Study On The Hydrogen Bond-induced Aggregation Luminescence And Stimulus Response Luminescence Of Organic Molecules Containing Nitrogen Heteroatoms

Hydrogen bonds play an important role in the regulation of the photo-physical and chemical properties of organic photo-functional molecules.In this paper,two series of photo-functional molecules containing hydrogen bonding sites are designed and synthesized.In the aggregate state,intermolecular hydrogen bonds and intramolecular hydrogen bonds can be generated respectively.The focus is on their aggregation luminescence and stimulus response luminescence properties.And we obtained the following research progress:(1)We developed a class of organic molecules containing C-N-C structure.By introducing carboxyl groups at the end of the molecule,it can produce intermolecular hydrogen bonds in the aggregate state to achieve aggregated induced emission with the fluorescent color tuned from blue to green.The luminescence color of the solid material changes from green to blue under mechanical stimulation,which realizes the luminescence in response to mechanical stimulation.Reference compounds have been obtained,and the photo-physical characterization suggests that the pyridine ring plays a key role in the formation of conjugated structures.The presence of carboxyl groups can provide hydrogen bonds in the aggregate state to form a specific framework network and on the other hand,due to its special electron-withdrawing effect,it avoids the n-?* transition between the pending benzene ring and the pyridine ring,with luminescence efficiency greatly improved.Through careful research,it is found that the mechanism of aggregate induced luminescence is attributed to tuning of the emission from invisible purple to visible green emission,which is mainly caused by hydrogen bonds formation.The stimulus-response luminescence mechanism is attributed to the destruction of the hydrogen bond network under mechanical stimulation,with molecular stacking mode changing from crystalline to amorphous state.(2)ESIPT emitters based on phenanthroimidazole derivatives have been obtained,and the solid-state emission color has been successfully adjusted from blue to green to orange light by ESIPT for conjugation of intra-molecular hydrogen bond formation,with luminescence quantum yield greatly increased.By introducing of the classic AIE structure cyanostyrene into the ESIPT molecule,we obtained proton responsive material with aggregated induced emission effect.And the intra-molecular hydrogen bond can be adjusted by acid stimulation to realize the mutual conversion of ketone and alcohol luminescence,realizing proton responsive emission.