NIR‐FT Raman, FT‐IR and surface‐enhanced Raman scattering spectra, with theoretical simulations on chloramphenicol

Abstract

Chloramphenicol (CLM), originally derived from the bacterium Streptomyces venezuelae, is an inhibitor of bacterial ribosomal peptidyl transferase activity. The near infrared Fourier transform (NIR-FT) Raman, surface-enhanced Raman spectroscopy (SERS) and Fourier transform infrared (FT-IR) spectral analyses of CLM, a potential antibacterial drug for the treatment of typhoid fever, were carried out along with density functional computations. The vibrational spectral analysis reveals that the CH 2 asymmetric and symmetric stretching modes are shifted to higher wavenumbers than the computed values, owing to the electronic effects resulting from induction of methylene group with the adjacent electronegative atom. The lowering of C O stretching wavenumber is due to the presence of the strong electronegative atom, nitrogen, attached to the carbonyl carbon, causing large degree of molecular p-electron delocalization and redistribution of electrons, which weakens the C O bond. The absence of a C-H stretching vibration and the observed C-H out-of-plane bending modes suggest that the CLM molecule may be adsorbed in a flat orientation with respect to the silver surface.

Determination of chloramphenicol and crystal violet with surface enhanced Raman spectroscopy

“…In addition, the main peaks appeared in the spontaneous Raman spectrum could be downshifted, upshifted, broadened, or even disappeared in the SERS spectrum (Fig. 4) [11,18]. The peaks at 857 and 998 cm -1 in the SERS spectrum may be due to the downshift of 867 and 1011 cm -1 with respect to Raman spectrum, though it is also possible that they were due to the upshift of 847 and 975 cm -1 .…”

“…3. The three most prominent peaks at 1108, 1350, 1601 cm -1 were attributed to the N-H in-plane bending, N-O 2 symmetric stretching, and ring stretching vibration of chloramphenicol molecule, respectively [18]. In addition, the C=O stretching, C-H out-of-plane bending, NO 2 scissoring, and ring breathing were observed at 1686, 975, 867 and 847 cm -1 , respectively (Table 1) [18].…”

“…The molecular orientations when attached to the substrate and the types of adsorption sites also affect the wavenumbers of the Raman signals. The wavenumbers of vibrational modes are normally found downshifted when the bonds of pertinent functional groups were weakened, but upshifted when the bonds were strengthened [18]. The intensity of some prominent peaks, such as those at around 857, 998, 1108, 1350, 1440 and 1601 cm -1 , increased with an increase of chloramphenicol concentration.…”

Application of surface enhanced Raman spectroscopy for analyses of restricted sulfa drugs

“…For example, the peak at 919 cm -1 in the normal Raman spectrum of sulfamethoxazole was upshifted to 929 cm -1 in the SERS spectrum. The wavenumbers of vibrational modes are normally found downshifted when the bonds of pertinent functional groups were weakened, but upshifted when the bonds were strengthened [26,28]. Again, the molecular orientations attached to the surface and the types of adsorption sites affect the molecular frequencies.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part III

“…Quite often, SERS was also employed to determine the orientation of the molecules on a metal surface. Such studies are compiled here for the following molecules: 1H-and 3H-imidazo [4,5-b]pyridine and their methyl derivatives, [113] copper(II) chloride and bromide compounds of KCuBr 3 , [114] 5,6-diméthyluracile, [115] [C(NH 2 ) 3 ] 2 M II (H 2 O) 4 (SO 4 ) 2 , M II = Mn, Cd and VO, [116] potassium trimethylsilanolate, [117] 2-aminopyridinium-4-hydroxybenzenosulfonate, [118] the H 4 I 2 O 10 2− ion in CuH 4 I 2 O 10 · 6H 2 O, [119] 2-amino-4,6-dihydroxypyrimidine, [120] 3 (or 4 or 6)-methyl-5-nitro-2-pyridinethiones, [121] 2-methyl-4-nitroaniline (MNA) crystal, [122] 2-amino-5-chloropyridinium hydrogen selenate, [123] the food dye amaranth, [124] transstilbene in the excited singlet state, [125] chloramphenicol, [126] oroxylin, [127] 4-fluoro-N-(2-hydroxy-4-nitrophenyl)benzamide, [128] phenanthridine, [129] 3,5 dichloro hydroxy benzaldehyde and 2,4 dichloro benzaldehyde. [130] Solid State (Minerals, Crystals, Linear Chains, Glasses, Ceramics and Disordered Materials) Minerals A great number of minerals have been studied during 2008 by the Frost group [131 -146] using both Raman and infrared spectroscopies: smithsonite, [131] the uranyl carbonate mineral voglite, [132] hydrotalcite with CO 3 2− and (MoO 4 ) 2− anions in the interlayer, [133] the uranyl phosphate minerals phosphuranylite and yingjiangite, [134] the uranyl carbonate mineral zellerite, [135] the molybdate-containing uranyl mineral calcurmolite, [136] the oxalate mineral wheatleyite Na 2 Cu 2+ (C 2 O 4 ) 2 ·2H 2 O, [137] the nickel silicate mineral pecoraite, [138] synthetic nesquehonite, [139] the uranyl mineral, compreignacite, K 2 [(UO 2 ) 3 O 2 (OH) 3 ] 2 ·7H 2 O, [140] the hydroxy nickel carbonate minerals nullaginite and zaratite, …”