Contribution of hydrogen bonds to equilibrium alpha-beta transition of resorcinol

Article Abstract:

The equilibrium alpha-beta transition temperature, T-alpha-beta, between the alpha crystalline phase and the beta crystalline phase of resorcinol has been determined when both superheating and supercooling effects vanished. A precision pycnometer was used to determine the latent volume and dT-alpha-beta/dp.The higher-temperature, higher-density polymorpyh beta crystal exhibited larger values than the lower-temperature, lower-density polymorph alpha crystal in terms of the thermal expansion coefficient, isothermal compressibility and internal pressure.

Protons, Polymorphism (Crystallography)

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Change of internal hydrogen bonding of methyl red upon photoisomerization monitored by forced Rayleigh scattering

Article Abstract:

A study was conducted to analyze changes in the internal hydrogen bonding of methyl red during photoisomerization. Forced Rayleigh scattering (FRS) was utilized to carry out the analysis. Ab initio computations were then performed on the methyl red. In addition, the possible conformers of the cis and trans isomers of the methyl red were examined with and without internal hydrogen bonding. Results indicated that hydrogen bonding promotes the decay-growth-decay FRS signal of methyl red.

Polymers, Rayleigh scattering

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Quantum cluster equilibrium theory of liquids: temperature dependence of hydrogen bonding in liquid N-methylacetamide studied by IR spectra

Article Abstract:

A study was conducted to compute the temperature-dependent infrared spectra for liquid N-methylacetamide using the ab initio quantum cluster equilibrium and Gaussian-94 techniques. The computations were based on conventional ab initio self-consistent-field methods at the 3-21G levels for various molecular clusters. Results indicated the effectiveness of using quantum cluster equilibrium to study various liquid types supporting different clustering patterns.

Liquids, Spectra, Gaussian distribution, Normal distribution, Infrared spectra

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