Mesomorphic properties of resorcinol

• There is no Crβ →→ Crα transition; Crystal α can only be obtained from melt or solution.
• The likely reason is the stabilizing role of tight H-bond network in solid phase.
• The role of H-bonds confirmed by vibrational spectra and DFT calculations.
• In DFT, 3-zeta basis with b-lyp functional performs better that 2-zeta with b3-lyp.
• The above makes a hint for resources-limited DFT calculations of like large systems.

It is believed that hydrogen bonds to a great extent determine the polymorphism of resorcinol. In order to understand this more deeply, complementary studies of ambient pressure polymorphism of high-purity resorcinol were carried out by Differential Scanning Calorimetry (DSC), Polarizing Optical Microscopy (POM) and Transmitted Light Intensity (TLI), together with X-ray diffraction. Temperature-dependent infrared spectroscopy studies of this compound involved two-dimensional analysis. The present study delivers complex insight into the evolution of the vibrational spectra upon phase transitions, covering the whole range of frequencies. New results on thermal stability and the influence of thermal history upon the phase transitions are reported. The equilibrium geometries, vibrational frequencies, and infrared intensities were additionally computed using the Density Functional Theory (DFT) with semi-empirical dispersion corrections, for hydrogen-bonded aggregates of resorcinol molecules.

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