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Concomitance, Reversibility, and Switching Ability of Centrosymmetric and Non-Centrosymmetric Crystal Forms: Polymorphism in an Organic Nonlinear Optical Material
Crystal Growth & Design ( IF 3.8 ) Pub Date : 2017-12-29 00:00:00 , DOI: 10.1021/acs.cgd.7b01560
Kunal K. Jha 1 , Sanjay Dutta 1 , Parthapratim Munshi 1
Affiliation  

Reversibility between two concomitant polymorphs and their switching ability is demonstrated for the novel organic nonlinear optical (NLO) material Z-3-(3-methoxyphynyl)-2-(4-nitrophenyl)acrylonitrile. The appearances of their concomitant as well as exclusive polymorphic forms were discovered upon systematic crystallization experiments using various solvents. Determination of X-ray crystal structures confirmed that the polymorphs crystallize in centrosymmetric (P21/n) and non-centrosymmetric (Fdd2) space groups. A search using the Cambridge Structural Database revealed that there exist only 10 such polymorphic pairs. Reversible phase transitions and the switching ability between the polymorphs can be achieved via both heat and solvents as stimuli. Structural analysis confirmed that the polymorphs have two-dimensional similarity. Further, quantitative and qualitative analysis of interaction energies based on the UNI force field and energy frameworks indicate that they possess very similar energies, although the centrosymmetric form is slightly lower in energy. A comparably high value of second harmonic generation activity and the NLO properties as estimated based on gas-phase and in-crystal calculations suggest that the non-centrosymmetric form could be a potential NLO material. To the best of our knowledge, this study is the rarest of its kind to show the reversibility and switching ability between centrosymmetric and non-centrosymmetric polymorphic phases in an organic material, induced via both thermal and solvent stimuli.

中文翻译:

中心对称和非中心对称晶体形式的伴随性,可逆性和转换能力:有机非线性光学材料中的多态性

对于新型有机非线性光学(NLO)材料Z -3-(3-甲氧基苯基)-2-(4-硝基苯基)丙烯腈,证明了两种伴随的多晶型之间的可逆性及其转换能力。在使用各种溶剂进行系统的结晶实验后,发现了它们的伴随形式和排他性多晶型物的外观。X射线晶体结构的确定证实了多晶型物在中心对称(P 2 1 / n)和非中心对称(Fdd2)空间群。使用剑桥结构数据库进行的搜索显示,仅存在10个这样的多态对。可通过加热和溶剂刺激来实现可逆的相变和多晶型之间的转换能力。结构分析证实该多晶型物具有二维相似性。此外,基于UNI力场和能量框架的相互作用能的定量和定性分析表明,尽管中心对称形式的能量稍低,但它们具有非常相似的能量。根据气相和晶体内计算估算出的二次谐波产生活性和NLO性质较高,表明非中心对称形式可能是潜在的NLO材料。据我们所知,
更新日期:2017-12-29
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