Mishra Monika, Tiwari Karishma, Shukla Sachin, Mishra R, Singh Vinod P
Department of Chemistry, Banaras Hindu University, Varanasi 221005, India.
Department of Zoology, Banaras Hindu University, Varanasi 221005, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Nov 11;132:452-64. doi: 10.1016/j.saa.2014.05.007. Epub 2014 May 15.
The ligand, N'-(phenyl-pyridin-2-yl-methylene)-thiophene-2-carboxylic acid hydrazide (Hpmtc) derived from thiophene-2-carboxylic acid hydrazide and 2-benzoyl pyridine, and its metal complexes with Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized. These compounds are characterized by elemental analyses, magnetic susceptibility measurements, IR, NMR and UV-Vis spectral studies. The molecular structures of Hpmtc and its Co(II) (1), Ni(II) (2), Cu(II) (3) and Zn(II) (4) complexes are finally determined by X-ray crystallography. Various spectral and single-crystal X-ray diffraction studies suggest that Hpmtc coordinates with metal ions as a monobasic tridentate ligand forming mononuclear distorted octahedral complexes of the type [M(pmtc)2]. The molecular structures of the complexes are stabilized by CH⋯N, CH⋯O intermolecular H-bonding, and CH⋯π and π⋯π interactions. The DNA binding experiment of the complexes 1, 3 and 4 by UV-Vis absorption, and EB-DNA displacement by fluorescence spectroscopy, reveal an intercalative mode of binding between CT-DNA (calf-thymus DNA) and the metal complexes. These complexes exhibit a moderate ability to cleave pBR322 plasmid DNA. A comparative bovine serum albumin (BSA) protein binding activity of the complexes 1, 3 and 4 has also been determined by UV-Vis absorption and fluorescence spectroscopy. The DNA binding and protein binding studies suggest that the complex 3 exhibits more effective binding activity (Kb=5.54×10(5) and Kq=1.26×10(6) M(-1), respectively) than complexes 1 and 4. However, the complex 1 shows better hydrolytic DNA cleavage activity compared to 3 and 4 complexes.
由噻吩 - 2 - 羧酸酰肼和2 - 苯甲酰吡啶衍生而来的配体N'-(苯基 - 吡啶 - 2 - 基亚甲基) - 噻吩 - 2 - 羧酸酰肼(Hpmtc)及其与Co(II)、Ni(II)、Cu(II)和Zn(II)的金属配合物已被合成。这些化合物通过元素分析、磁化率测量、红外光谱、核磁共振光谱和紫外 - 可见光谱研究进行表征。Hpmtc及其Co(II) (1)、Ni(II) (2)、Cu(II) (3)和Zn(II) (4)配合物的分子结构最终通过X射线晶体学确定。各种光谱和单晶X射线衍射研究表明，Hpmtc作为一元三齿配体与金属离子配位，形成[M(pmtc)₂]型单核扭曲八面体配合物。配合物的分子结构通过CH⋯N、CH⋯O分子间氢键以及CH⋯π和π⋯π相互作用得以稳定。通过紫外 - 可见吸收对配合物1、3和4进行DNA结合实验，以及通过荧光光谱进行EB - DNA位移实验，揭示了CT - DNA(小牛胸腺DNA)与金属配合物之间的插入结合模式。这些配合物表现出适度的切割pBR322质粒DNA的能力。还通过紫外 - 可见吸收和荧光光谱测定了配合物1、3和4相对牛血清白蛋白(BSA)的蛋白质结合活性。DNA结合和蛋白质结合研究表明，配合物3表现出比配合物1和4更有效的结合活性(分别为Kb = 5.54×10⁵和Kq = 1.26×10⁶ M⁻¹)。然而，配合物1与配合物3和4相比，显示出更好的水解DNA切割活性。
