Model Calculations on the Influence of Mechanical and Electrical Anharmonicity on Infrared Intensities: Relation to Hydrogen Bonding

1972 ◽  
Vol 50 (19) ◽  
pp. 3161-3166 ◽  
Author(s):  
Thérèse Di Paolo ◽  
C. Bourdéron ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Dipole Moment ◽  
Model Calculations ◽  
First Derivative ◽  
Infrared Intensities ◽  
Stretching Vibrations ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

The influence of mechanical and electrical anharmonicity on the intensity of X—H stretching vibrations is investigated by means of model calculations in relation to hydrogen bonding. It is found that while both kinds of anharmonicities have a significant effect on the intensity, they cannot explain the characteristic increase in intensity of the fundamental and the equally characteristic decrease in the intensity of the first overtone. It is shown that not only the first but both these phenomena are due to the large value of the first derivative of the dipole moment in hydrogen bonded systems. This is linked to the possibility that the effect of electrical anharmonicity (d2μ/dQ2) might be cancelled by a high value of (dμ/dQ)c in the expression of the overtone intensity.

CAN SEMIEMPIRICAL QUANTUM MODELS CALCULATE THE BINDING ENERGY OF HYDROGEN BONDING FOR BIOLOGICAL SYSTEMS?

2009 ◽  
Vol 08 (04) ◽  
pp. 691-711 ◽  
Author(s):  
FENG FENG ◽  
HUAN WANG ◽  
WEI-HAI FANG ◽  
JIAN-GUO YU
Keyword(s):  
Hydrogen Bonding ◽  
Amino Acid ◽  
Amino Acid Residue ◽  
Density Functional ◽  
Biological Systems ◽  
Binding Energies ◽  
Semiempirical Model ◽  
Hydrogen Bonded Systems ◽  
High Level ◽  
Hydrogen Bonded

A modified semiempirical model named RM1BH, which is based on RM1 parameterizations, is proposed to simulate varied biological hydrogen-bonded systems. The RM1BH is formulated by adding Gaussian functions to the core–core repulsion items in original RM1 formula to reproduce the binding energies of hydrogen bonding of experimental and high-level computational results. In the parameterizations of our new model, 35 base-pair dimers, 18 amino acid residue dimers, 14 dimers between a base and an amino acid residue, and 20 other multimers were included. The results performed with RM1BH were compared with experimental values and the benchmark density-functional (B3LYP/6-31G**/BSSE) and Möller–Plesset perturbation (MP2/6-31G**/BSSE) calculations on various biological hydrogen-bonded systems. It was demonstrated that RM1BH model outperforms the PM3 and RM1 models in the calculations of the binding energies of biological hydrogen-bonded systems by very close agreement with the values of both high-level calculations and experiments. These results provide insight into the ideas, methods, and views of semiempirical modifications to investigate the weak interactions of biological systems.

Photoelectron studies on intramolecularly hydrogen-bonded systems. I. The photoelectron spectra of cis- and trans-2-aminocyclopentanol, and cis- and trans-2-(N,N-dimethylamino)cyclopentanol

1976 ◽  
Vol 54 (4) ◽  
pp. 642-646 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Ionization Energy ◽  
Lone Pair ◽  
Intramolecular Hydrogen Bonding ◽  
Photoelectron Spectra ◽  
Hydrogen Bonded Systems ◽  
Intramolecular Hydrogen ◽  
Cis And Trans ◽  
Infrared Data ◽  
Hydrogen Bonded

The photoelectron spectra of cis- and trans-2-aminocyclopentanol and cis- and trans-2-(N,N,-dimethylamino)cyclopentanol have been recorded and interpreted. The cis isomers exhibit N lone pair ionizations at higher ionization energy, and O lone pair ionizations at lower ionization energy than their trans isomers.The results are most consistent with the existence and observation of intramolecular hydrogen-bonding in the cis isomers. Infrared data on these systems also show that the cis isomers exist in the intramolecularly hydrogen-bonded state.

