Band-shape correlations in the electronic absorption spectra of para-(+M)-substituted nitrobenzene derivatives

Electrophilic Substituent Constant σ+ of Electron Donor Substituents in Nonpolar Media

“…The UV−vis absorption maxima of the p -nitrobenzenes (entries 1−14), measured in cyclohexane, are in agreement with published values from the literature . The 4-nitrophenolate ion (entry 26) was obtained by the addition of TBAF (0.1 M in THF) to 4-nitrophenol in dichloromethane solution.…”

“…The energy level of the HOMO is determined by the electron-donating capacity of the substituent R. In the 4-nitrobenzene series, the energy gap between the HOMO and the LUMO decreases with the increasing donating capacity of the corresponding substituent. This is accompanied by a shift of the UV−vis absorption to lower energies . The measurement of the UV−vis absorption can be carried out either directly in the gas phase or very easily in nonpolar solvents. , In order to minimize spectral shifts, based on solvatochromic effects, the UV−vis spectra should be measured in cyclohexane. , UV−vis data of nitrobenzenes, with highly polar substituents, charged groups in particular, which are not soluble in cyclohexane, can be obtained, for instance, from dichloromethane solution.…”

Nonradiative Relaxation Processes and Electronically Excited States of Nitrobenzene Studied by Picosecond Time-Resolved Transient Grating Method

“…[12][13][14][15][16][17][18] Furthermore, derivatives of NB and nitro substituted aromatic hydrocarbons have attracted the interest many scientists because of their unique properties such as the prominent charge transfer phenomena. [19][20][21][22][23][24][25] In spite of the fundamental importance of the photophysical characters of NB, the photophysical properties, dynamics, and nature of the excited states of NB have not been well understood. In 1970, Khalil et al reported phosphorescence at low temperature with a lifetime 0.1-1 s, 26 which suggested that the lowest excited triplet (T 1 ) state is of 3 ππ* character.…”

“…Nitrobenzene (NB) is one of the most fundamental molecules and it possesses a variety of unique optical properties. For example, NB is one of the well-known optical Kerr media and used as the standard substance for new nonlinear optical spectroscopies. − NB is frequently used as an energy acceptor, such as an excited state or fluorescence quencher, − and as an optical heat source in photoacoustic and photothermal spectroscopies. − Furthermore, derivatives of NB and nitro substituted aromatic hydrocarbons have attracted the interest many scientists because of their unique properties such as the prominent charge transfer phenomena. − In spite of the fundamental importance of the photophysical characters of NB, the photophysical properties, dynamics, and nature of the excited states of NB have not been well understood. In 1970, Khalil et al reported phosphorescence at low temperature with a lifetime 0.1−1 s, which suggested that the lowest excited triplet (T 1 ) state is of 3 ππ* character.…”

Ultraviolet spectrometry

“…The effect of pressure on the spectra of aromatic molecules was studied (89). The correlation between bandwidth and frequency of maximum absorption in para-substituted nitrobenzenes was examined (149). The correlation between the ultraviolet absorption spectra and the photoelectron spectra of thiocarbonyl heterocycles (83), azastilbenes (58) and spiro [4.4]nonatetraene, -triene and -diene (17) were studied.…”