Solvent Effects on the Thermodynamics and Kinetics of Coralyne Self-Aggregation

Abstract

The role of solvent effects on the thermodynamics and kinetics of the coralyne self-aggregation process has been investigated in ethanol-water mixtures of different compositions. The changes in the UV/visible spectra of coralyne and FAB/LSIMS mass spectrometry agreed well with the formation of a dimer species. 1D and 2D 1H experiments have allowed one to look into the features of the self-aggregation process and to determine the equilibrium constant and the deltaH0 and deltaS0 values for the aggregate formation in 0-50% ethanol-water mixtures. The kinetics of self-aggregation has been investigated by the T-jump chemical relaxation method, and the results have been interpreted in terms of dimer formation. The dependence of the relative viscosity of coralyne solutions on the dye concentration was studied in different ethanol-water mixtures. Finally, it was found that coralyne behaves as a solvatochromic indicator which is preferentially solvated according to the sequence ethanol > ethanol-water > water. All of the results concur in elucidating the relevant role of the hydrophobic interaction process of coralyne stack formation.

New aspects of the interaction of the antibiotic coralyne with RNA: coralyne induces triple helix formation in poly(rA)•poly(rU)

“…As the polynucleotide was added to the spectrophotometric cell containing the dye solution, the intensity of the spectral band of coralyne (420 nm), initially present mainly as an aggregate (23), is progressively reduced as the polymer level increases, while the monomer band (438 nm) raises and becomes more intense than the band of the aggregate. The inversion of the band intensity ratio reveals that, if free coralyne is present as an aggregate, the bound coralyne is present mainly as a monomer.…”

“…The interaction of coralyne-like molecules with RNA has been even far less investigated. It should be noticed that the data analysis is difficult because of the high tendency of coralyne to self-aggregation (6,22,23). Fluorescence techniques, which enable a precise observation of very low dye concentrations, provide a powerful tool to overcome difficulties due to aggregation.…”

Dimer-promoted fluorescence quenching of coralyne by binding to anionic polysaccharides

“…A recent paper, published during the preparation of our revised manuscript, also demonstrates the concentration dependence of the coralyne absorption. 12 As a representative example, the inset to …”

The origin of the dual fluorescence of protonated ellipticine in water

“…The interaction of the tropolone moieties of colchicine was found to result in weakly-bound dimers [15]. The fully conjugated ring system of coralyne promoted the formation not only of dimers but also of multiple aggregates [16,17].…”