scholarly journals A study of the ir spectra of the copigments of malvin chloride with organic acids

2001 ◽  
Vol 66 (7) ◽  
pp. 451-462 ◽  
Author(s):  
Jasmina Dimitric-Markovic ◽  
Ubavka Mioc ◽  
Jelisavetam Baranac ◽  
Zoran Nedic
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Thermodynamic Properties ◽  
Organic Acids ◽  
Ir Spectra ◽  
Infrared Spectra ◽  
Molecular Structures ◽  
Oxonium Ions ◽  
Hydroxy Groups ◽  
Formed Hydrogen

The infrared spectra of the copigments of malvin with several organic acids: caffeic, ferulic, sinapic, chlorogenic, and tannic, were analyzed in order to elucidate the bonding of the molecules in the copigments. It was established that copigmentation is realized through hydrogen bonding between malvin molecules and the acids under study. The infrared spectra reveal that two groups of hydrogen bonds are formed, which include interactions of different molecular structures: hydroxy groups (bands around 3500 cm-1) and oxonium ions of the molecules (bands below 3000 cm-1). The formed hydrogen bonds were found to be of different strengths. The strengths of the hydrogen bonds were tentatively correlated with thermodynamic properties of the corresponding copigmentation reactions.

scholarly journals Crystal structures of butyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate and 2-methoxyethyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate

2019 ◽  
Vol 75 (6) ◽  
pp. 880-887 ◽  
Author(s):  
Rosita Diana ◽  
Angela Tuzi ◽  
Barbara Panunzi ◽  
Antonio Carella ◽  
Ugo Caruso
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Molecular Structures ◽  
Antitumoral Activity ◽  
Space Group ◽  
One Dimensional ◽  
Axis Direction ◽  
Hydrogen Bonding Pattern ◽  
Butyl Group

The title benzofuran derivatives 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate (BF1), C19H18N2O6, and 2-methoxyethyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate (BF2), C18H16N2O7, recently attracted attention because of their promising antitumoral activity. BF1 crystallizes in the space group P\overline{1}. BF2 in the space group P21/c. The nitrophenyl group is inclined to benzofuran moiety with a dihedral angle between their mean planes of 69.2 (2)° in BF1 and 60.20 (6)° in BF2. A common feature in the molecular structures of BF1 and BF2 is the intramolecular N—H...Ocarbonyl hydrogen bond. In the crystal of BF1, the molecules are linked head-to-tail into a one-dimensional hydrogen-bonding pattern along the a-axis direction. In BF2, pairs of head-to-tail hydrogen-bonded chains of molecules along the b-axis direction are linked by O—H...Omethoxy hydrogen bonds. In BF1, the butyl group is disordered over two orientations with occupancies of 0.557 (13) and 0.443 (13).

scholarly journals The infrared spectra of protic ionic liquids: performances of different computational models to predict hydrogen bonds and conformer evolution

2020 ◽  
Vol 22 (14) ◽  
pp. 7497-7506 ◽  
Author(s):  
O. Palumbo ◽  
A. Cimini ◽  
F. Trequattrini ◽  
J.-B. Brubach ◽  
P. Roy ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Infrared Spectra ◽  
Computational Models ◽  
Far Infrared ◽  
Protic Ionic Liquids ◽  
Far Infrared Spectra

DFT calculations with the ωB97-D functional reproduce hydrogen bonding features of the far-infrared spectra of diethylmethylammonium methanesulfonate and diethylmethylammonium trifluoromethanesulfonate.

scholarly journals (3aR*,8bR*)-3a,8b-Dihydroxy-1-(4-methylphenyl)-2-methylsulfanyl-3-nitro-1,8b-dihydroindeno[1,2-b]pyrrol-4(3aH)-one

2014 ◽  
Vol 70 (3) ◽  
pp. o279-o280
Author(s):  
R. A. Nagalakshmi ◽  
J. Suresh ◽  
R. Ranjith Kumar ◽  
V. Jeyachandran ◽  
P. L. Nilantha Lakshman
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Three Dimensional ◽  
Dihedral Angles ◽  
Asymmetric Unit ◽  
Compound C ◽  
Dimensional Network ◽  
Independent Molecules ◽  
Hydroxy Groups

