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Two N-(2-(hydroxy)-3-methoxybenzylidene)tryptophan coordinated Ni(ii) complexes have been synthesized and structurally characterized. Magnetic analysis reveals antiferromagnetic behaviour for both the compounds.

Two novel coordination compounds of cadmium, [Cd2L1(ssal)2(H2O)3]2·10H2O (1) and {[Cd2L1(dca)4(H2O)]·H2O}n (2) (where L1 = 2,2′,2″-(1-(pyridin-2-ylmethyl)imidazolidine-2,4,5-triyltripyridine), ssal...

Two novel mixed valence CoII–CoIII complexes, namely [CoIICoIII(L1)(ab)(mb)2(H2O)]·dmf (1) and [CoIII2CoII(L2)4(H2O)4]·2H2O (2) [H2L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol, ab = 2-amino-butan-1-ol anion, mb = p-methyl benzoate, H2L2 = 3-((2-hydroxy-3-methoxy-benzylidene)-amino)-propionic acid, and dmf = N,N-dimethyl-formamide], were synthesized and characterized by single crystal X-ray diffraction and magnetic studies at low temperature. The structure determination reveals that both complexes belong to the monoclinic system with P21/c (1) and I2/a (2) space groups. Complex 1 is a dinuclear CoIIICoII compound with distorted octahedral cobalt centers showing different coordination environments. In 2, a bent trinuclear CoIII2CoII complex, the coordination environments around the two terminal CoIII sites are alike, whereas they are different in the central CoII ion. Alternating current/direct current (ac/dc) magnetic studies revealed that both complexes show field-induced slow magnetic relaxation. The dc magnetic susceptibility and magnetization data were analyzed with the following Hamiltonianwhere D and E are the axial and rhombic zero-field splitting (zfs) parameters, respectively, and a good agreement between experimental and simulated results was found using the parameters g⊥ = 2.585, g∥ = 2.437, D = +98.1 cm−1, E/D = 0.008 and F = 8.2× 10−5 for 1 and g⊥ = 2.580, g∥ = 2.580, D = +55.4 cm−1, and E/D = 0.000 for 2.

Two Schiff bases HL and HL′, having potential tridentate O,N,N′ donor sets, have been used for the synthesis of two copper(II) complexes, namely [Cu(HL)(pdc)]2 (1) and [Cu(L′)2]2 (2′), where HL = 2-([2-(piperazin-yl)ethylimino]methyl)phenol, pdc = py-2,5-dicarboxylate and HL′ = 2-(((2-(di-isopropylamino)ethyl)imino)methyl)phenol. X-ray single crystal analysis of complex 1 shows a centro-symmetric dimer. It crystallizes with a number of lattice water molecules that form a network of H-bonds, also involving the protonated piperazinium fragment, giving rise to a 3D supramolecular architecture. Complex 2′ also crystallizes as dinuclear, formed through mutual bridging phenol oxygen atoms as [Cu(L′)2]2, whilst an ESI mass spectrometry study evidences that in solution the complex exists as mononuclear [Cu(L′)2] (2). The interaction of complexes 1 and 2 with calf thymus DNA (CT-DNA) and with bovine serum albumin (BSA) was investigated using electronic absorption and fluorescence spectroscopic techniques. In both studies the results show a higher binding affinity of complex 1 in comparison to 2. The anticancer activity of the complexes against human breast (MCF7) cancer cell lines reveals that complex 1 has moderate growth suppression activity against these cells with an IC50 value of 24 ± 6.24 μM.

Using tridentate O,N,O/N,N,O donor Schiff bases and 1,10-phenanthroline, five coordinated copper(II) complexes, {[Cu(L1)(phen)][Cu(L1)(phen)]∙5H2O}(1) and {[Cu(L2)(phen)](ClO4)}(2) [H2L1 = 3-[(2-hydroxy-benzylidene)-amino]-propionic acid, HL2 = 2-methoxy-6-[(3-methylamino-propylimino)-methyl]-phenol, phen = 1,10-phenanthroline] have been synthesized and structurally characterized. Complex 1 is a co-crystal, where two geometrically different (trigonal bipyramidal (TBP) and square pyramidal (SP)) complexes of same compositions [Cu(L1)(phen)] are within a unit cell. Complex 2 exhibits a trigonal bipyramidal geometry and counter balanced by perchlorate anion. In solid state, complex 1 contains both SP and TBP geometries, but theoretical calculation reveals that in solution it exists only in one form with SP geometry. DFT/TD-DFT calculations for the complexes were performed to explain the structures and electronic spectral properties of the complexes. Both the complexes are active for catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) in presence of molecular oxygen and the calculated values of turnover numbers are 62 ± 3 and 52 ± 3 h−1 for 1 and 2, respectively. Interactions of complexes with calf thymus-DNA have been studied using fluorescence spectroscopic techniques and the calculated values of binding constants are (2.20 ± 0.06) × 104 and (2.27 ± 0.07) × 104 L mol−1 for complexes 1 and 2, respectively.

The Schiff base 2-[(3-Methylamino-propylimino)-methyl]-phenol (HL) has been used for the synthesis of three dinuclear Cu(II) complexes, namely [Cu2L2(dca)2] (1), [Cu2L2(2,5-pdc)2]·6H2O (2), [Cu2L2(tp)] (3), where dca = dicyanamide, 2,5-pdc = pyridine-2,5-dicarboxylate and tp = terephthalate. In 2, HL acts as bidentate (O, N) chelating ligand, while tridentate (O, N, N) in 1 and 3. In all the complexes copper(II) is in its five coordination with distorted trigonal bipyramidal geometry in 1, whereas distorted square pyramidal in 2 and 3. Non covalent interactions give rise supramolecular architectures in all complexes. Cytotoxicity of the complexes was examined using breast cell lines MCF7 and MDA-MB- 231. Complexes 1 and 2 show dose dependent suppression of MCF7 and MDA-MB- 231 cells and the related IC50 values are 26 ± 2.9 µM and 51 ± 4.7 µM for MCF7 cell, 16.4 ± 1.6 µM and 43.2 ± 3.1 µM for MDA-MB- 231 cell. Interaction of complexes 1–3 with bovine serum albumin (BSA), human serum albumin (HSA) and calf thymus DNA have been studied by electronic absorption and fluorescence spectroscopic technique. Molecular docking study has been used to explain the interaction of complexes with serum albumins.

