The synthesis and characterization of sulfinate addition-responsive fluorescent molecules are described. We found that addition reaction of sulfinates to naphthalimide-substituted azocarboxylates afforded the corresponding sulfonyl hydrazides with high fluorescence quantum yields (up to 0.91 in THF and 0.54 in methanol), which exhibited a large Stokes shift (105 nm) in protic methanol solvent, while the unsubstituted hydrazide and the sulfonyl-position isomer showed no fluorescence in polar solvents.

Diverse emission behaviors are demonstrated by investing the impact of protonated/deprotonated Carbon Dots and their interactions with solvents. Ultrafast spectroscopy reveals that the surface modification significantly affects the carrier relaxation rate and quantum yield, emphasizing a distinct preference for deprotonated surface structure in facilitating carrier radiation recombination

Abstract

The intricate nature of the surface structure of carbon dots (CDs) hinders a comprehensive understanding of their emission behavior. In this study, we employ two types of CDs created through acid-alkali treatments, one with surface protonation and the other with surface deprotonation, with the objective of investigating the impact of these surface modifications on carrier behavior using ultrafast spectroscopy techniques. TEM, XRD, FTIR and Raman spectra demonstrate the CDs’ structure, featuring graphitic core and abundant surface functional groups. XPS confirms the successful surface modifications of CDs via protonation and deprotonation. Ultrafast transient absorption (TA) spectroscopy reveals that deprotonation modification may decelerate the relaxation process, thereby increasing the visible PL quantum yields (PLQY). Conversely, protonation may accelerate the relaxation process due to the induced low-energy absorption band, resulting in self-absorption and reduced PLQY. Furthermore, TA analysis of CDs in mixed solvents with different proportions of ethanol shows the beneficial effect of ethanol in decelerating the relaxation process, leading to an increased PLQY of 33.7 % for deprotonated CDs and 22.1 % for protonated CDs. This study illuminates the intricate relationship between surface deprotonation/protonation modifications and carrier behavior in CDs, offering a potential avenue for the design of high-brightness CDs for diverse applications.

Organic coatings were degraded via UV-generated sulfate radicals. The degradation allowed the restoration of the original surface properties on the substrate, offering the potential for substrate recycling. Furthermore, the applicability of this approach to the degradation of the adhesive layer existing between the substrate interfaces, underscoring its versatility.

Abstract

Degradation of organic coatings is essential for recycling valuable substrates. Despite the development of strategies for this purpose, the resulting degradations are typically constrained by the composition of the coating. This paper presents a simple strategy utilizing radicals induced by UV for the degradation of diverse organic coatings. The sulfate radicals, generated from UV-exposed ammonium persulfates, induce the degradation of various organic coatings, including layer-by-layer assembled coating composed of alginate and chitosan polymers as well as polydopamine coating. This strategy also facilitates the separation of two adhered substrates by degrading the adhesive polymer layer positioned between them. This novel approach enables the complete degradation of various organic coatings in aqueous conditions without imposing restrictions on their composition, leading to the recovery of the original surface properties of the substrate.

Functionalization of unactivated C(sp³)−H bonds represents one of the most explored transformation in organic synthesis. This review highlights the most recent breakthroughs in the Iron-catalyzed functionalization of unactivated C(sp³)−H bonds.

Abstract

The use of iron as a core metal in catalysis has become a research topic of interest over the last few decades. The reasons are clear. Iron is the most abundant transition metal on Earth's crust and it is widely distributed across the world. It has been extracted and processed since the dawn of civilization. All these features render iron a noncontaminant, biocompatible, nontoxic, and inexpensive metal and therefore it constitutes the perfect candidate to replace noble metals (rhodium, palladium, platinum, iridium, etc.). Moreover, direct C−H functionalization is one of the most efficient strategies by which to introduce new functional groups into small organic molecules. The majority of organic compounds contain C(sp³)−H bonds. Given the enormous importance of organic molecules in so many aspects of existence, the utilization and bioactivity of C(sp³)−H bonds are of the utmost importance. This review sheds light on the substrate scope, selectivity, benefits, and limitations of iron catalysts for direct C(sp³)−H bond activations. An overview of the use of iron catalysis in C(sp³)−H activation protocols is summarized herein up to 2022.

We report a heterogeneous photocatalytic system for the construction of valuable γ-amino acid scaffolds through the carboxylation of alkenes with the ambient CO₂. The system provides a green and sustainable methodology to the synthesis of amino acid derivatives in one-step with visible light.

Abstract

A metal-free heterogeneous protocol is established herein for the synthesis of value-added γ-amino acid scaffolds via carbocarboxylation of alkenes with CO₂ and alkylamines under visible light irradiation. The protocol shows broad substrate scope under mild reaction conditions and good stability of the catalyst for recycle tests. Moreover, the methodology could be feasible to the late-stage derivatization of several natural products, enriching the chemical arsenal for practical application.