Tailoring the physical properties of molecular crystals though the construction of solid solutions requires the existence of isostructural crystals. Simple substitutions of a given molecular framework can give a range of different crystal structures. A set of quinoxaline derivatives, C₈H₄N₂(C₆H₄X)₂, Q3,3′X₂, has been investigated (X = F, Cl, Br, I and Me) where kinetic factors generated a set of isostructural crystals for the lighter halogens (F, Cl, Br) alone. Computational analysis shows that the stabilising interactions are maximal for Cl, while DSC studies demonstrate the existence of more stable polymorphs for both F and Br containing systems. Steric factors appear to have a lower contribution than the balance of weaker hydrogen and halogen bonding shown by the Me and I containing systems displaying different packing driven by CH⋯N/CH⋯π bonds and I⋯I bonds respectively.

中文翻译：

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喹喔啉晶相的同构性：弱氢键和卤素键的相互作用

尽管构建固溶体需要同构晶体的存在，但调整分子晶体的物理性质。给定分子骨架的简单取代可以产生一系列不同的晶体结构。一组喹喔啉衍生物，C ₈ H ₄ N ₂ (C ₆ H ₄ X) ₂ , Q3,3'X ₂, 已被研究 (X = F, Cl, Br, I 和 Me)，其中动力学因素单独为较轻的卤素 (F, Cl, Br) 生成一组同构晶体。计算分析表明，Cl 的稳定相互作用最大，而 DSC 研究表明，含 F 和 Br 的系统都存在更稳定的多晶型物。空间因子似乎比含 Me 和 I 的系统显示的较弱氢键和卤素键的平衡的贡献更低，这些系统显示出分别由 CH⋯N/CH⋯π 键和 I⋯I 键驱动的不同堆积。