Access tetracoordinate boron-doped polycyclic aromatic hydrocarbons with aggregation-induced emission under mild conditions

The boron-doped polycyclic aromatic hydrocarbons (PAHs) have attracted ongoing attention in the field of optoelectronic materials due to their unique optical and redox properties. To investigate the effect of tetracoordinate boron in PAHs bearing N-heterocycles (indole and carbazole), a facile approach to four-coordinate boron-doped PAHs was developed, which does not require elevated temperature and pre-synthesized functionalized boron reactants. Five tetracoordinate boron-doped PAHs (NBNN-1 – NBNN-5) were synthesized with different functional groups. Two of them (NBNN-1 and NBNN-2) could further undergo oxidative coupling reactions to form fused off-plane tetracoordinate boron-doped PAHs NBNN-1f and NBNN-2f. Compared to the three-coordinate boron-doped counterparts, the UV/Vis absorption and fluorescent emission are significantly red-shift. Unlike the distinct impact of coordination number of boron on optoelectronic properties, the difference of functional groups on the boron atom has negligible impact on their optical and electrochemical properties. The compounds NBNN-1f and NBNN-2f show aggregation-induced emission.

The structure of natively iodinated bovine thyroglobulin

Thyroglobulin is a homodimeric glycoprotein that is essential for the generation of thyroid hormones in vertebrates. Upon secretion into the lumen of follicles in the thyroid gland, tyrosine residues within the protein become iodinated to produce monoiodotyrosine (MIT) and diiodotyrosine (DIT). A subset of evolutionarily conserved pairs of DIT (and MIT) residues can then engage in oxidative coupling reactions that yield either thyroxine (T4; produced from coupling of a DIT `acceptor' with a DIT `donor') or triiodothyronine (T3; produced from coupling of a DIT acceptor with an MIT donor). Although multiple iodotyrosine residues have been identified as potential donors and acceptors, the specificity and structural context of the pairings (i.e. which donor is paired with which acceptor) have remained unclear. Here, single-particle cryogenic electron microscopy (cryoEM) was used to generate a high-resolution reconstruction of bovine thyroglobulin (2.3 Å resolution in the core region and 2.6 Å overall), allowing the structural characterization of two post-reaction acceptor–donor pairs as well as tyrosine residues modified as MIT and DIT. A substantial spatial separation between donor Tyr149 and acceptor Tyr24 was observed, suggesting that for thyroxine synthesis significant peptide motion is required for coupling at the evolutionarily conserved thyroglobulin amino-terminus.

Core–shell Cu2S:NiS2@C hybrid nanostructure derived from a metal–organic framework with graphene oxide for photocatalytic synthesis of N-substituted derivatives

A series of MOF modified with GO was fabricated by a facile method and the Cu:Ni sulfide encapsulated on porous C with reduced GO (Cu2S:NiS2@C/rGO) showed superior photocatalytic activity for three kinds of C–N oxidative coupling reactions.

Oxidative cross-coupling processes inspired by the Chan–Lam reaction

This feature article describes our discovery and application of Cu-catalyzed oxidative coupling reactions of activated methylene derivatives or carboxylic acids with nucleophiles including aryl boronic esters and amines.

Vinylene-bridged donor–acceptor type porous organic polymers for enhanced photocatalysis of amine oxidative coupling reactions under visible light

Two vinylene-bridged D–A structural POPs are constructed by the electron-rich triarylamine and electron-deficient tricyanomesitylene, which exhibited highly effective photocatalytic activities for aerobic oxidative coupling of amines to imine.

Formation of Carbon-Nitrogen Bond Mediated by Hypervalent Iodine Re-agents Under Metal-free Conditions

: In the past several decades, hypervalent iodine chemistry has witnessed prosperous development as hypervalent iodine reagents have been widely used in various organic transformations. Specifically, hypervalent iodine reagents have been vastly used in various bond-forming reactions. Among these oxidative coupling reactions, the reactions involving the formation of C-N bond have been extensively explored to construct various heterocyclic skeletons and synthesize various useful building blocks. This review article is to summarize all the transformations in which carbon-nitrogen bond formation occurred by using hypervalent iodine reagents under metal-free conditions.