scholarly journals Vibrational Studies of Species Derived from Potent S(+) and R(-) Ecstasy Stimulant by Using Ab-initio Calculations and the SQM Approach

2020 ◽  
Vol 10 (6) ◽  
pp. 6783-6809
Keyword(s):  
Chemical Shifts ◽  
Attenuated Total Reflectance ◽  
Free Base ◽  
1H And 13C Nmr ◽  
Vibrational Assignments ◽  
Solvation Energies ◽  
Deformation Modes ◽  
Aim And Nbo ◽  
Ir Bands ◽  
Ft Raman

B3LYP/6-311++G** calculations and the scaled quantum mechanical force field (SQMFF) approach have been used to study the structures and vibrational spectra of three species derived from potent S(+) and R(-) ecstasy stimulant. The complete vibrational assignments of free base, cationic, and hydrochloride species of both enantiomeric forms of ecstasy have been reported by using the normal internal coordinates and the experimental available attenuated total reflectance ATR-IR and FT-Raman spectra. SQM calculations predicted that the three species could be present in the IR spectrum of hydrochloride species because the IR bands of medium intensity at 2794 cm-1 is assigned to the stretching C4-H15 and symmetric CH3 modes of the free base while the strong IR band at 1508 cm-1 is assigned easily to NH2 stretching mode of hydrochloride species and NH2 deformation modes of cationic species. The calculations reveal the same energy values for both enantiomers, indicating that both could exist simultaneously in the two media with similar corrected solvation energies in solution probably because the R(-) form is quickly converted to the S(+) one. Three types of charges studied in both media evidence higher effect on the N atoms belonging to N-CH3 groups of three species of S(+) form of ecstasy in both media than on the O atoms of R1 ring. The high gap value predicted for the hydrochloride species of S(+) form in solution supports the low reactivity of this species, in agreement to its higher stability evidenced in this medium by AIM and NBO calculations. The predicted Ultraviolet-visible and Electronic Circular Dichroism ecstasy (ECD) support the presence of both enantiomeric forms in solution while excellent concordance evidence the comparisons between the predicted 1H- and 13C-NMR chemical shifts for the three species of S(+) form of ecstasy with the corresponding experimental ones.

scholarly journals DFT study of species derived from the narcotic antagonist naloxone

2020 ◽  
Vol 10 (2) ◽  
pp. 5096-5116
Keyword(s):  
Force Fields ◽  
Normal Modes ◽  
Tropane Alkaloids ◽  
Solvation Energy ◽  
Basis Set ◽  
Free Base ◽  
Harmonic Force ◽  
Energy Value ◽  
Vibrational Assignments ◽  
Solvation Energies

The functional hybrid B3LYP and the 6-31G* basis set have been employed to study the theoretical structures of free base, cationic and hydrochloride species of naloxone in gas phase and in aqueous solution. The SCRF methodology and the PCM method were used to optimize the species in solution while the solvation energies were computed with the universal solvation model. The harmonic force fields of three species in the two media were computed with the SQMFF methodology and the Molvib program while the complete vibrational assignments of bands observed in the experimental available ATR and Raman spectra were performed by using the harmonic force fields and the normal internal coordinates. Therefore, the expected 129, 132 and 135 vibration normal modes for the free base, cationic and hydrochloride species of naloxone, respectively are here reported. The free base of naloxone evidence the higher solvation energy value, as compared with those reported for S(-)-promethazine, R(+)-promethazine, cyclizine, morphine, cocaine, scopolamine, heroin, and tropane alkaloids. The cationic species shows a solvation energy value (-302.45 kJ/mol) closer to observed for morphine (-309.19 kJ/mol) while the value for the hydrochloride species (-122.28 kJ/mol) is near to scopolamine value (-122.74 kJ/mol). AIM analyses show ionic characteristic of N-HCl bonds in the hydrochloride species and suggest that this species in both media is as cationic one, as supported by the positive MK charges on the N5 atoms in the hydrochloride species in both media and by the absence in the ATR spectrum of band at 2405 cm-1, associated to N5-H46 stretching mode. Moreover, frontier orbitals studies evidence that the allyl chains present in the three species of naloxone diminishing the gap values increasing their reactivities, as compared with the other species containing the N-CH3 group. The f(N-H) force constants for the hydrochloride species is lower than the corresponding in solution, a result also observed for morphine (2.73 and 4.61 mdyn Å-1), cocaine (3.23 and 4.79 mdyn Å-1) and tropane (2.70 and 4.69 mdyn Å-1) alkaloids. Comparisons between experimental infrared, Raman and ultraviolet-visible spectra with the corresponding predicted show good correlations.

scholarly journals Molecular Structure and Quantum Chemical Calculations of 2, 4-difluoroanisole

