Infrared Absorption Band Shape Studies: Fundamental OH Stretching Vibration of Benzyl Alcohol Conformers in Dilute Carbon Tetrachloride Solution

1973 ◽  
Vol 51 (19) ◽  
pp. 3250-3262 ◽  
Author(s):  
P. J. Krueger ◽  
B. F. Hawkins
Keyword(s):  
Molecular Conformation ◽  
Rotational Relaxation ◽  
Alcohol Molecule ◽  
Band Model ◽  
Band Shape ◽  
Benzyl Alcohols ◽  
Electronic Nature ◽  
Shape Indices ◽  
Stretching Vibration ◽  
Donor Acceptor

The fundamental OH stretching doublet in the i.r. spectra of a series of a monomeric p-X-benzyl alcohols (X = OCH3, CH3, H, Cl, NO2) observed in dilute CCl4 solution over the temperature range −5 to+40 °C is resolved into two components corresponding to different molecular conformers, using digital computing techniques and a Cauchy–Gauss sum band model. The temperature and substituent dependence of frequencies, band shape indices, and band widths are discussed in terms of intramolecular (electronic displacements and [Formula: see text] hydrogen bonds) and intermolecular ([Formula: see text] and π–σ electron donor–acceptor) interactions. The OH band shapes, which range from 60–98% Cauchy character, reflect variations in the intermolecular interactions which impede molecular re-orientation, and can be correlated with the electronic nature of X and the molecular conformation. The formation of an intramolecular [Formula: see text] hydrogen bond results in significantly slower rotational relaxation of the alcohol molecule. The enthalpy differences between the two conformers are found to be 1.52 ± 0.13, 1.57 ± 0.15, 1.53 ± 0.08, 1.06 ± 0.13, and 1.15 ± 0.11 kcal/mol for the compounds in the order stated above.

Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. II. Band shapes and widths in the absorption spectrum of gaseous CF3I-N(CH3)3

1971 ◽  
Vol 24 (12) ◽  
pp. 2493 ◽  
Author(s):  
A Mishra ◽  
ADE Pullin
Keyword(s):  
Vibrational Mode ◽  
Low Frequency ◽  
Molecular Complexes ◽  
Wave Number ◽  
Centrifugal Distortion ◽  
Band Shape ◽  
Gaseous Mixtures ◽  
Factors Affecting ◽  
Donor Acceptor ◽  
Vibration Rotation

The absorption band centred at c. 77 cm-1 in gaseous mixtures of CF3I and N(CH3)3 previously reported and attributed to the N-I stretching mode of the complex CF3I-N(CH3)3 has been carefully re-examined. This band is of interest as an example of a low frequency ?dissociative type? vibrational mode of a weak molecular complex. The band is asymmetric and apparently structureless with a half intensity width at room temperature of 28-30 cm-1. The width of the band may be accounted for as arising from transitions vi + vi+1 where vi is the vibrational quantum number of the N-I stretching mode with vi up to c. 10 making appreciable contribution to the intensity on the low wave-number side. Centrifugal distortion in the complex is considered. Centrifugal stretching and consequent weakening of the bond may shift the band envelope 2-3 cm-1 to lower wave numbers. Assessment of these and other factors affecting the band shape suggest that the fundamental frequency is probably c. 90 cm-1. The band shape of the vibrational mode of the complex at c. 272 cm-1 is briefly discussed. Many of the considerations presented in this paper should apply to vibration-rotation band shapes in other weak molecular complexes. Some general consequences of anharmonicity for the interpretation of the spectra of weak molecular complexes are discussed.

