Synthesis And Properties Of Coordination Polymers Constructed By Carboxylic Acid And Nitrogen-containing Heterocyclic Ligands

Coordination polymers（CPs）as new materials have attracted widespread attention in the field of coordination chemistry.The application of CPs as fluorescence sensors for the detection of heavy metal ions and antibiotics in wastewater has become the focus of research.Ten CPs were synthesized by chemical reaction between three bis（benzimidazole）ligands and aromatic carboxylic acids with metal salts.The CPs were characterized by various experimental methods.The four new CPs（1～4）were constructed by reaction of 1,4-bis（benzimidazol-1-ylmethyl）benzene（L1）and1,8-naphthalenedicarboxylicwith Cd（Ⅱ）/Co（Ⅱ）/Ni（Ⅱ）/Ag（Ⅰ）,respectively.Three Cd（Ⅱ）/Co（Ⅱ）/Ni（Ⅱ）based on CPs（5～7）were synthesized by hydrothermal reaction of 1,3-bis（benzimidazol-1-ylmethyl）benzene（L2）with aromatic carboxylic acids.8～10 were obtained by the reaction of 1,5-bis（1-benzyl-2-benzimidazole）pentane（L3）,1,3,5-benzenetricarboxylate and 2,5-dichloroterephthalic acid with Zn（Ⅱ）/Cd（Ⅱ）/Ag（Ⅰ）.1～3 display 1D ladder chains.4 exhibits 2D hcb layer.5～7 can be simplified as sql networks.8 can be simplified as 3,5L52 network,9 and 10 are 1D chains.According to Hirshfeld surface analysis,1～5 can be extended into higher dimensions throughπ···πreactions.1～10 possess excellent fluorescence properties based solid-state fluorescence spectra.The results of localized orbital locator analysis display fluorescence of CPs can be attributed to their bigger conjugatedπsystems.Thermal stability of 1～10 is positively correlated to coordination bond strength.The fluorescence sensing experimental displays 1～4、5～7、8～10 can act as fluorescence sensors for Fe³⁺,Cr₂O₇^2-,tetracycline with favorable selectivity,respectively.The fluorescence quenching mechanisms of 1～4 and 8～10 are electronic transfer,6 is resonance energy transfer,5 and7 are electronic transfer and resonance energy transfer.The fluorescence of ligands and CPs and fluorescence quenching mechanisms of CPs were analyzed.It provides certain reference for synthesis of other CPs with excellent fluorescence.Figure 81;Table 15;Reference 76...