Tuning intramolecular anharmonic vibrational coupling in 4-nitroaniline by solvent-solute interaction

Abstract

Applying a combined experimental and theoretical approach we demonstrate that doublets of the nu(s)(NO(2)) band of 4-nitroaniline which have been observed in several environments originate from Fermi resonances. Changes of the line shapes typical for Fermi resonances are reported also for other isotopomers of 4-nitroaniline, however, for each of them in different solvents and solvent mixtures. Simulations of the infrared spectra based on the solvatochromic frequency shifts of the nu(s)(NO(2)) vibration determined experimentally together with calculated cubic couplings with overtones and combination bands account for the experimental findings.

Probing Lewis Acid–Base Interactions with Born–Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum ofp-Nitroaniline in Supercritical CO2

“…64 Data for the ν s (NO 2 ) stretch frequency shifts for PNA solvated in DMSO−CCl 4 and toluene−CCl 4 mixtures have also been reported. 63 These data also strongly indicate that ν s (NO 2 ) is dependent on the solute−solvent interactions and that it is shifted by ∼25 cm −1 when we move from PNA in pure CCl 4 to PNA in pure DMSO. Moreover, Dreyer et al 63 also provided evidence that there is a correlation between vibrational and electronic solvatochromism.…”

“…Therefore, the above results provide further evidence on the relationship between vibrational and electronic solvatochromism. 63 Moreover, our results for PNA in scCO 2 strongly indicate that this correlation is driven by LA−LB interactions.…”

Is Our Way of Thinking about Excited States Correct? Time‐Resolved Dispersive IR Study on p‐Nitroaniline

“…The origin of the doublet feature at around 1320 cm −1 has been a subject of debate 13–15. 17, 19, 21 Two possible mechanisms for this doublet have been suggested: one is a Fermi resonance13, 17 and the other is the existence of two distinct solvated forms of PNA 14.…”

“…The origin of the doublet feature at around 1320 cm −1 has been a subject of debate 13–15. 17, 19, 21 Two possible mechanisms for this doublet have been suggested: one is a Fermi resonance13, 17 and the other is the existence of two distinct solvated forms of PNA 14. 21 However, according to our calculations, the higher‐ and lower‐wavenumber components of the doublet are attributed to the NO 2 symmetric stretch coupled with out‐of‐phase and in‐phase combinations of the CNH 2 and CNO 2 stretches, respectively (see Table 1).…”

“…p-Nitroaniline is a prototypical push-pull molecule exhibiting a large first hyperpolarizability [5][6][7][8][9][10][11] and nonlinear optical properties with possible applications for electrooptic and second-harmonic generation materials. As a model system, PNA has long been studied both experimentally [4,[12][13][14][15][16][17][18][19][20][21][22] and theoretically. [23][24][25][26][27] A number of ultrafast spectroscopic studies [28][29][30][31] have been done to understand the dynamics of PNA after photoexcitation.…”