Influence of modification of the amino acids ionic liquids on their physico-chemical properties: Ionic liquids versus ionic liquids-supported Schiff bases

Amino acid ionic liquids and amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde or benzaldehyde and various amino acids (l-valine, l-leucine, L-isoleucine, l-threonine, l-histidine, l-methionine and l-tryptophan) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR). Their physico-chemical properties (glass transition temperature (Tg), decomposition temperatures at 5% (Td5%) and 50% (Td50%) weight loss, specific rotation [α], miscibility) have been also determined and compared. The influence of the Schiff base formation and presence of the intramolecular hydrogen bond on spectral parameters, thermal stability, glass transition temperature of tetrabutylammonium salts of amino acids have been shown.