The unique optical properties of squaraines render these molecules useful for applications that range from xerography to photodynamic therapy. In this regard, squaraines derived from the condensation of nitrogenbased heterocycles and squaric acid have many promising attributes. Key solution-phase photophysical properties of six such squaraines have been characterized in this study. One feature of these molecules is a pronounced absorption band in the region ∼600-720 nm that has significant spectral overlap with the fluorescence band (i.e., the Stokes shift is small). As such, effects of emission/reabsorption yield unique excitation wavelength dependent phenomena that are manifested in quantum yields of both fluorescence and sensitized singlet oxygen production. Comparatively small squaraine-sensitized yields of singlet oxygen production and, independently, large rate constants for squaraine-induced deactivation of singlet oxygen are consistent with a model in which there is appreciable intra- and intermolecular charge-transfer in the squaraine and squaraine-oxygen encounter complex, respectively. The results reported herein should be useful in the further development of these compounds for a range of oxygen-dependent applications. © 2010 American Chemical Society.

Salice, P., Arnbjerg, J., Pedersen, B., Toftegaard, R., Beverina, L., Pagani, G., et al. (2010). Photophysics of Squaraine Dyes: Role of Charge-Transfer in Singlet Oxygen Production and Removal. JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY, 114(7), 2518-2525 [10.1021/jp911180n].

Photophysics of Squaraine Dyes: Role of Charge-Transfer in Singlet Oxygen Production and Removal

SALICE, PATRIZIO;BEVERINA, LUCA;PAGANI, GIORGIO ALBERTO
;
2010

Abstract

The unique optical properties of squaraines render these molecules useful for applications that range from xerography to photodynamic therapy. In this regard, squaraines derived from the condensation of nitrogenbased heterocycles and squaric acid have many promising attributes. Key solution-phase photophysical properties of six such squaraines have been characterized in this study. One feature of these molecules is a pronounced absorption band in the region ∼600-720 nm that has significant spectral overlap with the fluorescence band (i.e., the Stokes shift is small). As such, effects of emission/reabsorption yield unique excitation wavelength dependent phenomena that are manifested in quantum yields of both fluorescence and sensitized singlet oxygen production. Comparatively small squaraine-sensitized yields of singlet oxygen production and, independently, large rate constants for squaraine-induced deactivation of singlet oxygen are consistent with a model in which there is appreciable intra- and intermolecular charge-transfer in the squaraine and squaraine-oxygen encounter complex, respectively. The results reported herein should be useful in the further development of these compounds for a range of oxygen-dependent applications. © 2010 American Chemical Society.
Articolo in rivista - Articolo scientifico
singlet oxygen;
English
2010
114
7
2518
2525
none
Salice, P., Arnbjerg, J., Pedersen, B., Toftegaard, R., Beverina, L., Pagani, G., et al. (2010). Photophysics of Squaraine Dyes: Role of Charge-Transfer in Singlet Oxygen Production and Removal. JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY, 114(7), 2518-2525 [10.1021/jp911180n].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/15957
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