Chiroptical Polymer Functionalized by Chiral Nanofibrillar Network

Chirality is one of the basic factors that influence a wide range of activities from chemical synthesis to tissue construction in life phenomena. Recently, researchers have attempted to use chirality as an optical signal. In animals, it is used to transmit information to insects and crustaceans, and it has also been confirmed that it promotes growth in plants. This chapter presents a new organic system that produces a chiral optical signal, that is, circularly polarized luminescence (CPL), which has been attracting attention in recent years. In particular, the chapter is focused on the generating CPL through chirality induction with the chiral self-assembling phenomenon and explaining its application as an optical film

Binding Behavior of Crystalline and Noncrystalline Phases: Evaluation of the Enthalpic and Entropic Contributions to the Separation Selectivity of Nonpolar Solutes with a Novel Chromatographic Sorbent

In this paper, we describe studies of the retention characteristics of nonpolar molecules with a novel liquidcrystalline, silica-supported, comb-shaped polymer chromatographic phase, Sil-ODA 18 . These results extend and amplify previous reports of the roles of enthalpic-and entropic-driven processes in the modulation of the selectivity of nonpolar and polar compounds in reversed-phase high-performance liquid chromatography (RP-HPLC). The investigations reveal that phase reorganization is the most important factor controlling selectivity enhancement with silica-supported, comb-shaped polymer phases as the temperature, T, of the system is varied. Moreover, these studies demonstrate that contributions from the stationary and the mobile phases can be independently fine-tuned to achieve enhanced selectivity via partition and/or adsorption binding processes. The relevant thermodynamic parameters, namely, the changes in enthalpy, entropy, and heat capacity for various nonpolar solutes with this comb-shaped polymeric sorbent, have also been determined using recently developed analytical procedures for the evaluation of nonlinear van't Hoff plots. These investigations into the thermodynamic properties of the comb-shaped polymeric sorbent in its ordered crystalline and noncrystalline states clearly delineate the differences in binding behavior compared to conventional types of monolayer n-alkylsilica sorbents and thus should facilitate wider application of this new class of reversed-phase sorbents in the separation sciences. Introduction Reversed-phase chromatography (RPC) is currently the most widely used of all of the high-performance liquid chromatographic (HPLC) modes of separations. The evaluation of the physicochemical basis of the retention mechanisms of different classes of solutes in RPC has received extensive attention, with the experimental results often interpreted in terms of the solvophobic model proposed by Horvath et al. 1,2 A central question pertaining to all RPC separations is, What drives the retention process? This question has been the subject of considerable debate and investigation since the concept of RPC was first used in 1950 as an analytical separation method by Howard and Martin. 3 Two primary RPC mechanisms can be considered, namely, the solvation/desolvation model, 1,2 whereby expulsion of solutes from a polar mobile phase dominates the free energy of transfer with nonpolar sorbents acting as receptive but passive surfaces, and the partitioning model, 4-6 where the stationary phase contributes in a much more significant way to the overall distribution process. On the basis of solvophobic considerations that encompass the solvation/desolvation model, Horvath and co-workers 1 have proposed that the interaction between the solute and the mobile phase provides the primary driving force. According to this model, retention in the high-performance modes of RPC can then be attributed to adsorption rather than partitioning processes between the solutes and the nonpolar sorbent. 1,2 In the solvation/desolvation model, the contributio

[1.1]meta-Stilbenophanes as calixarene analogs: preparation, crystal structure, and cis-trans photoisomerization

Abstract-Three isomers of [1.1]meta-stilbenophane were synthesized by the McMurry reaction of diarylmethane dialdehyde and their crystal structures and photochemical properties were investigated. X-ray crystallographic analyses of these isomers revealed that they were assigned to a trans-trans (t-t) form with a 1,3-alternate conformation, a cis-trans (c-t) form with a distorted-cone conformation, and a cis-cis (c-c) form with a 1,2-alternate conformation. A 1 H NMR study indicated that a t-t isomer could be completely transformed into a 35:65 mixture of c-t and c-c isomers by photoirradiation at 254 nm

Dioctadecyl l-glutamide-derived lipid-grafted silica as a novel organic stationary phase for RP-HPLC

Abstract Dialkyl l-glutamide-derived lipids have been found to form supramolecular assemblies and to show specific properties based on their highly ordered structures in aqueous and organic media. To use these unique properties to create molecular recognition systems, dioctadecyl l-glutamide-derived lipid-grafted porous silica particles (Sil-DSG) were newly prepared and used as a stationary phase in reversed phase liquid chromatography. Compared with conventional ODS (octadecylated silica), the Sil-DSG column showed remarkably higher selectivity for polycyclic aromatic hydrocarbons (PAHs). Especially, Sil-DSG recognized the molecular linearity and planarity of PAHs. Suspension state 1 H NMR and 13 C CP/MAS-NMR spectroscopies showed that the alkyl chains on the Sil-DSG are in gauche form and their mobility is strongly restricted at room temperature. This paper discusses higher selectivity of Sil-DSG with a carbonyl -benzene interactions

Org. Chem. Front.

The synthesis and characterization of an original π-extended cationic azahelicene is reported. The phenanthrene-fused aza[7]helicene derivative encompasses a total of ten aromatic fused rings leading to a dissymmetric yet helically folded structure, as revealed by NMR and X-ray diffraction analyses. The polyaromatic and cationic nature of the new azahelicenium makes it soluble in both organic and aqueous media, which allowed photophysical studies in solvents of different polarities. The extended chromophoric species demonstrates a broad absorption over the whole visible range and orange-red fluorescence emission. Chiral resolution of the racemate was performed subsequently, affording two optically pure and configurationally stable azahelicenium enantiomers. Multi-band circular dichroism and long-wavelength circularly polarized emission were observed, associated with remarkable absorption and luminescence dissymmetry factors, both in organic and aqueous media.Program Initiative d’Excellenc

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target