Synthesis, spectroscopic (FT–IR and UV–Vis), crystallographic and theoretical studies, and a molecular docking simulation of an imatinib-like template

2019 ◽  
Vol 75 (12) ◽  
pp. 1681-1689
Author(s):  
Rodolfo Moreno-Fuquen ◽  
Kevin Arango-Daraviña ◽  
Esteban Garcia ◽  
Juan-C. Tenorio ◽  
Javier Ellena
Keyword(s):  
Crystal Growth ◽  
Hydrogen Bonds ◽  
Docking Simulation ◽  
Myelogenous Leukemia ◽  
Amino Group ◽  
Protein Residues ◽  
Function Analyzer ◽  
Stretching Vibration ◽  
Donor Acceptor ◽  
Ft Ir

The aim of the present study was to report the crystal structure and spectroscopic, electronic, supramolecular and electrostatic properties of a new polymorph of 4-(pyridin-2-yl)pyrimidin-2-amine (C9H8N4). The compound was synthesized under microwave irradiation. The single-crystal X-ray structure analysis revealed an angle of 13.36 (8)° between the planes of the rings, as well as molecules linked by Nsp 2—H...N hydrogen bonds forming dimers along the crystal. The material was analyzed by FT–IR vibrational spectroscopy, while a computational approach was used to elucidate the vibrational frequency couplings. The existence of Nsp 2—H...N hydrogen bonds in the crystal was confirmed spectroscopically by the IR peaks from the N—H stretching vibration shifting to lower wavenumbers in the solid state relative to those in the gas phase. The supramolecular studies confirmed the formation of centrosymmetric R 2 2(8) rings, which correspond to the formation of dimers that stack parallel to the b direction. Other weak C—H...π interactions, essential for crystal growth, were found. The UV–Vis spectroscopic analysis showed a donor–acceptor process, where the amino group acts as a donor and the pyridine and pyrimidine rings act as acceptors. The reactive sites of the molecule were identified and their quantitative values were defined using the electrostatic potential model proposed in the multifunctional wave function analyzer multiwfn. The calculated interaction energies between pairs of molecules were used to visualize the electrostatic terms as the leading factors against the dispersion factors in the crystal-growth process. The docking results showed that the amino group of the pyrimidine moiety was simultaneously anchored by hydrogen-bonding interactions with the Asp427 and His407 protein residues. This compound could be key for the realization of a series of syntheses of molecules that could be used as possible inhibitors of chronic myelogenous leukemia.

Elektronentransfer und Ionenpaar-Bildung, 47 [1] Titrationen von 1,2,4,5-Tetracyanbenzol und 7,7,8,8-Tetracyan-p-chinodimethan mit Natriummetall in aprotischen Lösungen / Electron Transfer and Ion Pair Formation, 47 [ 1 ] Titrations of 1,2,4,5-Tetracyanobenzene and 7,7,8,8-Tetracyano-p-quinodimethane with Sodium Metal in Aprotic Solutions

1996 ◽  
Vol 51 (9) ◽  
pp. 1215-1221 ◽  
Author(s):  
Hans Bock ◽  
Markus Kleine
Keyword(s):  
Electron Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Transfer Reactions ◽  
The Novel ◽  
Band Shape ◽  
Novel Technique ◽  
Sodium Metal ◽  
Mndo Calculations ◽  
Donor Acceptor

In an especially designed and sealed glass apparatus, a combination of UV/VIS and ESR spectroscopy measurements are performed to follow electron transfer reactions in aprotic (cH⊕ < 0,1 ppm) solution. For the sodium metal reductions of the tetracyano-substituted title compounds, the novel technique provides the following detailed information: 1,2,4,5- tetracyanobenzene is uniformly reduced to its radical anion, for which additional geometryoptimized MNDO calculations predict an already significant cyanine disortion. For 7,7,8,8- tetracyano-p-quinodimethane, UV/VIS band shape analysis allows to detect in the saturated THF reduction solution the 16300 cm-1 absorption of the donor/acceptor complex formed in the equilibrium TCNQ·⊖ + TCNQ ⇆ {TCNQ·⊖···TCNQ}, which according to a literature search has been crystallized and structurally characterized in paramagnetic salts such as [Me2⊕ (TCNQ·⊖)2(TCNQ)].

