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Tunable Emissive Lanthanidomesogen Derived from a Room‐Temperature Liquid‐Crystalline Schiff‐Base Ligand
Author(s) -
Pramanik Harun A. R.,
Das Gobinda,
Bhattacharjee Chira R.,
Paul Pradip C.,
Mondal Paritosh,
Prasad S. Krishna,
Rao D. S. Shankar
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201301666
Subject(s) - schiff base , ligand (biochemistry) , materials science , liquid crystalline , base (topology) , liquid crystal , chemistry , optoelectronics , polymer chemistry , mathematics , biochemistry , receptor , mathematical analysis
A novel photoluminescent room‐temperature liquid‐crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH) 3 (NO 3 ) 3 ] (Ln=La, Pr, Sm, Gd, Tb, Dy; LH=( E )‐5‐(hexyloxy)‐2‐ [{2‐(2‐hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, 1 H and 13 C NMR, UV/Vis, and FAB‐MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Col h ) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (Col L ) phase at around 120 °C with high thermal stability. Based on XRD results, different space‐filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright‐orange light (ca. 560–644 nm) and the terbium complex emitting green light (ca. 490–622 nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine‐coordinate structure for the lanthanide complexes.