Density functional theory investigations on the conformational stability, molecular structure and vibrational spectra of 6-methyl-2-chromenone

Vibrational spectroscopic analysis of 2, 3:4,5-Bis-O-(1-methylethylidene)beta-D-fructopyranose Sulfamate(Topiramate) by density functional method

2,3:4,5-Bis-O-(1-methylethylidene)-beta-D- fructopyranose sulfamate otherwise called as Topiramate is a drug used for the treatment of alcohol dependence. Topiramate is a safe and consistently efficacious medication for treating alcohol dependence. The spectroscopic properties of Topiramate are investigated by Fourier Transform Infrared (FT-IR), Fourier Transform Raman (FT-Raman), Fourier Transform Nuclear magnetic Resonsnce(FT-NMR) andUltra Violet Visible (UV-visible) spectroscopic techniques. The FTIR, FT-Raman, FT-NMR and UV-visible spectra of Topiramate have been recorded and analyzed. Theoretical vibrational frequencies, geometric parameters, thermodynamic properties, Natural population analysis and Mulliken atomic charges of Topiramateare obtained by the Restricted Hartree-Fock (RHF) and density functional theory (DFT) using 6-31 + G(d,p) basis set. The calculated harmonic vibrational frequencies for Topiramate are compared with the experimental values of FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analysed using natural bond orbital (NBO) analysis. The first-order hyperpolarizability (βtot) and other related properties such as dipole moment(µ), polarizability(αo)values of the investigated molecule are computed using HF and DFT/B3LYP with 6-31 + G(d,p) basis set. The calculated results also show that the Topiramate molecule may have microscopic nonlinear optical (NLO) behaviour.

Identifying Brazilwood’s Marker Component, Urolithin C, in Historical Textiles by Surface-Enhanced Raman Spectroscopy

The fugitive nature of the colorants obtained from sappanwood (Caesalpinia sappan L.) or the South American species commonly known as ‘brazilwoods’ (including other Caesalpinia species and Paubrasilia echinata (Lam.)) makes the identification of brazilwood dyes and pigments in historic artefacts analytically challenging. This difficulty has been somewhat alleviated recently by the recognition and structural elucidation of a relatively stable marker component found in certain brazilwood dyes and pigments—the benzochromenone metabolite urolithin C. This new understanding creates an ideal opportunity to explore the possibilities for urolithin C’s localization and identification in historical artefacts using a variety of analytical approaches. Specifically, in this work, micro-destructive surface-enhanced Raman spectroscopic methods following a one-sample two-step (direct application of the colloid and then subsequent exposure of the same sample to HF before reapplication of the colloid) approach are utilized for the examination of four historical brazilwood dyed textiles with the results confirmed via HPLC-DAD analysis. It is shown that characterization of reference urolithin C is possible, and diagnostic features of this molecule can also be traced in faded historical linen, silk and wool textiles, even in the presence of minor quantities of flavonoid, indigoid and tannin components. The exploitation of the same micro-sample through a series of SERS analyses affords a fuller potential for confirming the characterization of this species.

Synthesis, spectroscopic investigation and computational study of 3-(1-(((methoxycarbonyl)oxy)imino)ethyl)-2H-chromen-2-one

The molecular structure and vibrational modes of 3-acetylcoumarin oxime carbonate (abbreviated as 3-ACOC) have been investigated by FT-IR, FT-Raman, NMR spectra and also by computational methods using HF and B3LYP with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths, bond angles and dihedral angles) were in good agreement with the corresponding experimental values of 3-ACOC. The calculated vibrational frequencies of normal modes from DFT method matched well with the experimental values. The complete assignments were made on the basis of the total energy distribution (TED) of the vibrational modes. NMR ((1)H and (13)C) chemical shifts were calculated by GIAO method and the results were compared with the experimental values. The other parameters like dipole moment, polarizability, first order hyperpolarizability, zero-point vibrational energy, E(HOMO), E(LUMO), heat capacity and entropy have also been computed.