Rajdip Dey

X-ray crystal structure of a Cu(II) complex with the antiparasitic drug tinidazole, interaction with calf thymus DNA and evidence for antibacterial activity

Interaction of metal ions with biologically active molecules like 5-nitroimidazoles modulates their electronic environment and therefore influences their biological function. In the present work, an antiparasitic drug tinidazole (tnz) was selected and a Cu(II) complex of tnz [Cu2(OAc)4(tnz)2] was prepared. A dinuclear paddle-wheel [Cu2(OAc)4(tnz)2] was obtained by single-crystal XRD and further characterized by spectroscopic techniques and cyclic voltammetry. To understand the biological implications of complex formation, interaction of tnz and its complex was studied with calf thymus DNA, bacterial and fungal cell lines. Results of calf thymus DNA interaction using cyclic voltammetry indicate the overall binding constant (K*) of Cu2(OAc)4(tnz)2 [(59 ± 6) × 104 M−1] is ~17 times greater than that of tnz [(3.3 ± 0.4) × 104 M−1]. Minimum inhibitory concentration values suggest that [Cu2(OAc)4(tnz)2] possesses better antibacterial activity than tnz on both bacterial strains, while the activity on a fungal strain was comparable. Tinidazole, a 5-nitroimidazole is active on protozoan and bacterial infections. This study made an attempt to see if a Cu(II) complex of tinidazole had comparable efficacy on chosen bacteria and fungi. The prepared complex was characterized by XRD, spectroscopy, elemental analysis cyclic voltammetry. DNA interaction was studied using cyclic voltammetry and fitted by non-linear analysis.

Flexible dicarboxylate based pillar-layer metal organic frameworks: differences in structure and porosity by tuning the pyridyl based N,N′ linkers

Dicarboxylate supported metal organic hybrids of Co(II), Zn(II) and Cd(II) have been synthesized using two different pyridyl based N,N′ linkers having Schiff base functionalized site. The use of flexible dicarboxylate glutarate in designing such frameworks has created a marked diversity in topology. The different N,N′ donor linkers also played an active part in the channel modification in the synthesized MOFs. The structural and topological diversity has been analyzed from the single crystal X-ray structure. Five compounds, {[Co(azpy)(glut)]·(CH3OH)}n (1), {[Co(meazpy)(glut)(H2O)2]·(H2O)3}n (2), {[Zn(azpy)0.5(glut)(H2O)]·(azpy)0.5}n (3), {[Zn(meazpy)0.5(glut)(H2O)]·(H2O)2}n (4) and {[Cd(azpy)(glut)]·(CH3OH)}n (5), show porous structures with solvent accessible voids. The nature of the pores as well as the existence of lattice solvent molecules in 1 and 2 are different due to the use of a different pillar ligand in their fabrication. In case of 3 and 4 there are some nice effects of non-covalent interaction in the construction of their solid state structure, which has also originated by the change of pillar N,N′ donor linkers. Complex 5 is topologically as well as structurally similar to 1 forming a 2D-grid like structure. In {[Cd2(meazpy)2(glut)(NO3)]2}n (6) there is a formation of 2D sheets with the coordinated counter anion. Interestingly, here the sheets are disposed in a perpendicular fashion to each other and do not contain any solvent accessible void. Upon removal of the solvent molecules, the frameworks 1–5 show moderate CO2 and H2 uptake at 273 K and 77 K, respectively. The desolvated frameworks show different quantities of CO2 and H2 uptake which has been corroborated to their structures.

