Phenylboronic acids in crystal engineering: Utility of the energetically unfavorable syn,syn-conformation in co-crystal design

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2011,（12）
• 页码范围: 1909-1919
• 页数: 11页
• 语种: 英文
• DOI: 10.1007/s11426-011-4412-x

摘要

Phenylboronic acids can exist,in principle,in three different conformers (syn,syn;syn,anti and anti,anti) with distinct energy profiles.In their native state,these compounds prefer the energetically favored syn,anti-conformation.In molecular complexes,however,the functionality exhibits conformational diversity.In this paper we report a series of co-crystals,with N-donor compounds,prepared by a design strategy involving the synthons based on the syn,syn-conformation of the boronic acid functionality.For this purpose,we employed compounds with the 1,2-diazo fragment (alprazolam,1H-tetrazole,acetazolamide and benzotriazole),1,10-phenanthroline and 2,2'-bipyridine for the co-crystallization experiments.However,our study shows that the mere presence of the 1,2-diazo fragment in the coformer does not guarantee the successful formation of co-crystals with a syn,syn-conformation of the boronic acid.