Solute-solvent complex kinetics and thermodynamics probed by 2D-IR vibrational echo chemical exchange spectroscopy.
Solute-solvent complex kinetics and thermodynamics probed by 2D-IR vibrational echo chemical exchange spectroscopy.
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DOI：
10.1021/jp804087v
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发表时间：
2008-07
期刊：
影响因子：
--
通讯作者：
Junrong Zheng;M. Fayer
中科院分区：
文献类型：
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作者：
Junrong Zheng;M. Fayer
本文用超快二维红外化学交换光谱法测定了一系列三乙基硅醇/溶剂弱氢键复合物的形成和解离动力学，其形成速率为-1.4 ~-3.3kcal/mol。生成和解离速率常数的复杂函数之间的相关性可以用类似于Arrhenius方程的方程表示。实验结果雅阁以前对八种酚/溶剂络合物的观察，其生成焓为-0.6 ~-2.5kcal/mol。发现溶质-溶剂络合物解离速率常数的倒数与exp（-Δ H 0/RT）线性相关，其中Δ H 0是络合物的生成焓。结果表明，三乙基硅醇-溶剂络合物的比例常数与三乙基硅醇-溶剂络合物的比例常数相同，即五个硅醇络合物和八个酚络合物的13个点都落在同一条线上。此外，使用三乙基硅醇体系，在长反应时间（光谱扩散完全）的二维红外化学交换光谱的特点进行了解释。它示出的非对角的化学交换峰的形状是一个组合（外积）的物质的吸收线的形状，产生的对角峰。
The formation and dissociation kinetics of a series of triethylsilanol/solvent weakly hydrogen bonding complexes with enthalpies of formation ranging from -1.4 to -3.3 kcal/mol are measured with ultrafast two-dimensional infrared (2D IR) chemical exchange spectroscopy in liquid solutions at room temperature. The correlation between the complex enthalpies of formation and dissociation rate constants can be expressed with an equation similar to the Arrhenius equation. The experimental results are in accord with previous observations on eight phenol/solvent complexes with enthalpies of formation from -0.6 to -2.5 kcal/mol. It was found that the inverse of the solute-solvent complex dissociation rate constant is linearly related to exp(-DeltaH0/RT) where DeltaH0 is the complex enthalpy of formation. It is shown here, that the triethylsilanol-solvent complexes obey the same relationship with the identical proportionality constant, that is, all 13 points, five silanol complexes and eight phenol complexes, fall on the same line. In addition, features of 2D IR chemical exchange spectra at long reaction times (spectral diffusion complete) are explicated using the triethylsilanol systems. It is shown that the off-diagonal chemical exchange peaks have shapes that are a combination (outer product) of the absorption line shapes of the species that give rise to the diagonal peaks.