Interaction of Pyrene-1-Carboxaldehyde with micelles and mixed micelles of polyoxyethylene nonyl phenol (Igepal): A spectroscopic study

The absorption and steady-state fluorescence of a non-amphiphilic derivative of pyrene, Pyrene-1-Carboxaldehyde (1-PyCHO) is sensitive to the probe's environment. Association of the surfactants in aqueous medium as micelles and mixed micelles has been studied from the photophysical changes of 1-PyCHO in these media. The physicochemical characteristics of the micelles, i.e. CMC, aggregation number have been determined. The obtained CMC values from different methods are close to each other. The association constants of the 1-PyCHO molecules with the non-ionic micelle of Igepal and location of the fluorophore in the micellar environment have been determined. Micropolarity of Igepal micelle and Igepal/Igepal mixed micelle surrounding 1-PyCHO has been ascertained comparing the shift in fluorescence maximum with ET(30) values of standard solutions.