New crystalline forms (a polymorph and a co-crystal) and a previously reported solvate of the parent compound 5-fluoroisatin have been characterized by thermal, structural, and computational methods. The mechanical responses (hardness, H, and elastic modulus, E) of the co-crystal and the solvate have been characterized using nanoindentation experiments on the major faces. Results show that H and E of the solvated form of the molecule are 11 and 13 fold higher than those of the co-crystal, respectively. Energy decomposition analyses have been performed on these crystal structures to understand the primary building blocks and the role of different intermolecular interaction energies in the observed nanomechanical properties. These suggest that a nearly similar layered interaction topology of molecules is present in both the co-crystal and the solvated form. Interestingly, the presence of relatively strong interlayer interactions of molecules in the solvate prevents long-range molecular layer migration, which minimizes the scope for plastic deformation in comparison to the co-crystal.

中文翻译：

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探索新的共晶体和5-氟异丁香的已知溶剂化物的独特纳米力学行为，并鉴定新的多晶型物

已经通过热，结构和计算方法表征了新的晶体形式（多晶型物和共晶体）和先前报道的母体化合物5-氟异丁香素的溶剂化物。共晶和溶剂化物的机械响应（硬度H和弹性模量E）已通过在主要面上进行的纳米压痕实验进行了表征。结果显示H和E分子的溶剂化形式的分子量分别比共晶体高11倍和13倍。已对这些晶体结构进行了能量分解分析，以了解主要的结构单元以及不同的分子间相互作用能在观察到的纳米机械性能中的作用。这些表明在共晶和溶剂化形式中都存在分子的几乎相似的分层相互作用拓扑。有趣的是，溶剂化物中分子之间较强的层间相互作用的存在阻止了长程分子层迁移，与共晶相比，这使塑性变形的范围最小化。