Characterizing Solvent Dynamics in Nanoscopic Silica Sol鈥揋el Glass Pores by 2D-IR Spectroscopy of an Intrinsic Vibrational Probe

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• 作者：Christopher J. Huber ; Aaron M. Massari
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 6, 2014
• 年：2014
• 卷：118
• 期：44
• 页码：25567-25578
• 全文大小：440K
• ISSN：1932-7455

文摘

Porous sol鈥揼el matrices were synthesized with IR-active Si鈥揌 vibrational chromophores integrated into the silica network. The Si鈥揌 vibrational mode was found to be highly accessible to solvents within the nanoscopic pores. Vibrational solvatochromism of the silane vibration was controlled largely by interactions between infiltrating solvents and the oxygen and hydroxide sites in the silica. Exchanging solvents in the silica matrices produced reversible solvatochromic shifts in some cases but led to irreversible shifts when strongly interacting solvents were tested, suggesting that a layer of solvent was not exchangeable. 2D-IR spectroscopy was used to monitor spectral diffusion and extract the homogeneous line widths of the Si鈥揌 mode for a range of infiltrating solvents as well as solvent-free aerogel samples. It was demonstrated that the silane vibration is sensitive to the nature of the infiltrating solvent, making these vibrationally active sol鈥揼el films a general platform for solvent dynamics in nanoscopic confined volumes.