Study On Free Radicals And Properties Of Triphenylamine Derivatives Induced By Metal Ion

Triphenylamine（TPA）is an important propeller structure appended organic compound with nitrogen atom as the center.The propeller structure of triphenylamine makes TPA have good hole transport capacity and high hole mobility.Meanwhile,TPA and its derivatives also have unique free radical properties.The results show that TPA radical has significant UV-visible absorption changes,which can be used in chemosensor field.Based on the above research background,three kinds of TPA derivatives were designed and synthesized in this thesis.The details are as follows:1.The donor-acceptor（D-A）structure appended derivatives（d-OMe-TPA-Br,d-OMe-TPA-py and d-OMe-TPA-py⁺）were designed and synthesized fom 4-bromo-N-（4-bromophenyl）-N-（4-methoxyphenyl）aniline parent.Experiment results suggested that the addition of Cu²⁺and Fe³⁺to the acetonitrile solution of d-OMe-TPAs can induce the corresponding cationic radical,and strong UV-vis absorption in near infrared region were observed.Further studies showed that the TPAs derivatives only can be reduced by Cu²⁺in acetonitrile/water mixture solvent,and thereby showing a high sensitivity and selective colorimetric detection of Cu²⁺.At the same time,d-OMe-TPA-py⁺can also be used as a bacteriostatic agent to inhibit the growth of Gram-negative and gram-positive bacteria.2.4-bromo-N,N-bis（4-methoxy phenyl）aniline,4-pyridine phenyl boric acid as raw materials,a series of mono-substituted TPA derivatives（m-OMe-TPAs）were synthesized.Similarly,m-OMe-TPAs only can be reduced by Cu²⁺to form the corresponding organic radical cations in a mixture solution of acetonitrile/water,which also can be used as a sensitive colorimetric sensor for Cu²⁺.In particular,the detection results show that the sensors have higher sensitivity and lower detection limit than d-OMe-TPAs derivatives.Further studies showed that the organic free radical cations triggered by Cu²⁺recognition could be used as antibacterial agents,with high bacteriostatic efficiency against both Gram-negative and gram-positive bacteria at low concentrations.This study provides a new idea for designing sensitive colorimetric sensors and efficient antibacterial agents.3.A series of m-TPAs series guest molecules were synthesized from4-bromotriphenylamine and 4-（4-pyridine）phenylboric acid and d-TPAs guest molecules were synthesized from 4,4’-dibromotriphenylamine and 4-（4-pyridine）phenylboric acid,respectively.In acetonitrile solution,adding one equiv.of Cu²⁺,the corresponding organic radical cation can be generated through chemical redox reaction.However,the addition of Cu²⁺to m-TPAs and d-TPAs acetonitrile/water mixture solution could not be redox to form corresponding organic radical cations.Further studies showed that when a certain amount of Cu²⁺was added to the high concentration of m-TPA-Br and d-TPA-Br acetonitrile solutions,the corresponding organic radical cations could undergo further dimerization reaction,and tetraphenylbenzidine derivatives could be generated.This method exhibits more efficient than uhrmann’s reaction,which usually requires high temperature and extended reaction time,and whose yield is often unpredictable due to side reactions such as dehalogenation and coupling.