Interaction between p-toluenesulfonic acid (pTSA) and water is studied at −20 °C in a CCl₄ matrix. In CCl₄ water exists as monomers with restricted rotational motion about its symmetry axis. Additionally, CCl₄ is transparent in the hydrogen-bonded region; CCl₄ thus constitutes an excellent ambient thermal energy matrix isolation medium for diagnosing interactions with water. Introducing pTSA-nH₂O gives rise to two narrow resonances at 3642 cm^–1 and at 2835 cm^–1 plus a broad 3000–3550 cm^–1 absorption. In addition, negative monomer symmetric and asymmetric stretch features relative to nominally dry CCl₄ indicate that fewer water monomers exist in the cooled (−20 °C) acid solution than in room-temperature anhydrous CCl₄. The negative peaks along with the broad absorption band indicate that water monomers are incorporated into clusters. The 3642 cm^–1 resonance is assigned to the OH-π interaction with a cluster containing many water molecules per acid molecule. The 2835 cm^–1 resonance is assigned to the (S-)O–H stretch of pTSA-dihydrate. The coexistence of these two species provides insights into interactions in this acid–water CCl₄ system.

中文翻译：

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基质分离光谱：对甲苯磺酸水溶液

在-20°C的CCl ₄基质中研究了对甲苯磺酸（pTSA）与水之间的相互作用。在CCl _4中，水作为单体存在，绕其对称轴的旋转运动受到限制。另外，CCl ₄在氢键区域是透明的。因此，CCl ₄构成了一种出色的环境热能基质隔离介质，可用于诊断与水的相互作用。引入pTSA- n H ₂ O会在3642 cm ^–1和2835 cm ^–1处产生两个窄的共振，再加上3000–3550 cm ^–1处的宽共振。吸收。另外，相对于名义上干燥的CCl _4的负单体对称和不对称拉伸特征表明，与室温无水CCl ₄相比，冷却的（-20°C）酸溶液中存在的水单体更少。负峰以及宽吸收带表明水单体被结合到簇中。3642 cm ^–1的共振被分配给与每个酸分子包含许多水分子的簇的OH-π相互作用。2835 cm ^–1的共振被分配给pTSA-二水合物的（S-）O–H延伸。这两种物质的共存提供了对这种酸-水CCl ₄系统相互作用的见解。