Synthesis,Structure And Properties Of Novel Schiff Bases And Its Metal Complexes Derived From 2,2'-dipyridylketone Hydrazone

Heterocyclic Schiff bases are important compounds in Chemistry and Biochemistry due to their flexibility,easy preparation,and also due to their broad spectrum of biological and pharmaceutical activities,such as antimicrobial,anti-inflammatory and anticancer properties.Moreover,heterocyclic Schiff bases also play an important role in coordination chemistry.It provides more coordination sites because of characteristic group?>C=N-?of Schiff base and heteroatom of heterocyclic groups.So the chemistry of heterocyclic Schiff base has always been a promising field of research.In this paper,we firstly prepared five novel heterocyclic Schiff bases analogs containing pyridine and indole groups?abbr.2-DPHI,3-DPHI,4-DPHI,6-DPHI and3-DPHMI?.Then three of them?2-DPHI,4-DPHI,and 3-DPHMI?was selected as ligand to preform coordination experiments.Finally,we obtained eight novel Schiff Base complexes,which contain one silver complex?abbr.Ag3m?,one cobalt complex?abbr.Co3m?,two copper complexes?abbr.Cu4,Cu3m?and four cadmium complexes?abbr.p Cd2,p Cd4,Cd3m,p Cd3m?.We successfully obtained their crystals except3-DPHI and 6-DPHI,and clarified their structure and crystal stacking mode by single crystal X-ray diffraction.It was found that C-H????and/or?????interactions play a key role in crystal stacking of three Schiff Bases,while the complexes mainly rely on virous weak hydrogen bonds.In addition,theoretical studies?TD-DFT?have been investigated to compare with the experimental findings.It was found that all Schiff Bases have three main absorption bands,which can be assigned as the joint action of???*and n??*transitions.And the absorption of Cu4 at 424.5nm has the characteristics of LC and MLCT.More,we found p Cd3m has good solid-state fluorescence properties with a maximum emission peak around 590nm.Finally,all products were evaluated for their in vitro anti-tumor activity against three cancer cell lines:A375?human melanoma cell line?,A549?human lung cancer?,HELA?cervical cancer cell line?by MTT assay.The results show that 2-DPHI has significant cytotoxicity to A375 and A549 and has modest cytotoxicity to normal HFF-1?human foreskin fibroblasts?.In addition,one Schiff Base copper complex Cu3m showed severe toxicities against the above three cancer cell lines,and the IC₅₀values of three cell lines were 5.10?M,3.42?M and 6.06?M,which was similar to the standard cisplatin.