Ru-catalyzed ortho-oxidative alkenylation of 2-arylbenzo[d]thiazoles in aqueous solution of anionic surfactant sodium dodecylbenzenesulfonate (SDBS)

Palladium Catalyzed C3-(sp2)-H Alkenylation of Pyrroles via a Benzothiazole Directing Group: A Direct Access to Organic Thermally Activated Delayed Fluorescence Materials

A Pd (II)-catalyzed direct C3-(sp2)-H alkenylation of heteroarenes using benzothiazole as a directing group was successfully achieved. A wide range of 2-N-alkylpyrroles undergo an oxidative coupling with a variety of acrylates to furnish highly regio- and chemoselective E-alkenylation products at the C3 position. An important intermediate complex has been isolated and characterized so as to have an insight into the mechanism. This convenient protocol proved to be practical to access thermally activated delayed fluorescence materials (TADF). These molecules proved to be blue-emitting TADF materials (∼ms lifetime). A detailed and systematic investigation has been carried out to study the photophysical properties, and this has been further validated by the time-dependent density functional theory calculations.

Micellar Catalysis as a Tool for C-H Bond Functionalization toward C-C Bond Formation

Micelles generated upon dissolving surfactants in water can be employed as nanovessels for catalytic transformations, in the so-called micellar catalysis methodology. This review is focused on the use of micellar catalysis in the context of the catalytic functionalization of carbon-hydrogen bonds. The micelles accumulate catalyst and reactants in their inner volume in such a high local concentration that kinetics are favored. The consequence is that, in most cases, processes that in conventional organic solvents require high temperatures and long reaction times are achieved in milder conditions when micellar catalysis is employed.

Recent Advances in the Synthesis and Applications of 2-Arylbenzothiazoles

This review firstly covers the applications of 2-arylbenzothiazoles as amyloid imaging agents, antitumor agents, and organic luminescent materials. Then we review the recent advances in the synthesis of 2-arylbenzothiazole derivatives. On the one hand, we introduce the approaches for construction of the 2-arylbenzothiazole core, including the following categories: (i) classic condensation of 2-aminothiophenols, (ii) direct arylation of benzothiazoles, (iii) intramolecular cyclization of thiobenzanilides, and (iv) tandem cyclization of anilines/ nitroarenes­ with elemental sulfur or sulfides. On the other hand, the transition-metal-catalyzed direct C–H functionalizations of 2-aryl­benzothiazoles are also involved in this review.

1 Introduction

2 Applications of 2-Arylbenzothiazoles

3 Construction of the 2-Arylbenzothiazole Core

4 Synthesis 2-Arylbenzothiazoles via Direct C–H Functionalization

5 Conclusion

Revisiting the mechanism of the Fujiwara–Moritani reaction

A new perspective of the Fujiwara–Moritani reaction is presented, including its kinetic profile and catalyst deactivation studies.

A selective detection approach for copper(ii) ions using a hydrazone-based colorimetric sensor: spectroscopic and DFT study

The development of an efficient and miniaturized analytical approach to determine trace levels of toxic ions in aqueous fluids presents a current research challenge. Hydrazone-based chemosensors are considered potential candidates due to their high sensitivity and selectivity towards heavy metal ions. Computational techniques can be properly implemented to elucidate possible modes of ligand-metal interaction and provide an in-depth understanding of the chemistry involved. The present study reports the use of 3-hydroxy-5-nitrobenzaldehyde-4-hydroxybenzoylhydrazone (3-HNHBH) ligand for highly sensitive, quick and re-usable colorimetric sensing of copper(ii) ions in aqueous media. DFT calculations suggest that the complexation of 3-HNHBH with copper(ii) ions adopts a seesaw coordination geometry and results in the largest HOMO-LUMO gap and most effective coulombic interaction compared to Zn and Ni counterparts. It demonstrated a high selectivity towards copper ions with a detection limit of 0.34 μg L-1. The ligand was readily regenerated using a 0.5 M HCl solution, indicating its feasibility to be used as a re-usable sensor for the convenient detection of copper ions in aqueous media. The influence of metal interference, pH and solvents on the selectivity and regeneration of the ligand was also investigated.

Sodium Hydroxide-Free Soy Protein Isolate-Based Films Crosslinked by Pentaerythritol Glycidyl Ether

The soy protein isolate (SPI), sodium dodecylbenzenesulfonate (SDBS) and pentaerythritol glycidyl ether (PEGE) were used to make biodegradable films in this study. Unlike the usual method that adding sodium hydroxide (NaOH) during the SPI-based film casting, SDBS was used as a surfactant playing the similar role as NaOH. Since NaOH is a chemical with corrosiveness and toxicity, the replacing of NaOH by SDBS might reduce the hazard threat during the utilization of SPI-based films in food packing application. Furthermore, the presentation of SDBS helped dispersing the hydrophobic PEGE into the hydrophilic SPI. PEGE is a crosslinking agent with multiple reactive epoxy groups. The chemical structures and micro morphologies of the fabricated films were investigated by means of FTIR, XRD, and SEM. The thermal stabilities of the films were examined by means of the thermo-gravimetric analysis. After the chemical crosslinking, the ultimate tensile strength of the film was significantly increased, meanwhile, the water absorption was dramatically decreased. It was concluded that the SPI-based film containing 4% PEGE achieved the optimal performance.

Mechanistic view of Ru-catalyzed C-H bond activation and functionalization: computational advances

Ru-Catalyzed aromatic C-H bond activation and functionalization have emerged as important topics because they have resulted in remarkable progress in organic synthesis. Both experimental and theoretical studies of their mechanisms are important for the design of new synthetic methodologies. In this review, a mechanistic view of the Ru-mediated C-H bond cleavage step is first given to reveal the C-H bond activation modes, including oxidative addition, metathesis and base-assisted deprotonation. In this process, directing groups play an important role in determining the reactivity of the C-H bond. The C-H bond activation generally leads to the formation of a Ru-C bond, which is further functionalized in the subsequent steps. The mechanisms of Ru-catalyzed arylation, alkylation, and alkenylation of arenes are summarized, and these transformations can be categorized into cross-coupling with electrophiles or oxidative coupling with nucleophiles. In addition, the mechanism of ortho-ruthenation-enabled remote C-H bond functionalization is also discussed.