Synthesis Of The Novel Water-soluble Iridium Complexes And Their Applications As Phosphorescence Probes

Phosphorescent iridium complexes have gained much attention as luminescent sensors owing to their unique photophysical properties such as large Stokes shift,relatively high phosphorescence emission efficiency and longer luminescence lifetime.These advantageous properties make them useful tool for enabling their widespread use in photochemical and electrochemiluminescence sensing,biological cell imaging,catalytic decomposition,catalysts,organic light-emitting diode?OLED?and organic electronic devices?OED?.Among them much research attention has been given to their application as luminescent sensor.Phosphorescent iridium complexes can be effectively used to avoid the interference of background stray light and intracellular autofluorescence.Therefore iridium complexes are better choice for chemical detection and biological imaging by using time resolved technique in real sample or live cell imaging.Due to this researchers have growing interest in phosphorescent chemosensors with long phosphorescence lifetime and good biocompatibility.The present dissertation work is based on design and synthesis of three novel water-soluble cyclometallated iridium.The structure,photophysical properties and the application of iridium complexes in protein detection are studied.The main work is divided into three distinct parts:1.This chapter concerns about design and synthesof a quaternary ammonium salt water-soluble iridium complex[Ir?pq?₂?qpy?]³⁺3Cl^-?Irqpy?.The structure was characterized by NMR and mass spectrometry,and its photophysical and phosphorescence properties were studied.It was found that after adding BSA,Irqpy has a good phosphorescent response to BSA.By optimizing the experimental conditions for the detection of BSA,it was found that pH,protein denaturing agents,salts,and temperature all had a great influence on the luminescence.Supposedly,the hydrophobic structure of the BSA structure played crucial for the luminescence.Under optimized conditions,quantitative detection of BSA was achieved with a detection limit of 0.1 mg/m L and a linear range of 0-1 mg/m L.This response allows the construction of an Irqpy phosphorescent probe for BSA.2.Compared to quaternary ammonium salts,carboxylate-type cyclometallated metal water-soluble iridium complexes are rarely reported.This chapter is dealing with synthesis of carboxylate-type cyclometallated water-soluble iridium complex?Irdc?,it was found that in the presence of gluten,the luminescence of the system increased dramatically,and thus a“turn-on”phosphorescent probe was constructed for use in gluten and wheat,oats and other biological samples were tested.The results showed that this phosphorescent probe has low detection limit?2.6?g/m L?,wide linear range?5-200?g/m L?,and high specificity;therefore,it was used to determine the actual commercial the gluten-containing wheat flour,oats and gluten-free wheat flour.The probe showed good results in actual detection and can meet the needs of actual sample testing.In summary,this is the first report of a method for detecting gluten using a phosphorescent probe method.This phosphorescent probe can be further developed to assess the content of gluten in actual foods to ensure a safe diet for patients suffering from allergic celiac disease.3.In order to further improve the water solubility of the cyclometallated water-soluble iridium complex,and to obtain a multifunctional phosphorescent probe for the field of biomonitoring,this chapter introduces the sulfonate salt which is more water-soluble than the carboxylate salt.The sulfonate-type cyclometallated water-soluble iridium complexe?Ir?were successfully prepared.It was found through experiments that it can be used as a high-sensitivity pH indicator under acidic to weak alkaline conditions,and the luminescence mechanism was studied by density functional theory.In addition,it was also found that Ir significantly increased in the presence of HSA.As a result,a"turn-on"type of phosphorescent probe was used for detection.Compared with BSA,the significance and practical application range was even greater.Through thermodynamic experiments,it was found that the binding mode between HSA and ruthenium complexes proved to be both hydrophobic and electrostatic.The phosphorescent probe shows low detection limit?0.8 nmol/L?,wide linear range?1-280 nmol/L?and good stability.Therefore,it was also used to determine HSA in the actual human serum and urine samples.In addition,the mechanism of action has proven to be widely applicable to other proteins that have similar hydrophobic cavities.