Synthesis And Properties Of Cyclometalated Pt(?) Complexes With A 2,2'-bipyridine Ligand

The formation of carbon-carbon bonds plays an important role in organic synthesis.The cross-coupling reaction catalyzed by transition metals is one of the most effective ways to construct carbon-carbon bonds.Among them,the Suzuki coupling reaction catalyzed by palladium has been widely used to synthesize natural products,pharmaceuticals and complex functional materials due to its mild reaction conditions,wide application range of substrates,and high yields.In this thesis,a highly efficient ligand-free catalytic system of Pd/C/EtOH/H₂O/K₂CO₃has been developed.This catalytic system can be used for the simple and efficient synthesis of nitrogen heteraryl-substituted biaryl compounds and sulfur heteraryl-substituted biaryl compounds.Furthermore,a series of cationic cyclometalated platinum???complexes containing 2-phenylpyridine derivatives as the C^N cyclometalated ligands and2,2'-bipyridine as the N^N auxiliary ligand were designed and synthesized.The relationships between photophysical,electrochemical and oxygen sensing propertie of these complexes and their structures were systematically investigated.The main contents and results are as follows:?1?A simple and general Suzuki reaction system was developed under aerobic and ligand-free conditions with Pd/C as catalyst,K₂CO₃ as base and aqueous ethanol solution as reaction medium.The optimal reaction conditions were obtained through condition screening.Under the optimal reaction conditions,a series of nitrogen-heteraryl-substituted biaryl compounds and sulfur-heteraryl-substituted biaryl compounds were synthesized,with the highest yield of 99%.Furthermore,six new cationic cyclometalated platinum???complexes Pt1-Pt6 containing 2-phenylpyridine derivatives as the C^N cyclometalated ligands and2,2'-bipyridine as the N^N auxiliary ligand were synthesized and their structures have been comfirmed by ¹H NMR,¹³C NMR and H RMS.?2?Photophysical,electrochemical and oxygen sensing properties of Pt1-Pt6 were systematically investigated.The results indicate that the introduction of a phenyl or a diphenylamino group in the 4-position of phenyl ring of the cyclometalating ligands makes these platinum complexes exhibit a obvious bathochromic shift of the maximum emission wavelength.In addition,introducing a trifluoromethyl group at the 5-position of the pyridyl ring of cyclometalating ligands,the maximum emission wavelength can be also tuned to red-shift.When immobilized in ethyl cellulose film,Pt6 bearing a diphenylamino group in the4-position of phenyl ring and a-CF₃ group in the 5-position of pyridine exhibits the highest oxygen sensitivity.