Iron(III) metallomesogen of [N₂O₂] donor Schiff base ligand containing 4-substituted alkoxy chains

ABSTRACT

Two new square pyramidal iron(III)-complexes of ‘salen’-type Schiff base ligands containing 4-substituted long alkoxy arms on the aromatic rings, [Fe(4-C₁₆H₃₃O)₂salcn)]Cl and [Fe(4-C₁₆H₃₃O)₂salophen)]Cl {salcn = N,Nʹ-cyclohexanebis(salicylideneiminato) and salophen = N,Nʹ-phenylenebis(salicylideneiminato)}, have been successfully synthesised, and their mesomorphic property investigated. The ligands and complexes were characterised by elemental analyses, UV–Vis, FT-IR, ESI–MS, ¹H and ¹³C NMR (for ligands only). The phase behaviour of the iron(III) complexes were ascertained by differential scanning calorimetry, polarising optical microscopy and variable temperature PXRD study. Ligands are non-mesomorphic, however, mesomorphism got induced upon complexation with the iron(III) centre. X-ray diffraction study revealed a layer-like arrangement of the five coordinated mesomorphic iron(III) complexes. The mesophase is stable over a wide range of temperature. The density functional theory calculations were carried out using Gaussian 09 program at B3LYP level using unrestricted 6–31G (d, p) basis set to obtain the optimised geometry of the iron(III) complexes.

Graphical Abstract

KEYWORDS:

• Iron(III)
• metallomesogen
• Schiff base
• density functional theory

Acknowledgements

Authors gratefully acknowledge the instrumental facility provided under UGC-SAP and DST-FIST programme, New Delhi. HARP is thankful to the Council of Scientific and Industrial Research (CSIR), New Delhi for research fellowship (No. 09/747(0006)/2011-EMR-I). Sophisticated Analytical Instrumentation Facility, North-Eastern Hill University, Shillong is acknowledged for some spectral results.

Disclosure statement

No potential conflict of interest was reported by the authors.

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