Crystals that show mechanical response against various stimuli are of great interest. These stimuli induce polymorphic transitions, isomerizations, or chemical reactions in the crystal and the strain generated between the daughter and parent domains is transcribed into mechanical response. We observed that the crystals of modified dipeptide LL (N₃-l-Ala-l-Val-NHCH₂C≡CH) undergo spontaneous twisting to form right-handed twisted crystals not only at room temperature but also at 0 °C over time. Using various spectroscopic techniques, we have established that the twisting is due to the spontaneous topochemical azide–alkyne cycloaddition (TAAC) reaction at room temperature or lower temperatures. The rate of twisting can be increased by heating, exploiting the faster kinetics of the TAAC reaction at higher temperatures. To address the role of molecular chirality in the direction of twisting the enantiomer of dipeptide LL, N₃-d-Ala-d-Val-NHCH₂C≡CH (DD), was synthesized and topochemical reactivity and mechanoresponse of its crystals were studied. We have found that dipeptide DD not only underwent TAAC reaction, giving 1,4-triazole–linked pseudopolypeptides of d-amino acids, but also underwent twisting with opposite handedness (left-handed twisting), establishing the role of molecular chirality in controlling the direction of mechanoresponse. This paper reports (i) a mechanical response due to a thermal reaction and (ii) a spontaneous mechanical response in crystals and (iii) explains the role of molecular chirality in the handedness of the macroscopic mechanical response.

对各种刺激表现出机械反应的晶体引起了人们的极大兴趣。这些刺激引起晶体中的多晶型转变，异构化或化学反应，并且在子域和父域之间产生的应变被转录为机械响应。我们观察到，改性二肽LL的晶体（N ₃ -升-Ala-升-Val-NHCH ₂C≡CH）不仅在室温下而且随着时间的流逝在0°C时都会自发扭曲形成右旋扭曲晶体。使用各种光谱技术，我们发现扭曲是由于室温或更低温度下自发的拓扑化学叠氮化物-炔烃环加成（TAAC）反应引起的。通过在较高温度下利用TAAC反应的更快动力学，可以通过加热来增加扭曲速率。为了解决分子手性在扭曲二肽LL对映体方向上的作用，N ₃ - d -Ala- d -Val-NHCH ₂合成了C≡CH（DD），研究了其晶体的拓扑化学反应性和力学响应。我们发现二肽DD不仅经历TAAC反应，得到1,4-三唑连接的d-氨基酸假多肽，还经历了相反手性的加捻（左手加捻），从而确立了分子手性在控制氨基酸中的作用。机械响应的方向。本文报道（i）由于热反应引起的机械响应，以及（ii）晶体中的自发机械响应，并且（iii）解释了分子手性在宏观机械响应的顺手性中的作用。