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Active pharmaceutical ingredients (APIs) in the form of crystalline solid are commonly produced in drug manufacturing industries. However, crystalline solid APIs have a low solubility and the ability to cause polymorphism transformation. In order to overcome these problems, a modification of APIs in the form of protic ionic liquids (PILs) has been proposed. In the present study, a series of five ferulate-based PILs were successfully synthesised and characterised by appropriate spectral analysis. The antioxidant activity of synthesised PILs was determined through the 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) free radical scavenging assays. The spectroscopy analysis confirmed the formation of PILs supported by the Density Function Theory (DFT) calculation. The synthesised ferulate-based PILs exhibited low EC50 ranging from 12.93 ± 0.05 to 17.40 ± 0.04 μM indicating a strong antioxidant activity compared to parent acid (EC50 of 21.40 ± 0.05 μM). Prediction of antioxidant activity of the PILs and their ionic interactions at the molecular level were studied by applying DFT calculation at B3-LYP/6-311G*** level and COSMO-RS. Based on the optimised geometry, the ion-pair of PILs formed a strong directional intermolecular hydrogen bond between the –NH group of the cation with the –COOH group of the anion with interaction energy of −111 to −120 kcal mol−1. Predicted antioxidant activity indicated that the PILs's cation has a weak interaction with an anion as observed from the σ-potential analysis.

Molecular dynamics (MD) simulations were performed to study the structures and properties of a deep eutectic solvent (DES) synthesised from tetrabutylammonium bromide (TBAB) paired with ethylene glycol (EG). Measurements were performed at different mol ratios of TBAB:EG (1:2 to 1:6) and temperatures (303 to 333 K). Upon validation, MD simulations of DES’s density confirmed results to be in good agreement with previously validated experimental density (Maximum Deviation = 3.91%). The effects of different ratios and temperatures on radial distribution function (RDF), spatial distribution function (SDF), hydrogen bonding, mean square displacement (MSD) and self-diffusion coefficient of the TBAB:EG system were investigated. From RDF analysis, it was observed that Br− moved further away from TBA+ and formed a hydrogen bond with the hydroxyl group (OH) on EG at the closest distance of 0.270 nm. The self-diffusion coefficient of TBA+, Br− and EG increased proportionately to EG. High numbers of hydrogen bonds were observed at a high EG ratio as more intermolecular bondings between EG-Br were established. Hence, the introduction of EG molecules significantly affected ionic interaction within the resulting DES and changed its properties. Experimental data from infrared (IR) spectra and NMR were used to show a correlation between the formation of hydrogen-bonded EG-Br as observed in RDF. Increasing temperatures also altered the RDF, MSD and hydrogen bonding properties of the DES. Meanwhile, the main factor determining ionic movement was found to be the presence of TBA, as the ability of its cation’s long alkyl side chain to form clustering ions dictated the behaviour of the liquid. Therefore, the changes in ratios and temperatures in DESs are essential in predicting their properties and subsequently, in ascertaining the industrial applicability of a particular DES. The presented results showed that the studied DES can be used for many applications and suit the requirement for DNA technology, especially for DNA solvating medium.

The properties of DNA in ionic liquids (ILs) have been well studied. However, it is not widely known about the quantitative analysis of ILs such as the binding profile, which could offer a detailed insight of their binding characteristic. In this study, the binding energy of alkylimidazolium-based ILs ([Cnbim]Br where n = 2, 4 and 6) to calf thymus DNA was determined using fluorescence spectroscopy. It was found that the binding constant increased while the values of binding Gibbs energy decreased linearly with increase of alkyl chain length of the ILs. Based on these data, the contribution of each methylene group in the tail of ILs in IL-DNA complex was determined. Moreover, low quenching constant was observed from the competitive displacement of intercalation of ethidium bromide to DNA, hence confirming that ILs are not intercalator. The length of alkyl chain contributed to the increase in the thermal stability of DNA as observed from UV–visible spectra while the CD results indicated that DNA retained its B-form without significant change in the conformation of its base pairs. The findings show that although the stability of DNA is mainly due to the electrostatic attraction between cationic head charge group of imidazolium cation and the DNA phosphate groups, the contribution from the length of alkyl chains also plays a significant role in IL-DNA complex.

Sulfur containing compounds (SCC) in fuel oil is now becoming a worldwide concern as it released sulfur dioxide, a toxic molecule which give detrimental impact towards human and environment. To encounter this, production of ultra-low sulfur fuel oil that fulfil Euro V standard (

Solvation free energy of H2S in five cholinium-based amino acid ILs was computed using Bennet Acceptance Ratio (BAR) method under molecular dynamics (MD) simulation. From the predicted free energy, degree of removal of acid gases in liquids system can be measured and quantified by looking at excess chemical potential (μex) and Henry's law constant (kH). In order to obtain accurate value of predicted free energy, the optimised potential for liquid simulation (OPLS) force field used was validated against experimental density. The predicted density of five cholinium-based amino acid ILs showed a great agreement with the experimental results showing percentage error of

Deep eutectic solvent (DES) is an alternative solvent which has the basic characteristics as conventional ionic liquid. The uniqueness lies on its easy synthesis, less toxic and low-cost production. Three glycol-based DES (ethylene glycol, tetraethylene glycol and poly (ethylene glycol)) with tetrabutylammonium chloride (TBAC) as the hydrogen bond acceptor were successfully prepared. Unusually, all DES was achieved their eutectic mixing as low as 50 °C within 60 min. Thermal analysis study revealed that the most stable DES was the one with higher ethoxy chains. Structure elucidation study via Fourier transformation infrared (FTIR) spectroscopy confirmed the formation of eutectic mixture based on the intermolecular interaction from decreasing hydroxy group stretching frequency. Modifying ethoxy repeating unit in hydrogen bond donor could tailor the design of DES for numerous applications.

A mono- and di-substituted ionic liquid-β-cyclodextrin (β-CD-ILs) were synthesized and their host-guest inclusion complex with 2, 4-dichlorophenol (2,4-DCP) were evaluated by electrochemical study. First, both β-CD-ILs which is β-CD-1-BIMOTs and β-CD-2-BIMOTs were fabricated on carbon paste electrode (CPE) for determination of 2,4-DCP. The cyclic voltammetry results indicate that both β-CD-IL/CPEs exhibit higher oxidation peak current compared to native β-CD/CPE. Both complexes possess high sensitivity, stability and reproducibility. However, as the degree of substitution of ionic liquid (IL) increases, the selectivity of β-CD-IL towards 2,4-DCP decreases. Thus, it can be deduced that the degree of substitution of IL is influencing the host-guest inclusion complex of β-CD-ILs with 2,4-DCP.