Closed Nanocontainer Enables Thioketones to Phosphoresce at Room Temperature in Aqueous Solution
- 31 March 2010
- journal article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 114 (45), 14320-14328
- https://doi.org/10.1021/jp911698s
Abstract
Thiocarbonyl compounds possess unusual photophysical properties: they fluoresce from S(2), phosphoresce from T(1) only at extremely low concentrations in solution at room temperature, have unit quantum yield of intersystem crossing from S(1) to T(1), undergo self-quenching at diffusion-controlled rates, and are quenched by ground-state oxygen leading to self-destruction. In this article, we are concerned with finding a new method to observe phosphorescence from thioketones at room temperature in aqueous solution at high concentrations. To achieve this goal, one needs to find ways to eliminate diffusion-limited self-quenching and oxygen quenching. We present here a general strategy that has allowed us to record phopshorescence from a number of thioketones in aqueous solution at room temperature. The method involves encapsulation of thioketone molecules within a "closed nanocontainer" made up of two cavitand molecules known by its trivial name as octa acid. In these supramolecular complexes, despite two thiocarbonyl compounds being present in close proximity, no self-quenching occurs within the confined space due to curtailment of their rotational freedom. Although phosphorescence could also be observed when these thioketones are included in open containers, such as cucurbiturils and cyclodextrines, the closed container made up of octa acid is found to be the best medium to observe phosphorescence from thioketones whose excited state chemistry is essentially controlled by self-quenching.Keywords
This publication has 37 references indexed in Scilit:
- Triplet states of aromatic thioketones supported on cellulosePhysical Chemistry Chemical Physics, 1999
- A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectricsThe Journal of Chemical Physics, 1997
- Primary photophysical properties of 4H-1-benzopyran-4-thione in cyclodextrin complexesJournal of the Chemical Society, Faraday Transactions, 1997
- Photophysics of xanthione and 4H-1-benzopyran-4-thione in β-cyclodextrin complexesChemical Communications, 1997
- The Photoreactivity of Thiocarbonyl CompoundsSulfur reports, 1992
- Photophysics and intramolecular photochemistry of thiones in solutionAccounts of Chemical Research, 1988
- Decay dynamics of aromatic thione triplet states in fluid solutionCanadian Journal of Chemistry, 1983
- Photochemical oxidation of thio ketones: steric and electronic aspectsThe Journal of Organic Chemistry, 1983
- The detection of transients in thiocarbonyl flash photolysisJournal of the Chemical Society, Chemical Communications, 1972
- Phosphorescence in Fluid Media and the Reverse Process of Singlet-Triplet AbsorptionJournal of the American Chemical Society, 1945