POLYCYCLIC AROMATIC HYDROCARBON SOLUTE PROBES .12. DISSIMILAR FLUORESCENCE EXCITATION EMISSION BEHAVIOR BETWEEN ALKYLPYRENE AND ALKYLCORONENE DERIVATIVES AND THE PARENT PAH MOLECULE/

Fluorescence excitation and emission behavior are reported for methylc oronene, 1,2-dimethylcoronene, 2-isopropylpyrene, 4-isopropylpyrene, 2 ,4,7,1O-tetraisopropylpyrene, 1,3,6,8-tetraisopropylpyrene, 1,3,5,7,9- pentaisopropylpyrene, 2,7-di-tert-butylpyrene, 2,7-di-(dimethylpropyl) pyrene, 1,3,6,8-tetracyclopentylpyrene and 1,3,6,8-tetracyclohexylpyre ne dissolved in various organic solvents of varying solvent polarity. Experimental results are used to test a potential screening method for determining whether a given alkyl-substituted polycyclic aromatic hyd rocarbon (PAH) solute is likely to exhibit probe character, as evidenc ed by a systematic variation in the ratios of the fluorescence intensi ties of select emission bands with solvent polarity. Of the eleven sol utes studied, only 4-isopropylpyrene, methylcoronene and 1,2-dimethylc oronene showed useful solvent polarity probe character. 1,3,6,8-Tetrai sopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 1,3,6,8-tetracyclohexy lpyrene and 1,3,6,8-tetracyclopentylpyrene exhibited slight probe beha vior; however, the dynamic ranges covered in emission intensity ratios were believed to be too small for many practical applications when co mpared against the experimental uncertainty associated with the measur ed values.