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

Schiff bases and their metal complexes with biologically compatible metal ions; biological importance, recent trends and future hopes

Schiff bases are in the field of medicinal and material chemistry for a long time. There are several advancements from time to time towards facile synthesis and potential applications. As medicines they have been applied as organic molecules as well as their metal complexes. The activities of metal complexes have been found to increase due to increase lipophilicity in comparison to the corresponding free ligand. Besides simple coordination compounds they have been applied as ionic liquid (IL)- supported and IL-tagged species with far enhanced efficiency. Among metal complexes recent advancement deals with photodynamic therapy to treat a number of tumors with fewer side effects. Schiff bases are efficient ligands and their complexes with almost all metal ions are reported. This mini-review article deals with complexes of Schiff bases with biologically compatible metal ions, Co(II), Cu(II), Zn(II), Pd(II), Ag(I), Pt(II) and their potential uses to combat cancerous cells. Strong hopes are associated with photodynamic therapy and IL-tagged and IL-supported Schiff bases and their complexes.

Spectroscopic Identification of Hydrogen Bond Vibrations and Quasi-Isostructural Polymorphism in N-Salicylideneaniline

The ortho-hydroxy aryl Schiff base 2-[(E)-(phenylimino)methyl]phenol and its deutero-derivative have been studied by the inelastic incoherent neutron scattering (IINS), infrared (IR) and Raman experimental methods, as well as by Density Functional Theory (DFT) and Density-Functional Perturbation Theory (DFPT) simulations. The assignments of vibrational modes within the 3500–50 cm⁻¹ spectral region made it possible to state that the strong hydrogen bond in the studied compound can be classified as the so-called quasi-aromatic bond. The isotopic substitution supplemented by the results of DFT calculations allowed us to identify vibrational bands associated with all five major hydrogen bond vibrations. Quasi-isostructural polymorphism of 2-[(E)-(phenylimino)methyl]phenol (SA) and 2-[(E)-(phenyl-D₅-imino)methyl]phenol (SA-C₆D₅) has been studied by powder X-ray diffraction in the 20–320 K temperature range.

The Relationship between the Structure and Properties of Amino Acid Ionic Liquids

Ionic liquids based on different l-amino acids (glycine, l-valine, l-leucine, l-isoleucine, l-histidine, l-methionine, l-tyrosine, l-tryptophan, l-arginine, and l-threonine) and different cations (tetrabutylammonium (TBA), tributylmethylammonium (tBMA), didecyldimethylammonium (DDA), (2-hydroxyethyl)trimethylammonium (choline) (Chol), alkyl(C₁₂-C₁₄) dimethylbenzylammonium (benzalkonium) (BA), dodecyltrimethylammonium (DDTMA), hexadecyltrimethylammonium (HDTMA), octadecyltrimethylammonium (ODTMA) and 1-ethyl-3-methylimidazolium (EMIM)) have been synthesized and characterized by NMR and FTIR. Viscosity, specific rotation, surface activity, thermal stability (TG), and phase transformations (DSC) have been determined and compared with available data. Furthermore, benzalkonium, didecyldimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, and octadecyltrimethylammonium amino acid ionic liquids have been shown to exhibit surface activity. The dissolution of cellulose in amino acid ionic liquids (AAILs) composed of various cations was also investigated. Cellulose was only dissolved in EMIM salts of amino acids. In particular, the influence of the cation type on selected physicochemical and spectroscopic properties were discussed. The article is a mini review on amino acid ionic liquids.

Novel and effective strategy of dual bis(trifluoromethylsulfonyl)imide imidazolium ionic liquid immobilized on periodic mesoporous organosilica for greener cycloaddition of carbon dioxide to epoxides

Novel periodic mesoporous organosilica supported ionic liquids were prepared, characterized and evaluated as catalysts for cycloaddition of CO₂ to epoxides.

Chemical and structural changes of pretreated empty fruit bunch (EFB) in ionic liquid-cellulase compatible system for fermentability to bioethanol

The pretreatment of empty fruit bunch (EFB) was conducted using an integrated system of IL and cellulases (IL-E), with simultaneous fermentation in one vessel. The cellulase mixture (PKC-Cel) was derived from Trichoderma reesei by solid-state fermentation. Choline acetate [Cho]OAc was utilized for the pretreatment due to its biocompatibility and biodegradability. The treated EFB and its hydrolysate were characterized by the Fourier transform infrared spectroscopy, scanning electron microscopy, and chemical analysis. The results showed that there were significant structural changes in EFB after the treatment in IL-E system. The sugar yield after enzymatic hydrolysis by the PKC-Cel was increased from 0.058 g/g of EFB in the crude sample (untreated) to 0.283 and 0.62 ± 06 g/g in IL-E system after 24 and 48 h of treatment, respectively. The EFB hydrolysate showed the eligibility for ethanol production without any supplements where ethanol yield was 0.275 g ethanol/g EFB in the presence of the IL, while lower yield obtained without IL-pretreatment. Moreover, it was demonstrated that furfural and phenolic compounds were not at the level of suppressing the fermentation process.

Benzalkonium Salts of Amino Acids – Physicochemical Properties and Anti-Microbial Activity

New salts combining a benzalkonium cation and chiral amino acid anions were synthesized and characterized. The identification was performed by NMR spectroscopy. Properties such as temperature of phase transformation, specific rotation, thermal stability and surface activity and antimicrobial activity were determined and compared with that of benzalkonium chloride. Benzalkonium amino acids salts can be used as conditioners in cosmetics. It has been shown they have weak impact on symbiotic microorganisms which occupy a wide range of skin, and this confirms that they do not disturb the biological balance of human skin.