Oil-in-water-in-oil (O/W/O) Pickering double emulsions are stabilized by water and oil-swollen microgels. The binary microgels can efficiently reduce the interfacial tension and co-assemble on droplet surfaces. Owing to the thermal sensitivity of microgels, the destabilization of certain phases of double emulsions can be achieved by simply changing the ambient temperature.

Abstract

Microgels are excellent emulsifiers that can self-assemble to reduce interfacial tension and form a steric barrier at an oil-water interface. Herein, we report a two-step emulsification approach to prepare oil-in-water-in-oil (O/W/O) Pickering double emulsions through the dispersion of microgels in two immiscible phases. The stabilization mechanism depends on the uneven distribution and adsorption of hydrophilic water-swollen microgels and hydrophobic octanol-swollen microgels on either outer water droplets or inner oil droplets. Our results reveal that binary microgels outperformed single microgels in terms of interfacial tension reduction and emulsion stabilization. Notably, the binary microgel-stabilized Pickering double emulsions show excellent temperature responsiveness owing to the intrinsic thermal sensitivity of microgels. Consequently, the selective and rapid release of encapsulated substances in different phases can be achieved through the adjustment of the ambient temperature.

Four new rigid heterocyclic binders for each canonic base pair have been designed and synthesized. In silico, their PNA adduct allows oligomerization into PNA strands with perfect complementarity to dsDNA, without any sequence restriction.

Abstract

We present the design and synthesis of artificial specific nucleobases, each one recognizing a single base pair within the major groove of duplex DNA. Computational calculations indicate that PNAs modified with these nucleobases enable the formation of highly stable triple helices with no sequence restrictions through multiple hydrogen bonding and π⋅⋅⋅π stacking interactions, without significantly widening the DNA double helix. New synthetic routes were developed to the structures of these fused heterocycles which have rarely been described in the literature. NMR titration experiments indicate specific hydrogen bonding at the Hoogsteen sites. The new building blocks allow the construction of four PNA monomers for each canonic base pair and their covalent connection to PNA oligomers. These can be designed complementary to any given DNA sequence. With high efficiency and relative simplicity of operation, the described methodologies and strategies hence form the basis for a new supramolecular ligand system targeting double-stranded DNA without strand invasion.

Photochromic cholesteric liquid crystals (CLCs) were prepared, which could be applied for the preparation of colourful polymer-stabilized CLC (PSCLC) patterns. Based on handedness inversion, the obtained PSCLC patterns were suitably applied for anti-counterfeiting.

Abstract

Handedness inversion has been widely studied in supramolecular chemistry and material sciences. Herein, a photoisomerizable chiral dopant was synthesized, which could induce the formation of a cholesteric phase with right-handedness. The Bragg reflection band of the cholesteric liquid crystal (CLC) mixture shifted to the long wavelength with extending 365 nm UV light irradiation time. Based on this photochromic property, a colourful polymer-stabilized CLC (PSCLC) film was prepared using a grayscale mask. A handedness reversible CLC mixture was prepared using a mixture of this chiral dopant and S5011. With extending the UV light irradiation time, the handedness of the CLC mixture changed from right- to left-handedness. A patterned PSCLC film was prepared using this CLC mixture. Complementary images were observed under right- and left-handedness circularly polarized lights. The results shown here not only give us a better understanding the competition between photopolymerization and photoisomerization, but also lay the foundations for decoration and anti-counterfeiting.

Supramolecular assemblies of PBI-SAH have been developed which could detect chlorpyrifos in the nanomolar range and could also mimic AChE inhibitory activity of CPF to show promising aptitude as ‘safe insecticide’.

Abstract

Supramolecular assemblies of perylene bisimide derivative (PBI-SAH) have been developed which show ‘turn-on’ detection of chlorpyrifos in aqueous media, apple residue and blood serum. Differently from the already reported fluorescent probes for the detection of CPF, PBI-SAH assemblies also show affinity for acetylcholinesterase (AChE) which endow the PBI-SAH molecules with mixed inhibitory potential to restrict the AChE catalysed hydrolysis of acetylthiocholine (ATCh) in MG-63 cell lines (in vitro) and in mice (in vivo). The molecular docking studies support the inhibitory activity of PBI-SAH assemblies and their potential to act as safe insecticide with high benefit to harm ratio. The insecticidal potential of PBI-SAH derivative has been examined against Spodoptera litura (S. litura) and these studies demonstrate its excellent insecticidal activity (100 % mortality in nineteen days). To the best of our knowledge, this is the first report regarding development of PBI-SAH assemblies which not only detect chlorpyrifos but also mimic AChE inhibitory activity of CPF to show promising aptitude as safe insecticide.

An organocatalytic asymmetric domino [3+2]-cycloaddition-acyl transfer reaction between in situ generated azomethine ylides and α-nitro-α,β-unsaturated ketones has been developed.

Abstract

Herein we have developed an organocatalytic asymmetric domino [3+2]-cycloaddition-acyl transfer reaction between in situ generated azomethine ylides and α-nitro-α,β-unsaturated ketones. The desired penta-substituted pyrrolidine products were obtained in high yields and in moderate to good enantio- and diastereoselectivities. Also, an isomerization reaction in silica gel was performed for the formation of another diastereomer in high yields with retention of enantioselectivities.

Facile synthetic routes for fused metallaaromatic compounds have been developed by CH activation strategy of designed alkyl-bridged diphenol derivatives. The developed reactions provide benzo- and benzofuran-fused iridaoxabenzenes with fully delocalized π-conjugated systems.