The asymmetric unit of the title compound, C19H16N2O5S, contains four independent molecules (A,B,CandD), with two molecules (BandD) displaying disorder in their methylsulfanyl groups [occupancy ratios of 0.797 (11):0.203 (11) and 0.85 (2):0.15 (2)]. The nitro groups are twisted slightly out of the planes of the 2-pyrroline rings to which they are bonded with dihedral angles of 10.17 (1), 8.01 (1), 9.44 (1) and 8.87 (1)° in moleculesA,B,CandD, respectively. The 2-pyrroline rings are almost orthogonal to the attached tolyl rings, forming dihedral angles of 73.44 (1), 81.21 (1), 88.18 (8) and 73.94 (1)° for moleculesA,B,CandD, respectively. A weak intramolecular O—H...O interaction is observed in moleculesBandC. The two hydroxy groups in each molecule are involved in intermolecular O—H...O hydrogen bonding. In the crystal, molecules are connectedviaO—H...O and C—H...O hydrogen bonds, forming a complex three-dimensional network.

The influence of hydrogen bonding on the character of N—H and C=O stretching modes in 2-thiopyrrole-1,2-dicarboximide

1984 ◽  
Vol 62 (9) ◽  
pp. 1845-1849 ◽  
Author(s):  
Shanker Ram
Keyword(s):  
Hydrogen Bonding ◽  
Transition Temperature ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Spectral Data ◽  
Infrared Spectra ◽  
Cyclic Dimer ◽  
Dilute Solutions ◽  
Two Phases ◽  
Thermodynamical Functions

The infrared spectra (200–4000 cm−1) of 2-thiopyrrole-1,2-dicarboximide (TPH) in solid and solution forms have been measured as a function of temperature, and a direct correlation has been obtained between the two phases and the type and extent of hydrogen bonding. It is suggested that TPH exists as cyclic dimer in the solid state (below 310 K) and in dilute solutions by the formation of two equivalent hydrogen bonds. At the transition temperature, ~310 K, the cyclic dimer undergoes to the open-cyclic dimer and persists in this structure till 410 K. In addition, the thermodynamical functions ΔH0, and ΔS0 have been estimated using the spectral data in solution.

scholarly journals Threefold helical assembly via hydroxy hydrogen bonds: the 2:1 co-crystal of bicyclo[3.3.0]octane-endo-3,endo-7-diol and bicyclo[3.3.0]octane-endo-3,exo-7-diol

2021 ◽  
Vol 77 (3) ◽  
pp. 270-276
Author(s):  
Isa Y. H. Chan ◽  
Mohan M. Bhadbhade ◽  
Roger Bishop
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydroxy Group ◽  
Network Structure ◽  
General Position ◽  
Three Dimensional ◽  
Screw Axis ◽  
Hydroxy Groups

Reduction of bicyclo[3.3.0]octane-3,7-dione yields a mixture of the endo-3,endo-7-diol and endo-3, exo-7-diol (C8H14O2) isomers (5 and 6). These form (5)2·(6) co-crystals in the monoclinic P21/n space group (with Z = 6, Z′ = 1.5) rather than undergoing separation by means of fractional recrystallization or column chromatography. The molecule of 5 occupies a general position, whereas the molecule of 6 is disordered over two orientations across a centre of symmetry with occupancies of 0.463 (2) and 0.037 (2). Individual diol hydroxy groups associate around a pseudo-threefold screw axis by means of hydrogen bonding. The second hydroxy group of each diol behaves in a similar manner, generating a three-dimensional hydrogen-bonded network structure. This hydrogen-bond connectivity is identical to that present in three known helical tubuland diol–hydroquinone co-crystals, and the new crystal structure is even more similar to two homologous aliphatic diol co-crystals.

Cluster-model DFT simulations of the infrared spectra of triazine-based molecular crystals

2018 ◽  
Vol 20 (32) ◽  
pp. 20779-20784 ◽  
Author(s):  
Xiaohong Yuan ◽  
Kun Luo ◽  
Nan Liu ◽  
Xueqiang Ji ◽  
Chao Liu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ir Spectra ◽  
Infrared Spectra ◽  
Cluster Model ◽  
Molecular Crystals ◽  
Dft Simulations ◽  
Independent Molecules ◽  
Model Approach

A cluster-model approach is developed to simulate the IR spectra of triazine-based molecular crystals, and the distinct hydrogen-bonding environments of the crystallographically independent molecules can be clearly revealed.

