Synthesis and characterization of a chiral Schiff base containing α-d-altropyranoside unit and its zinc(II) complex

Syntheses, structures and properties of two new isostructural zinc(II) complexes based on 1-[(benzotriazol-1-yl)methyl]-1H-imidazole

Due to their strong coordination ability and the diversities of their coordination modes, N-heterocyclic organic compounds are used extensively as ligands for the construction of complexes with fascinating structures and potential applications in many fields. Two new complexes, namely bis{1-[(benzotriazol-1-yl)methyl]-1H-imidazole-κN³}dibromidozinc(II), [ZnBr₂(C₁₀H₉N₅)₂], (I), and bis{1-[(benzotriazol-1-yl)methyl]-1H-imidazole-κN³}diiodidozinc(II), [ZnI₂(C₁₀H₉N₅)₂], (II), have been synthesized by reaction of the unsymmetrical N-heterocyclic ligand 1-[(benzotriazol-1-yl)methyl]-1H-imidazole (bmi) with Zn(acetate)₂ in the presence of KBr or KI. Single-crystal X-ray diffraction analysis shows that both complexes exhibit a mononuclear structure, in which the bmi ligands coordinate to the central metal ion in a monodentate mode. In the solid state, both complexes possess a three-dimensional network formed by hydrogen bonds and π-π interactions. In addition, the IR spectroscopic properties, PXRD patterns and fluorescence properties of both complexes have been investigated.

Metal based photosensitizers of tetradentate Schiff base: promising role in anti-tumor activity through singlet oxygen generation mechanism

In the present investigation, a Schiff base N'(1),N'(3)-bis[(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbodihydrazide (L1) and its Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized as novel photosensitizing agents for photodynamic therapy (PDT). The interaction of these complexes with calf thymus DNA (CT DNA) has been explored using absorption, thermal denaturation and viscometric studies. The experimental results revealed that Co(II) and Ni(II) complexes on binding to CT DNA imply a covalent mode, most possibly involving guanine N7 nitrogen of DNA, with an intrinsic binding constant Kb of 4.5×10(4)M(-1) and 4.2×10(4)M(-1), respectively. However, interestingly, the Cu(II) complex is involved in the surface binding to minor groove via phosphate backbone of DNA double helix with an intrinsic binding constant Kb of 5.7×10(4)M(-1). The Co(II), Ni(II) and Cu(II) complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to UV-visible light of 365nm, through (1)O2 generation with quantum yields of 0.28, 0.25 and 0.30, respectively. Further, these complexes are cytotoxic in A549 lung cancer cells, showing an enhancement of cytotoxicity upon light irradiation.

Tetradentate schiff base ligands of 3,4- diaminobenzophenone: Synthesis, characterization and thermodynamics of complex formation with Ni(II), Cu(II) and Zn(II) metal ions

Some new symmetrical diimino tetradentate Schiff base ligands were synthesized by the reaction of 3,4-diaminobenzophenone with salicylaldehyde derivatives, such as [N,N?-bis(4-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L1), [N,N?-bis(5-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L2), [N,N?-bis(5-bromosalicylaldehyde)-3,4- diaminobenzophenone] (L3), [N,N?-bis(5-nitrosalicylaldehyde)-3,4- diaminobenzophenone] (L4). Additionally, a tetradentate Schiff base ligand [N,N?-bis(3-methoxysalicylaldehyde)-3,4-diaminobenzophenone] (L5), was synthesized. All the Schiff bases and their Ni(II), Cu(II) and Zn(II) complexes were characterized using elemental analysis and infrared, electronic, mass and 1H-NMR spectroscopy. The formation constants of the complexes were measured using UV-Vis spectroscopic titration at constant ionic strength 0.1 M (NaClO4), at 25?C in dimethylformamide (DMF) as solvent.