Spectroscopic Investigation of Fluorescence Quenching Agents: Effect of Nitromethane on the Fluorescence Emission Behavior of Select Cyclopenta-PAH, Aceanthrylene, and Fluorene Derivatives

Abstract

Nitromethane is examined as a selective fluorescence quenching agent for “alternant” alkyl-substituted polycyclic aromatic hydrocarbons (PAHs). Fluorescence emission behavior is reported for 11 H-benz[bc]aceanthrylene, 4 H-cyclopenta[def]phenanthrene, 4 H-cyclopenta[def]chrysene, 13 H-dibenzo[a,g]fluorene, 13 H-dibenzo[a,i]fluorene, 4 H-benzo[b]cyclopenta[mno]chrysene, 4 H-cyclopenta[pqr]picene, 7 H-dibenzo[c,g]fluorene, 9 H-benz(6,7)indeno[1,21]phenanthrene, 4 H-benzo[b]cyclopenta[jkl]triphenylene, 13 H-dibenz[bc,k]aceanthrylene, 13 H-dibenz[bc,l]aceanthrylene, and 4 H-benzo[def]cyclopenta[mno]chrysene dissolved in organic solvents of varying polarity and in acetonitrile or aqueous-acetonitrile solvent mixtures at various nitromethane concentrations. Results of these measurements show that nitromethane quenches fluorescence emission of the thirteen solutes studied, which is in complete agreement with what would be expected on the basis of the fact that all solutes are “alternant” polycyclic aromatic hydrocarbons.

Spectroscopic Investigation of Fluorescence Quenching Agents. Part IV: Selectivity of Nitromethane for Discriminating between Alternant versus Nonalternant Polycyclic Aromatic Hydrocarbons in Solvents of Differing Polarities

“…Mathematical expressions, computational procedures, and interrogation zone dimensions are given elsewhere. [17][18][19]26,27 Every effort was made to work at solution absorbances below Acm -~ _< 0.95 ([prim -< 3.00) where the inner-filtering correction equation is valid. Secondary inner-filtering corrections were not necessary in the present study since nitromethane is "optically transparent" in most of these PAHs' emission ranges.…”

Polycyclic Aromatic Nitrogen Heterocycles. Part V: Fluorescence Emission Behavior of Select Tetraaza- and Diazaarenes in Nonelectrolyte Solvents

“…Interestingly, not all PANHs behave in this fashion. Various emission intensity ratios of 1-azapyrene, 2-azapyrene, 4-azapyrene, 4-azachrysene, benzo[lmn]- [3,8]phenanthroline, and benzo [4,10]anthra [1,9,Scdef]-cinnoline remained constant, irrespective of solvent polarity. Fluorescence emission spectra of benzo[a]-phenazine, acenaphtho [1,2]pyridine, indeno [1,2,3ij]-isoquinoline, and indeno [1,2,3ij] [2,7]naphthyridine showed very little structured emission.…”

Simultaneous determination of 11 polycyclic aromatic hydrocarbons (PAHs) by second-derivative synchronous spectrofluorimetry considering the possibility of quenching by some PAHs in the mixture

“…Several workers have used the second-derivative technique to increase the selectivity of synchronous spectroscopy for determining different compounds in samples of motor oil, waters and human serum. [22][23][24] Several papers in which the quenching of PAHs by other compounds such as chlorine 25 was described and studies in which nitromethane was evaluated as a selective quenching agent for alternant alkyl-substituted PAHs 26,27 have been published recently. However, the different studies published on the simultaneous determination of several PAHs by synchronous luminescence did not describe the possibility of quenching of fluorescence of some compounds (PAHs) by others present in the mixture.…”