Cu(II) complexes [Cu(L)(bipy)]ClO4 (1) and [Cu(L)(phen)]ClO4 (2) (where HL = 2-[(3-Methylamino-propylimino)-methyl]-phenol, bipy = 2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesized and characterized by single crystal X-ray diffraction studies, FT-IR spectra, ESI-MS, electronic absorption, and emission spectroscopy. Both the Cu(II) complexes are mononuclear with five coordinated distorted trigonal bipyramidal geometries and the π-conjugated bipy and phen favor the formation of 2D supramolecular structures with CH … π and π … π interactions. DFT/TD-DFT calculations were performed using B3LYP, B3PW91 and MPW1PW91 functionals to explain the experimentally observed molecular structure and electronic absorption spectral properties. Complexes are active for catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) in presence of molecular oxygen. Interactions of complexes with bovine serum albumins (BSA) and human serum albumins (HSA) have been studied by electronic absorption and emission spectroscopy and the calculated values of binding constants are 6.91 × 105 L mol−1 (1-BSA), 6.16 × 105 L mol−1 (1-HSA), 6.57 × 105 L mol−1 (2-BSA) and 3.80 × 105 L mol−1 (2-HSA). Electronic absorption and fluorescence spectroscopic studies reveal that interactions of complexes with CT-DNA occur through intercalative binding mode.

Search for cost effective, earth abundant electrocatalysts for hydrogen generation through water splitting is the challenge of the hour whereas multifunctional applicability of the materials is the extremely sought issue for multi-tasking smart materials. In this work, nitrogen doped reduced graphene oxide (N-rGO) supported nickel phosphide (NixPy) nanomaterial has been prepared and characterized. Details electrocatalytic measurements exhibit the commendable performance of the composite materials against hydrogen evolution reaction in acid medium. The reduction of the required overpotential for reaching 10 mA/cm2 from 265 mV (NixPy) to 248 mV (NixPy/N-rGO) is observed in 0.5 M H2SO4 solution which proves the benefit for attaching N-rGO with NixPy. The electrochemical active surface area measurement also ascertains the quality of the composite and the enhancement of an active surface area is attributed to the attachment of N-rGO matrix. Furthermore, the NixPy/N-rGO composite confirms it’s stability in the acidic medium for 1200 min at 248 mV without any significant loss of current. Ground state ferromagnetic behavior has been demonstrated by NixPy/N-rGO in sharp contrast to the paramagnetic behavior exhibited by the bare NixPy nanoclusters at low temperature. Thus, the N-rGO matrix supported NixPy manifests both electrocatalytic proficiency and magnetic ordering with potential application in the future green energy as well as in data storage technologies.

Two Cu(II) complexes, [Cu(L1)(OCN)(H2O)] (1) and [Cu(L2)]·H2O (2) [HL1, bis(2-pyridyl carbonyl)amine; H2L2, 2{3-[5-(2-hydroxy-3methoxy)-pent-4-enylamino]-propylimino}methyl-6-methoxy phenol], were synthesized and characterized by single crystal X-ray crystallography, thermal analysis, FTIR and mass spectroscopic techniques. Complexes 1 and 2 show a square pyramidal and trigonal bipyramidal Cu(II) coordination sphere, respectively. In the solid state complex 1 forms hydrogen bonded 1D supramolecular structure and complex 2 forms 1D supramolecular structure with C H…π interactions. Results of experimental electronic absorption and FTIR spectral studies have been compared with the calculated results obtained by density functional theory (DFT) and time dependent density functional theory (TD-DFT) using the CAM-B3LYP functional, with LanL2DZ basis set. Catecholase activity of the compounds have been studied using 3,5-di-tert butyl catechol (3,5-DTBC) as model substrate and found that both of these are active for catalyzing oxidation of 3,5-DTBC to 3,5-di-tert butyl benzoquinone (3,5-DTBQ) in presence of molecular oxygen. Calculated values of the turnover numbers (Kcat) are 29.2 ± 3 and 112.14 ± 5 h−1 for 1 and 2, respectively. The interactions of complexes 1 and 2 with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using electronic absorption and fluorescence spectroscopic methods and the results show that both the compounds interact with BSA/HSA with ground state association process.

Two new Cu(II)/Na(I) coordination polymers, namely, {[(Cu(L1)Na)2(ox)(ClO4)2]∙dmf}n (1) and {[(Cu(L2)Na)2(nph)]∙H2O}n (2) were synthesized by using the Schiff base N-(2-hydroxyethoxy)ethyl-iminomethyl-phenol (H2L1) with oxalate (ox) and (3-methoxy-2-hydroxybenzylidene)propanoic acid (H2L2) with naphthalene-2,6-dicarboxylate anions (nph), respectively. Both the complexes were characterized using elemental analysis, FT-IR, UV–vis spectroscopic analyses. The solid state structures of complexes 1–2 were determined using single crystal X-ray crystallography that revealed for 1 the presence of dinuclear copper(II) species, [(L1)Cu(ox)Cu(L1)], while 2 consists of stair-like 1D -[CuL2]2-(nph)]n- polymers. Both these fragments are further connected by Na(I) cations to form 2D supramolecular assemblies. In both the compounds the copper and sodium atoms exhibit a square pyramidal and a distorted octahedral coordination geometry, respectively. The catalytic activity of complexes 1–2 for the degradation of methylene blue (MB) was investigated under UV irradiation and in the presence of very small amount of H2O2. Both the compounds were found to be photo-catalytically active, and the mechanism of photocatalysis has been discussed in detail.

Two novel tetranuclear Cu(II) complexes [Cu4(L1)4]·3(H2O) (1) and [Cu4(H2L2)4(H2O)4] (2) ( H2L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol; H4L2 = 2-((2-hydroxy-3-methoxybenzylidene)amino)-2-hydroxymethylpropane-1,3-diol) were synthesized from the self-assembly of copper(II) perchlorate and the tridentate Schiff base ligands. Both complexes crystallize in the tetragonal system with space group I 41/a and form tetranuclear species with closed-cubane like core framework. Both the complexes possess a S4 axis but of different stereochemistry due to the different arrangement of the ligands about the copper ions. Variable temperature magnetic susceptibility measurements indicate an overall weak antiferromagnetic exchange coupling in 1, while ferromagnetic exchange coupling in 2. In agreement with their closed-cubane structure, the magnetic behavior of the two complexes have been studied by employing the isotropic spin Hamiltonian of type H = J1 (S1S3 + S1S4 + S2S3 + S2S4) - J2 (S1S2 + S3S4) (J1 describes the magnetic exchange coupling between the four Cu(II) pairs with short Cu···Cu distances, while J2 characterizes the magnetic exchange coupling between the remaining two intermetallic pairs with long distances). The PHI program was used to study their magnetic behavior. A good agreement between the experimental and fitted curves was found with the following parameters: g = 2.14, J1 = -20.3 cm-1 and J2 = 0 cm-1 for 1 and g = 2.10, J1 = 101.1 cm-1 and J2 = -51.5 cm-1 for 2.

