Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Faculty of Science, Department of Chemistry, University of Cairo, 12613 Giza, Egypt.
Nat Chem. 2018 Feb;10(2):126-131. doi: 10.1038/nchem.2909. Epub 2018 Jan 1.
Infrared (IR) excitation of vibrations that participate in the reaction coordinate of an otherwise thermally driven chemical reaction are believed to lead to its acceleration. Attempts at the practical realization of this concept have been hampered so far by competing processes leading to sample heating. Here we demonstrate, using femtosecond IR-pump IR-probe experiments, the acceleration of urethane and polyurethane formation due to vibrational excitation of the reactants for 1:1 mixtures of phenylisocyanate and cyclohexanol, and toluene-2,4-diisocyanate and 2,2,2-trichloroethane-1,1-diol, respectively. We measured reaction rate changes upon selective vibrational excitation with negligible heating of the sample and observed an increase of the reaction rate up to 24%. The observation is rationalized using reactant and transition-state structures obtained from quantum chemical calculations. We subsequently used IR-driven reaction acceleration to write a polyurethane square on sample windows using a femtosecond IR pulse.
红外（IR）激发参与反应坐标的振动，而反应坐标原本是由热驱动的化学反应，据信这会导致化学反应加速。迄今为止，由于导致样品加热的竞争过程，实际实现这一概念的尝试受到了阻碍。在这里，我们使用飞秒 IR 泵浦 IR 探针实验证明，由于反应物的振动激发，分别为苯异氰酸酯和环己醇以及甲苯-2,4-二异氰酸酯和 2,2,2-三氯-1,1-二醇的 1:1 混合物中，氨基甲酸酯和聚氨酯的形成会加速。我们通过选择性振动激发测量了反应速率变化，而样品几乎没有加热，并观察到反应速率提高了 24%。使用从量子化学计算中获得的反应物和过渡态结构对观察结果进行了合理化解释。随后，我们使用 IR 驱动的反应加速，使用飞秒 IR 脉冲在样品窗上写入了一个聚氨酯正方形。