Formation of three new metal organic hybrids of Cd(II) with N,N′ donor spacer: an in situ perchlorate to chloride transformation

Three new metal–organic hybrids have been synthesized in a reaction of Cd(II) with 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpdb) and disodium succinate (Na2suc). All three compounds, i.e., {[Cd(3-bpdb)(Cl)]·ClO4}n (1), {[Cd(3-bpdb)3(H2O)2]·(3-bpdb)(ClO4)2}n (2) and {[Cd(3-bpdb)(suc)(H2O)2]·(H2O)2}n (3) are characterized by single-crystal X-ray diffraction and other physicochemical methods. Structure determination reveals that 1 shows an α-polonium type 3D coordination network created by an exactly perpendicular Cl–Cd–Cl linkage. The framework of 1 contains 1D channels, which are filled with ClO4−. Compound 2 shows a 1D coordination structure with two bridging and two pendent 3-bpdb ligands. These pendent ligands are involved in H-bonding, π–π and C–H⋯π interactions with its coordinated water molecules and lattice 3-bpdb ligands, to form the 3D supramolecular structure. Compound 3 is a 2D 4-connected net with succinate and the 3-bpdb ligand and extended to 3D supramolecular architecture by H-bonding and π–π interactions. During the syntheses, an in situ chemical transformation of perchlorate to chloride has occurred along with the oxidation of imine to amide and the chlorides so produced are found integrated in compound 1, which facilitates the oxidation of imine in a very unprecedented way.

Synthesis, crystal structure and photo luminescent property of a 3D metal-organic hybrid of Cd(II) constructed by two different bridging carboxylate

AbstractA solvothermal reaction of cadmium (II) nitrate with succinic acid and isonicotinic acid creates a novel 3D metal-organic framework, [Cd3(isonicotinate)2(suc)2]n(1). Single crystal X-ray structure determination reveals that complex 1 posses two crystallographically independent Cd(II) centres. The succinate anion acts here as a heptadented ligand and binds five Cd(II) centre simultaneously. The heptacoordinated Cd(II) centres are oxo-bridged by succinate moiety and the hexacoordinated metal centres are terminally connected through four different succinate moiety to make the overall 2D sheet arrangement. In unit cell, the ratio of hexadented Cd(II) and heptadented Cd(II) is 1:2. The new compound was also characterized by luminescence spectra and compared with the luminescence spectra of the pure isonicotinic acid. Graphical AbstractA novel 3D metal–organic framework of Cd(II) has been synthesized by solvothermal reaction using two different carboxylate, succinate and isonicotinate ligands. The succinate anion acts as a heptadentate ligand and binds to five Cd(II) centers.

Correction: Syntheses, X-ray structures, gas adsorption and luminescent properties of three coordination polymers of Zn(II) dicarboxylates mixed with a linear, neutral, and rigid N,N′-donor ligand

In this article, three new zinc(II) coordination polymers have been synthesized using 4,4′-azobipyridine (azbpy) and three different aliphatic dicarboxylates. The reaction was carried out through the slow diffusion technique at room temperature giving rise to {[Zn2(μ3-OH)(azbpy) (suc)1.5]·(H2O)2}n (1), {[Zn(azbpy)0.5(glut)(H2O)]·(H2O)}n (2), and {[Zn2(azbpy)2(fum)2]·(H2O)}n (3) (suc = succinate dianion, glut = glutarate dianion and fum = fumarate dianion). The structures of these complexes were determined by single-crystal X-ray diffraction analysis and also by other physicochemical methods. Compound 1 is a three-dimensional (3D) framework, whereas compound 2 shows a one-dimensional ladder-like structure which is further extended in two dimensions through supramolecular interactions (H-bonding). Compound 3 displays a three-dimensional (3D) 5-fold interpenetrated diamondoid network structure. In the case of 1 and 2, the structures contain void spaces which are occupied by guest water molecules, whereas in 3, the pores are totally blocked through interpenetration. TGA and PXRD analysis showed that all three compounds were thermally stable up to a high temperature. The desolvated framework of compounds 1 and 2 show adsorption of different gas molecules and exhibit a higher adsorption preference for CO2 over N2. The photoluminescence study in the solid state of compounds 1–3 indicates ligand based florescence emissions at room temperature.