Molecules

Organic light-emitting diodes (OLEDs) have attracted remarkable interest in display and lighting. To effectively address triplet exciton harvesting and enhance external quantum efficiency (EQE), delayed fluorescence AIEgens have gained significant prominence. The primary luminescence mechanism involves the efficient harvesting of triplet excitons via reverse intersystem crossing (RISC) channels, categorized into three types: thermally activated delayed fluorescence (TADF), hybridized local and charge transfer (HLCT), and triplet–triplet annihilation (TTA). In this review, we summarize the recent development of doped and non-doped delayed fluorescent AIEgens-based OLEDs. This review mainly discusses the molecular design strategies and photophysical properties of delayed fluorescent AIEgens and the electroluminescent properties of OLEDs as emitting layers. Finally, the challenges and prospects of delayed fluorescent AIEgens for the fabrication of OLEDs are also briefly discussed.

Amino acid derivatives, such as β-keto esters and pyrrolones, were used as nucleophiles in organocatalyzed Michael additions to nitroalkene acceptors, while fatty acid derivatives acted as both nucleophiles (β-keto esters) and electrophiles (nitroalkene acceptors). Bifunctional noncovalent organocatalysts were employed as asymmetric organocatalysts. Twenty compounds—including fatty acid and amino acid derivatives, as well as fatty acid–amino acid conjugates—were prepared with enantioselectivities of up to 98% ee. All novel products were fully characterized. This research demonstrates the ease of assembling readily available fatty acid and amino acid building blocks under ambient conditions.

Converting agricultural solid waste into porous biochar for HCHO adsorption is considered as a “two birds with one stone” strategy, which can achieve the environmental goal of “treating waste with waste”. Unfortunately, the HCHO adsorption performance of pristine biochar is generally unsatisfactory, which is derived from its poor surface activity and insufficient number of pores. In this study, a series of nitrogen-doped porous biochars with adjustable N-containing groups and porosity were synthesized by one-step pyrolysis of melamine and waste jujube pit in different mass ratios (NBC-x, x represented the mass ratio of melamine to waste jujube pit, x = 4–12) for HCHO adsorption. The HCHO adsorption tests indicated that the insertion of nitrogen-containing species improved the adsorption capacity of pristine biochar (BC). However, after the insertion of excessive nitrogen-containing species, the porosity of the samples significantly decreased due to the blockage of pores, which could be disadvantageous for HCHO adsorption. DFT calculation results showed that N doping (especially pyrrolic-N) significantly increased the maxima of absolute ESP values of the carbonaceous models and consequently enhanced the affinity between polar HCHO and carbonaceous models (varied from −20.65 kJ/mol to −33.26 kJ/mol). Thus, the NBC-8 possessing both substantial nitrogen content (19.81 wt. %) and developed porosity (specific surface area of 223 m²/g) exhibited the highest HCHO uptake of 6.30 mg/g. This was approximately 6.4 times larger than that of BC. This work not only deepens the understanding of the HCHO adsorption mechanism at molecular scale, but also concurrently offers a facile and eco-friendly route of N-doped porous biochar preparation, an efficient technology with high-value utilization of waste biomass resources, and a sustainable method of pollution remediation.