Solvation dynamics and red-edge effect of two electrically charged solutes in an imidazolium ionic liquid

Abstract

Steady state and time-resolved fluorescence behavior of two electrically charged solutes, viz., negatively charged l-anilinonaphthalene-8-sulfonate (ANS) and positively charged efhidium bromide (EB), have been studied in an imidazolium ionic liquid. It is found that EB shows a much less pronounced excitation wavelength dependent fluorescence behavior (red-edge effect) as compared to ANS. The solvation dynamics of these probes in [bmim][BF 4] is found to be similar to those observed with neutral dipolar probes. A higher solvation time of EB as compared to ANS is possibly a reflection of hydrogen bonding interaction of the former system with the anionic component of the ionic liquid.