobenzimidazole (2cbz), 2-benzimidazolecarbamate (2cmbz) and 2-guanidinobenzimidazole (2gbz). Their cytotoxic activity was evaluated using human cancer cell lines, PC3 (prostate), MCF-7 (breast), HCT-15 (colon), HeLa (cervic-uterine), SKLU-1 (lung) and U373 (glioblastoma), showing that the zinc(II) and copper(II) compounds [Zn(2mbz)₂Cl₂]·0.5H₂O, [Zn(2cmbz)₂Cl₂]·EtOH, [Cu(2cmbz)Br₂]·0.7H₂O and [Cu(2gbz)Br₂] had significant cytotoxic activity. The isostructural cobalt(II) complexes showed not significant activity. The cytotoxic activity is related to the presence of halides in the coordination sphere of the metal ion. Recuperation experiments with HeLa cells, showed that the cells recuperated after removing the copper(II) compounds and, on the contrary, the cells treated with the zinc(II) compounds did not. These results indicate that the mode of action of the coordination compounds is different.     

Syntheses, crystal structures and properties of Cd(II) and Co(II) complexes with 4,4′-dipyridylsulfide ligand

Two new coordination polymers [Cd(dps)₂Cl₂] (1) and [Co(dps)₂(H₂O)₂]·(abs)₂(H₂O)₂ (2) (dps = 4, 4′-dipyridylsulfide, Habs = 4-amino benzenesulfonic acid) have been synthesized under similar conditions and characterized by elemental analysis, fluorescence spectra and single crystal X-ray diffraction. Compound 1 displays a dps-bridged 2D puckered, grid-like layer, which is further linked by C-H?Cl hydrogen bonds to form a 3D supramolecular architecture. Compound 2 shows a dps-bridged double-stranded chain structure, which is extended by N-H?O and O-H?O hydrogen bonds generating a 3D network. Solid-state fluorescence results reveal that both complexes can emit strong emission bands, at 467 nm and 518 nm for 1 and 344 nm for 2, respectively. Magnetic measurements show that there are weak antiferromagnetic interactions between the adjacent Co(II) ions in 2.     

Self-assembled synthesis, characterization and antimicrobial activity of zinc(II) salicylaldimine complexes

One-pot metal promoted reactions between salicylaldehyde and 4-methyl-1,3-phenylenediamine in the presence of metal salts acting as template agents yield zinc(II) salicylaldimine complexes containing N,N′-bis(salicylidene)-4-methyl-1,3-phenylenediamine (H₂L) as a result of the [2 + 1] Schiff base condensation. The complexes of formula [Zn(HL)Cl(H₂O)₂] · C₂H₅OH and [Zn(H₂L)₂Cl(NO₃)(H₂O)] · CH₃OH were characterized as powder solids and in solution by spectroscopic methods (IR, ¹H and ¹³C NMR, FAB-MS, ESI-MS, UV-Vis), thermogravimetric and elemental analysis, potentiometry, and tested for antimicrobial activity against Staphylococcusaureus in a minimum inhibitory concentration (MIC) experiment. In these two powder solid species, the salicylaldimine, formed in a self-assembly process, acts in two different coordination modes: as monodeprotonated bidentate chelator with an N,O donor set or as a neutral monodentate using exclusively oxygen as the donor atom without involving the nitrogen atoms in the coordination. However, crystals of these two complexes are isomorphous, with 1:2 metal:ligand stoichiometry, and display the latter, relatively rare coordination pattern. In solution, the presence of a 1:1 complex of monodeprotonated state is only detected. The complexes exhibit antimicrobial activity against S.aureus.     