Three copper(II) complexes namely [Cu4(L1)4]·0.5(H2O) (1), [Cu4(L2)2(HL2)2(H2O)2](sq)·H2O (2) and {[Cu2(L2)2(tp)]·(H2O)}n (3) (H2L1 = [(E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol], H2L2 = [(E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol], sq = squarate and tp = terephthalate ion) have been characterized by structure determination and magnetic analysis. Both 1 and 2 are tetranuclear Cu4O4 species with closed cubane core and double-open cubane like core structure, respectively. On the other hand complex 3 is a 1D polymeric chain, where Schiff base chelated dinuclear copper units are linked through terephthalate ions. C-H…π interactions among the 1D polymeric chains form a 2D supramolecular architecture. Variable temperature magnetic property study indicates overall antiferromagnetic exchange coupling in all complexes.

Two tetranuclear Schiff base copper(II) complexes, namely [Cu 4 (L) 2 (LH) 2 (H 2 O) 2 ](ClO 4 ) 2 ·3H 2 O (1) and [Cu 4 (L) 2 (LH) 2 (H 2 O) 2 ](ClO 4 )·(tp) 0.5 ·3H 2 O (2) (where H 2 L = 2-[(2-hydroxy-ethylimino)-methyl]-6-methoxy-phenol, tp = terephthalate), were synthesized and characterized by X-ray single crystal diffraction. Both complexes 1 and 2 are comprised of structurally similar tetranuclear cationic [Cu 4 (L) 2 (LH) 2 (H 2 O) 2 ] ²⁺ species with a double open cubane core, in which two metal centers possess a square pyramidal environment and the other two exhibit a slightly distorted octahedral coordination geometry. The interaction of complexes 1 and 2 with calf thymus DNA (CT-DNA) was investigated using electronic absorption and fluorescence studies, and the results showed that the complexes interact with CT-DNA with the related intrinsic binding constants (K ib ) of 1.8 × 10 ⁶ and 1.1 × 10 ⁷ L mol ⁻¹ for 1 and 2, respectively. Their interactions with bovine serum albumin (BSA) and human serum albumin (HSA) were also investigated and spectroscopic techniques showed that both complexes interact with these proteins through a ground state association process. Using 3,5-di-tertbutylcatechol (3,5-DTBC) as a model substrate, both complexes show catecholase-like activity, being able to oxidase 3,5-DTBC to 3,5-di-tert-butylquinone (3,5-DTBQ) in the presence of oxygen.

Two mononuclear square planer Ni(II) complexes, [Ni(L1)2] (1) and [Ni(L2)2] (2) [HL1 = 2-[(2-Methoxy-ethylimino)-methyl]-phenol; HL2 = 2-Methoxy-6-[(2-methoxy-ethylimino)-methyl]-phenol] have been synthesized and characterized through X-ray single crystal structure determination and DFT/TDDFT calculation. Both the complexes crystallize with P21/c space group. C-H…π interactions results 2D and 1D supramolecular network of complexes 1 and 2, respectively. Interaction of complexes with calf thymus DNA (CT-DNA), bovine serum albumin (BSA) and human serum albumin (HSA) were studied by using both UV–vis absorption and emission spectroscopic techniques, and the calculated values of intrinsic binding constants with CT-DNA are (1.43 ± 0.56) × 106 M−1 (for 1) and (1.25 ± 0.79) × 106 M−1 (for 2).

Na3Fe2(PO4)2F3 has been synthesized under mild hydrothermal conditions. The structure of Na3Fe2(PO4)2F3 has been solved using single-crystal X-ray diffraction and the phase purity has been evaluated by Rietveld refinement from high resolution synchrotron powder X-ray diffraction data. Both methods establish the accuracy of P42/mnm space group and synthesis of so called beta2-polymorph. Room temperature 57Fe Mossbauer spectroscopic studies confirm 3+ oxidation state of the compound. The electrochemical properties have been investigated with respect to Li- and Na-ion batteries. Galvanostatic charge-discharge studies indicate that up to ~0.6 lithium ions and only ~0.4 sodium ions per Fe can be inserted at an average voltage of 2.82 and 2.42 ​V with respect to Li+/Li and Na+/Na in lithium and sodium ion batteries, respectively. The cycle-life studies indicate that Li-ion batteries show very stable capacity retention over long cycles while Na-ion batteries tend to lose capacity after ~35 cycles at C/5 rate.

The Ni(II) complex, {[Ni(HL)(SCN)2(H2O)]·2(DMF)} (1) [HL = 6-methoxy-2-{[2-(1-piperazinyl)ethylimino]methyl}phenol], was synthesized and characterized by X-ray crystal structure analysis and spectroscopic methods. The crystal structure of complex 1 reveals a distorted octahedral coordination geometry around the nickel centre which forms a supramolecular assembly through hydrogen bonds. The interaction of complex 1 with the calf thymus DNA (CT-DNA) was investigated using electronic absorption and fluorescence spectroscopic methods. The results show that complex 1 has binding affinity to CT-DNA in the order of 6.06 × 105 M−1. The interactions of complex 1 with bovine serum albumin (BSA) and human serum albumin (HSA) were also studied using electronic absorption and fluorescence spectroscopic techniques and the analysis show that interaction of complex 1 with BSA/HSA occur mainly with ground state association process. The number of binding sites and binding constant were calculated using double logarithm regression equation. Anticancer activity of 1 in human breast (MCF7) cancer cell lines reveals dose dependent suppression of cell viability with IC50 value 64 ± 3.7 μM. Catecholase activity of 1 has been investigated in methanol medium using 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate and the result shows that 1 is active for catalyzing aerobic oxidation of 3,5-DTBC to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ).

The complexes [Cu(L)(pa)] (1) and [Cu(L)(mb)] (2) (HL = o-{(3-morpholinopropylimino)methyl}phenol; pa = 3-phenylacrylate; mb = p-methylbenzoate) have been synthesized and characterized by elemental analysis, single crystal X-ray crystallography, FT-IR, UV-vis electronic absorption spectroscopic analysis. Complexes 1 and 2 are mononuclear with distorted square pyramidal geometries where the Schiff base coordinates to copper(II) in the tridentate (O, N, N) chelating mode. These three atoms plus one carboxylate oxygen define the equatorial plane of the square pyramid while the axial position is occupied by carboxylate oxygen at a relatively longer distance. Weak C–H⋯π interactions result the formation of 2D supramolecular structures for both complexes. At room temperature complexes 1 and 2, exhibit fluorescence with a quantum yield (Φs) of 0.129 and 0.117, respectively. The UV-vis electronic absorption and IR spectral data of complexes have been compared with the results obtained by employing DFT and time dependent density functional theory (TD-DFT) calculation using the B3LYP, B3PW91 and MPW1PW91 functionals, with LanL2DZ basis set. The results of these calculations are functional-dependent and among the functionals, B3LYP proved to better reproduce the experimental results. The interactions of complexes with the calf thymus DNA (CT-DNA) were investigated using electronic absorption and fluorescence spectroscopic techniques. The studies reveal that the binding affinities of complexes 1 and 2 with CT-DNA are in the order of 1.68 × 105 M−1 and 2.271 × 105 M−1, respectively. A study of the effect of various metal ions on the electronic absorption and fluorescence spectra of HL reveals that it selectively senses the Cu(II) ions.

