Back close

Conformational Switching and Exciton Interactions in Hemicyanine-Based Bichromophores

Publication Type : Journal Article

Publisher : Journal of the American Chemical Society

Source : Journal of the American Chemical Society, vol. 123, pp. 7859-7865, 2001

Url : http://dx.doi.org/10.1021/ja010199v

Campus : Amritapuri

School : School of Arts and Sciences

Department : Chemistry

Year : 2001

Abstract : Conformational changes in two hemicyanine-based bichromophores were demonstrated by varying the polarity as well as temperature of the medium. Dramatic changes in the ground and excited singlet state properties were observed upon folding of the bichromophores, due to the formation of intramolecular aggregates of H-type. These aspects were studied, in detail, using steady-state absorption and time-resolved fluorescence spectroscopy. Time-resolved fluorescence studies indicate that both the bichromophores exhibit a monoexponential decay, with a short lifetime, in mixed toluene−CH2Cl2 solvents having lower proportions of toluene. Interestingly, biexponential decay with short and long-lived species was observed at higher proportions of toluene, due to the presence of unfolded and folded forms. Folding results in the intramolecular stacking of the chromophores which restrict their torsional dynamics, leading to a longer lifetime. Upon laser excitation, the folded form of the bichromophore undergoes rapid conformational changes, due to photoinduced thermal dissociation.

Cite this Research Publication :
Dr. Zeena S. Pillai and K. George Thomas, “Conformational Switching and Exciton Interactions in Hemicyanine-Based Bichromophores”, Journal of the American Chemical Society, vol. 123, pp. 7859-7865, 2001

Admissions Apply Now