作者:Christina A. Capacci-Daniel、Cameron Mohammadi、Jessica H. Urbelis、Katrina Heyrana、Natasha M. Khatri、Marina A. Solomos、Jennifer A. Swift
DOI:10.1021/acs.cgd.5b00168
日期:2015.5.6
Hydrogen bonding between 1,3-bis ureas is a commonly used motif in the assembly of supramolecular structures such as gels, capsules and crystals. The title compound, 1,3-bis(m-cyanophenyl)urea (mCyPU), has previously been shown to crystallize in both an anhydrous and monohydrate phase (α and H–I). An expanded search for polymorphs and cocrystals of mCyPU revealed a much greater diversity of solid forms including three additional polymorphs (β, δ, ε), a second hydrate (H–II) and two cocrystal phases with dimethyl sulfoxide and triphenylphosphine oxide. Analysis of the single crystal structures obtained in this study shows that the typical 1-dimensional H-bonding between 1,3-bis urea groups is disrupted by the presence of other H-bond acceptors including cyano, water, sulfoxide and phosphine oxide functionalities. Re-examination of α-mCyPU additionally showed both blade and plate-like morphologies could be obtained from different growth solvents, with crystals of the latter morphology exhibiting a grain boundary migration prior to melting.
1,3-双脲之间的氢键是组装凝胶、胶囊和晶体等超分子结构时常用的结构单元。标题化合物1,3-双(间氰基苯基)脲(mCyPU)之前已被证明可以无水和一水合物形式结晶(α和H-I)。对mCyPU的多晶型和共晶型的扩展搜索显示,固体形态的多样性要大得多,包括另外三种多晶型(β、δ、ε)、第二种水合物(H-II)以及两种与二甲基亚砜和三苯基氧化膦的共晶相。对这项研究中获得的单晶结构进行分析后发现,1,3-双脲基团之间典型的1维氢键会因其他氢键受体(包括氰基、水、亚砜和氧化膦官能团)的存在而中断。对α-mCyPU的重新检查还显示,叶片状和板状形态可以通过不同的生长溶剂获得,后一种形态的晶体在熔化前会表现出晶界迁移。