The Study Of Mechanochromic Property Of Organic Boronfluorine Compounds With Donor-Acceptor Structure

Mechanochromic materials,as a kind of smart materials,possess enormous potential applications in sensors,inkless writing,and biomedical care.Developing new functional mechanochromic materials and expanding the practical applications have become one of the hotspots in material field.A series of boron-fluorine molecules were designed and synthesized,and the influence of twisted structures and DA structures in organic mechanochromic materials were studied.The results can be summarized as follows:1.Three BOPIM complexes(BOMPIM-Ph,BOPIM-Th,and BOPIM-TTh)with different aromatic side groups have been developed,and their crystal structures and photophysical and mechanochromic luminescence properties were systematically studied.Under the anisotropic force,the fluorescence maximum of BOPIM-Ph,BOPIM-Th,and BOPIM-TTh were shifted 19 nm,22 nm,and 45 nm,respectively.The PXRD and DSC analysis showed that mechanochromic properties of materials were due to the transition between crystalline state to amorphous state.In order to further study of mechanochromic materials at the molecular level,isotropic force was applied on crystals of the three BOPIM complexes.The results showed that BOPIM-TTh,with largest twisted structures and intramolecular charge transfer,has the largest fluorescence maximum changes about 134 nm.Since the isotropic force did not destroy the crystal,steric and electronic effects of the aromatic donating substitutes were proved playing significant roles in regulating the intermolecular interactions and intramolecular charge transfer effect.2.Borofluorine derivatives B1,B2 and B3 were designed and synthesized.In order to highlight the importance of substituents for mechanochromic materials,B1,as comparative molecule,was a planar molecule with no substituents.Mechanochromic properties under mechanical force were systematically studied,and the fluorescence maximum of B1,B2,and B3 were redshifted of 0 nm,35 nm,and 50 nm,respectively.And the fluorescence changes of the materials after grinding resulted from the transition from the crystalline state to the amorphous state.The mechanochromic properties could be due to larger twist angles and the intramolecular charge transfer of the materials.