Synthesis, crystal structure studies and solvatochromic behaviour of two 2-{5-[4-(dimethylamino)phenyl]penta-2,4-dien-1-ylidene}malononitrile derivatives

2019 ◽  
Vol 75 (8) ◽  
pp. 1175-1181 ◽  
Author(s):  
Georgii Bogdanov ◽  
John P. Tillotson ◽  
Victor N. Khrustalev ◽  
Sergei Rigin ◽  
Tatiana V. Timofeeva
Keyword(s):  
Crystal Structure ◽  
Optical Materials ◽  
Crystalline State ◽  
Molecular Conformation ◽  
Order Effects ◽  
Asymmetric Unit ◽  
Nonlinear Materials ◽  
Donor Acceptor ◽  
Independent Molecules ◽  
Potential Use

The synthesis, crystal structure studies and solvatochromic behavior of 2-{(2E,4E)-5-[4-(dimethylamino)phenyl]penta-2,4-dien-1-ylidene}malononitrile, C16H15N3 (DCV[3]), and 2-{(2E,4E,6E)-7-[4-(dimethylamino)phenyl]hepta-2,4,6-trien-1-ylidene}malononitrile, C18H17N3 (DCV[4]), are reported and discussed in comparison with their homologs having a shorter length of the π-conjugated bridge. The compounds of this series have potential use as nonlinear materials with second-order effects due to their donor–acceptor structures. However, DCV[3] and DCV[4] crystallized in the centrosymmetric space group P21/c which excludes their application as nonlinear optical materials in the crystalline state. They both crystallize with two independent molecules having the same molecular conformation in the asymmetric unit. The series DCV[1]–DCV[4] demonstrated reversed solvatochromic behavior in toluene, chloroform, and acetonitrile.

Self-reversible thermofluorochromism of D–A–D triphenylamine derivatives and the effect of molecular conformation and packing

CrystEngComm ◽  
2017 ◽  
Vol 19 (46) ◽  
pp. 6979-6985 ◽  
Author(s):  
Anu Kundu ◽  
Subramanian Karthikeyan ◽  
Dohyun Moon ◽  
Savarimuthu Philip Anthony
Keyword(s):  
Solid State ◽  
Molecular Conformation ◽  
Donor Acceptor ◽  
Solid State Fluorescence

Triphenylamine based donor–acceptor–donor compounds exhibited conformation and packing dependent solid state fluorescence and self-reversible thermofluorochromism.

Cyano-Functionalized Diarylethene Derivatives with Aggregation-Induced Emission Enhancement and Piezofluorochromic Behaviours

2019 ◽  
Vol 72 (5) ◽  
pp. 369 ◽  
Author(s):  
Ying Liu ◽  
Yuqi Cao ◽  
Xue Li ◽  
Yang Li ◽  
Bowei Wang
Keyword(s):  
Photoluminescence Spectrum ◽  
Molecular Conformation ◽  
Alkyl Chain ◽  
Weak Interactions ◽  
Bathochromic Shift ◽  
Phenothiazine Derivatives ◽  
Aggregation Induced Emission ◽  
Emission Enhancement ◽  
Fluorescent Materials ◽  
Donor Acceptor

Four donor–acceptor (D-A) type phenothiazine derivatives were designed and synthesized and all of them exhibited an aggregation-induced emission enhancement (AIEE) effect and red-shifted piezofluorochromic (PFC) behaviour. Moreover, it was found that the compound containing a shorter alkyl chain displayed more remarkable PFC properties. This result was probably ascribed to highly twisted conformations which can lead to loose solid molecular packing with cavities and weak interactions. After they were pressed, the planarization of the molecular conformation increased and molecular conjugation degree enhanced, resulting in a red-shift in the photoluminescence spectrum. In addition, optimized geometric structures indicate that the compound with a longer alkyl chain has a more planer geometric structure, which leads to a smaller bathochromic shift upon grinding. In summary, we provide a new path to regulate the PFC behaviours of fluorescent materials by changing the length of their substituted alkyl chain.

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