Initial employment of pyridine-2-amidoxime in zinc(II) chemistry: Synthetic, structural and spectroscopic studies of mononuclear and dinuclear complexes

The first employment of pyridine-2-amidoxime [(py)C(NH₂)NOH] in zinc(II) chemistry is reported. The syntheses, crystal structures, and spectroscopic characterization are described for complexes [Zn(O₂CR)₂{(py)C(NH₂)NOH}₂] (R = Me; 1, Ph; 2), [Zn₂(acac)₂{(py)C(NH₂)NO}₂] (3), and [Zn(NO₃){(py)C(NH₂)NOH}₂](NO₃) (4). The reactions between Zn(O₂CR)₂·2H₂O (R = Me, Ph) or Zn(NO₃)₂·5H₂O and two equivalents of (py)C(NH₂)NOH in MeOH led to mononuclear compounds 1, 2 and 4, respectively. All three complexes contain two neutral N,N′-chelating (η²) (py)C(NH₂)NOH ligands, coordinated through the N_pyridyl and N_oxime atoms. In contrast, the use of Zn(acac)₂·H₂O in place of Zn(O₂CR)₂·2H₂O gives the dinuclear compound 3, which instead contains the anionic, η¹:η¹:η¹:μ bridging form of the organic ligand; the Zn^II atoms are doubly bridged by the diatomic oximate groups of the (py)C(NH₂)NO⁻ groups. Strong intra- and intermolecular hydrogen bonding interactions provide appreciable thermodynamic stability and interesting supramolecular chemistry for compounds 1-4. The photoluminescence properties of complexes 1-4 recorded in the solid state at room temperature are also presented.     

Palladium(II) complexes of quinolinylaminophosphonates: synthesis, structural characterization, antitumor and antimicrobial activity

Three types of palladium(II) halide complexes of quinolinylaminophosphonates have been synthesized and studied. Diethyl and dibutyl [α-anilino-(quinolin-2-ylmethyl)]phosphonates (L1, L2) act as N,N-chelate ligands through the quinoline and aniline nitrogens giving complexes cis-[Pd(L1/L2)X₂] (X═Cl, Br) (1-4). Their 3-substituted analogues [α-anilino-(quinolin-3-ylmethyl)]phosphonates (L3, L4) form dihalidopalladium complexes trans-[Pd(L3/L4)₂X₂] (5-8), with trans N-bonded ligand molecules only through the quinoline nitrogen. Dialkyl [α-(quinolin-3-ylamino)-N-benzyl]phosphonates (L5, L6) give tetrahalidodipalladium complexes [Pd₂(L5/L6)₃X₄] (9-12), containing one bridging and two terminal ligand molecules. The bridging molecule is bonded to the both palladium atoms, one through the quinoline and the other through the aminoquinoline nitrogen, whereas terminal ligand molecules are coordinated each only to one palladium via the quinoline nitrogen. Each palladium ion is also bonded to two halide ions in a trans square-planar fashion. The new complexes were identified and characterized by elemental analyses and by IR, UV-visible, ¹H, ¹³C and ³¹P nuclear magnetic resonance and ESI-mass spectroscopic studies. The crystal structures of complexes 1-4 and 6 were determined by X-ray structure analysis. The antitumor activity of complexes in vitro was investigated on several human tumor cell lines and the highest activity with cell growth inhibitory effects in the low micromolar range was observed for dipalladium complexes 11 and 12 derived from dibutyl ester L6. The antimicrobial properties in vitro of ligands and their complexes were studied using a wide spectrum of bacterial and fungal strains. No specific activity was noted. Only ligands L3 and L4 and tetrahalidodipalladium complexes 9 and 11 show poor activities against some Gram positive bacteria.     

Synthesis,physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X–ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N– and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest as the ground state. X–ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

Structure, antimicrobial activity and DNA-binding properties of the cobalt(II)-sparfloxacin complex

The neutral mononuclear cobalt(II) complex with sparfloxacin has been prepared and characterized with physicochemical, spectroscopic and electrochemical techniques, and molecular mechanics calculations. The interaction of the complex with calf-thymus DNA has been investigated with UV spectroscopy, cyclic voltammetry, and competitive studies with ethidium bromide. The antimicrobial activity of the complex has been tested against three microorganisms.     

Syntheses and crystal structures of three Mn(II) complexes with 2-hydroxynicotinate

Three new Mn(II) complexes [Mn(HnicO)₂(H₂O)₂] (1), [Mn₂(HnicO)₂SO₄(H₂O)₂]_n (2), and [NaMn(HnicO)₃]_n (3) (H₂nicO = 2-hydroxynicotinic acid) have been synthesized and determined by X-ray diffraction. For complex 1, the mononuclear units with two bidentate HnicO⁻ ions and two water molecules are assembled into a 3D architecture via hydrogen bonding and π-π interactions. For 2, Mn(II) ions are connected by μ₃-HnicO⁻ and bridging ligands, producing a 2D (6,3) coordination network. For 3, binuclear Na(I)-Mn(II) units with three carbonyl oxygen bridges are interlinked by carboxylate groups, resulting in a 3D 6-connected coordination network with distorted α-Po topology. The magnetic properties of 2 are discussed.     

