| Polymorphs differ in physicochemical properties because of their distinct structures so that they show different applications.Polymorphism enlarges the applicable area of chemicals and offers a wide range of possibilities.A series of chalcone polymorphs were prepared through solution evaporation method and recrystallization.And the correlation between crystal structures and optical properties were thoroughly investigated in this thesis.There are four chalcone compounds bearing the basic 1,3-diarypropenone moiety being synthesized:3-(9-anthryl)-1-(4-chloro)prop-2-en-1-one(Ⅰ),3-(1-pyrenyl)-1-(4-chlorophenyl)pr-op-2-en-1-one(Ⅱ),1-phenyl-3-(1-pyrenyl)prop-2-en-1-one(Ⅲ)and 3-(1-pyrenyl)-1-(4-nitrophenyl)prop-2-en-1-one(Ⅳ).The aryl groups of these compounds are anthracene or pyrene and benzene ring with different substituents.Eleven polymorphs including Ⅰa,Ⅰb,Ⅱa,Ⅱb,Ⅱc,Ⅲa,Ⅲb,Ⅲc,Ⅲd,Ⅳa,Ⅳb were obtained by means of solution evaporation way and recrystallization.We determined structures of these polymorphs and researched into the luminescent properties directly related to structures of all the crystals with the combination of analytical methods such as X-ray diffraction analysis,thermal analysis,spectroscopic analysis and so on.Besides,Hirshfeld Surface was used to observe the intermolecular interactions in detail.It has been found configurational polymorphism(with respect to the central C=C bond)and conformational isomorphism exist in these crystals.Ib and Ⅲ.adopt cis-confihuration while the others except for those(Ⅱc,Ⅲc,Ⅳb)without single crystal X-ray analysis show tran-configuration.Furthermore,two crystallographically independent molecules were detected in Ib and Ⅲb which has never been reported in chalcone polymorphism before.Polymorphs with cis-configuration exhibit higher melting point with no fluorescence.In contrast,those crystals with trans-configuration are fluorescent and.their emission wavelengths are mainly affected by molecular coplanarity and J-aggregates formation. |
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