The J-aggregate 5,5′,6,6′-Tetrachloro-1,1′-diethyl-3,3′-bis(4-sulfobutyl)benzimidazolocarbocyanine Sodium Salt in Aqueous Solution

Abstract

Abstract The aggregation of the title dye in a dilute alkaline aqueous solution is investigated at 283–303 K by measuring the electronic absorption spectra. The association number is estimated to be 8, the heat of formation and the entropy change for the association are found as ΔH=−91.5 kcal mol−1 (1 cal=4.184J) and ΔS=−139.3 cal K−1 mol−1, respectively. The structure of the octamer is discussed from a view of spectral shift, intermolecular force and the crystalline structural data. The lifetimes, quantum yields and polarization of fluorescence are investigated on the monomeric and the J-aggregate state of the dye. The energy transfer between several J-aggregate units is indicated in the excited state.