Synthesis,Structures And Properties Of Tetrazolate Coordination Complexes With Indole Derivatives As Ligands

As an organic ligand,tetrazole can coordinate with metal ions in nine coordination modes,such as monodentate,bidentate and tridentate et al.In recent years,more and more attention has been paid to the use of tetrazolate-based complexes,especially for functional applications.In this dissertation,a series of tetrazole-based transition metal complexes were synthesized by in situ hydro(solvo)thermal method.Their structures,thermal stability,fluorescence properties and sensing applications were studied.The main contents are as follows:First,we selected monocyanate organic ligand L1{3-(2-(pyridin-4-yl)-2,3-dihydro-1H-benzo[e] indol-1-yl)benzonitrile} and three transition metal complexes were synthesized by in situ hydrothermal method.One of them is a one-dimensional tetrazole-based coordination polymer,[C24H15N6Zn0.5]·H2O(1).Two of them are two-dimensional complexes,[C48H30Cd N8O2]·2C2H6O·3H2O(2)and [C48H30Co N8O2]·CH3OH·H2O(3),and their ligands are carboxyl and tetrazole.Among them,complex 1 has no selectivity to metal ions,but the fluorescence emission wavelength of complex 1 is switched between 490 nm and 530 nm in different solvents.Complex 2 is selective to the nitro compound TNP.Secondly,the organic ligand L2{4-(2-(pyridin-4-yl)-2,3-dihydro-1H-benzo[e]indol-1-yl)benzonitrile}is obtained by changing the position of the cyano group in the ligand L1.Three completely new tetrazole-based complexes [C48H30N12Zn]·2H2O(4),[C24H15Cd Cl N6O]·C3H7OH·H2O(5)and [C24H15Co N6O]·2CH3OH·3H2O(6)were obtained by the in-situ synthesis method.Both 4 and 5 are selective for TNP.Finally,the dicyano-containing organic ligands L3{1-(3-cyanophenyl)-2-(pyridin-4-yl)-3H-ben zo[e]indol-5-carbonitrile)} and L4{4,4-(2,3-dihydro-1H-benzo[e]indol-1,2-diyl)dibenzonitrile} were synthesised,By using this ligand,two-dimensional complex C25H14 Cd N10O(7)and a one-dimensional complex [C26H15N9O2Zn2]·H2O(8)having a hole-like structure were obtaned through the in situ synthesis.One of the two cyano groups in the ligand L3 is tetrazole and the other remains unchanged.Two cyano groups in the ligand L4 are all generated as tetrazole.Through the analysis of fluorescence sensing of metal ions and nitro compounds,the results show that TNP has a static quenching effect on complex 8 and the quenching process includes electron transfer and energy transfer in two forms with a minimum titration concentration of 7.28×10-7 M.At the same time,the metal ions Al3+ and Cr3+ have fluorescence enhancement effect on the complex 8.In summary,eight novel tetrazole-based complexes were synthesized using in situ syntheses of transition metal salts with organic ligands containing mono-and dicyano groups.These new compounds provide useful information for further design on this elusive class of tetrazole-based compounds and give useful input into the fluorescence sensing in related complexes.