2020 ◽  
Vol 8 (4S4) ◽  
pp. 125-130
Keyword(s):  
Molecular Structure ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Vibrational Analysis ◽  
1H And 13C Nmr ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Homo Lumo ◽  
Orbital Analysis ◽  
Ft Raman

FTIR / FT-Raman spectra in the regions 4000-400 cm-1 /3500-50 cm-1 are utilized for studying the molecular vibrations of 2,4-difluoroanisole (DFA). The optimized molecular structure and vibrational analysis of the DFA were estimated with the experimental as well as quantum chemical studies from ab initio and DFT calculations. The chemical shifts of 1H and 13C NMR were calculated. In addition, the thermodynamic and important electronic properties like HOMO-LUMO, NPA charge analyses have been examined. With the aid of NBO (Natural Bond Orbital) analysis, inter and intra molecular interactions are also illustrated.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

Synthesis, Conformational Analysis, Infrared, Raman and UV-Visible Spectra of Novel Schiff Bases compiled with DFT Calculations

2020 ◽  
Vol 23 (7) ◽  
pp. 568-586
Author(s):  
Samy M. Ahmed ◽  
Ibrahim A. Shaaban ◽  
Elsayed H. El-Mossalamy ◽  
Tarek A. Mohamed
Keyword(s):  
Schiff Bases ◽  
1H Nmr ◽  
Electronic Absorption Spectra ◽  
Chemical Shifts ◽  
Basis Set ◽  
Oh Groups ◽  
Vibrational Assignments ◽  
Cartesian Coordinate ◽  
Surface Scan ◽  
Ir And Raman

Objective: Two novel Schiff bases named, 2-((2-Hydroxybenzylidene)amino)-4,5,6,7- tetrahydrobenzo[b] thiophene-3-carbonitrile (BESB1) and 2-((Furan-2-ylmethylene)amino)-4,5,6, 7-tetrahydro-benzo[b]thiophene-3-carbonitrile (BESB2) were synthesized. Methods: The structures were characterized based on CHN elemental analysis, mid-infrared (400– 4000 cm-1), Raman (100-4000 cm-1), 1H NMR, mass and UV-Vis spectroscopic measurements. In addition, quantum mechanical calculations using DFT-B3LYP method at 6-31G(d) basis set were carried out for both Schiff bases. Initially, we have carried out complete geometry optimizations followed by frequency calculations for the proposed conformational isomers; BESB1 (A–E) and BESB2 (F–J) based on the orientations of both CN and OH groups against the azomethine lonepair (NLP) in addition to the 3D assumption. Results: The computational outcomes favor conformer A for BESB1 in which the C≡N and OH moieties are cis towards the NLP while conformer G is preferred for BESB2 (the C≡N/furan-O are cis/trans towards the NLP) which was found consistent with the results of relaxed potential energy surface scan. Aided by normal coordinate analysis of the Cartesian coordinate displacements, we have suggested reliable vibrational assignments for all observed IR and Raman bands. Moreover, the electronic absorption spectra for the favored conformers were predicted in DMSO solution using TD-B3LYP/6-31G(d) calculations. Similarly, the 1H NMR chemical shifts were also estimated using GIAO approach implementing PCM including solvent effects (DMSO-d6). Conclusion: Proper interpretations of the observed electronic transition, chemical shifts, IR and Raman bands were presented in this study.

Using 1H and 13C NMR chemical shifts to determine cyclic peptide conformations: a combined molecular dynamics and quantum mechanics approach

2018 ◽  
Vol 20 (20) ◽  
pp. 14003-14012 ◽  
Author(s):  
Q. Nhu N. Nguyen ◽  
Joshua Schwochert ◽  
Dean J. Tantillo ◽  
R. Scott Lokey
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Cyclic Peptide ◽  
Chemical Shifts ◽  
Low Energy ◽  
Functional Prediction ◽  
1H And 13C Nmr ◽  
New Approach ◽  
Solution Structures ◽  
Peptide Conformations

Conformational analysis from NMR and density-functional prediction of low-energy ensembles (CANDLE), a new approach for determining solution structures.

scholarly journals The quantitative infrared and NIR spectrum of CH<sub>2</sub>I<sub>2</sub> vapor: vibrational assignments and potential for atmospheric monitoring

2006 ◽  
Vol 6 (1) ◽  
pp. 1275-1299
Author(s):  
T. J. Johnson ◽  
T. Masiello ◽  
S. W. Sharpe
Keyword(s):  
Gas Phase ◽  
Near Infrared ◽  
Point Group ◽  
Aerosol Formation ◽  
Atmospheric Monitoring ◽  
Vibrational Assignments ◽  
Quantitative Absorption ◽  
First Time ◽  
Phase Spectra ◽  
Ft Raman

