A series of 4-benzyl-4-methylmorpholinium salts have been synthesized producing morpholinium ionic liquids with inorganic (chloride, nitrate, tetrafluoroborate, hydrogen sulphate) and organic (formate, acetate, methoxyacetate, 2-(2-methoxyethoxy)acetate, hexanoate, octanoate, dodecyl sulphate, 2-ethylbutyrate, lactate, crotonate, maleate, salicylate, saccharinate) anions. Their physicochemical properties, cytotoxicity to the promyelocytic leukaemia rat cell line IPC-81, oral toxicity and biodegradability were determined. The anion significantly determined the state of aggregation and cytotoxicity. The results enabled 4-benzyl-4-methylmorpholinium ionic liquids to be classified as being of moderate or low toxicity (EC₅₀ between 0.15 and 14.13 mM). The acute toxicity for 4-benzyl-4-ethylmorpholinium acetate is between 300–2000 mg kg⁻¹b.w. in female rats. The activity of these morpholinium salts against bacteria and fungi was very low. It was found that new 4-benzyl-4-methylmorpholinium-based ionic liquids with anions commonly used for dissolving cellulose, such as formate or acetate, can also be used as new biomass solvents.

A new group of quaternary ammonium ionic liquids with azolate (benzotriazolate, 1,2,4-triazolate, 4-nitroimidazolate, 2-methyl-4-nitroimidazolate) anions was prepared and characterized. The synthetic method employed was easy and quick, and required a polar solvent. The obtained ionic liquids were tested as anti-microbial and anti-fungal plant protection agents. Additionally, the surface-active properties and the phytotoxicity of the quaternary ammonium azolates were also studied. These clearly defined ionic liquids were found to be very effective anti-bacterial and anti-fungal agents.

The method of synthesis of the novel bis(ammonium) herbicidal ionic liquids with the cation containing two quaternary nitrogen atoms was described. New compounds, containing three structurally different linkers, were prepared via acid–base reaction between the corresponding bis(ammonium) hydroxides and herbicides in the form of free acids. In addition, phase transitions, thermal stability and solubility in common solvents were determined. The herbicidal efficacy was tested in greenhouse experiments, wherein test plants were lambsquarters (Chenopodium album L.) cornflower (Centaurea cyanus L.), white mustard (Sinapis alba L.) and winter rape (Brassica napus L.). The biological activity of the anion (2,4-D, MCPA, Mecoprop, Dicamba) in all new HILs was preserved. Moreover, the efficacy of some salts was several times higher when compared to commercial formulations.