Synthesis and Structural Analysis of Triphenylmethane-Based Alkanecarboxamides and Their Assembly into Nanometer-Size Fibrous Objects
作者:Hirohiko Houjou、Tatsuya Koga、Midori Akiizumi、Isao Yoshikawa、Koji Araki
DOI:10.1246/bcsj.82.730
日期:2009.6.15
A series of C3-symmetric trialkanecarboxamido derivatives was synthesized via a triphenylmethane derivative. The triamides with short alkyl chains (1–6 carbons) crystallized as either prisms or plates, whereas those with long alkyl chains (7–11 carbons) formed gel-like objects composed of fibrous crystals with 100-nm diameters. A discontinuity as a function of alkyl chain length was also observed for the melting points, the vibrational frequencies of the amide groups, and the powder X-ray diffraction patterns of the triamides. On the basis of analysis of the crystal structures of two of the compounds, we make some proposals about the molecular packing and the local structure of the molecular assembly. Our results suggest that there were critical differences in inter-core interactions and in the hydrogen-bonding network, depending on the length of the alkyl chains. We interpret the drastic change in morphology brought about by the tuning of the chain length as a consequence of a change in the mode of molecular assembly.
一系列C3对称的三烷基甲酰胺衍生物通过三苯基甲烷衍生物合成。具有短烷基链(1-6个碳原子)的三酰胺以棱柱或板状结晶,而具有长烷基链(7-11个碳原子)则形成由直径约100纳米的纤维状晶体构成的凝胶状物体。在熔点、酰胺基团的振动频率和三酰胺的粉末X射线衍射图谱中,观察到烷基链长度的变化也表现出不连续性。根据对其中两个化合物晶体结构的分析,我们提出了一些关于分子堆积和分子组装局部结构的建议。我们的结果表明,烷基链长度的不同导致了核心间相互作用和氢键网络的显著差异。我们将通过调节链长度而带来的形态变化解读为分子组装模式改变的结果。