Vibronic couplings in vibrational spectra of the non‐centrosymmetric 2‐naphthol crystal. Comparative study of IR, Raman and inelastic incoherent neutron scattering spectra

Abstract

The polarized IR and Raman spectra of 2-naphthol as a single crystal, in solution and as a KBr pellet or powder, and the inelastic incoherent neutron scattering spectra of the powder were measured and compared with the comesponding naphthalene spectra. The previous assignments of fundamental vibrations were confirmed, except for the in-plane and out-of-plane 0-H bending modes in the crystal. The mediumdependent relative intellsities and frequencies of the vibrational bands are interpreted in terms of the competition between an intramolecular charge transfer interacting with vibrations (vibronic coupling) and hydrogen bonding.

Exciton-Free, Nonsensitized Degradation of 2-Naphthol by Facet-Dependent BiOCl under Visible Light: Novel Evidence of Surface-State Photocatalysis

“…Curve b also shows the weak stretching vibrations of the aromatic ring (1400−1600 cm −1 ), the weak stretching vibrations of the phenolic group (1160−1300 cm −1 ), and the weak bending vibrations of C−H bonds (1100 cm −1 ) due to weak adsorption capacities of 2-NAP. 33 The disappearance of FTIR peaks (such as γ(O−H), 741 cm −1 , δ(O−H), 1633 cm −1 ) to the naphtholate groups is observed in 2-NAP/BiOCl (010). The FTIR data also suggest the surface complex formed over BiOCl surface via a naphtholate linkage, as displayed in eq 1.…”

“…The strong absorption bands around 520 cm –1 should be considered as the vibrations of chemical bond in BiOCl; both can be seen in BiOCl (010) and 2-NAP/BiOCl (010). The absorption band appearing around 847 cm –1 (curve b) could be considered the bending vibration of C–H bonds, whereas there is none for the BiOCl. Curve b also shows the weak stretching vibrations of the aromatic ring (1400–1600 cm –1 ), the weak stretching vibrations of the phenolic group (1160–1300 cm –1 ), and the weak bending vibrations of C–H bonds (1100 cm –1 ) due to weak adsorption capacities of 2-NAP .…”

Polymorphism of 2-nitroaniline studied by calorimetric (DSC), structural (X-ray diffraction) and spectroscopic (FT-IR, Raman, UV–Vis) methods

“…On the basis of measured UV-Vis spectra the differences, Dm el , between the first electronic transition in crystals or in solutions and the forbidden B 2u A 1g benzene transition in the gas phase at 38,089 cm À1 have been calculated. This difference was introduced as a measure of benzene derivatives ability to the intramolecular charge transfer and optical nonlinearity generation [47] and then also to vibronic couplings [14][15][16][17][18][19]. The Dm el , values for the b and c forms are equal to 18,780 cm À1 and 18,850 cm À1 , respectively, and for the a form: 17,310 cm À1 .…”

“…It was stated that in the m-NA [14] and meta-aminophenol (m-APh) [16] crystals the ICT's and intermolecular H-bonds cooperate, what enhances their nonlinear optical (NLO) properties. The absence of optical nonlinearity in the noncentrosymmetric 2-NO crystal [19] and the weak nonlinearity of the orthorhombic meta-nitrophenol (m-NPh) crystal [17] were elucidated by the competition between ICT's and intermolecular Hbonds.…”

“…The intra-and intermolecular interactions of some disubstituted benzene derivatives [14][15][16][17][18] and of 2-naphthol [19] were investigated in our Laboratory by means of vibrational spectroscopy. It was stated that in the m-NA [14] and meta-aminophenol (m-APh) [16] crystals the ICT's and intermolecular H-bonds cooperate, what enhances their nonlinear optical (NLO) properties.…”