Polycyclic Aromatic Hydrocarbon Solute Probes. Part XI: Unusual Solvent-Modulated Fluorescence Emission Behavior of 1-Methylcoronene and Select Dimethylcoronenes in Nonelectrolyte Solvents

Abstract

Fluorescence emission spectra are reported for 1-methylcoronene, 1,2-dimethylcoronene, 1,4-dimethylcoronene, 1,6-dimethylcoronene, 2,3-dimethylcoronene, and 2,5-dimethylcoronene dissolved in organic nonelectrolyte solvents of varying polarity. Four of the five coronene derivatives were found to exhibit probe character, as evidenced by a systematic variation in emission intensity ratio with solvent poplarity. Mathematical expressions which correlate measured intensity ratios and solvent polarity probe behavior of 1-methylcoronene and 1,2-dimethylcoronene with pyrene in 46 solvents of varying polarity are reported. Also reported is the preferential solvation behavior of both solutes in binary mixtures of n-heptane + tetrahydrofuran and n-heptane + 1,4-dioxane.