Room-Temperature, Deep-Red/NIR-Emissive, C 3-Symmetric (n,π-conjugated) Columnar Liquid Crystals: C 3 h -Tris(keto-hydrazone)s

Rashmi Ashwathama Nayak; Bhyranalyar Nagarajappa Veerabhadraswamy; Doddamane S Shankar Rao; Achalkumar Ammathnadu Sudhakar; Channabasaveshwar V Yelamaggad

doi:10.1021/acsomega.0c05779

Room-Temperature, Deep-Red/NIR-Emissive, C ₃-Symmetric (n,π-conjugated) Columnar Liquid Crystals: C _{3 h} -Tris(keto-hydrazone)s

ACS Omega. 2021 Jan 22;6(4):3291-3306. doi: 10.1021/acsomega.0c05779. eCollection 2021 Feb 2.

Authors

Rashmi Ashwathama Nayak¹, Bhyranalyar Nagarajappa Veerabhadraswamy¹, Doddamane S Shankar Rao¹, Achalkumar Ammathnadu Sudhakar², Channabasaveshwar V Yelamaggad¹

Affiliations

¹ Centre for Nano and Soft Matter Sciences, P.B. No. 1329, Jalahalli, Bangalore 560013, India.
² Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.

Abstract

The first examples of deep-red/near-infrared (NIR) photoluminescent, (n,π-conjugated) discotics, namely, C _3h -tris(keto-hydrazone)s, which are the tautomers of tris(azo-enol)s, have been synthesized via a facile one-step triple azo-coupling and characterized. The n,π-resonance-assisted intramolecular H-bonding, rendering planarity and shape persistence to the central core, facilitates their self-assembly into either a hexagonal columnar (Col_h) phase (p6mm lattice) or a columnar rectangular (Col_r) phase (p2mm lattice), over an extended thermal range including room temperature, fluorescing in the deep-red/NIR-I region. The low band gap with deep-red/NIR emission makes them ideal candidates for NIR-organic light-emitting diodes (OLEDs) and bioimaging.