Irᴵᴵᴵ as a Strategy for Preorganization in H-Bonded Motifs

2019 ◽  
Author(s):  
Barbora Balonova ◽  
Helena J. Shepherd ◽  
Christopher Serpell ◽  
Barry Blight
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complexes ◽  
General Formula ◽  
Self Assembly ◽  
Structural Design ◽  
Functional Materials ◽  
Soft Materials ◽  
Thiourea Derivatives ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Here we present the synthesis and characterisation of four hydrogen bonded systems based on thiourea derivatives. These motifs are considered to be stable and desirable for supramolecular hydrogen-bonded functional materials. Interpretation of the structural design of thiourea based ligand and its incorporation into metal complexes can contribute to the understanding of preorganised self-assembly and open new pathways in design of novel soft materials. This work contributes to the unexplored library of hydrogen bonded metal complexes based on iridium. Further we examined the photoluminescence of the system of general formula [Ir(C^N)<sub>2</sub>(N^S)] and the effect of hydrogen bonding on the emission properties when combined with different <i>n</i>-heteroacenes.

Hydrogen bonding and vapor pressure isotope effect of ethanethiol

1979 ◽  
Vol 57 (11) ◽  
pp. 1350-1353 ◽  
Author(s):  
Jerzy Szydlowski ◽  
Hans Wolff
Keyword(s):  
Hydrogen Bonding ◽  
Vapor Pressure ◽  
Isotope Effect ◽  
Inverse Effect ◽  
Apparent Decrease ◽  
Stretching Vibrations ◽  
Intermolecular Vibrations ◽  
Hydrogen Bonded

The vapor pressure ratios of ethanethiol and ethanethiol-d1 between 223 and 323 K can be represented by the relation[Formula: see text]The PD/PH vs. T curve increases initially and reaches a flat maximum at 293 K; at higher temperatures there is an apparent decrease. This behavior can be explained by the superposition of predominantly the normal effect of the intermolecular vibrations and the SH and SD torsion vibrations, and the inverse effect of the SH and SD stretching vibrations. Contrary to the value of 0.91 reported previously, PD/PH values of 1.002 to 1.008 confirm that for weakly hydrogen-bonded substances and their deuterium-bonded analogues a negligibly normal or a slightly inverse vapor pressure isotope effect should be observed.

Raman and infrared spectroscopic study of the vivianite-group phosphates vivianite, baricite and bobierrite

2002 ◽  
Vol 66 (6) ◽  
pp. 1063-1073 ◽  
Author(s):  
R. L. Frost ◽  
W. Martens ◽  
P. A. Williams ◽  
J. T. Kloprogge
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Water Molecules ◽  
Infrared Spectroscopic Study ◽  
Tetrahedral Symmetry ◽  
Phosphate Anions ◽  
Stretching Vibrations ◽  
Bending Modes ◽  
Ir Bands ◽  
Hydrogen Bonded

Abstract The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy. The Raman spectra of the hydroxyl-stretching region are complex with overlapping broad bands. Hydroxyl stretching vibrations are identified at 3460, 3281, 3104 and 3012 cm−1 for vivianite. The high wavenumber band is attributed to the presence of FeOH groups. This complexity is reflected in the water HOH-bending modes where a strong IR band centred around 1660 cm−1 is found. Such a band reflects the strong hydrogen bonding of the water molecules to the phosphate anions in adjacent layers. Spectra show three distinct OH-bending bands fromstrongly hydrogen-bonded, weakly hydrogen bonded water and non-hydrogen bonded water. The Raman phosphate PO-stretching region shows strong similarity between the three minerals. In the IR spectra, complexity exists with multiple antisymmetric stretching vibrations observed, due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong IR bands around 800 cm−1 are attributed to water librational modes. The spectra of the three minerals display similarities due to their compositions and crystal structures, but sufficient subtle differences exist for the spectra to be useful in distinguishing the species.

Irᴵᴵᴵ as a Strategy for Preorganization in H-Bonded Motifs

2019 ◽  
Author(s):  
Barbora Balonova ◽  
Helena J. Shepherd ◽  
Christopher Serpell ◽  
Barry Blight
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complexes ◽  
General Formula ◽  
Self Assembly ◽  
Structural Design ◽  
Functional Materials ◽  
Soft Materials ◽  
Thiourea Derivatives ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Here we present the synthesis and characterisation of four hydrogen bonded systems based on thiourea derivatives. These motifs are considered to be stable and desirable for supramolecular hydrogen-bonded functional materials. Interpretation of the structural design of thiourea based ligand and its incorporation into metal complexes can contribute to the understanding of preorganised self-assembly and open new pathways in design of novel soft materials. This work contributes to the unexplored library of hydrogen bonded metal complexes based on iridium. Further we examined the photoluminescence of the system of general formula [Ir(C^N)<sub>2</sub>(N^S)] and the effect of hydrogen bonding on the emission properties when combined with different <i>n</i>-heteroacenes.

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