Abstract. Diiodomethane (CH2I2) photolysis in the presence of ozone is a suggested precursor to new particle aerosol formation, particularly in coastal areas. As part of the PNNL database of gas-phase infrared spectra, the quantitative absorption spectrum of CH2I2 has been acquired at 0.1 cm−1 resolution. Two strong b2 symmetry A-type bands at 584 and 1114 cm−1 are observed, but are not resolved at 760 Torr and appear as B-type. In contrast, the b1 symmetry C-type bands near 5953, 4426 and 3073 cm−1 are resolved with rotational structure, including Q-branches with widths ≤1 cm−1. The quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm−1) are reported for the first time and discussed in terms of atmospheric monitoring. FT-Raman spectra and ab initio calculations are used to complete vibrational assignments in the C2v point group.

scholarly journals Structural and spectroscopic characterization and DFT studies of 2-amino-1,10-phenanthrolin-1-ium chloride

2019 ◽  
Vol 10 (2) ◽  
pp. 95-101
Author(s):  
Sebile Işık Büyükekşi ◽  
Namık Özdemir ◽  
Abdurrahman Şengül
Keyword(s):  
Density Functional Theory ◽  
Electronic Absorption ◽  
13C Nmr ◽  
Density Functional ◽  
Electronic Absorption Spectra ◽  
Chemical Shifts ◽  
Atomic Orbital ◽  
Basis Set ◽  
Functional Theory ◽  
1H And 13C Nmr

A versatile synthetic building block, 2-amino-1,10-phenanthrolin-1-ium chloride (L∙HCl) was synthesized and characterized by IR, 1H and 13C NMR DEPT analysis, UV/Vis and single-crystal X-ray diffraction technique. The molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO), 1H and 13C NMR chemical shifts values of the title compound in the ground state were obtained by using density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set and compared with the experimental data. Electronic absorption spectrum of the salt was determined using the time-dependent density functional theory (TD-DFT) method at the same level. In the NMR and electronic absorption spectra calculations, the effect of solvent on the theoretical parameters was included using the default model with DMSO as solvent. The obtained theoretical parameters agree well with the experimental findings.

Curing of wood treated with vinyl acetate-epoxidized linseed oil copolymer (VAc-ELO)

Holzforschung ◽  
2016 ◽  
Vol 70 (4) ◽  
pp. 305-312 ◽  
Author(s):  
Shengzhen Cai ◽  
Mohamed Jebrane ◽  
Nasko Terziev
Keyword(s):  
Vinyl Acetate ◽  
Linseed Oil ◽  
Curing Temperature ◽  
Attenuated Total Reflectance ◽  
Linear Relationships ◽  
Reflectance Ftir ◽  
New Formulation ◽  
Time Linear ◽  
Ir Bands ◽  
Epoxidized Linseed Oil

Abstract Scots pine sapwood was treated with a new formulation consisting of vinyl acetate (VAc) and epoxidized linseed oil (ELO) catalyzed by potassium persulfate to impart protection to wood. The effects of various curing temperatures, durations, and solution uptakes on dimensional stability (DS) and leachability were studied. The new formulation provided good anti-swelling efficiency (ASE) ranging from 35% to 47% with negligible leaching of the treating agent after four cycles of water soaking and oven drying (2%–2.5%). The extent of polymerization in wood was observed by FTIR-attenuated total reflectance (FTIR-ATR) by evaluation of the areas below typical IR bands as a function of curing temperature and time. Linear relationships were found with high R2 values. The FTIR data of extracted samples were interpreted that chemical reactions took place between the resulting copolymer and wood components.

Preparation, 1H and 13C NMR, and ab initio/IGLO study of mono-O-protonated deltic acid and theoretical investigation of di-, tri-, and tetra-O-protonated deltic acids

1999 ◽  
Vol 77 (5-6) ◽  
pp. 525-529 ◽  
Author(s):  
GK Surya Prakash ◽  
Golam Rasul ◽  
George A Olah ◽  
Ronghua Liu ◽  
Thomas T Tidwell
Keyword(s):  
Nmr Spectroscopy ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
13C Nmr ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Molar Solution ◽  
Protonated Species ◽  
C Nmr

The hitherto elusive mono-O-protonated deltic acid C3O3H3+ was prepared by protolysis of di-tert-butoxy deltate in FSO3H-SO2ClF and in FSO3H:SbF5 (Magic Acid; 1:1 molar solution) in SO2ClF as solvent at -78°C and was characterized by 1H and 13C NMR spectroscopy. The structure and NMR chemical shifts were also calculated by the ab initio/IGLO method. No NMR evidence was found for persistent di-O-protonated deltic acid under these conditions, although a limited equilibrium with the mono-O-protonated species can be involved. Di-, tri-, and tetra-O-protonated deltic acids were also studied by ab initio/IGLO method.Key words: protonated deltic acid, aromaticity, superacids, NMR spectroscopy, ab initio and IGLO calculations.

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