Synthesis And Property Study Of Novel Secondary Amine Complexes

In the past few years, many researchers paid much attention to the molecular structure and biological activity of coordinated complexes in inorganic chemistry field. The study on interaction models and mechanism of metal complexes with DNA are of great importance in the fields of cantineoplastic pharmaceuticals, molecular biochemistry and bioengineering technology. The Schiff base Complexes have a typically representative. However, a disadvantage is that Schiff base ligands will be changed unstable in acid solution, i.g. the Schiff base ligands could be decomposed. To avoid the instability, reducing the imine (-CH=N-) group to the secondary amine (-CH₂-NH-) is a good idea. Not only the secondary amine is more stable than imines, but also it exhibits more flexible and is unconstrained to keep one coordination planar and the integrity of the molecular structure, which may also decrease the space steric hindrance and make the aryl residue in the complex easy to insert into groups between the biomacromolecule. So it is significant to design complex using secondary amine as ligand, and study the interaction of complex with DNA. And by changing the groups in chains, or the situation of groups, studing the effect to the interaction of complex with DNA may guide the design of medicine. Thus we synthesized and characterized three secondary amine ligands and four transition metal (Cu^II, Co^II, Ni^II, Zn^II) complexes, and studied the interaction of complexes with DNA using spectral techniques and viscosity measurement.1 A brief review of the research situations for the metal complexes was given, and the interactioon mechanisms of complexes with DNA had been described . At the same time, the methods used to study the interaction between complexes and DNA had been summarized. Also the development direction and development prospects of complexes in biochemistry had been expatiated.2 Three new ligands are the KBH4 reduction product of the Schiff base. Its complexes with transition metal sulfate(Cu^II, Co^II, Ni^II, Zn^II) were synthesized. These complexes were characterized by elemental analysis, molar conductivity, IR spectra and X-ray single crystal diffraction. The crystal structure of the complex(ML¹, ML³) showed a regular octahedral structure in which each metal ion is six-coordinated with four nitrogen atoms from two L and two oxygen atoms from sulfate. And the complexs of L² were six-coordinated too, with six nitrogen atoms from six L².3 The mechanism of the interaction between complexes and calf thymus (CT DNA) in tris buffer (pH=7.08) had been studied by electronic absorption and ethidium bromide(EB) fluorescence spectroscopy. The results showed that the absorptivity of the DNA solution increases considerably, with the addition of complexes, and the addition of complexes caused the quenching fluorescence of the EB-DNA system, which revealed that all the complexes can bind to DNA, and have strong binding affinity with DNA. Also by EB fluorescence spectroscopy, we obtained the model of complexes to DNA, and the the binding constant for the reaction. The effect of ligand to the binding affinity had also been studied.