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Alkyne annulation represents a versatile and powerful strategy for the assembly of structurally complex compounds. Recent advances successfully enabled electrocatalytic alkyne annulations, significantly expanding the potential applications of this promising technique towards sustainable synthesis. The metallaelectro-catalyzed C–H activation/annulation stands out as a highly efficient approach that leverages electricity, combining the benefits of electrosynthesis with the power of transition-metal catalyzed C–H activation. Particularly attractive is the pairing of the electro-oxidative C–H activation with the valuable hydrogen evolution reaction (HER), thereby addressing the growing demand for green energy solutions. Herein, we provide an overview of the evolution of electrochemical C–H annulations with alkynes for the construction of heterocycles, with a topical focus on the underlying mechanism manifolds. [ABSTRACT FROM AUTHOR]

A phosphine, base and additive free cross-coupling of arylboronic acid is reported via C–O bond cleavage of acetic anhydride using a switchable ferrocene functionalized n-heterocyclic carbene (NHC) palladium complex. The novel redox active catalytic system afforded the corresponding arylketones with good to excellent yields. [ABSTRACT FROM AUTHOR]

A second-generation hydrogen bond donor (HBD) anion receptor with an inner amide cavity and an outer urea cavity can selectively and efficiently extract arsenate (AsO43−) from water in the presence of competitive oxoanions and halides. The X-ray structure showed encapsulation of AsO43− in a π-stacked dimeric capsular assembly of the receptor, the first crystallography-based example of pentavalent AsO43− trianion recognition by a HBD receptor. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized two new [C, C] cyclometalated Ir(III)–NHC complexes, [IrCp*(C∧C:NHC)Br](1a,b), [Cp* = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C–H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1 : 5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study. [ABSTRACT FROM AUTHOR]

Atom economy is one of the major factors in developing catalysis chemistry. Using the minimum amount of catalyst to obtain the maximum product yield is of the utmost priority in catalysis, which drives us to use parts-per-million (ppm) levels of catalyst loadings in syntheses. In this context, a new ferrocene functionalized Schiff base and its copper(II) complex have been synthesized and characterized. This Cu(II) complex is employed as a catalyst for popular 'click chemistry', where 1,2,3-triazoles are the end product. As low as 5 ppm catalyst loading is enough to produce gram scale product, and highest turnover number (TON) and turnover frequency (TOF) values of 140 000 and 70 000 h−1 are achieved, respectively. Furthermore, this highly efficient protocol has been successfully applied to the preparation of diverse functionalized materials with pharmaceutical, labelling and supramolecular properties. [ABSTRACT FROM AUTHOR]

We developed excellent charge reversal photoresponsive nanoparticles for targeted delivery of the anticancer drug chlorambucil. The charge reversal photoresponsive nanoparticles were constructed using two main ingredients, namely folic acid decorated mesoporous silica and quinoline chromophore. The newly synthesized quinoline chromophore performed three important roles, i.e., (i) fluorescent chromophore for cell imaging, (ii) phototrigger for regulated release of anticancer drug, and (iii) charge reversal based on its zeta potential for nuclear localization. Furthermore, folic acid decorated mesoporous silica facilitated active internalization of the drug inside the cancer cells. In vitro biological studies reveal that our photoresponsive DDS could deliver the anticancer drug chlorambucil into the tumor cells, killing the cancer cells by both one photon (>365 nm) and two photon (675 nm) irradiation. [ABSTRACT FROM AUTHOR]

Correction for 'A ferrocene functionalized Schiff base containing Cu(II) complex: synthesis, characterization and parts-per-million level catalysis for azide alkyne cycloaddition' by Firdaus Rahaman Gayen et al., Dalton Trans., 2020, 49, 6578–6586, DOI: 10.1039/d0dt00915f. [ABSTRACT FROM AUTHOR]