A Cu(II) fluorescent chemosensor, 6-methoxy-2-{[2-(1-piperazinyl)ethylimino]methyl}phenol (HL), has been synthesized and characterized by FT-IR, NMR, electronic absorption and emission spectral studies. HL shows high selectivity for Cu(II) over a range of other metal ions. HL has a 24.87 μM (R2 = 0.9959) fluorometric detection limit for Cu(II), which is very close to the maximum allowable level of Cu(II) in drinking water as recommended by US EPA. Theoretical calculations at the B3LYP level revealed that the formation of a five-coordinated complex in solution is responsible for the observed sensing behavior. The binding constant for the 1:1 complex between Cu(II) and HL was determined using fluorescence titration, and the calculated value is 0.4 liter/mol. Using HL, {[Cu(HL)(pdc)(H2O)]·[Cu(HL)(pdc)]·10.5(H2O)} (1) (pdc = pyridine 2,5-dicarboxylate) has been synthesized and structurally characterized. Complex 1 is active for catalyzing aerobic oxidation of 3,5-di-tert butyl catechol (3,5-DTBC) to 3,5-di-tert butyl benzoquinone (3,5-DTBQ). Anticancer activity of 1 in human breast (MCF7) cancer cell lines reveals dose dependent suppression of cell viability with IC50 value 47 ± 5.2 μM.

Two Schiff base coordinated cadmium(II) complexes, namely [Cd(H4L1)(N3)2]n (1) and [Cd2(L2)(N3)2]·(H2O) (2) (where H4L1 = 2-((2-hydroxy-3-methoxybenzylidene)amino)-2-(hydroxymethyl)-propane-1,3-diol; and H2L2 = bis((3-methoxysalicylidene)ethyl)ethylamine), were synthesized and characterized by X-ray single crystal diffraction. Both the complexes 1 and 2 crystallize in monoclinic system with space group P 21/n. Complex 1 is a 1D coordination polymer where Cd(H4L1) species are doubly connected by bridging μ-1,1 azide anions. Complex 2 is a discrete dinuclear compound where the double deprotonated Schiff base (L2)2− acts as a two compartmental ligand coordinating two cadmium atoms. Photocatalytic activity of the complexes has been studied using UV–vis absorption spectroscopic technique and the results show that both the complexes are active for photocatalytic degradation of methylene blue (MB) in presence of UV light, and within 180 min MB decomposed by 37.64% and 32.60% in presence of complexes 1 and 2, respectively.

The copper(II) complexes [Cu4(L)2(HL)2(H2O)2]∙2(ClO4)∙2(H2O)∙DMF (1) and [Cu4(L)2(HL)2(H2O)2]∙(tp) (2) [H2L = 2-ethoxy-6-[(1-hydroxymethyl-propylimino)-methyl]-phenol; tp = terephthalate] have been synthesized and characterized by single crystal X-ray diffraction and spectroscopic studies. The structural determination reveals that both the complexes are tetranuclear with a double-open-cubane like core framework. The 2D supramolecular structure of 1 and 3D supramolecular structure of 2 are formed through C–H…π and hydrogen bonding interactions, respectively. At room temperature both the complexes exhibit fluorescence with quantum yields of 0.41 and 0.40. The interactions of the complexes with calf thymus DNA (CT-DNA) and serum albumins were investigated using electronic absorption and fluorescence spectroscopic techniques. The studies revels that the binding affinities of 1 and 2 with CT-DNA are of the order 8.86 × 105 M−1 and 7.14 × 105 M−1, respectively. Additionally, the interaction of the complexes with bovine serum albumin and human serum albumin were studied and the number of binding sites and binding constants were calculated using a double logarithm regression equation. The redox activities of the complexes were investigated in methanol solution by cyclic voltammetry.

Copper(II) complexes {[Cu(HL)(ClO4)(H2O)](ClO4)⋅3H2O} (1), {[Cu (HL)(m-phth)]⋅5H2O} (2) and {[Cu(HL)(NCS)]2(ClO4)2⋅2H2O} (3) (HL=2-{[2-(1-piperazinyl)ethylimino]methyl}phenol; m-phth= 1,3-benzenedicarboxylate] have been synthesized and characterized by structural determination and spectroscopic studies. The mononuclear square pyramidal complex 1 resulted from the reaction of HL with copper perchlorate hexahydrate. Then mononuclear square planar complex 2 and dinuclear thiocyanato bridged complex 3 were obtained by reacting 1 with disodium 1,3-benzenedicarboxylate (Na2(m-phth)) and potassium thiocyanate, respectively. The interactions of 1–3 with CTDNA / serum albumins were investigated by UV-visible absorption and fluorescence spectroscopy. The intrinsic binding constants of 1, 2 and 3 with CT-DNA were calculated. Study of the interactions of 1–3 with human serum albumin (HSA) / bovine serum albumin (BSA) showed that all the complexes could quench intrinsic fluorescence of HSA and BSA through a static quenching process. Molecular docking technique was utilised to confirm the mode of interaction of complexes with CT-DNA / serum albumin. Anticancer activities of the complexes have been tested using human breast cancer cell lines MCF7 and MBAMB- 231. Among the complexes studied 3 shows the higher cytotoxic activity and growth inhibition of cancer cells via induction of apoptotic cell death.

