Spectral manifestations of strong hydrogen bonds in seven-membered rings of pyrazolecarboxylic acid derivatives

1979 ◽  
Vol 44 (3) ◽  
pp. 781-787 ◽  
Author(s):  
Emil Svátek ◽  
Viktor Zikán ◽  
Miroslav Semonský
Keyword(s):  
Hydrogen Bonds ◽  
Ir Spectra ◽  
Frequency Shift ◽  
Bond Order ◽  
Electronic System ◽  
Uv Spectra ◽  
Carboxyl Group ◽  
Opinion Formation ◽  
Frequency Shifts ◽  
Resonance Stabilization

Strong downward frequency shifts of ν(C=O) of benzoyl or carboxyl group have been found in IR spectra of some pyrazolecarboxylic acid derivatives, and bathochromic shifts of maximum of the first band of π-π* transition have been found in their UV spectra, which can be explained by the presence of strong hydrogen bonds in seven-membered rings. Considerable frequency shift of ν(C=O) indicates lowering of order of this bond which is comparable with the bond order lowering of C=O group in six-membered conjugated chelates of the type of enolized β-diketones. In our opinion, formation of strong hydrogen bonds in seven-membered rings in pyrazolecarboxylic acids is due to the presence of the adjoining five-membered aromatic ring, which enables resonance stabilization of the whole π-electronic system in a pseudo-azulene structure.

scholarly journals DFT Study of Electronic Structure and Optical Properties of Kaolinite, Muscovite, and Montmorillonite

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 618
Author(s):  
Layla Shafei ◽  
Puja Adhikari ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Electronic Structure ◽  
Hydrogen Bonds ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Bond Order ◽  
Deep Understanding ◽  
Pharmaceutical Applications ◽  
Structure Properties

Clay mineral materials have attracted attention due to their many properties and applications. The applications of clay minerals are closely linked to their structure and composition. In this paper, we studied the electronic structure properties of kaolinite, muscovite, and montmorillonite crystals, which are classified as clay minerals, by using DFT-based ab initio packages VASP and the OLCAO. The aim of this work is to have a deep understanding of clay mineral materials, including electronic structure, bond strength, mechanical properties, and optical properties. It is worth mentioning that understanding these properties may help continually result in new and innovative clay products in several applications, such as in pharmaceutical applications using kaolinite for their potential in cancer treatment, muscovite used as insulators in electrical appliances, and engineering applications that use montmorillonite as a sealant. In addition, our results show that the role played by hydrogen bonds in O-H bonds has an impact on the hydration in these crystals. Based on calculated total bond order density, it is concluded that kaolinite is slightly more cohesive than montmorillonite, which is consistent with the calculated mechanical properties.

Preparation and Research of Polymolybdate/Polymer Composite Membrane by Electrospinning and its Photo-Catalytic Property

2013 ◽  
Vol 395-396 ◽  
pp. 415-418
Author(s):  
Zhi Ming Zhang ◽  
Ting Ting Li ◽  
Ce Liu
Keyword(s):  
Hydrogen Bond ◽  
Ir Spectra ◽  
Composite Membrane ◽  
Phosphomolybdic Acid ◽  
Uv Spectra ◽  
Polarizing Microscopy ◽  
Optimum Parameters ◽  
Anhydrous Alcohol ◽  
Cellulosic Membrane ◽  
Strong Absorption Peak

Composite cellulosic membrane of PMMA and phosphomolybdic acid was prepared by electrospinning. During the progress, the factor of electrospinning and the optimum parameters was found out within the orthogonal combination experiment program. Then the morphology of the composite cellulosic membrane was observed by polarizing microscopy. To resolve PMMA, DMF and anhydrous alcohol were used. When their ratios were 1:1, the diameter of the fibre was the most homogeneous. During the electrospinning, the concentration of PMMA was the most important factor. When the concentrations were less then 10%, there were hardly fibres on the foil. The diameter of the fibre ranged from 0.5 to 1.2 μm along with the increment of the concentration of PMMA. The addition of phosphomolybdic acid made the diameter of the fibre decrease. IR-spectra showed that phosphomolybdic acid kept its Keggin structure, and it interacted with PMMA through hydrogen bond. The composite cellulosic membrane changed its color when imposed in bright space. UV spectra represented that the composite cellulosic membrane had a strong absorption peak at 700nm.