A photoresponsive nano drug delivery system (DDS) was constructed using two new ingredients: fluorescent carbon dots and a quinoline based phototrigger. The strong fluorescent properties of carbon dots have been explored for in vitro cellular imaging application, and the phototrigger ability of quinoline was exploited for efficient anticancer drug release using both one-photon and two-photon excitation. [ABSTRACT FROM AUTHOR]

Biofilms, ubiquitous in nature, are three-dimensional complex microbial communities sheathed in a self-secreted extracellular polymeric matrix. Infections caused by these communities have sprouted as serious threats to global healthcare systems due to their intrinsic tolerance toward conventional antibiotics. There is a huge demand for alternative "cutting-edge" materials featuring strong antibiofilm abilities to mitigate and/or exterminate pre-matured biofilms. Natural or synthetic macromolecule-based compounds have evolved as one of the most sought-after materials because of their unique stimulus-directed selective targeting efficiency to the bacterial cell, antibiotic-encapsulation ability endowing them with a synergistic effect, and highly dense embedded cationic functionalities that promote accumulation within the biofilm. In this comprehensive review, we aim to highlight the progress made in inhibiting or eradicating bacterial biofilms using various forms of polymeric material including cationic and charge-switchable macromolecules, conjugated polymers, polymeric metal nanocomposites, hydrogels, and supramolecular polymers. We particularly emphasize understanding the underlying antibiofilm mechanisms of each presented example ushered in by state-of-the-art synthetic strategies. Lastly, focusing on bench-to-bedside, the review is concluded by providing some forthcoming aspects and possible future development directions to expand polymer-based antibiofilm research, keeping their clinical translations in mind.

A second-generation hydrogen bond donor (HBD) anion receptor with an inner amide cavity and an outer urea cavity can selectively and efficiently extract arsenate (AsO 4 3- ) from water in the presence of competitive oxoanions and halides. The X-ray structure showed encapsulation of AsO 4 3- in a π-stacked dimeric capsular assembly of the receptor, the first crystallography-based example of pentavalent AsO 4 3- trianion recognition by a HBD receptor.

Atom economy is one of the major factors in developing catalysis chemistry. Using the minimum amount of catalyst to obtain the maximum product yield is of the utmost priority in catalysis, which drives us to use parts-per-million (ppm) levels of catalyst loadings in syntheses. In this context, a new ferrocene functionalized Schiff base and its copper(ii) complex have been synthesized and characterized. This Cu(ii) complex is employed as a catalyst for popular 'click chemistry', where 1,2,3-triazoles are the end product. As low as 5 ppm catalyst loading is enough to produce gram scale product, and highest turnover number (TON) and turnover frequency (TOF) values of 140 000 and 70 000 h -1 are achieved, respectively. Furthermore, this highly efficient protocol has been successfully applied to the preparation of diverse functionalized materials with pharmaceutical, labelling and supramolecular properties.

Since temperature is one of the most significant physiological parameters that dictate the cellular status of living organisms, accurate intracellular temperature measurement is crucial and a valuable biomarker for the diagnosis and treatment of diseases. Herein, we introduce the foremost example of a non-conjugated polymer as a next generation fluorescent thermometer which is capable of addressing the key shortcomings including toxicity and thermal-induced fluorescence quenching associated with π-π conjugated system-based thermometers developed so far. We revealed, for the first time, the unique photophysical and aggregation-induced emission (AIE) characteristics of well-known thermoresponsive poly( N -vinylcaprolactam) (PNVCL) devoid of any classical fluorophore entity. PNVCL underwent a coil to globular conformational transition in an aqueous medium and appeared to be fluorescent above its lower critical solution temperature (LCST) near body temperature (38 °C). Eventually, this intriguing aspect enabled higher cellular uptake of PNVCL at the LCST boundary. By virtue of the AIE effect, the thermo-induced aggregation phenomenon has been ingeniously utilized to apply PNVCL as a novel fluorescent thermometer for intracellular temperature determination., (This journal is © The Royal Society of Chemistry 2020.)