Investigation On Novel Molecular Probes Based On Palladium-azo Complexes And The Sensing Of Tin

Optical molecular chemosensors(OMCSs) that convert molecular recognition into sensitive and detectable optical signals have emerged in the field of analytical chemistry as an application of the research on molecular recognition.OMCSs have become one of the current scientific fronts and have been actively investigated in recent years due to their unique importance and merits in probing the composition, structure or evolution of environmental or biological microsystems.The peculiar electronic and steric properties of cyclometalated platinum group complexes have made them great application foreground in photoactive materials including molecular chemosensors.Some OMCSs have been developed in this dissertation based on cyclometalated palladium-azo complexes,where a range of chemical substances, including some important anions,sulfureted hydrogen and tin-containing species (TCS).were explored as the sensing targets.This dissertation consists of three chapters summarized as follows:In chapter 1,a general introduction to OMCSs was presented.Emphasis was paid on the new developments of OMCSs,especially those based on platinum group metal complexes.Based on reviewing the research progresses of the utility of cyclometalated palladium-azo complexes as optical molecular chemosensors,the objective of this dissertation was presented.In chapter 2,some cyclometalated palladium-azo complexes were synthesized and used as optical molecular chemosensors for thiocyanate and sulfureted hydrogen gas in aqueous solution.This chapter was divided into two parts.In part 1,the spectral characters of two cyclometalated palladium-azo complexes, MoP and AbP,as OMCSs for anions was investigated,then comparative research was done to investigate the influence of the structure of azo ligands on the spectral character and reactivity of the developed chemosensors.Highly selective spectral and sensitive colour response were shown upon addition of SCN" into an aqueous solution of MoP.SCN^- could be quantitatively determined at the concentration level of 10^-7 mol L^-1 in the presence of coexisting common anions at high concentrations.But AbP showed a poor selectivity in SCN^- sensing.In part 2,a new optical probe for H₂S based on palladium-azo complexes was designed by modifying the structure of the ligand.The primary research showed a sensitive chromogenic response of the designed probe toward H₂S in aqueous solutions with high selectivity.The target gaseous species could be well quantitated by naked eyes in a concentration range from 0.10 to 50.0 mg L^-1.Further researches will aim at the utility of this probe in exploring the metabolic processes involving endogenous H₂S.In chapter 3,chemosensors for TCS were investigated.This chapter was divided into two parts.In part 1,a new optical probe for TCS based on palladium-azo complexes, named TAR-Pd,was described.Sensitive spectral and colour response with high selectivity were shown upon addition of TCS into sensing solution of TAR-Pd. Inorganic tin cations and organotin compounds(OTC) could be easily detected with naked eyes at the concentration levels of 10^-6mol L^-1 and 10^-5 mol L^-1,respectively. Meanwhile,the coordination-induced Pd-Pd interaction resulted in a sensitive NIR absorption response of TAR-Pd.In part 2,a new fluorescent probe for hydroxylated organotin(HOT) based on special fluorogenic metalloreceptor bearing a boric acid group was described.The primary research showed its high selectivity in sensing HOT.The concentration of HOT could be quantitatively determined in the range of 10^-6 - 10^-4mol L^-1.The developed probe is expected to see its application in the concerning toxicological studies.