Infrared spectra of synthetic almandine–grossular and almandine–pyrope garnet solid solutions: evidence for equivalent site behaviour

1989 ◽  
Vol 53 (370) ◽  
pp. 231-237 ◽  
Author(s):  
C. A. Geiger ◽  
B. Winkler ◽  
K. Langer
Keyword(s):  
Ir Spectra ◽  
Solid Solutions ◽  
Small Volume ◽  
Frequency Shifts ◽  
Short Range Ordering ◽  
Equivalent Site ◽  
Dodecahedral Site ◽  
Volume Of Mixing ◽  
Volumes Of Mixing ◽  
Long Range Ordering

AbstractThe infrared (IR) spectra of almandine-grossular and almandine-pyrope garnet solid solutions have been measured using the powder method. Frequency shifts of a band related to internal vibrations associated with the 8-co-ordinate dodecahedral site are nonlinear in almandine-grossular garnets and mimic the form of its molar volume of mixing curve. Almandine-pyrope solid solutions have nearly ideal molar volumes of mixing and the frequency shift of this same 8-co-ordinate site-related band is linear. The IR data support the empirically based crystal chemical model of Equivalent Site (ES) behaviour (Newton and Wood, 1980). The IR spectra give no indication of long-range ordering between Ca and Fe2+ in garnet, but thermodynamic calculations involving Ca-poor garnets might be affected by small volume or short-range ordering anomalies.

Thermo-optical switches using coated microsphere resonators

2001 ◽  
Vol 694 ◽  
Author(s):  
C. Tapalian ◽  
J.-P. Laine ◽  
P. A. Lane
Keyword(s):  
Resonant Frequency ◽  
Frequency Shift ◽  
Conjugated Polymer ◽  
Optical Switching ◽  
Optical Switches ◽  
Whispering Gallery Modes ◽  
Pump Light ◽  
Silica Microsphere ◽  
Frequency Shifts ◽  
Whispering Gallery

AbstractWe report optical switching by a silica microsphere optical resonator coated by a conjugated polymer. Microspheres were fabricated by melting the tip of an optical fiber and coated by dipping in a 1 mg/ml toluene solution of poly(2,5-dioctyloxy-1,4-phenylenevinylene) (DOO-PPV). The resonator properties were characterized by evanescently coupling 1.55 µm light propagating along a stripline-pedestal anti-resonant reflecting optical waveguide into optical whispering gallery modes (WGMs). WGM linewidths less than 2 MHz were measured, corresponding to cavity Q > 108. WGM resonant frequency shifts as large as 3.2 GHz were observed when 405 nm pump light with a power density of ~100 mW/cm2 was incident on the microsphere. The time constant of the observed frequency shifts is approximately 0.165 seconds, leading us to attribute the frequency shift to thermo-optic effects. Such a system should be capable of thermo-optically switching at speeds on the order of 10 kHz.

Hydrogen-bonding patterns in the cocrystal 2,4-diamino-6-phenyl-1,3,5-triazine–sorbic acid (1/1)

2007 ◽  
Vol 63 (11) ◽  
pp. o4450-o4451 ◽  
Author(s):  
Kaliyaperumal Thanigaimani ◽  
Packianathan Thomas Muthiah ◽  
Daniel E. Lynch
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Sorbic Acid ◽  
Carboxyl Group ◽  
Amino Group ◽  
Acid Molecule ◽  
Asymmetric Unit ◽  
Graph Set ◽  
Bonding Patterns

In the title cocrystal, C9H9N5·C6H8O2, the asymmetric unit contains one 2,4-diamino-6-phenyl-1,3,5-triazine molecule and a sorbic acid molecule. The triazine molecules are base-paired [with a graph set of R 2 2(8)] on either side via N—H...N hydrogen bonds, forming a supramolecular ribbon along the c axis. Each triazine molecule interacts with the carboxyl group of a sorbic acid molecule via N—H...O and O—H...N hydrogen bonds, generating R 2 2(8) motifs. The supramolecular ribbons are interlinked by N—H...O hydrogen bonds involving the 2-amino group of the triazine molecules and the carboxyl O atom of the sorbic acid molecule.

UV and IR Spectral Characteristics of Chloramben in Selected Environments

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 107-114 ◽  
Author(s):  
V. E. Berkheiser ◽  
J. L. Ahlrichs
Keyword(s):  
Ir Spectra ◽  
Water Content ◽  
Absorption Spectra ◽  
Spectral Characteristics ◽  
Uv Absorption ◽  
Hydration Water ◽  
Carboxyl Group ◽  
Amino Group ◽  
Acid Base ◽  
Uv Absorption Spectra

Ultraviolet (UV) absorption spectra were recorded of chloramben (3-amino-2,5-dichlorobenzoic acid) and selected relatives in solutions of different pH's. From these spectra, the Broensted acid-base properties of chloramben were deduced. Interpretations of solution spectra were applied to UV absorption spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Infrared (IR) transmittance spectra were recorded of chloramben and selected derivatives in KBr pellets and band assignments were made. Interpretations of these spectra were also applied to IR spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Both UV and IR measurements indicated that protonation of the amino group occurs and that the carboxyl group of chloramben is strongly hydrogen-bonded to the hydration water of the interlayer cations.