One dinuclear and one 1D polymeric nickel(II) complex, namely {[Ni2(HL)2(pa)2(H2O)2]·DMF} (1) and {[Ni2(HL)2(ppda)(H2O)2]·DMF·H2O}n (2) (H2L = (E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol, pa = 3-phenylacrylate, ppda = p-phenylenediacrylate) have been synthesized and characterized by X-ray single crystal structure determination. Complex 1 is double phenoxo-bridged dinuclear Ni(II) complex, whereas complex 2 is a 1D polynuclear chain where double phenoxo-bridged dinuclear units are connected through bridging ppda ligands. The variable temperature magnetic behavior of the complexes was studied using the Hamiltonian H = −JS1S2, S1 = S2 = SNi and confirms the presence of an overall antiferromagnetic interaction in both complexes. Good agreement between the experimental and simulated curves were found using the parameters: gNi = 2.15, DNi = 4.0 cm−1 and JNi–Ni = −0.60 cm−1 for 1, and gNi = 2.15, DNi = 4.8 cm−1 and JNi–Ni = −3 cm−1 for 2. The interactions of the complexes with CT-DNA were investigated using UV–Vis absorption and fluorescence spectroscopic methods and they show that both the complexes interact with CT-DNA. The intrinsic binding constants values for interaction with CT-DNA are 3.9(±0.10) × 105 and 3.43(±0.09) × 105 M−1 for 1 and 2, respectively. The interactions of the complexes with bovine serum albumins (BSA) and human serum albumins (HSA) were also studied using electronic absorption and fluorescence spectroscopic techniques and the results show that both complexes interact with the serum albumins via a ground state association process.

The supramolecular complexes {[Mn 2 (HSsal) 2 (dpyo) 3 (H 2 O) 6 ]·2(H 2 O)} ( 1 ) and {[Mn(4,4′-bipy)(H 2 O) 4 ]·(HSsal)·(H 2 O)} n ( 2 ) [dpyo = 4,4′-dipyridyl N , N ′-dioxide; 4,4′-bipy = 4,4′-bipyridine and HSsal = 5-sulfosalicylate dianion] have been synthesized and structurally characterized. Complex 1 is a rare Mn dinuclear species realized with bridging dpyo and coordinated HSsal ligands to form a 3D architecture through H-bonding and π⋯π interactions. In complex 2 , Mn(H 2 O) 4 fragments are bridged by 4,4′-bipy, giving rise to a 1D chain. The adjoining chains encapsulate HSsal anions to give a 3D structure through a R 2 2 (12) H-bonding synthon and π⋯π interactions. The complexes were tested in association with several aromatic compounds, since they exhibit intense fluorescence ( λ ex = 223 nm, λ em = 308, 325, 353 and 393 nm for 1 ; λ ex = 237 nm, λ em = 312, 335, 348 and 394 nm for 2 ). The outcome of DFT calculations on model compounds is discussed and compared with the experimental X-ray structural data.

Reaction of Cu(NO3)2·3H2O and 2-hydroxy-3-methoxybenzaldehyde (HL) in methanolic medium results [CuL2]·4H2O (1) [L− = 3-methoxy-2-oxo-benzaldehyde]. The complex was characterized by elemental analysis, IR, single crystal X-ray structure determination and DFT calculation. The X-ray single crystal structure determination reveals that 1 is a discrete mononuclear four coordinated complex with the metal in square planar coordination geometry and four lattice water molecules. The complex form dimer around the center of symmetry with short Cu⋯O interaction and exhibits intense fluorescence (λex = 270 nm, λem = 311, 328, 355 and 367 nm) in methanolic solution at room temperature with a fluorescence quantum yield Φs = 3.5. The complex 1 was tested with several aromatic compounds such as m-toluidine, aniline, nitrobenzene and o-nitrotoluene, and the results show that a pronounced fluorescence quenching and enhancement is observed in the presence of nitrobenzene and m-toluidine, respectively. Catecholase activity of 1 has been investigated in methanol medium by UV–Vis spectrophotometric study using 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate reveals that 1 is active for catalyzing aerobic oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ). The optimized geometry from density functional theory (DFT) study shows a good agreement with X-ray structural data. The electronic and IR spectrum of this compound is compared with result obtained by employing DFT and time dependent density functional theory (TD-DFT) calculation.

Distorted square pyramidal complexes [Cu(L1)(H2O)]·ClO4 (1), [Cu(L2)(H2O)]·ClO4 (2) and [Cu(L3)(H2O)]·ClO4 (3) (HL1 = o-{[2-(2-aminoethylamino)ethylimino]methyl}phenol; HL2 = 2-{[2-(2-aminoethylamino)ethylimino]methyl}-6-methoxyphenol; HL3 = o-{1-[2-(2-aminoethylamino)ethylimino]ethyl}phenol) have been synthesized, and characterized by X-ray crystallography and spectroscopic analysis. All the complexes exhibit fluorescence at room temperature [λex = 267 nm, λem = 312, 329 and 357 nm, φ = 0.52 for 1; λex = 272 nm, λem = 312, 329 and 355 nm, φ = 0.46 for 2; λex = 265 nm, λem = 312, 356 and 377 nm, φ = 0.33 for 3]. The electronic structure and photophysical properties of the ligands and complexes were calculated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods using the B3LYP, B3PW91 and MPW1PW91 functionals, with 6-31G (d-p) and LanL2DZ basis sets. The results of TD-DFT calculations are functional-dependent and among the functionals, B3LYP was able to best reproduce the experimental results. Catecholase activity of 1–3 has been investigated using 3,5-di-tert butyl catechol (3,5-DTBC) as the model substrate and found that complexes are active for catalyzing the aerobic oxidation of 3,5-DTBC to 3,5-di-tert butyl benzoquinone (3,5-DTBQ). The compound with more distorted square pyramidal geometry shows a higher rate of catalytic activity. All the complexes have been tested for their anticancer activities in human breast (MCF7) cancer cell lines. Complexes show dose dependent suppression of cell viability with IC50 values 30, 68 and >100 μM for 1, 2 and 3, respectively. Anticancer activities of 1–3 and cisplatin were compared, and found that 1–3 were relatively less active than cisplatin.

Two CoII–CoIII mixed-valence complexes of molecularformulas [Co2(H2L)2(H2O)2][Co2(H2L)2(H2O)(m-phth)]·8(H2O) {1;H2L2–= 2-[(2-hydroxy-3-methoxybenzylidene)amino]-2-(hydroxymethyl)propane-1,3-diolato, m-phth = 1,3-benzene-dicarboxylate} and [Co4(H2L)4(H2O)2(ppda)]·2(dmf)·3.2(H2O) {2;ppda = 1,4-phenylenediacrylate; dmf = N,N-dimethyl-formamide} were synthesized and characterized by single-crys-tal X-ray diffraction and magnetic studies at low temperature.The structural determination reveals that 1 is composed of di-nuclear ion pairs, namely, a cationic [Co2(H2L)2(H2O)2]+(1+) andan anionic [Co2(H2L)2(H2O)(m-phth)]–(1–) unit. In each of these ions, the CoIIand CoIIIcenters present distorted octahedralgeometries. Compound 2 is a centrosymmetric tetranuclearcomplex comprising two symmetry-related dinuclear CoII–CoIIIunits bridged by ppda anions.

