This study aimed to improve the conversion of E-alkenes to Z-alkenes using a recycling photoreactor. Specifically, E-alkenes bearing Weinreb amides or pinacolborane functionalities were examined, but yielded unsatisfactory results even after multiple reaction cycles using acetonitrile as the solvent. Importantly, the photoisomerization reaction proceeded in mixed solvents predominantly composed of n-hexane, a solvent commonly used in column chromatography. For Weinreb amides derived from cinnamic acid, a mixed solvent of ethanol or ethyl acetate in n-hexane accelerated the photoisomerization reaction and improved chromatographic separation by HPLC. These results indicate that the use of such mixed solvents enables the efficient production of Z-alkenes bearing Weinreb amides via photoisomerization in a recycling photoreactor. The finding that photoisomerization reactions proceed in mixed solvents containing n-hexane indicates potential for future applications in photoreactions.

Controlling indoor humidity is crucial for preventing health concerns, such as heatstroke and atopic dermatitis. Sugarcane bagasse (BG), a byproduct of sugar production primarily composed of cellulose, is a promising, sustainable, humidity-control material owing to its charcoal- and bamboo-like characteristics. This study systematically investigates the humidity-control ability of BG-derived porous carbons prepared over a wide range of calcination temperatures. BG calcined at 900°C exhibited excellent humidity-control ability (158.7 mg/g between water activity levels of 0.98 and 0.59) and retained sorbed water across a wide range of water activities. With increasing calcination temperature, the specific surface area increased, whereas the amount of acidic functional groups decreased above 300°C, indicating significant changes in the surface chemistry. Humidity-control ability was strongly correlated with specific surface area and mesopore volume. Differential heat analysis indicated that physisorption dominated in all samples, while chemisorption was present in raw BG and BG calcined at 200–700°C. Entropy analysis further suggested that BG calcined at 800–1000°C contained abundant free water and bottleneck-shaped pores, resulting in water retention over a broad range of water activities. These findings demonstrate the potential of BG calcined at 900°C as a sustainable humidity-control material for indoor environmental applications.

Unnatural base pairs (UBPs) provide a promising strategy for expanding the genetic alphabet; however, their practical application requires efficient recognition by DNA polymerases. Here, we report the polymerase-mediated incorporation of alkynylated purine–pyridazine (Pu–Pz) base pairs bearing pseudo-nucleobase recognition units positioned in the major groove. Single-nucleotide insertion assays revealed that complementary Pu–Pz pairs are selectively incorporated into DNA by KOD DNA polymerase with efficiencies comparable to those of natural base pairs. Furthermore, efficient primer extension was maintained following UBP incorporation, indicating that bulky major-groove modifications do not significantly impede polymerase processivity. These results demonstrate the polymerase compatibility of major-groove-functionalized UBPs and highlight the potential of Pu–Pz pairs as building blocks for expanded genetic systems and site-specific DNA functionalization.

Quantitative NMR (qNMR) provides a direct approach for determining the absolute purity of pharmaceutical substances. In this study, ¹⁹F- and ¹H-qNMR measurement conditions were systematically optimized and validated for three fluorinated pharmaceuticals listed in the Japanese Pharmacopoeia—fluorometholone (FM), flurbiprofen (FP), and flutamide (FT)—using interlaboratory data. Building on our prior experience with ³¹P-qNMR, careful selection of solvents and reference standards was emphasized. The aprotic solvent dimethyl sulfoxide-d₆ (DMSO-d₆) was employed to suppress proton–deuterium exchange, and the International System of Units (SI)-traceable certified reference material 3,5-bis(trifluoromethyl)benzoic acid (3,5-BTFMBA) was used as the reference standard for both ¹⁹F- and ¹H-qNMR. For ¹H-qNMR of FT, sodium 4,4-dimethyl-4-silapentanesulfonate-d₆ (DSS-d₆) was used as an alternative reference standard to avoid spectral overlap. Key qNMR parameters, including relaxation delay, spectral width, and pulse offset, were optimized. We then validated ¹⁹F-qNMR against the more established ¹H-qNMR technique across multiple laboratories (n = 6–10). The average purity values determined by ¹⁹F-qNMR were 98.79 ± 0.62% (n = 7) or 98.62 ± 0.34% (n = 6) for FM, 99.84 ± 0.40% (n = 9) for FP, and 99.84 ± 0.48% (n = 9) for FT; these values were in good agreement with those determined by ¹H-qNMR (99.23 ± 0.41% (n = 9), 100.04 ± 0.34% (n = 10), and 99.67 ± 0.38% (n = 10), respectively). Collectively, these results indicate that ¹⁹F-qNMR is a reliable and reproducible technique for absolute quantification of fluorinated pharmaceuticals, supporting its application in pharmaceutical quality control and regulatory assessment.

Orcinol synthase (RdORS) from Rhododendron dauricum is a plant type III polyketide synthase involved in the biosynthesis of orsellinic acid-derived metabolites. In contrast to the related Cannabis sativa tetraketide synthase (CsTKS), which preferentially accepts medium-chain acyl-CoAs, RdORS selectively utilizes short-chain starter substrates. Here, we investigated the structural basis underlying this substrate selectivity by combining X-ray crystallography, mutational analysis, and biochemical characterization. The crystal structure of RdORS revealed that its catalytic cavity is substantially smaller than that of CsTKS because of a bulky tryptophan (Trp) 357 residue positioned at the cavity bottom. In vitro enzymatic assays demonstrated that wild-type RdORS efficiently generated tetraketide-derived products from acetyl- and butyryl-CoAs with three malonyl-CoAs, whereas productive tetraketide formation progressively diminished as starter-substrate chain length increased. Structural analysis of the RdORS Trp357S mutant revealed marked cavity expansion without perturbation of the overall catalytic framework. Correspondingly, the Trp357S substitution enabled RdORS to utilize medium-chain acyl-CoAs up to decanoyl-CoA, thereby partially recapitulating the substrate preference of CsTKS. Thus, our results provided direct structural evidence that Trp357 is a key structural determinant underlying the distinct starter-substrate preferences of RdORS.