Synthesis,Structure And Properties Of D¹⁰ Metal Nitrogen Heterocyclic Complexes

The d¹⁰ metal nitrogen heterocyclic complexes exhibit excellent performance in catalysis,biomedicine and identification,making it applicated widely in the fields of environment,medicine and biology.Especially in terms of fluorescence properties,the luminescence of d¹⁰metal nitrogen heterocyclic complexes has obvious response to external environmental stimuli,which is strainful.Fluorescent materials of such complexes have attracted the attention of a great number of researchers.Therefore,it is of great significance to develop d¹⁰ metal nitrogen heterocyclic complexes with novel structures and good performances.In this thesis,two nitrogen heterocyclic ligands?1,4-[bis?2,2'-benzoxazole?]butane?BBO?,1,4-[bis?2,2'-benzimidazole?]butane?BBM??and a triphenylphosphine sulfide ligand?SPPh₃?are reacted with the d¹⁰ metal salts to obtain novel fourteen d¹⁰ metal nitrogen heterocyclic complexes.The complexes were characterized by IR,UV-Vis,elemental analysis and X-ray single crystal diffraction.The photoluminescence properties,electrochemical properties and antioxidant activities of the complexes were also investigated.The concrete research contents are as follows:1.The research progress of d¹00 metal nitrogen heterocyclic complexes was introduced.2.A new flexible bridging ligand 1,4-[bis?2,2'-benzoxazole?]butane was synthesized from o-aminophenol and adipic acid.Five silver complexes,namely,Ag₂?BBO?₂?ClO₄?₂]?1?,{[Ag?BBO??pic?]}_??2?,[Ag₂?BBO?₂?p-tso?₂]?3?,{[Ag?BBO?_1/2?o-cum?]·DMF}_??4?and{[Ag₂?BBO?₃]?PF₆?₂}??5??pic=picrate,p-tso=p-toluenesulfonate,o-cum=o-hydroxycinnamate?were synthesized by reaction with different silver salts.Structural analysis indicated that 1,3 are dinuclear complexes;2,4 are 1D coordination polymers;and 5is a two-dimensional coordination polymer.Except for the twisted tetrahedral structure of the silver ions in 3,the silver ions in other complexes are three-coordinated planar triangular configuration.According to structural comparison,it was found that the counter anion can adjust the spatial structure of the silver complexes through different coordination modes and steric hindrance,when the same bridging ligand was used.The solid-state fluorescence properties indicated that complexes 2-3 have a new emission peak at 470 and 428 nm,respectively,which are attributed to ligand-metal charge transfer?LMCT?.Moreover,the fluorescence intensity of complex 3 was significantly enhanced;however,the fluorescence of other silver complexes was quenched partly.It demonstrated that under the same main ligand,anions can regulate the photoluminescence properties of silver complexes.Electrochemical study shows that there are irreversible Ag⁺/Ag redox couples in 1-5.Coordination polymer 4has great ability of scavenge hydroxyl radicals and superoxide radicals.Their IC₅₀ values are?14.62±0.02?×10^-6 M and?2.03±0.02?×10^-5 M,respectively.3.A new flexible bridging ligand,1,4-[bis?2,2'-benzimidazole?]butane?BBM?,was synthesized from o-phenylenediamine and adipic acid.Reaction of this ligand with silver salts gave a binuclear complex[Ag₂?BBM?₂?sac?₂]·CH₃CN?6??sac=salicylate?and two one-dimensional silver coordination polymers{[Ag?BBM?]?pic?·CH₃CN}_??7?,[Ag?BBM??p-tso?]_??8?.It is worth mentioning that the central silver ion of the coordination polymer 7 is a two-coordinate linear structure,and the silver ions of the two complexes are three-coordinate planar triangular geometry.In addition,three dinuclear silver complexes were synthesized with the triphenylphosphine phosphine ligand,namely,[Ag₂?SPPh₃?₄]?BF₄?₂?9?,[Ag₂?SPPh₃?₄]?PF₆?₂?10?and[Ag₂?SPPh₃?₄]?ClO₄?₂?11?,respectively.And their central silver ions were all three-coordinated planar triangular structures.The solid-state photoluminescence properties of complexes 6-11 were studied that complex 6,the emission peak at 399 nm,can be owed to ligand-metal charge transfer?LMCT?.The red shift by 10-20nm were observed in the coordination polymers 7-8,which belong to the?-?*transition.Two peaks similar to the ligand??-?*and n-?*transitions?appeared in the emission spectrum of the complexes 9-11.The luminescence intensity of complexes 6,10-11 are higher than the ligand,because the ligand and the silver ion coordinate to enhance the rigidity of the ligand,thereby reducing the energy loss through the non-radiative pathway.The reason for the fluorescence quenching of other silver complexes is due to the heavy atomic effect of silver.By comparison with the silver complexes of benzoxazole,the choice of ligand has an important influence on the structure and properties of the complexes:especially in the formation of coordination polymers and in terms of fluorescent properties.Electrochemical experimental analysis showed that irreversible Ag⁺/Ag redox couples appeared in 6-11.The complexes 9-11 have excellent anti-hydroxyl radical scavenging activity.In particular,the complex 10 has the highest activity,and the IC₅₀ value is?13.09±0.03?×10^-6 M.4.Three zinc/cadmium coordination polymers were synthesized by reacting1,4-[bis?2,2'-benzimidazole?]butane?BBM?with zinc/cadmium salts,namely,{[Zn?BBM?Cl₂]·CH₃OH}_??12?,{[Cd?BBM?Cl₂]·CH₃OH}_??13?,[Cd₂?BBM?₂?TA?₄]_??14??TA=isophthalic acid?.Complexes 12-13 are one-dimensional and 14 is two-dimensional planar structure.The central zinc/cadmium ions of 12-13 are four-coordinated twisted tetrahedral configuration,while central cadmium ion in the coordination polymer 14 is a six-coordinate twisted octahedral configuration.Fluorescence analysis showed that compared to the ligand,12-14 are red-shifted by 21-42 nm,which could be attributed to the?-?*or n-?*transition.The fluorescence intensity of 12-14 is significantly weaker than that of1,4-[bis?2,2'-benzimidazole?]butane ligand,which probably due to the heavy atomic effect of zinc and cadmium atoms,resulting in the formation of polymers of the site undergoes fluorescence quenching.