H2O, HDO, and CH3OH Infrared Spectra and Correlation with Solvent Basicity and Hydrogen Bonding

1971 ◽  
Vol 49 (6) ◽  
pp. 837-856 ◽  
Author(s):  
D. N. Glew ◽  
N. S. Rath
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Dibasic Acid ◽  
Tertiary Amines ◽  
Type Symmetry ◽  
Solvent Basicity ◽  
Organic Amines ◽  
Lower Frequencies ◽  
Hydrogen Bonded

A study has been made of the infrared O—H bands for CH3OH, DOH, and H2O in solution and of their correlation with hydrogen bonding and solvent basicity. Infrared bands for the three fundamentals and the first bending overtone of H2O and for the O—H stretching fundamentals of DOH and CH3OH have been measured between 30 and −40 °C in a solvent range extending from weakly interacting fluorocarbons to strongly hydrogen-bonding organic amines. The O—H stretching bands for the weakly acidic solutes CH3OH, DOH, and H2O are mostly Lorentzian in shape and move to lower frequencies with higher extinctions in the more basic solvents. Many correlations are found between the stretching frequencies and band areas, and between the frequencies and solvent basicity. Monofunctional CH3OH is found to be a stronger acid and forms stronger hydrogen-bonds with a given base than do the doubly bonded DOH and HOH which show equal dibasic acid strengths.The wide, overlapped, fundamental stretching bands for H2O strongly hydrogen-bonded to the tertiary amines and for ice have been partially resolved and unequivocally assigned, showing that there is no cross-over of the ν 3 and ν1 bands despite the strong hydrogen-bonding.At higher temperatures in solvents containing both hydrophobic and strongly basic groups water was found with the lower Cs type symmetry, in which unbonded O—H groups gave sharp bands in the 3680–3650 cm−1 region in addition to the wide hydrogen-bonded bands at lower frequencies.

scholarly journals A study of the IR spectra of copigments formed by malvin chloride with flavones

2000 ◽  
Vol 65 (4) ◽  
pp. 245-253 ◽  
Author(s):  
Ubavka Mioc ◽  
Jasmina Dimitric-Markovic ◽  
Jelisaveta Baranac
Keyword(s):  
Ir Spectroscopy ◽  
Hydrogen Bonds ◽  
Ir Spectra ◽  
Formation Mechanism ◽  
Equilibrium Constants ◽  
Formed Hydrogen

Research into the essence of the process of copigmentation of anthocyan molecules was continued by applying IR spectroscopy, in an attempt to elucidate the formation mechanism of copigment molecules between malvin chloride and several variously substituted flavones. Analysis of the IR spectra of the formed copigments revealed that the process of copigmentation is achieved via the formation of hydrogen bonds. The strength of the formed hydrogen bonds was correlated with the equilibrium constants of the processes of copigmentation of these molecules. The found correlation was in accordance with the supposed mechanism of the copigmentation reaction.

scholarly journals DNA/TNA Mesoscopic Modeling of Melting Temperatures Suggest Weaker Hydrogen Bonding of CG than in DNA/RNA

2020 ◽  
Author(s):  
Maria Izabel Muniz ◽  
Hershel Lackey ◽  
Jennifer Heemstra ◽  
Gerald Weber
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Thermodynamic Properties ◽  
Stacking Interactions ◽  
Base Pairs ◽  
Melting Temperatures ◽  
Mesoscopic Modeling ◽  
Bond Strengths ◽  
Purine Pyrimidine

TNA/DNA hybrids share several similarities to RNA/DNA, such as the tendency to form A-type helices and a strong dependency of their thermodynamic properties on purine/pyrimidine ratio. However, unlike RNA/DNA, not much is known about the base-pair properties of TNA. Here, we use a mesoscopic analysis of measured melting temperatures to obtain an estimate of hydrogen bonds and stacking interactions. Our results reveal that the AT base pairs in TNA/DNA have nearly identical hydrogen bond strengths than their counterparts in RNA/DNA, but surprisingly CG turned out to be much weaker despite similar stability.

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