DFT Study of Structure, IR and RAMAN Spectra for Betulinic Acid Solvatomorphs

Combined experimental and theoretical studies on molecular structure of the betulinic acid solvatomorph of ethanol, 2-butanol and isopropyl alcohol solvents, grown by recrystallization method, are reported. Theoretical investigations, in the frame of DFT, are done using the new method of the betulinic acid solvatomorph molecule extraction from the corresponding molecular crystal, based on typical fragmentation scheme and chemical connectivity. For all electrons, a localized basis set of Gaussian type functions TZVP and local gradient corrected functional BP86 were used. Good correlation was found between the calculated and experimental data. Slight differences in the lattice modes spectral range (0-200 cm-1) from experimental Raman spectra suggest slight differences in the crystalline network and highlight the powerful Raman approach in evidencing BA pseudo-polymorphs or solvatomorphs. Data obtained suggest that incorporated solvents to the solvates generaly induced changes in crystal symmetry, intermolecular arrangements, stoichiometry and hydrogen bonding interactions of the analysed solvatomorphs.

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C2: An Asymmetric Specie ?

10.26434/chemrxiv.11913669.v1 ◽

2020 ◽

Author(s):

Robson de Farias

Keyword(s):

Chemical Bond ◽

Raman Spectra ◽

Density Functional ◽

Functional Approach ◽

Ir And Raman Spectra ◽

Basis Set ◽

Ir And Raman

The present work is another contribution to a better understanding of the chemical bond in C2. Several density functional approach/basis set provided calculated IR and Raman spectra with simultaneous active bands. Hence, the hypothesis of electronic asymmetry in C2 [1] was reinforced.

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Illumination- and Annealing-Induced Changes in the Infrared and Raman Spectra of a-Si:H

MRS Proceedings ◽

10.1557/proc-664-a14.3 ◽

2001 ◽

Vol 664 ◽

Cited By ~ 3

Author(s):

L.-F. Arsenault ◽

S. Lebiba ◽

E. Sacher ◽

A. Yelon

Keyword(s):

Raman Spectrum ◽

Raman Spectra ◽

Qualitative Agreement ◽

Raman Signal ◽

Infrared And Raman Spectra ◽

Matrix Elements ◽

Short Term ◽

Phonon Peak ◽

Induced Changes ◽

Ir And Raman

ABSTRACTWe have investigated the changes, produced by light-soaking, in both the IR and Raman responses of the Si-Hn stretching peaks in the 2000-2100 cm−1 range. Our observations of the IR response are in qualitative agreement with those of Kong and co-workers [1]: that is, short-term light soaking produces an increase in the intensity of the signal and a simultaneous shift to lower frequency. In contrast, short-term light soaking decreases the total intensity of the Raman signal in the 2000-2100 cm−1 range, when normalized to the TO phonon peak at about 480 cm−1. In both cases, these modifications are reversed on annealing at 200° C. We suggest that these changes are attributable to alterations in the environments of the Si-Hn bonds, with the resultant transfer of intensity between IR and Raman matrix elements. Details of the evolution of the components of the Raman spectrum in the 2000-2100 cm−1 range are presented, and compared with IR changes in the same range.

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C2: An Asymmetric Specie ?

10.26434/chemrxiv.11913669 ◽

2020 ◽

Author(s):

Robson de Farias

Keyword(s):

Chemical Bond ◽

Raman Spectra ◽

Density Functional ◽

Functional Approach ◽

Ir And Raman Spectra ◽

Basis Set ◽

Ir And Raman

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Infrared and Raman Spectra of and Isotopomers: A DFT-PT2 Anharmonic Study

Journal of Chemistry ◽

10.1155/2013/741472 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Andrea Alparone

Keyword(s):

Raman Spectra ◽

Density Functional ◽

Basis Set ◽

Functional Theory ◽

B3lyp Method ◽

Cyclic Molecules ◽

Out Of Plane ◽

Stretching Vibration ◽

Ir And Raman ◽

Vibrational Wavenumbers

IR and Raman spectra of selenophene and of its perdeuterated isotopomer have been obtained in gas phase through density-functional theory (DFT) computations. Vibrational wavenumbers have been calculated using harmonic and anharmonic second-order perturbation theory (PT2) procedures with the B3LYP method and the 6-311 basis set. Anharmonic overtones have been determined by means of the PT2 method. The introduction of anharmonic terms decreases the harmonic wavenumbers, giving a significantly better agreement with the experimental data. The most significant anharmonic effects occur for the C–H and C–D stretching modes, the observed H/D isotopic wavenumber redshifts being satisfactorily reproduced by the PT2 computations within 6–20 cm−1(1–3%). In the spectral region between 500 cm−1and 1500 cm−1, the IR spectra are dominated by the out-of-plane C–H (C–D) bending transition, whereas the Raman spectra are mainly characterized by a strong peak mainly attributed to the C=C + C–C bonds stretching vibration with the contribution of the in-plane C–H (C–D) bending deformation. The current results confirm that the PT2 approach combined with the B3LYP/6-311 level of calculation is a satisfactory choice for predicting vibrational spectra of cyclic molecules.

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Nitrogen substitutional defects in silicon. A quantum mechanical investigation of the structural, electronic and vibrational properties

Physical Chemistry Chemical Physics ◽

10.1039/c9cp03185e ◽

2019 ◽

Vol 21 (37) ◽

pp. 20939-20950 ◽

Cited By ~ 3

Author(s):

Alexander Platonenko ◽

Francesco Silvio Gentile ◽

Fabien Pascale ◽

Anna Maria Ferrari ◽

Maddalena D’Amore ◽

...

