Co-crystals of tetrakis-1,2,3,4-(4′-carboxyphenyl)cyclobutane with dipyridyl spacers: design and serendipity
作者:Goutam Kumar Kole、Geok Kheng Tan、Lip Lin Koh、Jagadese J. Vittal
DOI:10.1039/c2ce25513h
日期:——
Tetrakis-1,2,3,4-(4â²-carboxyphenyl)cyclobutane (TCCB), a tetracarboxylic acid, has been employed for making co-crystals with linear dipyridyl spacers molecules like 4,4â²-bipyridine (4,4â²-bpy), 1,2-bis(4â²-pyridyl)ethane (4,4â²-bpethane), trans-1,2-bis(4â²-pyridyl)ethylene (4,4â²-bpe) and 1,4-bis(4â²-pyridyl)-2,3-diaza-1,3-butadiene (4,4â²-bpdb). In the case of 4,4â²-bpy, a 2â:â1 co-crystal was obtained with TCCB having a three dimensional 5-fold interpenetrated dmp network. The diagonalâdiagonal interpenetrated isostructural (4,4)-connected 2D networks were obtained in 1â:â1 co-crystals of TCCB with 4,4â²-bpe and 4,4â²-bpdb. The (4,4)-connected nets in the 1â:â1 co-crystal of TCCB with 4,4â²-bpethane were found to stack parallel instead of interpenetrating. 1â:â1 co-crystals were always obtained in the last three cases regardless of molar ratio during co-crystallization, indicating the influence of kinetic factors. The structural diversity and similarities in this series of co-crystals in the context of composition variation and solvent interference are discussed. The serendipitous formation of (4,4)-connected networks is critically compared with designability of the system in presence of synthon competition.
四羧基化合物——四(4'-羧苯基)环丁烷(TCCB)已被用于与线性二吡啶间隔分子形成共晶,例如4,4'-联吡啶(4,4'-bpy)、1,2-双(4'-吡啶基)乙烷(4,4'-bp乙烷)、反式-1,2-双(4'-吡啶基)乙烯(4,4'-bpe)和1,4-双(4'-吡啶基)-2,3-二氮-1,3-丁二烯(4,4'-bpdb)。在4,4'-bpy的情况下,得到了具有三维5重穿插dmp网络的TCCB的2:1共晶。TCCB与4,4'-bpe和4,4'-bpdb的1:1共晶中获得了对角-对角穿插的同构型(4,4)-连接二维网络。TCCB与4,4'-bp乙烷的1:1共晶中的(4,4)-连接网络被发现是平行堆叠而非穿插的。在最后三种情况下总是得到1:1共晶,无论共晶过程中的摩尔比如何,这表明了动力学因素的影响。本文讨论了这一系列共晶在组成变化和溶剂干扰背景下的结构多样性和相似性。意外形成的(4,4)-连接网络与存在砌块竞争的系统的设计性进行了关键性比较。