| Usually traditional luminescent materials are highly emissive in a dilute solution,but their emission is often quenched in the aggregated state,which is known as aggregation-caused quenching（ACQ）.This phenomenon greatly limits the practical application of solid luminescent materials.The aggregation-induced emission（AIE）phenomenon provides a novel idea to solve the ACQ problem.So far,most of the AIE molecules are small organic molecules,only a few AIE-active transition metal complexes reported in the literature.Compared with small organic molecules,transition metal complexes have been widely used in many fields such as organic light-emitting diodes（OLEDs）,photocatalysis and chemosensors,due to their characteristics of long lifetime,large Stokes shift,and high luminenscent efficiency.In this thesis,a series of cyclometalated platinum（II）complexes containing a rotatable phenyl group have been designed and synthesized.The relationships between the structures of the complexes and photophysical,electrochemical properties and luminenscent properties in acetonitrile/water have been investigated systematically.The aggregates of some Pt（II）complexes formed in acetonitrile/water were analyzed by transmission electron microscope（TEM）.The main research content includes the following three parts:（1）A series of phenyl-modified 2-phenylpyridine derivatives prepared via a palladium-catalyzed Suzuki cross-coupling reaction were used as the cyclometalating ligands for the synthesis of nine cationic platinum（II）complexes Pt1-Pt9 bearing 1,10-phenanthroline or its derivatives as auxiliary ligands.These complexes were fully characterized by 1H NMR,13C NMR and HRMS.（2）The photophysical,electrochemical properties,and the luminescence properties in acetonitrile/water of the complexes Pt1-Pt6 with 1,10-phenanthroline as the auxiliary ligand,have been studied in detail.In the acetonitrile/water systems with the water contents at 0-70%,these six complexes were nearly non-emissive.However,the emission intensity of the complexes was significantly enhanced at the water content of 80%and even higher.The results demonstrate that these six complexes are AIE-active.In addition,the UV-Vis absorption spectra of these complexes in acetonitrile/water at different water contents show a new absorption band in the range of 450-600 nm.TEM images show that the complexes Pt2,Pt4 and Pt5 aggregate into nanofibers,nanosheets and nanorods in acetonitrile/water,respectively.（3）The photophysical,electrochemical properties,and the luminescence properties in acetonitrile/water of the complexes Pt7-Pt9 with 4,7-diphenyl-1,10-phenanthroline as the auxiliary ligand,have been studied in detail.In the acetonitrile/water systems with the water contents in the range of 0-50%,these complexes were nearly non-emissive.However,the emission intensity of the complexes was significantly enhanced at the water content of 60%and reached the maximum at the water content of 75%.Further increasing the water content,the intensity gradually decreased.These results demonstrate that the three complexes are AIE-active.Among the complexes Pt1-Pt9,Pt8 exhibits the most significant AIE properties. |
