Spectroscopic Properties of Polycyclic Aromatic Compounds: Examination of Nitromethane as a Selective Fluorescence Quenching Agent for Alternant Polycyclic Aromatic Nitrogen Hetero-Atom Derivatives (original) (raw)
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Applied Spectroscopy, 1991
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Applied Spectroscopy, 1991
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Applied Spectroscopy, 1992
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Applied Spectroscopy, 1993
To better assess the applicability of nitromethane as a selective quenching agent for alternant versus nonalternant polycyclic aromatic hydrocarbons in HPLC, TLC, and HPTLC analysis, we measured the effect that it has on the fluorescence emission behavior of 96 different polycyclic aromatic hydrocarbons dissolved in binary toluene/acetonitrile solvent mixtures. Results of these measurements revealed that the "selective quenching" rule is obeyed for the vast majority of PAHs, with the coronene derivatives being the only major exceptions. Fluorescence emission spectra are also reported for benzo[g]chrysene, naphtho[2,3g]chrysene, 4H-benzo[c]cyclopenta[mno]chrysene, dibenzo[ghi,mno]fluoranthene (commonly called corannulene), rubicene, diacenaphtho[1,2j:l',2'l]fluoranthene, 10-methylbenzo[b]fluoranthene, 3-methoxybenzo[k]fluoranthene, and 3-hydroxybenzo[k]fluoranthene in organic nonelectrolyte solvents of varying polarity. Calculated emission intensity ratios failed to vary systematically with solvent polarity, and all nine of the aforementioned solutes were thus classified as nonprobe molecules.
Applied Spectroscopy, 1992
Nitromethane is examined as a selective quenching agent for discriminating between "alternant" versus "nonalternant" polycyclic aromatic hydrocarbons in unknown mixtures. Of the 36 benzenoid solutes studied, only dibenzo[hi,wx]heptaphene failed to obey the selective quenching rule. Also reported are new experimental fluorescence probe studies for dibenzo[de,st]pentacene, dibenzo[fg,qr]pentacene, naphtho[8,1,2hij]hexaphene, benzo[vwx]hexaphene, benzo[1,2,3cd;4,5,6c'd']diperylene, dibenzo[hi,wx]heptacene, benzo[b]triphenylene, chrysense, and anthracene dissolved in nonelectrolyte solvents of varying polarity. Benzo- [vwx]hexaphene was found to exhibit probe character, as evidenced by a systematic variation in emission intensity ratio with solvent polarity.
Analytica Chimica Acta, 1996
Applicability of the ni~omet]ume selective quenching role for discriminating between al~numt ver-~s nonall~nant polycyclic aromatic hydrocarbons (PAils) is examined for 29 representative PAH solutes dissolved in micellar cety~ ylammonium bromide (CTAB) and micellar sodium dodecylsulfate (SDS) solvent media. Experimental reauRs show that niUmmethene quenched fluorescence emission of only the 17 altemant PAils in the cationic CTAB sorfactam solvent media as expected, Emission intensities of nonalC:mvalt PAHs, except for the few exceptions noted previously, were u~ by nitremethane addition. Unexpected quenching behavior was observed, however, in the case of nonaltenumt PAH$ di~,olved in miceIIar SDS solvent media. Nitromethaue quenched fluorescence emission of non~/ernant PAI~ studied in the SDS solvent media, which is contrary to the selective quenching rule.