Synthesis of pyridinium-based ionic liquids and their application to improve Candida rugosa lipase stability in a methanol-water solvent system.

This paper studied the effect of pyridinium-based ionic liquids as cosolvents in a methanol-water solvent system on the hydrolytic activity of Candida rugosa lipase. These ionic liquids were successfully synthesized using imidazolium-based ionic liquid synthesizing methods with a certain adjustment. The hydrolytic activity of Candida rugosa lipase was analyzed using 4-nitrophenol acetate (pNPA) and 4-nitrophenol palmitate (pNPP) as substrates. The addition of ionic liquids had no significant effect on the hydrolytic activity of lipase in a water solvent, and it had a greater effect in methanol. The addition of [C6Py] Br ionic liquid as a methanol cosolvent (methanol: ionic liquid, 10:5) could increase the hydrolytic activity of lipase. The use of ionic liquid as a cosolvent could increase the hydrolytic activity of lipase by about 15.61% while using pNPP as a substrate in the methanol system. A molecular dynamics study for the interaction between lipase and ionic liquids supported the experimental results. The ionic liquid using bromide as an anion provided more stability on lipase conformation. It tends to form the short-range interaction between the lipase and bromide anion.

Molecularly Imprinted Affinity Membrane: A Review.

A molecularly imprinted affinity membrane (MIAM) can perform separation with high selectivity due to its unique molecular recognition introduced from the molecular-printing technique. In this way, a MIAM is able to separate a specific or targeted molecule from a mixture. In addition, it is possible to achieve high selectivity while maintaining membrane permeability. Various methods have been developed to produce a MIAM with high selectivity and productivity, with their respective advantages and disadvantages. In this paper, the MIAM is reviewed comprehensively, from the fundamentals of the affinity membrane to its applications. First, the development of a MIAM and various preparation methods are presented. Then, applications of MIAMs in sensor, metal ion separation, and organic compound separation are discussed. The last part of the review discusses the outlook of MIAMs for future development.

Recent Developments of Liquid Chromatography Stationary Phases for Compound Separation: From Proteins to Small Organic Compounds.

Compound separation plays a key role in producing and analyzing chemical compounds. Various methods are offered to obtain high-quality separation results. Liquid chromatography is one of the most common tools used in compound separation across length scales, from larger biomacromolecules to smaller organic compounds. Liquid chromatography also allows ease of modification, the ability to combine compatible mobile and stationary phases, the ability to conduct qualitative and quantitative analyses, and the ability to concentrate samples. Notably, the main feature of a liquid chromatography setup is the stationary phase. The stationary phase directly interacts with the samples via various basic mode of interactions based on affinity, size, and electrostatic interactions. Different interactions between compounds and the stationary phase will eventually result in compound separation. Recent years have witnessed the development of stationary phases to increase binding selectivity, tunability, and reusability. To demonstrate the use of liquid chromatography across length scales of target molecules, this review discusses the recent development of stationary phases for separating macromolecule proteins and small organic compounds, such as small chiral molecules and polycyclic aromatic hydrocarbons (PAHs).

5,6-Dihydro-α-pyrones from the leaves of Cryptocarya pulchinervia (Lauraceae).

Three new 5,6-dihydro-α-pyrones derivatives, named (S)-rugulactone (1) pulchrinervialactone A (2), and pulchrinervialactone B (4), along with one known pyrone, cryptobrachytone C (3), and three known amide derivatives (5-7) have been isolated from the leaves of Cryptocarya pulchrinervia. The structures of 1-7 were elucidated based on extensive spectroscopic data and comparison with literatures. The configurations of compounds 3 and 4 were established by single crystal X-ray diffraction analysis. This is also the first report in finding (S)-rugulactone (1) as a natural product. In addition, the preliminary cytotoxic activity of the isolated compounds was evaluated against P-388 cells using the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. All the pyrones, except compound 4, were active significantly inhibiting the growth of P-388 cells, while the amides derivatives (5-7) showed moderate to weak activities. Therefore, compounds 1-3 could be potentially examined further for anticancer agents.

Revealing the Real Size of a Porphyrin Molecule with Quantum Confinement Probing via Temperature-Dependent Photoluminescence Spectroscopy.

The confinement energy of electrons in an aromatic molecule was studied by indirect and direct methods, namely, temperature-dependent photoluminescence (TDPL) spectroscopy and scanning tunneling microscopy (STM). We observed a decrease in the tetraphenylporphyrin (H2TPP) PL intensity with increasing temperature. The increase in temperature provides kinetic energy for the electrons to overcome the confinement energy barrier, making recombination via nonradiative pathways more favorable. The results of fitting the integrated TDPL intensity with a modified Arrhenius equation suggest two confinement energy values. We propose that these energy values are related to the size of the delocalized electron cloud along the plane and thickness of the H2TPP ring. These values quantitatively express an abstract form of the size of the aromatic ring system. These results are in good agreement with the topography images of single H2TPP molecules and monolayer H2TPP obtained by a direct probing method using STM. These results are also supported by the porphyrin ring orientation relative to the excited crystal face during the TDPL measurements.