Polymorphic selectivity within crystals grown via physical vapour transport (PVT) is dependent on the thermodynamic stabilities of differing molecular conformations and the kinetic regime within the growth apparatus. Crystals of bis(4-bromophenyl)fumaronitrile have been grown for the first time via this method, with the formation of both the conventional polymorph and a new, unforseen polymorph. Analysis suggests that the conventional form is less thermodynamically stable, with this form crystallising at higher temperature than the newly discovered form due to the release of binding energy of intermolecular interactions during the growth process. Fluorometry reveals the new form to exhibit weaker, red-shifted fluorescence emission owing to greater intermolecular π–π overlap.

中文翻译：

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双（4-溴苯基）富马腈晶体通过气相生长的多态性†

通过物理气相传输（PVT）生长的晶体内的多晶型选择性取决于不同分子构象的热力学稳定性和生长装置内的动力学机制。双（4-溴苯基）富马腈晶体是通过这种方法首次生长的，既形成了常规多晶型物又形成了新的，无法预料的多晶型物。分析表明，常规形式的热力学稳定性较差，由于在生长过程中分子间相互作用的结合能的释放，该形式比新发现的形式在更高的温度下结晶。荧光法揭示了由于分子间π-π重叠更大而显示出较弱的红移荧光发射的新形式。