Single crystals of the β polymorph, formic acid and propanoic acid solvates of the title compound (abbreviation APPP) have been obtained. Single-crystal X-ray analysis revealed that the APPP molecules in the β polymorph construct the homochiral helical chains and the pyrene fluorophores adopt a monomer arrangement. Analogous structures were also found in the two solvates, while a small π-overlap exists between the pyrene fluorophores. Moreover, apart from the acetic acid solvate (form I) in a previous report, a new crystalline form (form II) was discovered through a rapid crystallization method and confirmed by PXRD patterns. The thermal and optical-physical properties of these crystals were investigated. All the three solvates could transform into the β polymorph after desolvation, but the pure β polymorph could be isolated only from the formic acid solvate. The optical properties are closely related to the pyrene fluorophore stacking modes and intermolecular interactions in the solid-state. The immobilization of pyrene fluorophores may be responsible for the high quantum yields.

中文翻译：

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1-乙酰基-3-（苯基）-5-（1-吡啶基）吡唑啉的多态性和溶剂化物：结构，热和光学物理性质†

已获得标题化合物的β多晶型物，甲酸和丙酸溶剂化物的单晶（缩写APPP）。X射线单晶分析表明，β多晶型物中的APPP分子构成同手性螺旋链，and荧光团采用单体排列。在两个溶剂化物中也发现了类似的结构，而the荧光团之间存在小的π重叠。此外，除了以前的报告中的乙酸溶剂化物（形式I）以外，还通过快速结晶方法发现了新的晶体形式（形式II），并通过PXRD图案进行了证实。研究了这些晶体的热和光学物理性质。三种溶剂化物在去溶剂化后都可以转变为β多晶型物，但是纯的β多晶型物只能从甲酸溶剂合物中分离出来。光学性质与the荧光团的堆积模式和固态中的分子间相互作用密切相关。荧光团的固定化可能是高量子产率的原因。