Dandapat M, Mandal D. Local viscosity and solvent relaxation experienced by rod-like fluorophores in AOT/4-chlorophenol/m-xylene organogels.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017;
170:150-156. [PMID:
27428601 DOI:
10.1016/j.saa.2016.07.012]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 07/07/2016] [Indexed: 06/06/2023]
Abstract
Organogels prepared from AOT/4-chlorophenol/m-xylene are immobile in the macroscopic sense, with a well-characterized internal structure. However, the molecular level dynamics inside the gels is not too clear, although a very slow structural relaxation has been reported previously. Using a set of rod-like fluorophores, we find that the rotational mobility of a small guest molecule inside the gel can be extremely fast, indicating presence of sufficiently low-microviscosity domains. These domains consist of m-xylene solvent molecules trapped in the interstices of fiber bundles comprising columnar stacks of 4-chlorophenol surrounded by AOT molecules. However, interstitial trapping of m-xylene does retard its own dynamics, which explains the slow solvent relaxation inside the gels. Hence, the state of m-xylene in the organogel may be characterized as "bound", in contrast to the "free" state in neat m-xylene.
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