Design,synthesis And Optoelectronic Properties Of Phosphorescent Functional Platinum Complexes

Square planar platinum(II) complexes with phosphorescent emission have attracted numerous research interests due to their intriguing spectroscopic properties as well as great potentials in organic light emitting diodes (OLEDs), chemosensors and biosensors, cell imaging and self-assembly etc.Cyclometalated and ancillary ligands have profound effects on the photophysical properties of platinum complexes. Their luminescent properties are usually determined by cyclometalated and ancillary ligands, and can be tuned significantly by changing the conjugated degree of ligands as well as attaching the substituents with different electronic properties.β-Diketonate ligands are a very important class of ligands in the field of coordination chemistry. In this paper, we designed and synthesized a series of cyclometalized platinum(II) complexes containingβ-diketonate ligands with low triplet-state energy levels and studied the relationship between the structure and photophysical as well as electrochemical properties in detail. All complexes exhibit moderate emission both in solution and solid state. The emission colors of these complexes can be tuned from blue-green to yellow by simply changingβ-diketonate ligands. Importantly, the exclusive staining of cytoplasm, low cytotoxicity and good cell membrane permeability were observed for these complexes, which makes them promising candidates as phosphorescent probes for bio-imaging.The properties of organic luminescent materials can be governed by their molecular aggregation state, which are strongly dependent on molecular arrangement and packing structures. Therefore, understanding the relationship between molecular arrangement in solid state and properties is of great importance.A series of platinum(II) complexes with intense aggregation-induced phosphorescent emission (AIPE) were designed and synthesized. All complexes exhibited no emission in solution but strong emisson in solid state. The relationship between the structure and emission properties for these complexes in the solid state was investigated by single-crystal X-ray diffraction analysis as well as density functional theory (DFT) calculations. The results indicated that the intense emission in aggregation state can be attributed to the restricted distortion of excited-state structure (RDES) in aggregates. In light of this abnormal intense emission in solid state, typical three-layer organic light emitting devices were fabricated to evaluate their electroluminescent properties. All the devices showed characteristic emission of the platinum(II) complex with emission peak at 580 nm. By combining this emission with the blue emission of host CBP (4,4'-bis(N-carbazoly)-1,1'-biphenyl), we realized white emission with Commission Internationale de L'Eclairage (CIE) coordinate (x, y) values of (0.33, 0.30), very close to the balanced equienergy white point of (0.33, 0.33). Considering the excellent AIPE properties, this class of platinum(II) complexes also exhibit promising application in other optoelectronic fields.