Abstract

One-pot syntheses of new π-extended metallaaromatic compounds have been developed by utilizing Ir-mediated CH bond activation of ethylene- or ethylidene-bridged diphenol derivatives. Depending on the bridging alkyl groups, two types of iridaoxabenzenes, both of which are doubly fused with benzo and benzofuran units, have been obtained. Studies on their structures and electronic characters indicate that both complexes have an aromatic character on the iridaoxacycles, and their π-conjugated systems are fully delocalized over the whole molecular skeletons. These novel metallaaromatic complexes exhibited some reactivities which are distinct from those reported for the non-fused metallaaromatic compounds.

A systematic study has been reported to compare the pros and cons of both micellar and surfactant immobilized as self-assembled monolayer (SAM) on a nanoparticle system towards proton transfer catalysis. We showed the superiority of SAM compared to micelle at much lower concentration of headgroup compared to similar concentration of surfactants of even higher hydrophobicity.

Abstract

Both micelles and self-assembled monolayer (SAM)-protected nanoparticles are capable of efficiently hosting water-immiscible substrates to carry out organic reactions in aqueous media. Herein, we have analyzed the different catalytic effect of SAM-protected cationic nanoparticles and cationic surfactants of varying chain length towards base-catalyzed proton transfer mediated ring-opening reaction of 5-nitrobenzisoxazole (NBI) (also known as Kemp Elimination (KE) reaction). We use inorganic phosphate ion or different nucleotide (phosphate-ligated different nucleoside) as base to promote the reaction on micellar or nanoparticle interface. We find almost 2–3 orders of magnitude higher concentration of surfactants of comparable hydrophobicity required to reach the similar activity which attained by low cationic head group concentration bound on nanoparticle. Additionally, at low concentration of nanoparticle-bound surfactant or with high surfactant in micellar form, nucleotide-selectivity has been observed in activating KE reaction unlike free surfactant at low concentration. Finally, we showed enzyme-mediated nucleotide hydrolysis to generate phosphate ion which in situ upregulate the KE activity much more in GNP-based system compared to CTAB. Notably, we show a reasonable superiority of SAM-protected nanoparticles in activating chemical reaction in micromolar concentration of headgroup which certainly boost up application of SAM-based nanoparticles not only for selective recognition but also as eco-friendly catalyst.

Rhodium(III)-catalyzed C−H/N−H activation enables mild, direct synthesis of diverse pyrimidoindolones from N-carbamoylindoles and vinylene carbonate, including pyrrole substrates. Mechanistic insights are provided.

Abstract

Pyrimidoindolones are an important structural motif found in many natural products and are essential to the pharmaceutical and agrochemical industry. Direct synthesis of 3,4-unsubstituted pyrimidoindolones is not easily accessible. Here we report a rhodium(III)-catalyzed C−H/N−H activation and annulation approach for obtaining pyrimidoindolones from N-carbamoylindoles and vinylene carbonate. The reaction occurs at room temperature and does not require any external oxidants. A diverse spectrum of indoles were demonstrated to be viable substrates capable of producing the desired pyrimidoindolones in high yields. In addition, the reaction scope has been expanded to include pyrrole substrate. Furthermore, detailed mechanistic studies have been performed to delineate the working mode of the reaction.

Recent examples of the design of glycopolymers and their interactions with lectins are highlighted in this Review. In recent years, increasing attention has been paid to the emergence of new viruses such as SARS-Cov-2, and it is believed that some glycoconjugates are involved in their infection. The search for glycopolymers effective against unknown pathogens will greatly contribute to the fields of biochemistry and drug development. More information can be found in the Review by Yoshiko Miura, Masanori Nagao, and Hikaru Matsumoto.

This report describes the synthesis of a new NNSe pincer ligand and its palladium pincer complexes. Surprisingly, the reactivity of the ligand toward the palladium precursor is base-dependent. In the presence of the Et₃N base, a mononuclear pincer complex was formed whereas in the absence of a base, a dinuclear pincer complex was formed. The complexes were used as catalysts for decarboxylative direct C−H heteroarylation of (hetero)arenes. Among the complexes, the dinuclear complex was found to be more reactive. Only 2.5 mol % catalyst loading was needed to activate a broad substrate scope.

Abstract

This report describes the synthesis of a new NNSe pincer ligand and its mono- and dinuclear palladium(II) pincer complexes. In the absence of a base, a dinuclear palladium pincer complex (C1) was isolated, while in the presence of Et₃N base a mononuclear palladium pincer complex (C2) was obtained. The new ligand and complexes were characterized using techniques like ¹H, ¹³C{¹H} nuclear magnetic resonance (NMR), fourier transform infrared (FTIR), high-resolution mass spectrometry (HRMS), ultraviolet-visible (UV-Visible), and cyclic voltammetry. Both the complexes showed pincer coordination mode with a distorted square planar geometry. The complex C1 has two pincer ligands attached through a Pd−Pd bond in a dinuclear pincer fashion. The air and moisture-insensitive, thermally robust palladium pincer complexes were used as the catalyst for decarboxylative direct C−H heteroarylation of (hetero)arenes. Among the complexes, dinuclear pincer complex C1 showed better catalytic activity. A variety of (hetero)arenes were successfully activated (43–87 % yield) using only 2.5 mol % of catalyst loading under mild reaction conditions. The PPh₃ and Hg poisoning experiments suggested a homogeneous nature of catalysis. A plausible reaction pathway was proposed for the dinuclear palladium pincer complex catalyzed decarboxylative C−H bond activation reaction of (hetero)arenes.