Photoredox-Catalyzed Cascade Reactions Involving Aryl Radical: Total Synthesis of (±)-Norascyronone A and (±)-Eudesmol.

Herein, we have developed two types of photoredox-catalyzed cascade reactions using diaryliodonium salts for the concise synthesis of norascyronone A and ß-eudesmol. A rationally designed photoredox-catalyzed arylation/cyclization/Friedel-Crafts cascade reaction of enone was exploited to generate the norascyronone polycyclic skeleton. A visible-light-induced radical cyclization/acyloxy-migration reaction was explored to forge the decalin skeleton of eudesmol, and mechanistic studies indicated the reaction was initiated by one-electron oxidation of the enol ester.

Single-ion anisotropy effects on the critical behaviors of quantum entanglement and correlation in the spin-1 Heisenberg chain.

Quantum entanglement and correlations in the spin-1 Heisenberg chain with single-ion anisotropy are investigated using the quantum renormalization group method. Negativity and quantum discord (QD) are calculated with various anisotropy parameters △ and single-ion anisotropy parametersD. We focus on the relations between two abovementioned physical quantities and on transitions between the Néel, Haldane, and large-Dphases. It is found that both negativity and QD exhibit step-like patterns in different phases as the size of the system increases. Interestingly, the single-ion anisotropy parameterD, which can be modulated using nuclear electric resonance (2020Nature579205), plays an important role in tuning the quantum phase transition (QPT) of the system. Both the first partial derivative of the negativity and QD with respect toDor △ exhibit nonanalytic behavior at the phase transition points, which corresponds directly to the divergence of the correlation length. The quantum correlation critical exponents derived from negativity and QD are equal, and are the reciprocal of the correlation length exponent at each critical point. This work extends the application of quantum entanglement and correlations as tools for depicting QPTs in spin-1 systems.

Enantioselective Total Syntheses of Manginoids†A and†C and Guignardones†A and†C.

An enantioselective synthetic approach for preparing manginoids and guignardones, two types of biogenetically related meroterpenoids, is reported. This bioinspired and divergent synthesis employs an oxidative 1,3-dicarbonyl radical-initiated cyclization and cyclodehydration of the common precursor to forge the central ring of the manginoids and guignardones, respectively, at a late stage. Key synthetic steps include silica-gel-promoted semipinacol rearrangement to form the 6-oxabicyclo[3.2.1]octane skeleton and the Suzuki-Miyaura reaction of vinyl bromide to achieve fragment coupling. This synthesis protocol enables the asymmetric syntheses of four fungal meroterpenoids from commercially available materials.

Inherently fluorescent polystyrene microspheres for coating, sensing and cellular imaging.

Commercially available polystyrene (PS) fluorescent microspheres are widely used in biological field for tracing, in vivo imaging and calibration of flow cytometry, among other applications. However, these particles do suffer from some drawbacks such as the leakage and photobleaching of organic dyes within them. In the present study, inherently fluorescent properties of PS based microspheres have been explored for the first time. Here we find that a simple chloromethylation reaction endows the polystyrene particles with inherent fluorescence without any subsequent conjugation of an external fluorophore. A possible mechanism for fluorescence is elucidated by synthesizing and investigating p-ethylbenzyl chloride, a compound with similar structure. Significantly, no photobleaching or leaking issues were observed owing to the stable structure of the microspheres. Chloromethylated PS (CMPS) microspheres can keep their perpetual blue fluorescence even in dry powder state making them attractive as a potential coating material. Furthermore, the chloromethyl groups on CMPS microspheres make them very convenient for further functionalization. Poly(ethylene glycol) (PEG) grafted microspheres showed good biocompatibility and negligible cytotoxicity, and could be used to image intracellular Fe3+ due to the selective fluorescence quenching effect of aqueous Fe3+ in cytoplasm.

Exactly solvable antiferromagnetic Blume-Capel model on a sawtooth chain.

The geometrically frustrated spin-1 Blume-Capel model on an infinite sawtooth chain is exactly solved by the transfer matrix method. The magnetization, ground-state phase diagram, magnetocaloric properties, and specific heat of the system are investigated. The results indicate that: (i) Magnetization plateaus appear at zero temperature. Their number depends on the sign of the crystal field D. For D≥0 there are two magnetization plateaus; however, for D<0 five plateaus exist. At a finite temperature, thermal excitation will destroy these plateaus completely. (ii) Phase transition between any two long-range-ordered ground states, whose spin configurations are given in phase diagram, is the first-order one. The macroscopic degeneracy of the ground states described by the entropy only exists at phase coexistence points. (iii) As temperature approaches zero, magnetocaloric properties and entropy change sharply near phase coexistence points. (iv) The crossovers of the specific heat from a single-peak structure to double-peak ones can signal the phase coexistence points in ground-state phase diagram.

Thermo- and pH-responsive polymer brushes-grafted gigaporous polystyrene microspheres as a high-speed protein chromatography matrix.

Dual thermo- and pH-responsive chromatography has been proposed using poly(N-isopropylacrylamide-co-butyl methacrylate-co-N,N-dimethylaminopropyl acrylamide) (P(NIPAM-co-BMA-co-DMAPAAM)) brushes grafted gigaporous polystyrene microspheres (GPM) as matrix. Atom transfer radical polymerization (ATRP) initiator was first coupled onto GPM through Friedel-Crafts acylation with 2-bromoisobutyryl bromide. The dual-responsive polymer brushes were then grafted onto GPM via surface-initiated ATRP. The surface composition, gigaporous structure, protein adsorption and dual-responsive chromatographic properties of the matrix (GPM-P(NIPAM-co-BMA-co-DMAPAAM) were characterized in detail. Results showed that GPM were successfully grafted with thermoresponsive cationic polymer brushes and that the gigaporous structure was well maintained. A column packed with GPM-P(NIPAM-co-BMA-co-DMAPAAM presented low backpressure, good permeability and appreciable thermo-responsibility. By changing pH of the mobile phase and temperature of the column in turn, the column can separate three model proteins at the mobile phase velocity up to 2528cmh(-1). A separation mechanism of this matrix was also proposed. All results indicate that the dual thermo- and pH-responsive chromatography matrix has great potentials in 'green' high-speed protein chromatography.