Related Experiment Video
Updated: Aug 14, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
3H-Indoles in Cetyltrimethylammonium Bromide (CTAB) Micelles and Water: Spectroscopy and Photophysics at Various
1Département de Chimie, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec, H3C 3J7, Canada
Abstract:
An absorption and fluorescence spectral study has been carried out for four molecules: 2-[(p-amino)phenyl]-3,3-dimethyl-3H-indole (1), 2-[(p-dimethylamino)phenyl]-3,3-dimethyl-3H-indole (2), 2-[(p-amino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (3), and 2-[(p-dimethylamino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (4) in cetyltrimethylammonium bromide (CTAB) and water solutions. Arrhenius plots for the nonradiative decay processes competing with fluorescence are nonlinear in CTAB. This is ascribed to the fact that the probes are locked into a site where the twisting of the phenyl moiety is nearly inhibited in CTAB at room temperature. The binding constants increase in an increasing order of the molecular size (exponential growth) thereby showing that hydrophobic effects are the driving force behind the solubilization of these molecules in CTAB. Calculation of transfer free energies has confirmed the importance of the hydrophobic effect compared to the Coulombic interactions. The neutral-monocation equilibrium is lowered in presence of CTAB.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
IR Absorption Frequency: Hybridization
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...
Micelles

