Synthesis Of D-?-A Organic Molecules And Room Temperature Phosphorescent Behavior In Different Restricted Environments

Due to the characteristics of phosphorescent materials such as long-lasting luminescence and large Stokes shift,they have a wide range of applications in the fields of biological imaging,digital anti-counterfeiting and chemical sensing,etc.With the continuous deepening of research,many phosphorescent materials with high efficiency and long lifetime have been reported.However,the luminescence mechanism of many materials is not yet clear,and most can only achieve phosphorescent emission in the near ultraviolet region.Due to the short wavelength and high energy of near-ultraviolet light,which greatly limits the lifetime and application range of the materials,it is of great significance to develop a room temperature phosphorescent material excited by visible light wavelength.In this work,a series of short conjugated twisted molecules with a double D-?-A structure and no heavy halogen atoms were designed and synthesized.The molecules exhibit room temperature phosphorescence under visible light excitation in two different restricted environments,crystalline and polymer-based materials,and both of them have excellent phosphorescent properties.Among them,the crystalline MMCZ and its polymer materials can achieve ultra-high efficiency phosphorescent emission.While successfully realizing visible light excitation,the luminescence mechanism of the material is studied and a photophysical pathway(direct trilinear absorption of S₀?T₁^*and the upconversion process T₁^*?T₁^*in the system)is proposed different from the traditional phosphorescent luminescence mechanism(S₀?S₁?T₁).At the same time,this paper successfully realized the homogeneous polycrystal effect of the series of molecules.Both crystal forms can achieve room temperature phosphorescence under visible light excitation.In particular,the crystal form Y achieves white light emission at low temperatures.Because the crystal form G has a more regular molecular arrangement and tighter stacking,it can achieve high efficiency phosphorescent emission,and at low temperatures,the short wavelength emission of crystal form Y is complementary to the three-linear phosphorescent emission to achieve white light emission.In summary,through simple molecular design and polymer doping and polymorphic cultivate,the room temperature phosphorescence phenomena of organic molecules under visible light excitation in different restricted environments was successfully realized,and the photophysical process was enriched,bringing a new understanding of the phosphorescence mechanism.