Fluorescent pseudorotaxanes of a quinodicarbocyanine dye with gamma cyclodextrin
| Autor: | Tiffany E. McGee, Lisa E. Silzel, John W. Silzel, Olivia M. Bernstein |
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| Rok vydání: | 2017 |
| Předmět: |
Photoisomerization
Chemistry Relaxation (NMR) Quantum yield 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Fluorescence Atomic and Molecular Physics and Optics 0104 chemical sciences Analytical Chemistry Solvent Excited state Solubility 0210 nano-technology Instrumentation Spectroscopy Fragment molecular orbital |
| Zdroj: | Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy. 189 |
| ISSN: | 1873-3557 |
| Popis: | Spectrophotometric titration of buffered solutions of gamma cyclodextrin (γCD) and 1,1′-diethyl,2,2′-dicarbocyanine (DDI) demonstrates extension of the known 1:2 host:guest complex to form a previously unreported 2:2 complex near the γCD solubility limit. Though DDI is predominantly hosted as a non-fluorescent H-aggregate, both complexes exist in respective equilibria with two secondary complexes hosting unaggregated DDI as 1:1 and 2:1 complexes. The 2:1 complex exhibits significant fluorescence emission, with a quantum yield six times that of DDI in organic solvents, but ten times lower than that of an analogous indodicarbocyanine. Fragment Molecular Orbital calculations suggest that the 2:1 complex has the tail-to-tail conformation, and that solvent access to the dye strongly favors photoisomerization. In the host-guest complex, γCD limits solvent access to the dye and hinders rotation of the quinolyl terminal groups, but nevertheless pairwise rotation of methine carbons within the γCD cavity likely remains as a significant nonradiative relaxation pathway for the excited state. |
| Databáze: | OpenAIRE |
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