Measurement of the unit cell of (R)-BINOL over a 200° temperature range (300–100 K) reveals an anisotropic contraction where the c-axis contracts ca. 2.3% compared to a ca. 0.45% contraction of the a and b axes, a ca. six-fold difference in linear thermal expansion coefficient. This contraction corresponds to a decrease in the helical pitch of the 3₁ screw axis in the [001] direction. The anisotropic nature of the contraction is rationalised by a thorough analysis of intermolecular contacts within the crystal and their impact on the conformation of the molecule and crystal packing.

Graphical Abstract

The crystal structure of (R)-BINOL exhibits a pronounced anisotropic thermal expansion.

中文翻译：

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BINOL 晶体各向异性热膨胀的结构起源

在 200° 温度范围 (300–100 K) 内对 (R)-BINOL 晶胞的测量揭示了 c 轴收缩约 1 处的各向异性收缩。 2.3 % 相比之下a 轴和 b 轴收缩​​ 0.45%，a约。线性热膨胀系数相差六倍。该收缩对应于[001]方向上3 ₁螺杆轴的螺距的减小。通过对晶体内分子间接触及其对分子构象和晶体堆积的影响的彻底分析，使收缩的各向异性性质合理化。

图形概要

(R)-BINOL 的晶体结构表现出明显的各向异性热膨胀。