Keyword(s):

Raman Spectra ◽

Ir And Raman Spectra ◽

Basis Set ◽

Quantum Mechanical ◽

Vibrational Properties ◽

Bulk Silicon ◽

Mechanical Investigation ◽

Crystal Code ◽

Substitutional Defects ◽

Ir And Raman

The vibrational Infrared (IR) and Raman spectra of seven substitutional defects in bulk silicon are computed, by using the quantum mechanical CRYSTAL code, the supercell scheme, an all electron Gaussian type basis set and the B3LYP functional.

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Submicron Simultaneous IR and Raman Spectroscopy (IR+Raman): Breakthrough Developments in Optical Photothermal IR (O-PTIR) Combined for Enhanced Failure Analysis

ISTFA 2019: Conference Proceedings from the 45th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2019p0292 ◽

2019 ◽

Author(s):

Jay Anderson ◽

Mustafa Kansiz ◽

Michael Lo ◽

Curtis Marcott

Keyword(s):

Raman Spectroscopy ◽

Failure Analysis ◽

Data Quality ◽

Raman Spectra ◽

Spatial Resolution ◽

Far Field ◽

Field Mode ◽

Microscopic Scale ◽

Analytical Tools ◽

Ir And Raman

Abstract Failure analysis of organics at the microscopic scale is an increasingly important requirement, with traditional analytical tools such as FTIR and Raman microscopy, having significant limitations in either spatial resolution or data quality. We introduce here a new method of obtaining Infrared microspectroscopic information, at the submicron level in reflection (far-field) mode, called Optical-Photothermal Infrared (O-PTIR) spectroscopy, that can also generate simultaneous Raman spectra, from the same spot, at the same time and with the same spatial resolution. This novel combination of these two correlative techniques can be considered to be complimentary and confirmatory, in which the IR confirms the Raman result and vice-versa, to yield more accurate and therefore more confident organic unknowns analysis.

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

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200127161207 ◽

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.

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Molecular structure analysis of ascending aorta aneurysm upon atherosclerosis

European Heart Journal ◽

10.1093/ehjci/ehaa946.3798 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

I Mamarelis ◽

V Mamareli ◽

M Kyriakidou ◽

O Tanis ◽

C Mamareli ◽

...

Keyword(s):

Molecular Structure ◽

Raman Spectra ◽

Molecular Level ◽

Ascending Aorta ◽

Ir And Raman Spectra ◽

Aggregate Formation ◽

Aorta Aneurysm ◽

Ft Ir ◽

Molecular Structure Analysis ◽

Ir And Raman

Abstract Background The atherosclerotic ascending aorta could represent a potential source of emboli or could be an indicator of atherosclerosis in general with high mortality. The mechanism of aneurysm formation and atherosclerosis of the ascending aorta at the molecular level has not yet been clarified. To approach the mechanism of ascending aortic lesions and mineralization at a molecular level, we used the non-destructive FT-IR, Raman spectroscopy, SEM and Hypermicroscope. Methods Six ascending aorta biopsies were obtained from patients who underwent aortic valve replacement (AVR) cardiac surgery. CytoViva (einst inc) hyperspectral microscope was used to obtain the images of ascending aorta. The samples were dissolved in hexane on a microscope glass plate. The FT-IR and Raman spectra were recorded with Nicolet 6700 thermoshintific and micro-Raman Reinshaw (785nm, 145 mwatt), respectively. The architecture of ascending aorta biopsies was obtained by using scanning electron microscope (SEM of Fei Co) without any coating. Results FT-IR and Raman spectra showed changes arising from the increasing of lipophilic environment and aggregate formation (Fig. 1). The band at 1744 cm–1 is attributed to aldehyde CHO mode due to oxidation of lipids. The shifts of the bands of the amide I and amide II bands to lower are associated with protein damage, in agreement with SEM data. The bands at about 1170–1000 cm–1 resulted from the C-O-C of advanced glycation products as result of connecting tissues fragmentations and polymerization. The spectroscopic data were analogous with the lesions observed with SEM and hypermicroscopic images. Conclusions The present innovate molecular structure analysis showed that upon ascending aorta aneurysm development an excess of lipophilic aggregate formation and protein lesions, changing the elasticity of the aorta's wall. The released Ca2+ interacted mostly with carbonate-terminal of cellular protein chains accelerated the ascending aorta calcifications. Figure 1. FT-IR and Raman spectra Funding Acknowledgement Type of funding source: None

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Synthesis and Characterization of Tris(trimethyltin) Thiophosphate (Me3Sn)3PO3S

Zeitschrift für Naturforschung B ◽

10.1515/znb-1993-1214 ◽

1993 ◽

Vol 48 (12) ◽

pp. 1781-1783 ◽

Cited By ~ 2

Author(s):

Abdel-Fattah Shihada

Keyword(s):

Aqueous Medium ◽

Raman Spectra ◽

Mass Spectra ◽

Ir And Raman Spectra ◽

Synthesis And Characterization ◽

Polymeric Structure ◽

Ir And Raman

(Me3Sn)3PO3S has been prepared from the reaction of Me3SnCl with Na3PO3S • 12 H2O under cooling in aqueous medium. Its IR and Raman spectra are found to be consistent with a polymeric structure with tetra- and penta-coordinated tin atoms. The 31P NMR and mass spectra of (Me3Sn)3PO3S are reported and discussed.

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