Effects of electrolyte concentration on the rotational dynamics of resorufin

C E Hay, Frank Marken, G J Blanchard

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We report on the rotational diffusion dynamics of the anionic chromophore resorufin in water and N-octyl-2-pyrrolidone (NOP) solutions as a function of solution electrolyte concentration. Our data show that resorufin exhibits a single exponential anisotropy decay in aqueous solutions containing up to 0.1 M lithium perchlorate (LiClO4). In contrast to the observed behavior of resorufin in pure NOP, where biexponential decay occurs, we also observe a single exponential anisotropy decay for resorufin in NOP with the addition of up to 0.1 M tetrabutylammonium bromide (TBAB) or tetraoctylammonium bromide (TOAB). For resorufin in NOP, the reorientation time constant increases with increasing electrolyte concentration, consistent with complexation between the resorufin anion and the electrolyte ammonium cation. We observe a qualitatively different trend in the aqueous resorufin solutions and understand these data for both solvent systems in the context of interactions between the chromophore and cationic species present.
Original languageEnglish
Pages (from-to)12875-12880
Number of pages6
JournalThe Journal of Physical Chemistry A
Volume114
Issue number49
DOIs
Publication statusPublished - 16 Dec 2010

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