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CHARACTERIZATION OF THE SPECTROSCOPIC PROPERTIES OF A TETRAHYDROCHRYSENE SYSTEM CONTAINING A RIGIDIFIED HYDROXYNITROSTILBENE CHROMOPHORE: AN INHERENTLY FLUORESCENT LIGAND DESIGNED FOR THE ESTROGEN RECEPTOR
Author(s) -
Anstead Greorgy M.,
Hwang KwangJin,
Katzenellenbogen John A.
Publication year - 1993
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1993.tb02927.x
Subject(s) - photochemistry , solvatochromism , chemistry , excited state , chromophore , fluorescence , quantum yield , emission spectrum , intramolecular force , quenching (fluorescence) , solvent , stereochemistry , spectral line , atomic physics , organic chemistry , physics , quantum mechanics , astronomy
— A tetrahydrochrysene system that embodies a hydroxy‐ and nitro‐substituted stilbene chromophore held rigidly near planarity by the tetracyclic nature of the compound was prepared as a fluorescent ligand for the estrogen receptor. It shows strong solvent‐dependent fluorescence at long wavelengths. The solvent polarity dependence suggests that the fluorescence arises from an excited state with much nπ* character in cyclohexane; stronger emission comes from an intramolecular charge transfer state that has lower energy in more polar solvents, and finally progressive quenching of the charge transfer state occurs in solvents of higher polarity. The quenching effect is particularly evident in protic solvents. In water, however, the compound shows fluorescence of unusually high energy for an intramolecular charge transfer state, which suggests that photochemistry may be occurring. In solutions of gamma‐cyclodextrin, emission from the nitrotetrahydrochrysene is red shifted and intensified relative to water. Photobleaching occurs in H 2 O but not in ethanol or gamma‐cyclodextrin solution. The change in dipole moment between the ground and excited states for the nitrochrysene is 12.9 D, similar to our previous measurements for related nitrostilbenes. The compound displays red‐shifted emission in triethylamine, perhaps due to an excited state hydrogen‐bonded complex, The absorption and emission properties of the corresponding nitrophenolate were also studied. The nitrophenolate exhibits reverse solvatochromism in its absorption spectra. In conclusion, the high sensitivity of the emission energy and quantum yield of the title compound make it of potential utility as a fluorescent probe.