A new diamine containing disiloxane moiety and some derived Schiff bases: synthesis, structural characterisation and antimicrobial activity

Abstract

A new siloxane diamine, 1,3-bis(amino-phenylene-ester-methylene)tetramethyldisiloxane (1), was obtained by a two-step procedure and used to prepare a series of Schiff bases (2–5), by reaction with different carbonylic compounds: salicylaldehyde, 3,5-dibromosalicylaldehyde, 5-chlorosalicylaldehyde and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. All compounds, separated in crystalline form, were characterised by spectral (FTIR, UV–vis and NMR) analysis as well as by single-crystal X-ray diffraction. In these structures, different packing motifs occur depending on the different association degree determined by intra- and intermolecular π–π stacking interactions. Antimicrobial activity of the compounds was evaluated against three fungi and two bacteria, where the Schiff bases derived from salicylaldehyde and in special 5-chlorosalicylaldehyde showed remarkable activity.

Keywords:

• Schiff base
• amine
• siloxane
• supramolecular structure
• self-assembling

Acknowledgements

This research was financially supported by European Regional Development Fund, Sectoral Operational Programme ‘Increase of Economic Competitiveness’, Priority Axis 2 (SOP IEC-A2-O2.1.2-2009-2, ID 570, COD SMIS-CSNR: 12473, Contract 129/2010-POLISILMET).