Reactions give solvents a kick During a chemical reaction, the reorganization of solvent molecules not directly in contact with reactants and products is normally viewed as a simple diffusion response. Wang et al. studied molecular diffusion in six common reactions—including the copper-catalyzed click reaction and the Diels-Alder reaction—with pulsed-field gradient nuclear magnetic resonance. They observed a boost in mobility relative to Brownian diffusion that was stronger for the catalyzed reactions that were studied. The mobilities for the click reaction were verified with a microfluidic gradient method. They argue that energy release produces transient translational motion of reacting centers that mechanically perturbs solvent molecules. Science, this issue p. 537 Common organic reactions mechanically perturb solvents and increase molecular mobility beyond simple Brownian diffusion. Mobility of reactants and nearby solvent is more rapid than Brownian diffusion during several common chemical reactions when the energy release rate exceeds a threshold. Screening a family of 15 organic chemical reactions, we demonstrate the largest boost for catalyzed bimolecular reactions, click chemistry, ring-opening metathesis polymerization, and Sonogashira coupling. Boosted diffusion is also observed but to lesser extent for the uncatalyzed Diels-Alder reaction, but not for substitution reactions SN1 and SN2 within instrumental resolution. Diffusion coefficient increases as measured by pulsed-field gradient nuclear magnetic resonance, whereas in microfluidics experiments, molecules in reaction gradients migrate “uphill” in the direction of lesser diffusivity. This microscopic consumption of energy by chemical reactions transduced into mechanical motion presents a form of active matter.

中文翻译：

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在常见的化学反应中提高分子的流动性

反应给溶剂带来冲击 在化学反应过程中，不直接与反应物和产物接触的溶剂分子的重组通常被视为简单的扩散响应。王等人。使用脉冲场梯度核磁共振研究了六种常见反应中的分子扩散，包括铜催化的点击反应和 Diels-Alder 反应。他们观察到相对于布朗扩散的流动性提高，这对于所研究的催化反应更强。用微流体梯度方法验证点击反应的迁移率。他们认为能量释放会产生反应中心的瞬时平移运动，从而机械地扰乱溶剂分子。科学，这个问题 p。537 常见的有机反应会机械干扰溶剂并增加分子的流动性，超越简单的布朗扩散。当能量释放率超过阈值时，在几种常见的化学反应中，反应物和附近溶剂的流动性比布朗扩散更快。通过筛选 15 个有机化学反应家族，我们展示了催化双分子反应、点击化学、开环复分解聚合和 Sonogashira 偶联的最大推动力。也观察到增强的扩散，但对于未催化的 Diels-Alder 反应，扩散程度较小，但对于仪器分辨率内​​的取代反应 SN1 和 SN2 则没有。通过脉冲场梯度核磁共振测量扩散系数增加，而在微流体实验中，反应梯度中的分子向扩散性较小的方向“上坡”迁移。这种由化学反应转化为机械运动的微观能量消耗呈现出一种形式的活性物质。