Solvent-dependent changes in molecular reorientation dynamics: the role of solvent-solvent interactions

C E Hay, Frank Marken, G J Blanchard

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

We report on the rotational diffusion dynamics of two different chromophores, resorufin and 6-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)hexanoic acid (NBDHA) in water and N-octyl-2-pyrrolidone (NOP) solvents. We measure the induced orientational anisotropy function, R(t), using time-correlated single photon counting. Our data show that both chromophores exhibit single exponential anisotropy decays in aqueous solution and two-component exponential anisotropy decays in NOP. The change of the anisotropy decay functionality indicates that the effective rotor shape swept out by solute rotational motion is different in the two solvents. We interpret these findings in the context of Chuang and Eisenthal's theory of fluorescence depolarization by rotational diffusion. The similarity in the behavior of the two different chromophores in these solvent systems points to solvent-solvent interactions and local organization as the dominant factors in mediating motional dynamics.
Original languageEnglish
Pages (from-to)4957-4962
Number of pages6
JournalThe Journal of Physical Chemistry A
Volume114
Issue number14
DOIs
Publication statusPublished - 15 Apr 2010

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