Effect of N-Methylation on Dopamine Surface Chemistry.

Dopamine (DA) surface chemistry has received significant attention because of its applicability in a wide range of research fields and the ability to graft functional molecules onto numerous solid surfaces. Various DA derivatives have been newly synthesized to identify key factors affecting the coating efficiency and to advance the coating system development. The oxidation of catechol into quinone followed by internal cyclization via the nucleophilic attack of primary amine is crucial for DA-based surface coating. Thus, it is expected that the amine group's nucleophilicity control directly affects the coating efficiency. However, it has not been systematically investigated, and most studies have been conducted with the focus on the transformation of amines into amides, despite such approaches decreasing the coating efficiency; the nitrogen in amides is less nucleophilic than that in free amines. In this study, we investigated the effect of N-alkylation on dopamine surface chemistry. N,N-Dimethyldopamine (DMDA) was newly synthesized, and the coating efficiency was systematically compared with DA and N-methyldopamine (MDA). DA N-monomethylation improved the coating rate by increasing the nitrogen nucleophilicity, whereas N,N-dimethylation dramatically decreased the DA surface coating property. In addition, MDA remained capable of universal surface coating and secondary reactions using the surface catechols. This study provides opportunities for developing coating materials with advanced functions and an improved coating rate.

TEMPO-radical-bearing metal-organic frameworks and covalent organic frameworks for catalytic applications.

It is known that 2,2,6,6-tetramethylpiperidinyl-1-oxy (or TEMPO) is a stable, radical-containing molecule, which has been utilized in various areas of organic synthesis, catalysis, polymer chemistry, electrochemical reactions, and materials chemistry. Its unique stability, attributable to its structural features, and molecular tunability allows for the modification of various materials, including the heterogenization of solid materials. Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are porous and tunable because of their ligand or linker portion, and both have been extensively studied for use in catalytic applications. Therefore, synergistically combining the chemistry of TEMPO with the properties of MOFs and COFs is a natural choice and should allow for significant advancements, including improved recyclability and selectivity. This article focuses on TEMPO-bearing MOFs and COFs for use in catalytic applications. In addition, recent strategies related to the use of these functional porous materials in catalytic reactions are also discussed.

Physicochemical characteristics of fat blend from hydrogenated coconut oil and acyl migrated palm mid-fraction.

Palm mid-fraction (PMF), which has a high content of symmetric POP, was converted to asymmetric PPO (APMF) via acyl migration. After solvent fractionation, the liquid phase of acyl migrated PMF (APMF-L) was obtained and blended with hydrogenated coconut oil (HCO, 50:50, w/w) to produce a fat blend (namely, an alternative fat blend) which had reduced saturated fatty acid content while having similar melting behavior to HCO. In an alternative fat blend, the major fatty acids were lauric (27.94), palmitic (26.93) and oleic (15.75 mol%) acid. The solid fat index was quite similar to that of HCO, especially at 28-44 °C. Nevertheless, an alternative fat blend had lower saturated fatty acid content, by 18%, compared to HCO. The content of highly atherogenic myristic acid was reduced by approximately 40%. The alternative fat blend in this study could be used as a raw material for non-dairy cream with low saturated fat content.

Effects of cooking methods on the ß-carotene levels of selected plant food materials.

In the present study, the ß-carotene contents of 14 plant food materials prepared by boiling, steaming, or baking or when they are raw were analyzed and compared. After boiling three pulse species, namely, peas, kidney beans, and dried mung beans, ß-carotene contents of peas and kidney beans increased significantly, whereas that of mung beans (dried material) decreased. True retention factors of ß-carotene contents in the cooked kidney beans, peas, and mung beans after boiling were 174.2, 128.3, and 91.8%, respectively. After steaming, the ß-carotene content of regular millets significantly decreased but that of taros increased, in which the true retention factors were observed with ß-carotene contents of 72.4% in the steamed regular millets and 160.9% in the steamed taros. Moreover, ß-carotene contents in yellow-fleshed sweet potato (raw: 896.2 µg/100 g) decreased by baking (786.4 µg/100 g) and steaming (steaming: 553.1 µg/100 g). These results suggest that ß-carotene contents in the selected plant food materials markedly depend on the cooking method and plant food materials classification.