A six-coordinate Mn(IV) complex, [Mn(H2L)2] (1) [H4L = 2-methoxy-6-(tris(hydroxymethyl)methyliminomethyl)phenol], was synthesized and characterized by elemental analysis, single-crystal X-ray crystallography, FTIR, UV–Vis electronic absorption, and EPR spectroscopy. The single-crystal structural determination reveals that the complex crystallizes in tetragonal space group P41212 and the tridentate Schiff base ligands are arranged in mer configuration chelating manganese, which exhibits as slightly distorted octahedral coordination sphere with a N2O4 chromophore. Weak hydrogen bonding interactions of uncoordinated hydroxyl groups result in a 2-D supramolecular structure. The UV–Vis electronic absorption and IR spectral data of 1 have been compared with the results obtained by employing DFT and time-dependent density functional theory calculation using B3LYP, B3PW91, and MPW1PW91 functionals, with 6-31G (d-p) and LanL2MB basis sets. The results of these calculations are functional-dependent and, among those used, B3PW91 proved to better reproduce the experimental results.

Metal organic frameworks of Co(II), {[Co(bphz)1.5(tp)(H2O)2]⋅3.2H2O}n (1), {[Co(bphz)(ip)]⋅(bphz)0.5}n (2), and [Co(bpp)(ppda)(H2O)2]n (3) [where bphz=N,N′-bis-pyridin-4-ylmethylene-hydrazine; tp=1,4-benzenedicarboxylate; ip=1,3-benzenedicarboxylate; bpp=1,3-bis(4-pyridyl)propane; ppda=1,4-phenylenediacrylate] have been synthesized and characterized by single crystal X-ray diffraction and spectroscopic studies. Complex 1 is a ladder like 1D polymeric chain, 2 is a 2D porous sheet, while 3 is a 2D parallel interpenetrated network. The band gap of complexes has been calculated using solid state reflectance spectra, and results show that complexes act as semiconductor. In dispersed methanolic solution complexes 1–3 exhibit intense fluorescence at room temperature. The complexes were tested with several aromatic compounds such as benzene, nitrobenzene, o-nitrotoluene and p-nitrotoluene, etc., in dispersed methanol medium. Results show that complex 3 selectively senses nitro aromatic compounds and this behavior has been explained on the basis of PET and RET mechanisms.

Two Cu(II) complexes [Cu4(L)2(HL)2(H2O)2](pv)2 (1) and [Cu4(L)2(HL)2(H2O)2](ssal) (2) [H2L = 2-ethoxy-6-[(1-hydroxymethyl-propylimino)-methyl]-phenol; pv = pivalate; ssal = 2-Hydroxy-5-sulfosalicylate] have been synthesized and characterized by X-ray structure determination. Structure determination reveals that both the complexes are tetranuclear with double open cubane core framework, and C-H⋯π interactions results the formation of 1D supramolecular structure. At room temperature 1 and 2 show fluorescence (λex = 267 nm, λem = 329, 516 and 620 nm for 1; λex = 277 nm, λem = 315 and 413 nm for 2) with fluorescence quantum yield 0.41 and 0.46, respectively. Interactions of complexes with calf thymus DNA (CT-DNA), bovine serum albumin (BSA) and human serum albumin (HSA) were studied using UV–vis absorption and fluorescence spectroscopic techniques, and the calculated values of intrinsic binding constants of 1 and 2 with CT-DNA are 2.71(±0.07) × 104 M−1 and 1.58(±0.11) × 104 M−1, respectively. Molecular docking technique has been used to determine the mode of interaction of complexes with CT-DNA and serum albumins. The docking studies suggest that both the complexes can interact with DNA through groove binding mode, and possible binding sites of complexes with BSA and HSA are in the proximity of Tyr149 and Tyr150, respectively.

Two copper(II) complexes [Cu(pdc)(im)] (1) and {[Cu(pdc)(2-ap)(H2O)]·2H2O} (2) [pdc, pyridine-2,6-dicarboxylate; im, imidazole and 2-ap, 2-aminopyridine] have been synthesized and characterized by elemental analysis, IR spectroscopy, X-ray crystallography, and thermal analysis. Complexes 1 and 2 show a square planar and square pyramidal Cu(II) coordination sphere, respectively, and in solid state form hydrogen bonded 3D supramolecular networks. Both the complexes exhibit fluorescence in water–methanol solution at room temperature [λex = 261 nm, λem = 317 and 361 nm, quantum yield = 0.0149 for 1; λex = 278 nm, λem = 351 nm, quantum yield = 0.0031 for 2]. The effect of the presence of different aromatic compounds such as m-toluidine, aniline, nitrobenzene, p-cresol, phenol, etc., on the fluorescence of these copper complexes in solution has been inspected. Results indicate that complex 2 behaves as a fluorescence sensor for p-cresol, but loses its fluorescent properties in association with phenol. The optimized geometry from density functional theory (DFT) study shows a good agreement with the X-ray structural data. The electronic and IR spectra of these compounds are compared with results obtained by employing DFT and time-dependent density functional theory (TD-DFT) calculations.

The 1D copper(II) complex {[Cu2(L)2(fum)]·(H2O)·(MeOH)}n (1) has been synthesized using fumarate (fum2−) and a Schiff base (HL), derived from the condensation reaction of 2-amino-1-butanol and salicylaldehyde. Complex 1 has been characterized by its X-ray crystal structure, together with FT-IR, electronic absorption and fluorescence spectroscopic methods. The structural determination reveals that complex 1 crystallizes in the monoclinic system with the space group P21/n and forms a 1D polymeric chain, built by bridging fum ligands. Weak π⋯π and C–H⋯π interactions lead to the formation of a 3D supramolecular architecture. Complex 1 exhibits fluorescence (λex, 366 nm; λem, 410, 433 and 462 nm) at room temperature, with a quantum yield (Φs) of 0.257. The interactions of complex 1 with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using electronic absorption and fluorescence spectroscopic techniques, and the results show that the interaction of complex 1 with BSA/HSA occurs mainly with a ground state association process. The calculated values of the apparent association constants (at 300 K) are 1.34 × 104 and 1.81 × 104 L mol−1 for interactions with BSA and HSA, respectively. The number of binding sites and binding constants were calculated using a double logarithm regression equation. The interaction of complex 1 with calf thymus DNA (CT-DNA) was also investigated using electronic absorption and fluorescence spectroscopic methods. The results show that complex 1 has a binding affinity to CT-DNA of the order of 2.96 × 105 L mol−1. Low temperature magnetic measurements reveal the existence of an antiferromagnetic interaction in complex 1. The magnetic data have been fitted considering complex 1 as a pseudo-dinuclear system, with the two copper(II) ions bridged by two carboxylate oxygen atoms, since the coupling through long fum bridge is almost nil. The best-fit parameters obtained with this model are J = −60 cm−1 and gCu = 2.20.

