Computational Vibrational Spectroscopy of Hydrophilic Drug Irinotecan (original) (raw)
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In the present study, a molecular dynamics study of irinotecan molecule with the atom-centered density matrix propagation scheme was carried out at AM1 semiempirical level of theory, at series of different temperatures, ranging from 5 K to 300 K. Molecular dynamics simulations were performed within the NVE ensemble, initially injecting (and redistributing among the nuclei) various amounts of nuclear kinetic energies to achieve the desired target temperatures. Subsequently to initial equilibration phase of 2 ps, productive simulations were carried out for 8 ps. The accuracy of simulations and the closeness of the generated trajectory to those at the Born-Oppenheimer surface were carefully followed and analyzed. To compute the temperature-dependent rovibrational density of states spectra, the velocity-velocity autocorrelation functions were computed and Fourier-transformed. Fourier-transformed dipole moment autocorrelation functions were, on the other hand, used to calculate the temperature-dependent infrared absorption cross section spectra. The finite-temperature spectra were compared to those computed by a static approach, i.e. by diagonalization of mass-weighted Hessian matrices at the minima located on the potential energy surfaces. Thermally-induced spectral changes were analyzed and discussed. The advantages of finite-temperature statistical physics simulations based on semiempirical Hamiltonian over the static semiempirical ones in the case of complex, physiologically active molecular systems relevant to intermolecular interactions between drugs and drug carriers were pointed out and discussed.
Molecular structure and vibrational spectra of Irinotecan: A density functional theoretical study
The solid phase FTIR and FT-Raman spectra of Irinotecan have been recorded in the regions 400–4000 and 50–4000 cm1, respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d) as basis set. The vibrational frequencies were calculated for Irinotecan by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared spectrum was also simulated from the calculated intensities. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.
INTERNATIONAL CONFERENCE ON ADVANCES IN MATERIALS, COMPUTING AND COMMUNICATION TECHNOLOGIES: (ICAMCCT 2021), 2022
Vibrational spectral investigation and DFT computation have been performed on the anticancer drug 1-(ptoluenesulfonyl) imidazole (1PTSI). The structural parameters, intermolecular interactions and vibrational wavenumbers of the title molecule have been analysed with the help of B3LYP method. A detailed interpretation of the IR and Raman spectra of 1PTSI have been reported and analyzed. Vibrational modes of the title compound have been done on the basis of the potential energy distribution (TED) using VEDA software. The molecular electrostatic potential mapped onto total density surface has been obtained.The possible intramolecular interactions such as ICT, hyperconjucative interactions have been exposed by natural bond orbital analysis. The analysis of HOMO and LUMO gives an idea of the delocalization. The energy gap between HOMO and LUMO is found to be low and indicates electron transport in the molecule and thereby bioactivity. Effective docking of the drug molecule with different protein also enhances its bioactive nature.
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Mid-, far-infrared, and Raman vibrational spectra of Ibuprofen [2-(4-isobutylphenyl) propionic] acid, Naproxen [6-methoxy-a-methyl-2naphthalene acetic] acid and Tolmetin [1-methyl-5-(4-methylbenzoyl)-1H-pyrrole-2-acetic] acid have been measured at room and low temperatures and analyzed by means of ab initio calculations. The conformational space of these compounds has been scanned using molecular dynamics and complemented with functional density calculations that optimize the geometry of the lowest-energy conformers of each species as obtained in the simulations. The vibrational frequencies were assigned using functional density calculations. The Molecular Electrostatic Potential Maps were obtained and analyzed and the corresponding topological study was performed in the Bader's theory (atoms in molecules) framework.
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N-(3-chloro-4fluoro-phenyl-7-methoxy-6-(3-morpholin-4ylpropoxy)-quinazolin-4-amine (GEF), a quinalizoline derivative used as new anti-cancer agent, designed to target activity of epidermal growth factor receptor (EGFR) promoting the growth, division and spread of cancer cells, was examined from the vibrational and theoretical point of view. All calculations have been carried out both in gaseous and aqueous phases. In the calculations of both phases, the molecule has been optimized through conformer analysis beginning with the x-ray data. The conformer analyses have been carried out in each phases and the geometrical differences between the most stable structures in gaseous and in aqueous phases have been discussed. The solvent effect for GEF in aqueous solution was simulated by using selfconsistent reaction field (SCRF) calculations employing the integral equation formalism variant (IEFPCM) model. NBO analysis has been performed to indicate the presence of intramolecular charge transfer. The complete assignments of the vibrational spectra (IR&Raman) were made with the aid of calculated spectra both in gaseous and aqueous phases. The observed spectral data of the title compound were compared with the calculated spectra obtained by DFT/B3LYP and DFT/B3PW91 methods using 6-31G(d,p) basis set. The theoretical results were found to be in good agreement with the measured experimental data especially for the interpretation of intra molecular interactions.
IJERT-Scaled quantum chemical calculations and ft ir ft raman spectral analysis of 4 hydroxy
International Journal of Engineering Research and Technology (IJERT), 2012
https://www.ijert.org/scaled-quantum-chemical-calculations-and-ft-ir-ft-raman-spectral-analysis-of-4-hydroxy-3-nitrocoumarin https://www.ijert.org/research/scaled-quantum-chemical-calculations-and-ft-ir-ft-raman-spectral-analysis-of-4-hydroxy-3-nitrocoumarin-IJERTV1IS7364.pdf FT-IR and FT-Raman spectra of 4-Hydroxy-3-Nitrocoumarin have been recorded in the range of 4000-400 cm-1 and 4000-10 cm-1 respectively. A detailed vibrational analysis have been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions, relative intensities, fundamentals, overtones and combination bands. With the hope of providing more and effective information on the fundamental vibrations, Density Functional Theory (DFT)-Beck3-Lee-Yang-Parr(B3LYP) levels with 6-31G* basis set have been employed in quantum chemical analysis and normal coordinate analysis has been performed on 4-Hydroxy-3-Nitrocoumarin, by assuming Cs point group symmetry. The computational wavenumbers are in good agreement with the observed results. The theoretical spectra obtained agree well with the observed spectra.