Spectral Investigations of the Effects of 60Co-Gamma Irradiation on Iodothyronine and Iodotyrosines

1987 ◽  
Vol 41 (1) ◽  
pp. 74-79
Author(s):  
A. Obaid ◽  
S. Basahl ◽  
A. Diefallah ◽  
R. Abu-Eittah
Keyword(s):  
Ir Spectra ◽  
Gamma Irradiation ◽  
Uv Spectra ◽  
Uv And Ir Spectra ◽  
60Co Gamma ◽  
Carbonyl Absorption

Solids of 3-iodo-, 3–5–di-iodotyrosine and 3,5-di-iodothyronine were irradiated by 60Co-gamma irradiation for a period of about twenty hours. The effects of irradiation were investigated through a study of the UV and IR spectra of irradiated samples. UV spectra showed the presence of a new band at 360 nm which was assigned to the formation of IO−. IR spectra showed a strong carbonyl absorption and the removal of the carboxylate band in the case of thyronine only. For comparison, the spectra of the studied compounds were investigated before irradiation.

Solvent Effects on the IR Spectra of N-Methylacetamide

1981 ◽  
Vol 36 (6) ◽  
pp. 763-764 ◽  
Author(s):  
J. Manzur ◽  
G. González
Keyword(s):  
Ir Spectra ◽  
Solvent Effect ◽  
Solvent Effects ◽  
Mutual Influence ◽  
Frequency Shifts ◽  
Donor And Acceptor ◽  
Two Parameters ◽  
Ir Bands

Abstract The solvent effect on the v(N-H) amide I and amide II IR bands of N-methylacetamide were investigated. The frequency shifts could be related to the solvent donor and acceptor num-bers by mean of a two parameters relationship that accounts for the mutual influence between the two interacting sites of the amide.

Structural, spectroscopic and first-principles studies of new aminocoumarin derivatives

2019 ◽  
Vol 75 (12) ◽  
pp. 1617-1627
Author(s):  
Ameni Brahmia ◽  
Riadh Marzouki ◽  
Jan Rohlicek ◽  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Visible Region ◽  
Electronic System ◽  
Crystalline Lattice ◽  
High Electron ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Molecular Ground State ◽  
Space Approach

The new aminocoumarin derivatives 3-[1-(3-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (1), 3-[1-(4-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (2), and 3-[1-(2-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (3), all C17H13NO4, were synthesized by reacting an equimolar amount of 3-acetyl-4-hydroxycoumarin and the corresponding aminophenol in absolute ethanol. Structural and spectroscopic analysis of these phases revealed that derivatives (1) and (2) are isomers of previously reported (3) [Brahmia et al. (2013). Acta Cryst. E69, o1296]. The crystal structures of meta derivative (1) and para derivative (2) were ab initio determined from powder X-ray diffraction data using the direct-space approach. Both (1) and (2) adopt the orthorhombic space group P212121. These isomers show hydrogen bonds and rich π–π stacking, together with π...H interactions, which are built by conjugated systems of coumarin and phenol rings. In the crystalline lattice, the packing of (1) and (3) are mainly stabilized through O—H...O hydrogen bonding between neighbouring coumarin molecules, while hydrogen bonds between coumarin and water molecules build the stable crystal structure of derivative (2). A big similarity in the skeletons of the IR spectra of these isomers was noticed. Derivative (2) exhibits two weak bands which were not present in the spectra of the other two derivatives, at 2370 and 2948 cm−1, which can be assigned to the O—H vibrations of the solvent (H2O) trapped in the structure of (2). These aminocoumarin derivatives display absorption maxima in the visible region, attributed to π–π delocalization involving the whole electronic system of the compounds with a considerable charge-transfer character originating from the aminophenyl ring and pointing towards the coumarin system which is characterized by a high electron-accepting character. Additionally, the isolated molecular ground-state geometries were optimized at the PBE0/TZP level and the electronic properties, molecular electrostatic potential and Hirshfeld charges were determined.

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