Construction And Application Of Aggregation-induced Emission-active Smart Responsive Materials Based On Metal Iridium Complexes

In recent years,Ir(III)complexes have been widely attracted extensive attention by scientists because of their relatively long excited-state lifetime,excellent tunability of emission color,large Stokes shifts and good photostability.At the same time,they have made significant breakthroughs in emerging areas such as organic light emitting diodes,photocatalytic water reduction,chemical sensors,biosensors,photodynamic therapy,and smart materials.However,the theoretical guidance for the structure-property relationship of functional Ir(III)complexes with specific properties is relatively lacking,and the corresponding optoelectronic properties are also difficult to predict.In addition,the aggregation-induced quenching(ACQ)phenomenon widely exists in phosphorescent Ir(III)complexes,which greatly limits their practical application in the aggregated state.Therefore,how to efficiently and simply obtain high-performance Ir(III)complexes is a hot research topic.In 2001,a new concept of aggregation-induced emission(AIE)proposed by Tang and co-workers effectively solved the quenching phenomenon of luminescent materials in the aggregated state.The introduction of this concept has broadened the practical application of luminescent materials in the aggregated state,especially in the field of smart stimulus-responsive materials.Due to the advantages of simple and fast response of intelligent stimulus response materials,they exhibit potential application value in the fields of pressure sensing,anti-counterfeiting and information encryption.Therefore,it is of great significance to design and synthesize Ir(III)complexes with both AIE properties and stimulus-response properties.At the meanwhile,it can further realize better practical application of Ir(III)complexes by exploring the structure-property relationship deeply and controlling the properties and functions of Ir(III)complexes through reasonable molecular design.In this paper,we have simply synthesized two types of smart materials based on stimulus response through reasonable selection and modification of the auxiliary and cyclometalated ligands of Ir(III)complexes,and detailed research on their photophysical properties.The specific work is as follows:1.A new Ir(III)complex containing Schiff base ligands with AIE-active was designed and synthesized.Under the stimulation of acid-base vapor,a reversible protonation and deprotonation process would occur on the oxygen atom of the phenol unit on the Schiff base ligand,changing the emission color of complex from orange to green.Moreover,a phosphorescent sensing device based on the Ir(III)complex on a TLC plate was successfully prepared.This provides a very promising new strategy for the rapid,convenient,high-sensitivity and reversible detection of acid-base vapor.2.A new AIE-active neutral Ir(III)complex has been rationally designed and synthesized by introducing carboxyl and fluorine substituents into the ancillary and cyclometalating ligands,respectively,to construct different kinds of intermolecular interaction,leading to excellent piezochromic luminescence(PCL)properties.The emission colors are tunable by a grinding–fuming/heating process with good reversibility in the solid state.A combination of powder X-ray diffraction,differential scanning calorimetry,~1H NMR and Fourier-transform infrared spectroscopy unambiguously confirm that the mechanism of PCL involves disruption of the intermolecular π-π interactions and hydrogen bonding.The combined AIE and PCL properties have enabled an efficient re-writable data recording device to be fabricated using the Ir(III)complex as the active material.