On the photophysical properties of aggregates of 3-(2-phenyl)-indolocarbocyanines

• Published in: Chemical physics Vol. 119; no. 2; pp. 355 - 375
• Main Authors: Van Der Auweraer, M., Biesmans, G., De Schryver, F.-C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.1988; Elsevier
• Subjects: Atomic and molecular physics; Exact sciences and technology; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Molecular properties and interactions with photons; Physics; Fluorescence spectrum; Frontier orbital; Theoretical study; Experimental study; Cyanine dye; Absorption spectrum; Luminescence decay; Concentration effect; Electron interaction; Excitation spectrum; Molecular aggregation; Internal conversion; Alcoholic solution; Hamiltonian; Dipole moment; Organic compounds
• ISSN: 0301-0104
• DOI: 10.1016/0301-0104(88)87196-9

The absorption, fluorescence and fluorescence excitation spectra of N,N′-diethyl-3-(2-phenyl)-indolocarbocyanine perchlorate and N,N′-dioctadecyl-3-(2-phenyl)-indolocarbocyanine perchlorate in ethanol at 77 K reveal the presence of emission from a monomer, a dimer and a higher H-aggregate. The emission of the monomer at 618 nm decays exponentially with a decay time of 3.5 ± 0.5 ns. The dimer emission at 676 nm decays with a decay time of 10.5 ± 1.0 ns. In order to explain the large differences observed for the radiationless decay rates of excited dimers an existing model coupling the dimer ground state and its first singlet state is generalized and, as an alternative, the disproportionation of the excited dimer is discussed.