FT-IR, FT-Raman and computational study of 1H-2,2-dimethyl-3H-phenothiazin-4[10H]-one

Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy

“…The band at about 1150 cm À1 may be due to the stretching vibration of the C-N bond or to the stretching and wagging vibration of CH 2 (methylen groups) as assigned by Minitha et al [23] to the band at 1159 cm À1 of phenothiazine, which coincides with one of our measurements of pheomelanin. Alternatively, this band may be the same that was found by Centeno and Shamir [19] in eumelanin at 1135 cm À1 and assigned to the in-plane deformation of the N-H bond in the pyrrole ring or to ring breathing.…”

“…1). The band about 500 cm À1 is close to the band found at 521 cm À1 in a synthetic phenothiazine by Minitha et al [23], and also to the band at 518 cm À1 found by Centeno and Shamir [19] in eumelanin extracted from cuttlefish Sepia officinalis. These authors assigned these bands to the out-of-plane deformation of the phenyl rings, which occurs at this wavenumber range.…”

“…By contrast, the Raman spectrum of pheomelanin has never been characterized, maybe because of the difficulty to avoid damage to melanins under Raman excitation if the instrumentation requires high illumination power density and long data acquisition times [4,21]. If anything, previous papers tangential to this topic are those by Biliń ska [22], who reported the infrared spectrum of melanins isolated from human hair containing eu-and pheomelanin, and by Minitha et al [23], who obtained the Raman spectrum of a phenothiazine, a compound similar to the pheomelanin units but with two benzene rings instead of one as benzothiazines have. As eumelanin and pheomelanin are found mixed in most biological tissues [3], the application of Raman spectroscopy as a non-invasive method to detect melanins would be only completely useful if the Raman spectra of both pigments are known.…”

Synthesis, crystal structure, spectroscopic analysis and computational study of (Z)-1-(2,4-dinitrophenyl)-2-((E)-3-(4-methoxyphenyl)-1-(thiophen-2-yl) allylidene) hydrazine by DFT and AIM approach

“…Also C-N bond length are found to be much shorter than the average value for a single C-N bond (1.47Å), but significant longer than a C=N double bond (1.22Å) [45], suggesting the presence of multiple bond character. The C=C bond length is 1.3535Å and C-C bond lengths lie in the range 1.4843-1.4582Å which is in agreement with reported literature [46]. Espinoza-Hicks et.al [47] has reported O-C aromatic and O-CH 3 bond length as 1.365Å and 1.428Å.…”

Synergistic stabilization of shale by a mixture of polyamidoamine dendrimers modified bentonite with various generations in water-based drilling fluid

“…The bands at 1650 cm −1 and 1560, 1550 cm −1 were the C = O stretching vibration and C-N bending vibration respectively, corresponding to the characteristic absorption bands of amide I and amide II (Schmidt et al, 2006). The bands at 1460 and 1360 cm −1 indicated the C-H asymmetric and symmetric bending vibration, and the bands at 1110, 1120 and 1130 cm −1 were attributed to C-H inplane bending vibration (Shakila et al, 2012), CH 2 twisting vibration and C-N symmetric stretching vibration, respectively (Minitha et al, 2011;Wan et al, 2011).…”