One-dimensional helical coordination polymers of cobalt(II) and iron(II) ions with 2,2′-bipyridyl-3,3′-dicarboxylate (BPDC)

One-dimensional (1-D) helical coordination polymers, [M^II(H₂O)₃(BPDC)]_n · nH₂O (M = Co (1), Fe (2)), have been prepared by the self-assembly of cobalt(II) and iron(II) ions, respectively, with 2,2′-bipyridyl-3,3′-dicarboxylic acid (H₂BPDC) in an aqueous solution. X-ray crystal structures of compounds 1 and 2 show that each metal ion displays a distorted octahedral coordination geometry including three water oxygen atoms, one oxygen atom of the carboxylate of a BPDC²⁻ belonging to the adjacent metal ion and two nitrogen atoms from the BPDC²⁻ acting as a chelating ligand. In 1 and 2, one carboxylate oxygen atom of coordinated BPDC²⁻ binds to the neighboring metal ion, which give rise to 1-D helical coordination polymers. The helical chains of 1 and 2 are linked by the hydrogen bonding interactions between the carboxylate oxygen atom of the BPDC²⁻ ion belonging to a chain and the water molecule of the adjacent helical chain, which lead to 2-D networks extending along the ab plane. The supramolecules 1 and 2 show isomorphous structures regardless of the metal ions.     

Syntheses and structures of photochromic molybdenum(II) and rhodium(II) complexes with 1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene

Four novel Mo(II) and Rh(II) complexes with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (cis-dbe) or closed-dbe were synthesized and characterized. Employing [M(O₂CCF₃)₄] (M = Mo, Rh) with cis-dbe or closed-dbe afforded complex [Mo₂(O₂CCF₃)₄(cis-dbe)](benzene) (1), [Rh₂(O₂CCF₃)₄(cis-dbe)](benzene) (2), [{Mo₂(O₂CCF₃)₄}₂(closed-dbe)] (3), and [Rh₂(O₂CCF₃)₄(closed-dbe)](p-xylene) (4). The structures of four metal complexes were revealed by X-ray crystallographic analyses and the correlation between the crystal structures and the photochromic performance was discussed. In all complexes, two cyano groups of the ligand bridged two dimetal carboxylates to give a 1-D zigzag infinite chain structure. Upon irradiation with 405 nm light, complex 1 turned into reddish purple from yellow, and the color reverted to initial yellow on exposure to 563 nm light, indicating the reversible cyclization/ring-opening reaction in the crystalline phase. However, the Rh(II) complex 2 did not display similarities in reaction induced by light, which is attributable to the lower ratio of photoactive anti-parallel conformers compared with complex 1 and coordination effect of metal ions on photochromism of diarylethenes. The complexes of Rh(II) ions did not exhibit the expected reversible photoinduced behavior.     

Synthesis, structure and properties of bis[N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamidecopper(II)] perchlorate

In this account we report the synthesis, structure and characterization of a dimeric Cu(II) complex, [Cu₂(PaPy₃H)₂](ClO₄)₄ (bis[N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamidecopper(II)]). In this complex, the coordination of the designed ligand PaPy₃H to the Cu(II) centers is completed by the bis(picolyl)methyl amine portion of one PaPy₃H unit and the oxygen and pyridine nitrogen atoms of the pyridine-2-carboxamide moiety of a second PaPy₃H ligand. The resulting dimeric complex demonstrates a new mode of coordination of the ligand PaPy₃H.     

