The Preparation And Properties Of Cocrystals And Polymorphs

As a wide range of development and application for cocrystal in optoelectronic and semiconductor fields, the key of this paper is to prepare a series of charge transfer cocrystals by solution method and liquid-assisted grinding method and analyse its crystal structure, thermal properties and optical properties, as well as the effect of supermolecule structure on solid state fluorescent properties. The main results are summarized as following:(1) Three binary charge-transfer cocrystals (?,?,?) were designed in solvents, involving 1-acetyl-3-(4-methoxyphenyl)-5-(1-pyrenyl)-pyrazoline (AMPP),1-acetyl-3-phenyl-5-(1-pyrenyl)-pyrazoline (APPP),1-(5-(anthracen-9-yl)-3-(4-methoxyphen-yl)-4,5-dihydro-pyrazol-1-yl)ethanone (AMPE) as electron donor (D) and Tetrachloro-p-benzoquinone (TCQ) as electron acceptor (A), respectively. Crystal structure analysis revealed that cocrystal I and ? exhibits face-to-face mixed-stacking mode between pyrene moiety and TCQ while cocrystal ? adopts separated-stacking mode for AMPE and TCQ molecules with no ? overlap. The feature of charge transfer show distinctive CT bond in diffuse reflectance absorption spectroscopy and electronic distribution from pyrazoline derivative to TCQ molecule calculated at the PBE1PBE/6-311G level of Density Functional theory with Gaussian 09 package.(2) AMPP, APPP, and AMPE with TCQ were prepared by liquid-assisted grinding that AMPP or APPP could not generate cocrystal with TCQ whereas AMPE and TCQ could produce cocrystal ?. Comparing the PXRD patterns it is noted that some distinctive TCQ peaks in 1:1 whereas nothing in 2:1, which is coincide with crystal structure of cocrystal III, suggesting it is feasible to prepare cocrystal and speculate molar ratio by grinding method.(3) Three chalcones,3-(9-anthryl)-1-(4-methoxyphenyl)prop-2-en-1-one (I),3-(9-anthryl)-1-phenyl-prop-2-en-l-one (?) and 3-(1-pyrenyl)-1-(4-methoxyphenyl)prop-2-en-1-one (?), were synthesized and crystallized in different solvents to provide different forms, such as two forms of ? (?a, ?b), four forms of ? (?a, ?b, ?c, ?d) and four forms of ? (?a, ?b, ?c, ?d). Among them ?a, ?d, ?b and ?d own trans configuration, while ?b and ?b, ?c show cis configuration with higher melting point. These trans-forms are fluorescent that ?b exists a new red shifted fluorescent peak relative to ?d which can be explained by strong slipped face-to-face ?-stacked arrangement of pyrene chromophores in ?b. ?d shows a new red shifted fluorescent peak relative to Ia due to edge-to-face slipped ?-stacked arrangement in ?d.