Synergistic DFT and temperature-dependent Raman profiling of fluorinated mesogens

The temperature-dependent Raman spectra of 4'-butyl-4-(butylphenyl) ethynyl)-2,6-difluoro-1,1'-biphenyl, a nematic fluorinated liquid crystal substance, are thoroughly examined in this article. It has been observed that Raman spectroscopy is a crucial method for examining spectral properties and vibrational dynamics. For the theoretical analysis of Raman spectra, this study also uses density functional theory (DFT), with all DFT computations carried out using the Gaussian 09 program. There is significant agreement between the experimentally acquired Raman spectra and the theoretical Raman spectra produced by DFT. This agreement makes it easier to identify distinct functional groups, validate different spectral peaks, and clarify the numerous stretching bonds that have been seen. To further understand how these peaks behave under various thermal settings, the line width, peak position, and integral intensity of various Raman peaks at various temperatures have been examined. Peaks linked to C-C bands show less intensity in the experimental Raman spectra than in the compound's DFT-generated spectra. Near the phase transition temperatures of 45 °C and 95 °C, the line widths and peak intensities of the Raman peaks exhibit abrupt changes. Specifically, at ~ 45 °C and ~ 95 °C, there is a notable change in Raman peak and integral intensities observed. For instance, at 50 °C, the above-mentioned peaks (1075 cm⁻¹ and 1099 cm⁻¹) merge and shift at 1106 cm⁻¹. This pronounced behavior indicates a disturbance in molecular ordering within the compound as temperature increases, peak positions shift, supporting the vibrational properties of the compound. Additionally, polarizing optical microscopy (POM) structures corroborate the changes in structural properties near the phase transition temperatures, thereby reinforcing the correlation between structural and vibrational properties. The fluorinated LC compound's precise Raman spectra improve our knowledge of vibrational dynamics and molecular interactions, which is crucial for the creation of new optoelectronic devices and display technologies.