Syntheses, characterization and antimicrobial activity of the first complexes of Zn(II), Cd(II) and Co(II) with N-benzyloxycarbonylglycine: X-ray crystal structure of the polymeric Cd(II) complex

For the first time, complexes of Zn(II), Cd(II) and Co(II) (1-3) with N-benzyloxycarbonylglycine have been synthesized and characterized. The complexes adopt tetrahedral, pentagonal-bipyramidal and octahedral geometry, respectively. The structure of the polymeric cadmium complex was resolved by single crystal X-ray analysis. The cadmium ion has a distorted pentagonal-bipyramidal coordination formed by two water molecules and two N-benzyloxycarbonylglycinato ligands (N-Boc) coordinated in different fashions, one as bidentate and the second connecting three cadmium atoms. In a rather complicated 2D supramolecular structure, the phenyl rings interact mutually exclusively by the CH?π interactions.Investigation of the antimicrobial activity of the obtained complexes and N-benzyloxycarbonylglycine revealed that the ligand does not inhibit the growth of Candida albicans, whereas the newly synthesized complexes suppress the growth of this human fungal pathogen.     

Synthesis, characterization and antibacterial activity of new sulfonamide derivatives and their nickel(II), cobalt(II) complexes

Methanesulfonicacid hydrazide (a sulfonamide compound, msh: CH₃SO₂NHNH₂) derivatives: methylsalicylaldehydemethanesulfonylhydrazone (5msalmsh), 5-methyl-2-hydroxyaceto-phenonemethanesulfonylhydrazone (5mafmsh) and their Ni(II), Co(II) complexes have been synthesized for the first time. The structure of these sulfonamide compounds has been investigated by using elemental analyses; FT-IR, ¹H NMR, ¹³C NMR, LC-MS, and UV-Vis spectrometric methods; magnetic susceptibility; conductivity measurements; thermal studies. The crystal structure of 5msalmsh has been investigated by X-ray analysis. The antibacterial activities of synthesized compounds were studied against gram positive bacteria: Staphylococcus aureus, Bacillus subtilis, and Bacillus magaterium; and gram negative bacteria: Salmonella enteritidis, and Escherichia coli by using the microdilution broth method. The biological activity screening showed that ligands have more activity than complexes against the tested bacteria.     

Cis-trans isomerism in cobalt(II) complexes with 3-hydroxypicolinic acid. Structural, DFT and thermal studies

Pyridine and 4-picoline cobalt(II) complexes with 3-hydroxypicolinic acid, [Co(3-OHpic)₂(py)₂], (2), and [Co(3-OHpic)₂(4-pic)₂], (3), were prepared, their molecular and crystal structures were determined by X-ray structure analysis and their thermal stability by TGA/DTA methods. Complex 2 appears only as trans isomer and 3 as cis isomer. Based on DFT calculations, the most significant effect on orientation of (un)substituted ligands around cobalt, i.e.cis-trans isomerism, comes from crystal packing. Theoretical calculations show that exchange of methyl group in pyridine does not affect relative stability of one monomer unit, i.e.cis isomer is for about 1 kcal mol⁻¹ more stable than trans isomer. Hydrogen bonds of the O-H···O type are present only as intramolecular ones in the crystal structures of 2 and 3, while intermolecular C-H···O hydrogen bonds and π-π stacking interactions (π-π interactions present only in 3) assemble molecules in 3D architecture. Interactions between two monomer units in crystal packing could be separated and theoretically investigated to calculate interaction energy. In our case, both non-hypothetical models, i.e.trans isomer of 2 and cis isomer of 3, show more favorable interaction energies than hypothetical ones, i.e.cis isomer of 2 and trans isomer of 3, for the same type of interaction.     

Cobalt(II) coordination polymers assembled from polycarboxylate and benzotriazole: Syntheses, structures and physical properties

Hydrothermal reactions of cobalt(II) salt with H₂CAM or H₂SDBA and HBTA in the presence of NaOH afford two interesting coordination polymers, Co₃(CAM)₂(BTA)₂ (1) and Co₃(SDBA)₂(BTA)₂ (2) (H₂CAM = camphoric acid, H₂SDBA = 4,4′-dicarboxybiphenyl sulfone, HBTA = benzotriazole), both of which have been structurally characterized by single-crystal X-ray, elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Complexes 1 and 2 are isostructural and possess two-dimensional covalent network, comprising an unusual linear Co(II) chains of mixed T_d-O_h-T_d geometries. Temperature-dependent magnetic measurements indicate the existence of antiferromagnetic interactions in both 1 and 2.