Synthesis Of O-Carborane-Based Molecular Machines With Their Photophysical Properties

In recent years,molecular machines and circularly polarized luminesce-active materials have been attracted much attention from researchers.Circularly polarized luminescence refers to the phenomenon that organic chiral materials emit different left-handed and right-handed circularly polarized light,respectively.More importantly,their precisely excited structure changes can be facilely elucidated by the circularly polarized luminescence.The movement of designed molecular can be dirven by the external stimuli including the thermal energy,ligh,p H,and the like.Amazingly,if molecular chirality is introduced into molecular machine,the molecular machine will propose the functional of undirectional movement with the circularly polarized luminescence,which is beneficial for elucidating the magnetic and electric transition dipole moments changes in the rotational processes.In this paper,through precise molecular design:closed-loop change of intramolecular conformation,introduction of AIE group,chirality combined with phosphorescent group,etc.,the asymmetry factor g_lum is improved.In order to improve the circular polarization value of organic conjugated chiral molecules,studying the mechanism of chiral transmission and the direction of rotation provides new ideas and methods.At the same time,the process of cluster luminescence is used to effectively monitor the solid-state molecular motion of organic conjugated small molecules.The specific research content and main innovations are as follows:?1?First of all,we have designed and prepared carborane-modified binaphthol molecules.Experimental studies have shown that carborane in the crystal structure can effectively rotate,affecting the optical properties of the molecules,and providing a driving force for understanding circular polarization support.For example,the difference in carborane structure can not only affect the molecular stacking method in the crystal structure,but also affect the size of the corresponding circular polarization factor.Among them,the 6-substituted carborane binaphthol polarization value reaches 0.2.In addition,the variable temperature fluorescence test showed the movement of solid molecules in the process of cluster luminescence,proving the molecular machine properties of the 6-substituted carborane binaphthol molecules.?2?Secondly,we have designed and prepared organic conjugated small molecules based on tetrastyrene and phenyl carborane,through the introduction of two AIE groups:three-dimensional cage structure carborane and propeller-shaped tetrabenzene Ethylene adjusts the molecular conformation and the stacking mode between molecules to achieve the purpose of increasing the circular polarization value.The phenomenon of cluster luminescence also accomplishes the design goal of molecular motors.The results of the study show that the polarization value reaches a maximum of 0.012,and the variable temperature fluorescence also shows the movement of solid molecules during the cluster emission process.?3?At last,we have designed and synthesized two novel o-carborane-based fluorene dyads,which exhbited the room temperature phosphorescence and circularly polarized luminescence.These relationships between the room temperature phosphorescence and the molecular rotation were subjected to the low temperature phosphorescence,single crystal diffraction.In addition,the polarization value of chiral naphthyl carborane fluorene reached 0.013,which provided an effective design strategy for organic chiral phosphor materials with high polarization values.