Synthesis, characterisation and liquid crystalline behaviour of some lanthanides complexes containing two azobenzene Schiff base

Abstract

Schiff base ligand N,N′-di-(4-butylsalicylidene)-1′,3′-diaminopropane [H₂L] was synthesised by the reaction of substituted azobenzene and 1,3-diaminopropane in 2:1 molar ratio. Four mononuclear lanthanide complexes of the type [Ln(H₂L)LCl] (Ln = LaIII, CeIII, SmIII and GdIII) were synthesised and characterised by ¹H,¹³C NMR, fourier transform infrared (FT-IR) spectroscopy, elemental analysis (CHNO), gas chromotography-mass, magnetic susceptibility and molar conductivity. Thermal properties of the title compounds were studied using the thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and optical polarising microscopy (OPM). The ligand and coordination compounds exhibit liquid-crystalline properties (smectic A).

Keywords:

• liquid crystals
• azobenzene Schiff base
• lanthanides mesogens
• smectic A phase

Funding

The authors would like to thank University of Putra Malaysia for physical measurements and Al-Mustansiriyah University for the financial support.