Molecular Design Of Phosphorescent Pt(?) Complexes And Intermolecular Interactions In Dimers: A Theoretical Study

Organoplatinum???complexes can be widely used as a luminescent material in organic light-emitting diode?OLED?devices.Based on theoretical calculations,this study will aid better understanding of the structure-property relationship of phosphorescent Pt???complexes and provide constructive information for designing novel and efficient OLED materials.Encouragedbypreviousexperimentalworkthatboth[?C^N^N?Pt?C?NAr'?]PF₆?Ar'=2,6-Me₂C₆H₃??1?and[Pt?trpy??C?CC₆H₅?]PF₆?2?complexes show significantly red-shifted and have strong tendency to aggregate,in this contribution,the electronic structure spectral properties of both complexes are studied.Besides,three other Pt???molecules were designed by introducing different functional group to 1 and 2.The photophysical properties of the five Pt???complexes are investigated using density functional theory?DFT?and time-dependent DFT approaches.In addition,the dimeric structures and the distribution of intermolecular non-covalent weak interactions in dimers are explored in detailed by theoretical investigations.By analyzing and comparing the ground state and the excited state geometries,charge transport,absorption spectra,and phosphorescence properties of the five cationic Pt???complexes,it is possible to forecast that complex 4{[Pt?trpy??C?CAr'?]PF₆?Ar'=2,6-Me₂C₆H₃?}could be the best efficient phosphorescent material among them due to its biggest triplet emission wavelength,and best balanced electron/hole-transport performance.The smaller difference between?_e and?_h suggests that terpyridyl arylacetylide Pt???complexes have a better charge?hole and electron?transport balance than that of phenyl-bipyridine arylisocyanide Pt???complexes.In addition,the phosphorescent emission wavelength of the terpyridyl arylacetylide Pt???complexes is greater than that of the phenyl-bipyridine arylisocyanide Pt???complexes.The emission transition of terpyridyl arylacetylide Pt???complexes is associated with ³MLCT/³LLCT transitions,while the emission transition of phenyl-bipyridine arylisocyanide Pt???complexes has ³MLCT/³LLCT/³IL character.Square-planar Pt???complexes are inclined to interact with each other by intermolecular interactions and further aggregate into quasi-1D nano-structures.The DFT-D3?BJ?dispersion correction method is introduced to optimize the dimer structures for studying intermolecular non-covalent weak interactions.There are two stacking arrangements for dimeric structure,namely,head-to-tail and skewed.For the optimized dimeric structures,the Pt···Pt distances between the monomers are all shorter than the sum of van der Waals radii 3.44?.Reduced density gradient?RDG?analysis shows the visualization of intermolecular Pt···Pt and?-?interactions.The axial 5d_z2 orbitals of two Pt???ions in close proximity overlap to give orbital rearrangement and the band gap decrease.