An ultrafast molecular rotor based ternary complex in a nanocavity: a potential "turn on'' fluorescence sensor for the hydrocarbon chain

作者：Murudkar Sushant; Mora Aruna K; Singh Prabhat K; Bandyopadhyay Tusar; Nath Sukhendu^*

来源：Physical Chemistry Chemical Physics, 2015, 17(8): 5691-5703.

DOI：10.1039/c4cp04636f

Formation of a ternary complex by an ultrafast molecular rotor (UMR) with a macrocyclic cavitand has been investigated for the sensitive detection of the alkyl chain of a surfactant. A benzothiazole based UMR, Thioflavin-T (ThT), has been used as a fluorescent probe. It is shown that ThT forms a very weak inclusion complex with gamma-cyclodextrin (gamma-CD) with an association constant of 8.8 M-1. However, the addition of a small amount of surfactant results in a significant increase in the emission intensity of ThT in gamma-CD solution. From detailed steady-state and time-resolved fluorescence measurements and NMR studies, it has been inferred that the addition of the surfactant results in the formation of a ternary complex through the inclusion of its alkyl chain inside the gamma-CD nanocavity. In such a ternary complex, the non-radiative torsional motion in ThT is largely prevented due to a large increase in the frictional force inside the nanocavity and results in a significant fluorescence enhancement. The formation of the binary and the ternary complexes in the present system has been further supported by the molecular docking and subsequent molecular dynamics simulation studies. The present result indicates that the inclusion complex with an UMR as a guest could be a potential candidate for the efficient detection of insoluble organic molecules, especially hydrocarbons.

• 出版日期2015