Study On The Synthesis And Recognition Performance Of Ferrocenyl-based Carbazole Derivatives As Chemosensors Toward Cu²⁺、Hg²⁺,pH Value And H₂S

In this paper,two series of chemosensors containing ferrocene group were designed and synthesized,and the recognition performance of metal ions and pH value and H₂S were studied.This article is divided into two parts.In the first part,seven kinds of ferrocene-based azine derivatives containing carbazole,pyrene and pyrrole were synthesized,in which azine group（-C=N-N=C-）as the main identifying groups.These ligands have good specificity recognition toward Cu²⁺and Hg²⁺ions,and the solution of ligands changed colorless and the fluorescence enhanced following the pH value changes from 7 to 1.In the second part,one of ferrocenyl carbazole ligands containing nitroolefin group was synthesized,which can selectively recognize Cu²⁺,Hg²⁺and H₂S.The main contents are as follows:In the first part,we synthesized seven chemosensors containing ferrocenyl azines in a simple way.They are containing azine group（-C=N-N=C-）as the main identifying group,and their structure were characterized by NMR spectroscopy and high resolution mass spectrometry.In this study,it was found that the ligand 4a⁴g showed excellent recongnition property toward Cu²⁺,Hg²⁺ions and the acid changes of pH,in which the ligand 4a⁴e have shown to be excellent three-channel chemosensors.In the case of ligand 4b,the solution color changed to orange and red,fluorescence enhanced,and electrochemical current density decreased,upon addition of Cu²⁺and Hg²⁺ions.On the other hand,the detection limit of ligand 4b for Cu²⁺is8.02μM and for Hg²⁺is 16μM.When ligand 4b combined with H⁺ion,the solution color changed from yellow to colorless,and the fluorescence gradually increased.In addition,the ligand-metal coordination was removed when the instillment of H⁺ion after 4b has been complexed with Hg²⁺ion.Finally,the effects of different substituents and conjugation structures on the recognition results were determined by comparing the UV-vis spectra and fluorescence spectra of seven ligands.It was found that the aldehyde-containing ligand 4d had the best recognition effect(K_Cu 7.17×10¹³M^-2,K_Hg 9.8×10⁶ M^-1),the lowest detection limit(DL_Cu 8.02μM,DL_Hg 1.4μM).In the second part,an organic ligand 12a which can recognize H₂S through three-channel was synthesized by introducing nitroolefin group on the carbazole group,and its structure was characterized by NMR spectroscopy and high resolution mass spectrometry.The experimental results show that the ligand 12a can linearly recognize H₂S within 1 equivalent,and the solution changed colorless and fluorescence increased when the H₂S addition into solution,and the detection limit is0.97μM.In addition,the ligand 12a can also specifically recognize metal Cu²⁺,Hg²⁺ions,with the fluorescence increases 40-fold and 38-fold.