New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, Mohanpur 741 246, India.
Nat Chem. 2015 Jan;7(1):65-72. doi: 10.1038/nchem.2123. Epub 2014 Dec 8.
The exceptional mechanical flexibility observed with certain organic crystals defies the common perception of single crystals as brittle objects. Here, we describe the morphostructural consequences of plastic deformation in crystals of hexachlorobenzene that can be bent mechanically at multiple locations to 360° with retention of macroscopic integrity. This extraordinary plasticity proceeds by segregation of the bent section into flexible layers that slide on top of each other, thereby generating domains with slightly different lattice orientations. Microscopic, spectroscopic and diffraction analyses of the bent crystal showed that the preservation of crystal integrity when stress is applied on the (001) face requires sliding of layers by breaking and re-formation of halogen-halogen interactions. Application of stress on the (100) face, in the direction where π···π interactions dominate the packing, leads to immediate crystal disintegration. Within a broader perspective, this study highlights the yet unrecognized extraordinary malleability of molecular crystals with strongly anisotropic supramolecular interactions.
某些有机晶体表现出的非凡机械柔韧性，颠覆了人们普遍认为单晶是脆性物体的观念。在这里，我们描述了六氯苯晶体塑性变形的形态结构后果，这种晶体可以在多个位置弯曲到 360°，而宏观完整性得以保留。这种非凡的塑性是通过将弯曲部分分离成柔性层来实现的，这些柔性层相互滑动，从而产生具有略微不同晶格取向的畴。对弯曲晶体的微观、光谱和衍射分析表明，当在（001）面上施加应力时，晶体完整性得以保留，这需要通过打破和重新形成卤素-卤素相互作用来实现层的滑动。在（100）面上施加沿π···π相互作用主导堆积方向的应力会导致晶体立即解体。从更广泛的角度来看，这项研究强调了具有强烈各向异性超分子相互作用的分子晶体出人意料的高延展性。
