Department of Chemistry and Molecular Design Institute, New York University, 100 Washington Square East, Room 1001, New York City, NY, 10009, USA.
School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, P.R. China.
Angew Chem Int Ed Engl. 2017 Aug 14;56(34):10165-10169. doi: 10.1002/anie.201703028. Epub 2017 Jun 13.
DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), a contact insecticide with a rich and controversial history since its activity was discovered in 1939, has long been thought to be monomorphic. Herein we report the discovery and characterization of a second polymorph, designated Form II, which can be isolated as single crystals, but converts very slowly at room temperature to the form reported previously, now designated as Form I. Computations based on an evolutionary algorithm for crystal structure prediction revealed that Forms I and II are among the four lowest energy crystal structures of fifty calculated. A preliminary study of the contact insecticidal activity toward fruit flies (Drosophila melanogaster) indicates that Form II is more active, suggesting opportunities for more effective solid-state formulations that would allow reduced amounts of DDT, thereby minimizing environmental impact.
DDT（1,1,1-三氯-2,2-双（4-氯苯基）乙烷），自 1939 年发现其活性以来，具有丰富而有争议的历史，长期以来被认为是单形的。本文报道了第二种多晶型物的发现和表征，命名为 II 型，它可以作为单晶分离，但在室温下非常缓慢地转化为以前报道的形式，现在命名为 I 型。基于晶体结构预测的进化算法计算表明，I 型和 II 型是五十种计算的晶体结构中能量最低的四种之一。对接触杀虫剂对果蝇（Drosophila melanogaster）的杀虫活性的初步研究表明，II 型更具活性，这表明有机会开发出更有效的固体制剂，从而减少 DDT 的用量，从而最大限度地减少对环境的影响。
