Related Experiment Video
Updated: Feb 7, 2026
Total Internal Reflection Absorption Spectroscopy TIRAS for the Detection of Solvated Electrons at a Plasma-liquid Interface
Published on: January 24, 2018
Hindered Isomerization at the Silica/Aqueous Interface: Surface Polarity or Restricted Solvation?
Grace E Purnell1, Robert A Walker1
1Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States.
Abstract:
Time-resolved fluorescence measurements performed in a total internal reflection (TIR) geometry examined the photophysical behavior of coumarin 152 (C152) adsorbed to a silica/aqueous interface. Results imply that interfacial C152 has a remarkably different photoisomerization rate compared to its bulk solution value. C152's fluorescence in bulk water is dominated by a short, sub-nanosecond emission lifetime as the solute readily forms a nonemissive, twisted, intramolecular charge transfer (TICT) state. Time-resolved-TIR data from the silica/aqueous interface show that C152 emission contains a contribution from a longer-lived state (τ = 3.5 ns) that matches C152's fluorescence lifetime in nonpolar solvents where a photoexcited TICT state does not form. This long-lived excited state is assigned to C152 solvated in the interfacial region, where strong substrate-solvent hydrogen bonding prevents the aqueous solvent from stabilizing C152's TICT isomer. Similar results are observed for C152 in frozen water, emphasizing the silica surface's ability to restrict solvent mobility and change the interfacial solvation and reactivity from bulk solution limits.
Related Concept Videos
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
02:43Isomerism
02:05Entropy and Solvation
02:01Isomerism in Alkenes
An isomer is called cis-2-butene when the methyl groups are on the same side of the double bond, and the other stereoisomer, in which methyl groups are on the opposite side of the double bond, is called trans-2-butene. The cis and trans stereoisomers are not...
02:12Solvating Effects
01:01Group Polarization