Experimental and computational (DFT) methods: exploration of thermochromism in homophthalic acid and 4-N-alkyloxybenzoic acid comprised hydrogen bond liquid crystals

Abstract

Novel thermochromism is identified in hydrogen bond liquid crystal (HBLC) homologues series which is prepared from non-mesogenic Homophthalic acid (HPA) and mesogenic 4-n-alkyloxybenzoic acid (nOBA, n = 6 to 12). The occurrence of intermolecular interaction between HPA and nOBA, is confirmed by Fourier-transform infrared spectroscopic (FT-IR) technique and computation (DFT) methods. Thermochromic changes in nematic phase and thermo-optic properties of HPA + nOBA HBLC complex is investigated by polarizing optical microscope (POM) and differential scanning calorimetric (DSC) studies. The induced thermochromism in nematic phase which establish the possibility of temperature dependent sensor applications.

Keywords:

• DFT
• HBLC complex
• NBO
• thermochromism

Acknowledgments

One of the authors, V.N. Vijayakumar, acknowledges the financial support of the Department of Science and Technology (No. SERB/F/7454/2013-2014, dated February 21, 2014), New Delhi, and the Department of Atomic Energy (No. 34/14/14/2016-BRNS/34039, dated April 22, 2016), the Board of Research in Nuclear Science (DAE-BRNS), TNSCST/RFRS/VR/19/2018-2019/7666, dated June 6, 2019, and infrastructural support provided by the Bannari Amman Institute of Technology, Sathyamangalam.