Four coordination polymeric complexes, [{Cu2(aepn)2Pt(CN)4·H2O}(H2O){Pt(CN)4}]n, (1), [{Cu(dpt)2Pt(CN)4}]n (2), [{Cu(dien)Pt(CN)4}]n (3) and [{Cu(iprdien)Pt(CN)4}]n (4) (where aepn = N-(2-aminoethyl)-1,3-propanediamine, dpt = 3,3′-imino bispropylamine, dien = diethylenetriamine, iprdien = N′-isopropyldiethylenetriamine), have been synthesized and characterized by X-ray single crystal structure determination and variable temperature magnetic measurements. The formation of the supramolecular assemblies has been rationalized and it has been shown that competition between coordinative forces and hydrogen bonding interactions is crucial in the determination of final solid-state packing. A zig-zag/helical 1D chain (2 and 3) appears when the chelating amine at the Cu(II) center is capable of forming the maximum number of hydrogen bonds, on the other hand when one or more of the amine sites are blocked, due to the prevention of the maximization of hydrogen bonding, (4,2) ribbons (1 and 4) appear. Variable temperature magnetic measurement shows the presence of weak antiferromagnetic interactions in all the complexes.

Three dinuclear copper(II) complexes [Cu 2 (pdc) 2 (dpyo)(H 2 O) 2 ] n ( 1 ), {[Cu 2 (pdc) 2 (dabco)(H 2 O) 2 ]·2H 2 O} n ( 2 ) and {[Cu 2 (pdc) 2 (bpp)(H 2 O) 2 ]·2H 2 O} n ( 3 ) [pdc, pyridine-2,6-dicarboxylate; dpyo, 4,4′-dipyridyl- N , N ′-dioxide; dabco, 1,4-diazabicyclo[2.2.2]octane and bpp, 1,3-bis(4-pyridyl)propane] have been synthesized and structurally characterized by single crystal X-ray diffraction analysis and thermal study. Hydrogen bonding interactions, formed by coordinated and lattice water molecules, lead to a supramolecular architecture in all of them. Thermogravimetric analyses reveal that the complexes undergo reversible deaquation–reaquation process.

A one-pot reaction of [Co(NO3)(2)center dot 6H(2)O and piperazine] with NH4SCN/NaSCN in water-methanol (1:1) solvent leads to two polymorphs of [Co(SCN)(4)(ppz-H)(2)] (ppz, piperazine) (I and II). X-ray crystal structure reveals both have same space group but the differences in the alignment of pendant SCN- leads to two polymorphs. In I, trifurcated N-H...S hydrogen bonding plays a prominent role in crystal packing leading to S...S interactions between SCN fragments but in II, no such trifurcation arises and thereby the crystal packing occurs through hydrogen bonding interactions only leading to a distinctly different network topology. TG/DSC and FT-IR study reveal they are enantiotropically related. (c) 2007 Elsevier Ltd. All rights reserved.

A one-pot reaction of three components [MnII, isophthalate dianion (isop) and 4,4′-dipyridyl N,N′-dioxide (dpyo)] in water/methanol (1:1) causes self-assembly resulting in two 3D supramolecular isomers of the same stoichiometry, {[Mn(isop)(H2O)2]·(dpyo)·(H2O)}n (colorless) (1) and {[Mn(isop)(H2O)(dpyo)0.5]·(dpyo)0.5·(H2O)2}n (pink) (2). Both isomers crystallize in the same crystal system (triclinic) and space group (P). The structural determination of 1 reveals an isophthalato-bridged 1D coordination polymer, {[Mn(isop)(H2O)2]n, having 16- and 8-membered rings where isophthalate acts simultaneously as chelating and bridging ligand connected to three metal centers. In isomer 2 the 1D chains transform to a 2D arrangement through bridging dpyo that replaces a water molecule at metal axial position. Both the crystal structures result in a 3D supramolecular network achieved through H-bonding among the 1D (in 1) or 2D (in 2) coordination polymers with lattice water and dpyo molecules and also by means of π-π interactions in 1. Low-temperature magnetic measurement indicates antiferromagnetic interaction in both the isomers and the best fits are given by the exchange parameters J = –0.56 ± 0.02 cm–1, g = 2.01 ± 0.01 and R = 3.1 × 10–5 for 1 and J = –1.06 ± 0.03 cm–1, g = 2.01 ± 0.01 and R = 2.8 × 10–5 for 2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Three coordination complexes of Co(II)/Fe(II) with 4,4′-trimethylenedipyridine (bpp) and pseudohalides (SCN−, SeCN− and N3−) have been synthesized. The complexes have been characterized by X-ray single crystal structure determination. They are isomorphous having 2D layers in which two independent wavy nets display parallel interwoven structures. Pseudohalide binds metal centers through N terminal and occupies the trans axial positions of the octahedral metal coordination environment. Pseudohalide remains pendant on both sides of the polymeric layer and help the stacking through hydrogen bonding. The conformation of bpp in the interpenetrated nets is observed to be dependent on the choice of pseudohalide.

A three dimensional supramolecular network, {[Co(bpee)(H2O)4] · (tp) · 2(H2O)}n (1) [bpee = trans-1,2 bis(4-pyridyl)ethylene; tp = terephthalate dianion] has been synthesized and characterized by X-ray single crystal structure, magnetic measurement and thermal analysis. The structure determination reveals that the cobalt(II) ions, bridged by bpee and coordinated by four water molecules, give rise to covalently linked 1D polymeric chain. The parallel chains get involved in H-bonding with tp resulting in a 3D architecture. Upon heating 1, which is pink in color, transforms to [Co(bpee)(tp)] (1a, blue). The deaquated species (1a) reverts on keeping in humid atmosphere. Low temperature magnetic data indicate weak antiferromagnetic coupling.

Two coordination polymers, [Cu(bpp)(H 2 O) 2 (ClO 4 ) 2 ] n ( 1 ) and {[Cu(bpds) 2 (ClO 4 ) 2 ] · 1.5(H 2 O)} n ( 2 ) [bpp, 1,3-bis(4-pyridyl)propane and bpds, 4,4′-bipyridyl disulfide] have been synthesized and characterized by X-ray single crystal diffraction study and magnetic measurement. Both the coordination polymers display 1D chains with perchlorate anions acting as pendant ligands. In 1 undulated polymers are built by Cu(H 2 O) 2 (ClO 4 ) 2 units connected by single bpp and in complex 2 Cu(ClO 4 ) 2 fragments are linked by pairs of bpds ligands to form a double-stranded chain. The crystal packing evidences polymers of 1 involved in weak H-bonding interactions leading to a 3D supramolecular network. Magnetic study reveals weak antiferromagnetic interactions in both complexes.

