Influence of Pressure on the Spectral Properties of Dye−DNA Supermolecules

Abstract

We investigated a series of structurally and chemically different dye-DNA complexes via the specific behavior of spectral holes under pressure. In all samples chromophore and solvent were the same, only the DNA strands were different. The dominant interaction with the solvent is mainly electrostatic via the strongly polar BF 2 group of the chromophore. The relative change of the dipole moment upon excitation can be estimated from the experimental data. There is a significant color effect in the pressure-induced broadening of the holes, which signals a breakdown of the Gaussian approximation. The origin of this breakdown is associated with ordered structures around the chromophore due to the DNA strands but also because of the formation of ordered solvent cage structures as a consequence of the hydrophobic nature of the chromophore. The various DNA strands show characteristic features in the spectra under pressure that reflect specific structural features.

Interactions of Thionin with DNA Strands: Intercalation versus External Stacking

“…Pressure-tuning spectroscopy in combination with spectral hole burning is one of the most sensitive spectroscopic techniques for research on probe-solvent interactions. [20][21][22] Our aim is to characterize the various binding modes of thionin to the DNA molecules via the pressure-tuning response using the free thionin in solution as a reference standard. The investigation of the binding modes may stress the existence of the two tautomeric structures and † Part of the special issue "Gerald Small Festschrift".…”

“…In this paper we report on pressure-tuning hole-burning experiments using thionin as a probe and various short-stranded DNA chains as complex-forming partners. Pressure-tuning spectroscopy in combination with spectral hole burning is one of the most sensitive spectroscopic techniques for research on probe−solvent interactions. − Our aim is to characterize the various binding modes of thionin to the DNA molecules via the pressure-tuning response using the free thionin in solution as a reference standard. The investigation of the binding modes may stress the existence of the two tautomeric structures and reveal their specific features with respect to quadruplex and duplex DNA structures.…”

Interfacial Solvation within n-Alkane Monolayers in Contact with Supercritical CO2

“…Figure illustrates the BODIPY 494/503 attachment geometry at a C n -TM(E)OS/APTES surface. This particular BODIPY probe was selected because it exhibits a high fluorescence quantum yield, it has C 2 v symmetry, and its excitation and emission transition dipole moments are essentially parallel under the excitation and emission conditions used in the current experiments . These characteristics help simplify data interpretation.…”