Synthesis Of Cyclometallated Ruthenium Complexes Based On Thiophene Derivatives And Their Interactions With Hg²⁺

With the rapid development of technology,people's living standards are increasing day by day.However,at the same time,it also accompanies by increasingly serious environmental hazards,which pose a huge threat to public health and food safety.As a toxic and harmful heavy metal ion,Hg2+ ion will destory the central nervous system and cause brain and liver damage.Therefore,how to detect mercury ions quickly has attracted the attention of scholars.It is wellknown that absorption of cyclometallated ruthenium complexes is located in the visible light region due to its metal to ligand charge transfer transition(MLCT)absorption,whose structures are easily modified by introducing recognition units to specific ions or molecules to realize the recognitions and detections of these ions and molecules However,to date,there are few reports on the use of cyclometallated complexes for small molecules or ions recognition.Herein,several new cyclometallated Ruthenium complexes were designened,synthesized and used for the detection of Hg2+due to the affinity of mercury to sulfur.The main contents are as follows1.3-(3-Sulfonate)propyl-1,1,2-trimethylbenzo[e]indolium is successfully drafted onto C ^ N ligand to obtain a water-soluble cyclometallated ruthenium complex(1),which exhibites a great solution color change from red to yellow in the presence of Hg2+in water.It could be recognized by naked eyes.Moreover,its detection limit for Hg2+was as low as 21 nM.The mechanism of the interaction between 1 and Hg2+was analyzed by 1H NMR,13C NMR,UV-Vis and MS spectra The results showed that the solution color change in the presence of Hg2+should be assigned as a Hg2+-promoted conversion of Ru-C to Ru-S rather than the coordination betweem Hg2+and S from thienyl group in the complex 13.Two new cyclometallated ruthenium complexes(2 and 3)were synthesized by using 1-(thiophen-2-yl)-3-ethylimidazolium,1-(thiophen-2-yl)-3-ethylbenzo[d]-imidazolium as C ^N ligands,respectively.The results of UV-Vis absorption spectra showed that these two complexes all displayed obvious solution color changes when Hg2+ions were added.The detection limits for Hg2+are 43 and 150 nM,respectively3.A new cyclometallated ruthenium complex(4)involing thienyl group was synthesized by using 2,2'-bipyridine-5,5'-dicarboxylic acid as the N^N ligand.In water,it can recognize Hg2+with the detection limt of Hg2+as low as 47 nM.Then,it was successfully drafted onto mesoporous SiO2 nanoparticles to get a new hybrid nanomaterial 4@NH2-MSNs,which has been characterized by XPS,TEM,TG and nitrogen adsorption.