The coordination polymer, {[Co(tart)(phen)]·6H2O}n (1) (tart, tartrate dianion; phen, 1,10-phenanthroline) has been synthesized and characterized by single-crystal X-ray structure determination, magnetic measurement and thermal analysis. The structural analyses reveal two adjacent parallel 1D–[Co(phen)-tart-Co(phen)]– coordination polymers zipped through π-π interactions. The lattice water molecules, forming a 1D water cluster, function as glue to form a 3D supramolecular network through an extended hydrogen bonding. A comparison highlighting the structural differences with the corresponding 2,2′-bipyridine (bpy) derivative, {[Co(tart)(bpy)]·5H2O}n (2) containing a less amount of lattice water molecules is discussed. The variable-temperature magnetic study of 1 has been carried out and interpretation of the already reported complex 2 has been re-visited: both polymers 1 and 2 show weak antiferromagnetic interaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Four 3d–4f heterometallic coordination polymers, [Cu3(IDA)6Ln2] · n(H2O) [IDA = iminodiacetate dianion; Ln = Gd, n = 3 (1); Ln = Nd, n = 6 (2); Ln = Sm, n = 6 (3)] and [Cu(Cl)(NTA)Sm(H2O)6] · (ClO4) · (H2O) (4) [NTA = nitrilotriacetate trianion], have heen synthesized and characterized by single crystal X-ray diffraction analysis. Complexes 1–3 are isomorphous, showing a 3D coordination framework having tubular channels filled by lattice water molecules running parallel to the c axis. Whereas complex 4 is a 1D polymer of alternating copper and samarium ions connected by NTA, and the chains get involved in H-bonding interactions resulting in a 3D network. A low temperature magnetic study reveals ferromagnetic interactions for complex 1. Thermogravimetric and X-ray powder diffraction analyses of 1, 2 and 3 show that the covalently bonded 3D network remains almost unaffected after deaquation.

Three supramolecular complexes of Co(II) using SCN-/SeCN- in combination with 4,4‘-dipyridyl-N,N‘-dioxide (dpyo), i.e., {[Co(SCN)2(dpyo)2]·(dpyo)}n (1), {[Co(SCN)2(dpyo)(H2O)2]·(H2O)}n (2), {[Co(SeCN)2(dpyo)(H2O)2]·(H2O)}n (3), have been synthesized and characterized by single-crystal X-ray analysis. Complex 1 is a rare example of a dpyo bridged two-dimensional (2D) coordination polymer, and π-stacked dpyo supramolecular rods are generated by the lattice dpyo, passing through the rhombic grid of stacked layers, resulting in a three-dimensional (3D) superstructure. Complexes 2 and 3 are isomorphous one-dimensional (1D) coordination polymers [-Co-dpyo-Co-] that undergo self-assembly leading to a bilayer architecture derived through an (8) H-bonding synthon between coordinated water and dpyo oxygen. A reinvestigation of coordination polymers [Mn(SCN)2(dpyo)(H2O)(MeOH)]n (4) and {[Fe(SCN)2(dpyo)(H2O)2]·(H2O)}n (5) reported recently by our group [Manna et al. Indian J. Chem. 2006, 45A, 1813] reveals brick wall...

The complexes [Cu2(ox)(phen)2(H2O)2](NO3)2 (1), [Cu2(sq)(pmdien)2(H2O)2](ClO4)2 (2) and {[Cu3(pdc)3(4,4′-bipy)1.5(H2O)2.25] · 2.5(H2O)}n (3) [phen = 1,10-phenanthroline; pmdien = N,N,N′,N′,N″-pentamethyldiethylenetriamine; 4,4′-bipy = 4,4′-bipyridine; ox = oxalate dianion; sq = squarate dianion and pdc = pyridine 2,6-dicarboxylate] have been synthesized and characterized by X-ray single crystal structure determination, low temperature magnetic measurement and thermal study. Structure determination reveals that 1 and 2 are dinuclear copper(II) complexes bridged by oxalate and squarate dianions, respectively, while 3 is a hexanuclear species formed by three Cu(pdc)(H2O)-(4,4′-bipy)-Cu(pdc)(H2O) fragments, connected through long Cu–O(pdc) bonds in a centrosymmetric arrangement. In complex 1 H-bonds occurring between the coordinated water molecules and lattice nitrate anions result in eight-membered ring clusters with the concomitant formation of 1D supramolecular chain. The adjacent chains undergo π–π stacking forming a 2D architecture. In the crystal of 3 an extensive H-bonding scheme gives rise to a 3D supramolecular network. Low temperature magnetic study shows a strong antiferromagnetic coupling in 1 (J = −288 ± 2 cm−1, g = 2.21 ± 0.01, R = 1.2 × 10−6); and a very weak interaction in 2 and 3, the best-fit parameters being: J = −0.21 cm−1, g = 2.12 ± 0.01, R = 1.1 × 10−6 (2) and J = −1.34 cm−1 ± 0.1, g = 2.14 ± 0.01, R = 1.2 × 10−6 (3) (R defines as ∑ [ ( χ M ) obs - ( χ M ) calc ] 2 / ∑ ( χ M ) obs 2 ) .

Three new supramolecular networks of cobalt(II) and iron(II), {[Co(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (1), {[Fe(4,4′-bipy)(H2O)4] · (C5O5) · (H2O)2}n (2) and {[Co2(bpds)2(C5O5)2(H2O)4] · (H2O)3}n (3) [4,4′-bipy = 4,4′-bipyridyl, bpds = 4,4′-bipyridyl disulfide, C 5 O 5 2 - = croconate dianion ] have been synthesized and characterized by X-ray single crystal structure determination and thermogravimetric analysis. All of these coordination networks feature 1D polymers. Complexes 1 and 2 have a comparable structure based on metal centers coordinated by four water molecules and bridged by 4,4′-bipy ligands to give rise to a linear chain. Crystal packing shows a 3D supramolecular architecture through H-bonding occurring between lattice croconate dianions and water molecules. Conversely complex 3 is formed by Co(C5O5)(H2O)2 units connected by bridging bpds resulting a polymer with a zig zag arrangement. The metal coordination sphere comprises of two chelating oxygens from the croconate dianion, two water molecules and two bpds nitrogens located in cis positions. The coordinated water and lattice water molecules undergo H-bonding to form a 3D supramolecular network.