Synthesis and Spectral Studies of Some Homo Dinuclear Lanthanide(III) Complexes of a Mesogenic Schiff Base.

Prem Kumar Shrestha,Pawan Raj Shakya

doi:10.17344/acsi.2021.6887

Prem Kumar Shrestha, Pawan Raj Shakya

Open Access

https://doi.org/10.17344/acsi.2021.6887

Copy DOI

Abstract

A mesogenic Schiff base, N,N'-di(4-decyloxysalicylidene)-1',8'-diamino-3',6'-dioxaoctane (H2L) and a series of homo dinuclear lanthanide(III) complexes of the type [Ln2(LH2)3(NO3)4](NO3)2, (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) were synthesized and characterized by elemental analysis, mass spectrometry, FTIR, and NMR spectral techniques. The IR and NMR spectral evidences imply bonding of a neutral bidentate H2L species through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron - possibly distorted mono-capped octahedron. Differential scanning calorimetry (DSC) and polarizing optical microscopic (POM) studies reveal mesogenic properties (smectic-X, smectic-A and nematic mesophases) in the ligand over a wide range of temperature but none mesomorphism in the LnIII complexes synthesized under this study. Luminescence studies exhibit emissions of H2L and TbIII complex.

Highlights

Lanthanide(III) complexes have received much attention due to their potential scientific applications in design of various luminescent metallomesogens,[1,2] chemosensors,[1,3] and photoluminescence materials and devices.[4]
Differential scanning calorimetry (DSC) and polarizing optical microscopic (POM) studies reveal mesogenic properties in the ligand over a wide range of temperature but none mesomorphism in the LnIII complexes synthesized under this study
Lanthanide(III) complexes with high coordination number may be obtained by choice of nitrate as the counter-ion because it can coordinate in a bi-dentate fashion

Summary

Introduction

Lanthanide(III) complexes have received much attention due to their potential scientific applications in design of various luminescent metallomesogens,[1,2] chemosensors,[1,3] and photoluminescence materials and devices.[4]. Lanthanide(III) complexes with high coordination number may be obtained by choice of nitrate as the counter-ion because it can coordinate in a bi-dentate fashion. In continuation of our earlier work on metallomesogens,[12,13,14,15,16,17] we report here synthesis and spectral studies of a mesogenic Schiff base (having terminal alkoxy chain next to benzene ring) and of some homo dinuclear LnIII complexes

Experimental

Results and Discussion

Conclusion