Synthesis And Recognition Properties Of Acylhydrazone And Schiff Base Ion Receptors

This paper includes four chapters:Chapter1: This chapter introduces the principle of ion recognition based onsubject and object function, the research significance and the latest research progressof ion recognition are expounded. According to recognition mechanisms of thesesensors, we grouped them into five categories, the first kinds are deprotonation basedion sensors; the second kinds are hydrogen bonds based ion sensors; the third kindsare specific reaction based ion sensors; the fourth kinds are the coordination basedsensors; the fifth kinds, based on other recognition mechanism.Chapter2: A highly selective host L1was described, which could instantly detectCN-in water with specific selectivity and high sensitivity. The acylhydrazone groupand naphthalene group have been introduced to the sensor molecule as binding siteand fluorescence signal group, respectively. Moreover, to improve the water solubilityof L1, the hydrophilic benzimidazole group has been introduced to the sensormolecule. The detection of cyanide was performed via the nucleophilic attack ofcyanide anion on the carbonyl group, which could be confirmed by1H NMR,13CNMR, ESI-MS and DFT calculations. The addition of CN-to host L1induced aremarkable color change from colorless to yellow and generated a blue fluorescence,these sense procedure could not interfered by other coexistent competitive anions (F-,Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClO4-, SCN-, S2-, NO3-and SO42-). Moreover, thedetection process could be performed in a wide pH range from4to9. The detectionlimits were5.0×10-7mol L-1and2.0×10-9mol L-1of CN-using the visual fluorescentcolor changes and fluorescence spectra changes respectively, which is far lower thanthe WHO guideline of1.9×10-6mol L-1. Test strips based on sensor1were fabricated,which could act as a convenient and efficient CN-test kit to detect CN-in pure waterfor “in-the-field” measurement.Chapter3: A novel host L2based on the Schiff base has been designed andsynthesized. The host L2can not only detect AcO-by fluorescence spectrum but alsorecognize Ni2+by UV-vis spectrum and naked-eye. The host L2could instantly detectAcO-with specific selectivity and high sensitivity, these sense procedures could notinterfered by other coexistent competitive anions (such as F-, H2PO4-). Moreover, the procedure of detection Ni2+also could not be interfered by other coexistentcompetitive cations (such as Fe3+, Co2+, and Cu2+) and anions. Importantly, L2couldperform as a cyclical “Off-On-Off” molecular switch triggered by AcO-and H+ions.The test strips based on host LX were fabricated, which could act as a convenient andefficient Ni2+test for “in-the-field” measurement of Ni2+. The results indicated thathost L2selectivity binding with Y-shape AcO-via double hydrogen bonds anddetecting with Ni2+via coordination.Chapter4: A highly selective host L3based on an acylhydrazone group asbinding site and naphthalene group as the fluorescence signal group were designedand synthesized, which could instantly detect Zn2+in DMSO/H2O (1:4=v/v) withoutinterference by other cations such as Cd2+. It is very interesting that L3could notdetect Zn2+, but can recognize Mg2+without interference, when we changed ourexperiments system to DMSO/H2O (7:3=v/v, pH=8.5) HEPES buffer solution. Bystudying the detection abilities of L3, we found that L3could recognize Zn2+inslightly acidic condition from pH=5to7and detect Mg2+in weakly alkaline frompH=8to10. This unique identification characteristic of L3plays a very importantrole in biology, medicine and other fields.