Study of mesomorphism behavior and protonation-induced emission of symmetrical benzalazines

•New rod-like and polycatenar benzalazines were synthesized and characterized.•Benzalazines without 2-OH showed thermally reversible protonation-induced emission.•Emission capacity of AIEgens was investigated within the liquid crystalline phase.•Compounds showed emission in solution and solid state...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of molecular structure Vol. 1312; p. 138571
Main Authors:	Lopes, Bruno Galdino, de Araújo, Lidiane Gomes, Soares, Rafael Gomes, Lima-Junior, Claudio Gabriel, Vaz, Boniek Gontijo, Santos, Gabriel Franco dos, Will, Sabrina Felippe, Westphal, Eduard, Bechtold, Ivan H., Stadtlober, Carlos H., Eccher, Juliana, Cristiano, Rodrigo
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 15-09-2024
Subjects:	Aggregation-induced emission AIE Benzalazines Liquid crystals Protonation-induced emission SmC phase Benzalazines SmC phase Aggregation-induced emission AIE Liquid crystals Protonation-induced emission
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	•New rod-like and polycatenar benzalazines were synthesized and characterized.•Benzalazines without 2-OH showed thermally reversible protonation-induced emission.•Emission capacity of AIEgens was investigated within the liquid crystalline phase.•Compounds showed emission in solution and solid state after contact with HCl. Rod-shaped and polycatenar symmetric benzalazines with protonation-induced emission were synthesized, characterized, and studied for their thermal and optical behavior. Benzalazines lacking hydroxy groups at the ortho position did not show luminescence in the solid state or solution. In the presence of HCl (either in solution or vapor form) these compounds became good emitters. The protonation of azine nitrogen that may hinder the NN bond rotation by intermolecular interactions toward aggregates provided an explanation for the emission characteristics observed. The protonation-induced emission was thermally reversible. A benzalazine derived from 4-alkoxysalicylaldehyde with AIE property was prepared. For this compound with ortho-OH groups, the optical properties were not affected by the presence of acidic media. It exhibited a stable SmC phase characterized by POM, DSC, and XRD. The luminescence capability of the molecular arrangement within the smectic phase was investigated. The intense yellow-green emission in the crystals decreased significantly at the phase transition due to the non-radiative decay that occurs with increasing temperature, and loss of intermolecular H-bonding which prevents molecular rotations in the crystal. [Display omitted]
ISSN:	0022-2860 1872-8014
DOI:	10.1016/j.molstruc.2024.138571