标题： 解锁n-烷基-1-炔的构象：量子“触发指”与“刚性关节”构象 显示英文标题

标题： Unlocking n-alk-1-ynes Conformers: Quantum "Trigger Finger" versus "Stiff Joint" Conformations

摘要： 分子在n-炔-1-炔（CnA）中的构象通常被简化为全平面结构。 我们报告了一项全面的量子化学分析，揭示了乙炔末端的两种近等能的旋转异构体：平面（C$_s$）和扭曲（C$_1$）。 高且对称的旋转能垒（$\approx 150$ meV）源于靠近$\mathrm{sp}$中心的独特立体缓解以及C$_1$的电子稳定化。 这创造了一个独特的动力学特征：量子“扳机指”($\alpha$旋转)，它强制形成一个$\approx 50\%:\,50\%$ $\mathrm{C}_s/\mathrm{C}_1$ 集合，与烷基链的热力学偏倚“僵硬关节”($\delta$旋转)形成鲜明对比。 这种结构的简并性需要对光谱数据进行集合平均以进行解释，而缓慢的互变则允许在合成和分子结构筑过程中发生动力学捕获和有意的构象体富集。 我们的工作重新定义了炔烃锚点，为光谱数据的准确解释和分子电子学中的构象控制提供了蓝图。 显示英文摘要

摘要： Molecular conformation in n-alk-1-ynes (CnA) is conventionally simplified to an all-planar structure. We report a comprehensive quantum chemical analysis revealing two near-isoenergetic rotamers at the acetylenic terminus: planar (C$_s$) and skewed (C$_1$). The high, symmetric rotational energy barrier ($\approx 150$\,meV) arises from unique steric relief near the $\mathrm{sp}$ center coupled with electronic stabilization of C$_1$. This creates a unique kinetic profile: a Quantum ``Trigger Finger'' ($\alpha$ rotation) that enforces an $\approx 50\%:\,50\%$ $\mathrm{C}_s/\mathrm{C}_1$ ensemble, sharply contrasting with the thermodynamically biased ``Stiff Joint'' ($\delta$ rotation) of the alkyl chain. This structural degeneracy necessitates ensemble averaging for spectroscopic data interpretation, while the slow interconversion permits kinetic trapping and intentional conformer enrichment during synthesis and molecular junction fabrication. Our work redefines the alkyne anchor, providing a blueprint for accurate interpretation of spectroscopic data and achieving conformational control in molecular electronics.