Polycyclic Aromatic Hydrocarbon Solute Probes. Part VIII: Evaluation of Additional Naphthacene and Perylene Derivatives as Possible Solvent Polarity Probe Molecules

Abstract

Fluorescence emission spectra are reported for phenanthro[5,4,3,2efghi]perylene, dibenzo[cd,k]naphtho[8,1,2fghi]perylene, benzo[b]peryiene, dibenzo[e,ghi]perylene, and benzo[a]naphtho[8,1,2cde]-naphthacene dissolved in various organic solvents. Results of these measurements are used to screen PAHs for potential solvent polarity behavior. Of the five PAHs studied, only phenanthro[5,4,3,2efghi]perylene exhibited probe behavior, as evidenced by selective emission intensity enhancement of band I with increasing solvent polarity.

1,3,6,8-Tetraethynylpyrene and 1,3,6,8-tetrakis (trimethylsilylethynyl) pyrene: Photophysical properties in homogeneous media

“…The fluorescence decay profiles recorded for TEP and TEP-TMS followed a single exponential kinetics in all the solvents studied. A relatively short excited state lifetime (2-4 ns) was observed when compared to pyrene, which normally shows a quite high lifetime reaching 390 ns in non-polar solvents [17]. Molecules with a strongly allowed S 0 -S 1 transition usually exhibit short lifetimes.…”

“…A systematic experimental investigation on a series of polycyclic aromatic hydrocarbons (PAHs) [8,9,10,11,12,13,14,15,16,17,18] for a variation in selective vibronic bands with respect to solvent polarity show that the PAHs broadly fall in to three categories. The first category of PAHs include pyrene, benzo[ghi]perylene, etc which exhibit a selective emission intensity enhancement of vibronic band I relative to band III (I/III) in polar solvents.…”

“…Several preliminary ideas based on Kekule structures, point group and symmetry elements, dissimilarities between the excitation and emission spectra of the molecule, the relative length of the center aromatic row in the case of coronene derivatives were suggested to explain the enhancement phenomenon [17]. However, the study on PAHs have shown that there are no apparent correlation between probe character and molecular symmetry (point group), or between probe character and p-electron numbers, which is based upon the ''aromatic'' (4n+2) and ''anti-aromatic'' (4n) classification schemes used to divide PAHs according to chemical reactivity [18].…”

Spectroscopic Properties of Polycyclic Aromatic Compounds: Examination of Nitromethane as a Selective Fluorescence Quenching Agent for Alternant Polycyclic Aromatic Nitrogen Hetero-Atom Derivatives

“…To prevent misidentification, the data file should include both polar and nonpolar solvents, since electronic interactions between a solvent dipole and an excited PAH/PANH solute can lead to spectral distortions, wavelength shifts and/or intensity ratio variations, as was the case with many of the polycyclic aromatic compounds examined previously. [10][11][12][13][14][15][16][17][18][19][20][21] Solvent-induced fluorescence spectral changes can be rationalized qualitatively in a relatively straightforward Received 15 July 1991; revision received 9 August 1991. * Author to whom correspondence should be sent.…”

Electronic States and Structure of Dibenzo[j,lm]-phenanthro[5,4,3-abcd]perylene

“…For many larger hydrocarbons it was observed that the intensities of vibronic components in the absorption spectra vary in different solvents [6][7][8][9][10], which indicates the presence of several forms. For tetrabenzo[α, cd, f, lm]perylene, a discrepancy between absorption and fluorescence excitation spectra was interpreted (295) as evidence of more than one conformer present at room temperature [11].…”