Synthetic fentanyls evaluation and characterization by infrared spectroscopy employing in silico methods
TL;DR: In this article, the authors applied factorial design to decide the best conditions to perform quantum calculations to obtain the infrared spectra of 46 seized nonpharmaceutical fentanyls (NPFs) and used multivariate classification to establish the main spectral characteristics of these substances.
About: This article is published in Computational and Theoretical Chemistry.The article was published on 2021-10-01. It has received 2 citations till now.
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TL;DR: The crystal structure of the fentanyl base (C22H28N2O) is monoclinic, P21/n as discussed by the authors, and the unit cell dimensions at 293 K are a = 5.69263(10)A, b = 25.1851(5), c = 13.8608(3), β = 104.2037(7)°.
Abstract: The crystal structure of the fentanyl base (C22H28N2O) is monoclinic, P21/n. The unit-cell dimensions at 293 K are a = 5.69263(10)A, b = 25.1851(5)A, c = 13.8608(3)A, β = 104.2037(7)°. The R value is R = 0.0626 for 2208 reflections. The piperidine ring has a near-ideal chair conformation. In the packing, the intermolecular T-shaped π/π interactions were observed.
9 citations
TL;DR: In this paper, the effects of nucleobase tautomeric form and base pair hydrogen-bonding patterns were studied using IR spectroscopy of the nucleobases in the gas phase.
Abstract: IR spectroscopy of nucleobases in the gas phase reflects simultaneous advances in both experimental and computational techniques. Important properties, such as excited state dynamics, depend in subtle ways on structure variations, which can be followed by their infrared signatures. Isomer specific spectroscopy is a particularly powerful tool for studying the effects of nucleobase tautomeric form and base pair hydrogen-bonding patterns.
9 citations
16 May 2018
TL;DR: In this paper, the authors discuss three spectral calculations (UV-Vis, IR and NMR) that are the most widely used, and they employ time-dependent density functional theory (TDDFT) with B3LYP/631G(d,p) and CAM-B3lyP functional method to illustrate the characteristics of vertical electronic excitations.
Abstract: Spectra calculations are an important branch of theoretical modeling, and due to the significant improvements of high-level computational methods, the calculated spectra can be used directly and sometimes help to correct the errors of experimental observations. On the other hand, theoretical computations assist the experimental assignments. The authors discuss three spectral calculations (UV-Vis, IR and NMR) that are the most widely used. UV-Visible spectrum can be carried out employing time-dependent density functional theory (TDDFT) with B3LYP/631G(d,p) and CAM-B3LYP functional method to illustrate the characteristics of vertical electronic excitations. The vibrational spectra can be generated from a list of frequencies and intensities using a Gaussian broadening function method. NMR chemical shifts can be calculated by density functional theory individual gauge for localized orbitals (DFTIGLO) method and by gauge including atomic orbitals (GIAO) approach.
9 citations
TL;DR: A new correlation method is reported that is robust to spectral intensity variations and adaptively determines meaningful spectral regions for the identification target using the peak distribution of a given spectrum.
Abstract: The recognition capability of the identification system using Raman spectroscopy is increasing with the demands in the field. Among the various approaches that determine the identity of a target, s...
8 citations
TL;DR: In this paper, the use of molecular docking of the complexes between fentanyl analogues and the receptor model based on crystal structure of the μ-opioid receptor (5C1M) is described.
Abstract: Fentanyl is a synthetic opioid analgesic used as a pain reliever and an anaesthetic. Minor differences in the substituent on the N-phenylethyl or the N-phenylpropanamide groups may be a contributing factor in reducing or increasing the affinity of its derivatives. Recently, the Drug Enforcement Administration officially identified illicitly manufactured fentanyl as a threat. In this paper the use of molecular docking of the complexes between fentanyl analogues and the receptor model based on crystal structure of the μ-opioid receptor (5C1M) is described. The Fragment Molecular Orbital method (FMO) reveals an insight into the chemical nature of the ligand–receptor interaction. The ionic-electrostatic contacts between N–H and Asp147 (TM3) and those between His54 and the N-phenethyl group of ligand have stabilized interactions, while Lys233 (TM5) and Lys303 (TM6) have destabilized contacts. Furthermore, the predominant electrostatic term correlates with the total interaction energy. Correlations between the dispersion and exchange as well as the charge transfer and dispersion terms indicate that they can be used as descriptors to design ligand–receptor interactions of analogous derivatives.
8 citations