Switching photorelease to singlet oxygen generation by oxygen functionalization of phenothiazine photocages

Exploring the Theoretical Foundations of Thermally Activated Delayed Fluorescence (TADF) Emission: A Comprehensive TD-DFT Study on Phenothiazine Systems

This study conducts a thorough theoretical investigation of Thermally Activated Delayed Fluorescence (TADF) in phenothiazine-based systems, examining ten molecular configurations recognized experimentally as TADF-active. Employing Time-Dependent Density Functional Theory (TD-DFT), our analysis spans the investigation of singlet-triplet energy gaps (ΔEST), spin-orbit coupling, and excitation characteristics using Multiwfn. This approach not only validates the adherence to El Sayed's rule across these systems but also provides a detailed understanding of charge transfer dynamics, as visualized through heat maps. A significant aspect of our study is the exploration of different oxidation states of sulfur and site substitutions on phenothiazine. This systematic variation aims to identify additional TADF-active compounds, drawing parallels with properties characterizing other known TADF emitters. Our investigation into Reverse Intersystem Crossing (rISC) rates and the analysis of dihedral angles in relation to ΔEST values offer nuanced insights into the TADF behaviours of these molecules. By integrating rigorous computational analysis with practical implications, we provide a foundational understanding that enhances the design and optimization of phenothiazine-based materials for optoelectronic applications. This work not only advances our theoretical understanding of TADF in phenothiazine derivatives but also serves as a guide for experimentalists and industry professionals in the strategic design of new TADF materials.

Application of TNB in dual photo-controlled release of phenamacril, imidacloprid, and imidacloprid synergist

Pesticides can improve crops' yield and quality, but unreasonable applications of pesticides lead to waste of pesticides which are further accumulated in the environment and threaten human health. Developing the release of controlled drugs can improve the utilization rate of pesticides. Among these methods, light-controlled release is a new technology of controlled release, which can realize spatiotemporal delivery of drugs by light. Four compounds, named Imidacloprid-Thioacetal o-nitrobenzyl-Phenamacril (IMI-TNB-PHE), Imidacloprid-Thioacetal o-nitrobenzyl- Imidacloprid (IMI-TNB-IMI), Phenamacril-Thioacetal o-nitrobenzyl-Phenamacril (PHE-TNB-PHE), and Imidacloprid-Thioacetal o-nitrobenzyl-Imidacloprid Synergist (IMI-TNB-IMISYN), were designed and synthesized by connecting thioacetal o-nitrobenzyl (TNB) with pesticides TNB displaying simple and efficient optical properties in this work. Dual photo-controlled release of pesticides including two molecules of IMI or PHE, both IMI and PHE, as well as IMI and IMISYN were, respectively, studied in this paper. Insecticidal/fungicidal activities of the photosensitive pesticides showed 2-4 times increments if they were exposed to light. In addition, a synergistic effect was observed after the light-controlled release of IMI-TNB-IMISYN, which was consistent with the effect of IMISYN. The results demonstrated whether dual photo-controlled release of the same or different pesticide molecules could be achieved with a TNB linker with spatiotemporal precision. We envisioned that TNB will be an innovative photosensitive protective group for light-dependent application of agrochemicals in the future.

Phenothiazine and phenothiazine-5,5-dioxide based push-pull Derivatives: Synthesis, photophysical, electrochemical and computational Studies

A set of phenothiazine (PTZ) and phenothiazine-5,5-dioxide based π-conjugated push–pull chromophores PTZ 1–6 were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition retroelectrocyclic ring opening reaction in...