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Photofunctional materials based on donor-acceptor molecules have drawn intense attention due to their unique optical properties. Importantly, Systematic investigation of substitution effects on excited-state charge transfer dynamics of donor-acceptor molecules is a powerful approach for identifying application-relevant design principles. Here, by coupling phenothiazine (PTZ) at the ortho-, meta-, and para-positions of the benzene ring of benzophenone (BP), three regioisomeric BP-PTZ dyads were designed to understand the relationship between substituted positions and excited-state evolution channels. Ultrafast transient absorption is used to detect and trace the transient species and related evolution channels of BP-PTZ dyads at excited state. In a non-polar solvent, BP-o-PTZ undergoes the through-space charge transfer process to produce a singlet charge-transfer (1CT) state, which subsequently proceeds the intersystem crossing process and transforms into a triplet charge-transfer (3CT) state; BP-m-PTZ experiences intramolecular charge transfer (ICT) process to generate the 1CT state, which subsequently transforms into the 3CT state by the intersystem crossing (ISC) and finally converts into the local-excited triplet (3LE) state; as for BP-p-PTZ, only 3LE states can be detected after the ISC process from the 1CT state. On the other hand, the twisted ICT states are generated via twisted motion between the donor and acceptor for all BP-PTZ dyads or planarization of the PTZ unit in high polar solvents. The excited-state theoretical calculations unveil that the features of ICT and intramolecular interaction between the three dyads play a decisive role in determining the through-bond charge transfer and through-space charge transfer processes. Also, these results demonstrate that the excited-state evolution channels of PTZ derivatives could be modified by tuning the substituted positions of the donor-acceptor dyads. This study provides a deep perspective for the substitute-position effect on donor-acceptor-type PTZ derivatives. [ABSTRACT FROM AUTHOR]

An anion‐counterion strategy is proposed to construct organic mono‐radical charge‐transfer cocrystals for near‐infrared photothermal conversion and solar‐driven water evaporation. Ionic compounds with halogen anions as the counterions serve as electron donors, providing the necessary electrons for efficient charge transfer with unchanged skeleton atoms and structures as well as the broad red‐shifted absorption (200–2000 nm) and unprecedented photothermal conversion efficiency (~90.5 %@808 nm) for the cocrystals. Based on these cocrystals, an excellent solar‐driven interfacial water evaporation rate up to 6.1±1.1 kg ⋅ m−2 ⋅ h−1 under 1 sun is recorded due to the comprehensive evaporation effect from the cocrystal loading in polyurethane foams and chimney addition, such performance is superior to the reported results on charge‐transfer cocrystals or other materials for solar‐driven interfacial evaporation. This prototype exhibits the great potential of cocrystals prepared by the one‐step mechanochemistry method in practical large‐scale seawater desalination applications. [ABSTRACT FROM AUTHOR]

Vinyldiazo compounds are one of the most important synthons in the construction of a cyclic ring. Most photochemical transformations of vinyldiazo compounds are mainly focusing on utilization of their C═C bond site, while reactions taking place at terminal nitrogen atom are largely unexplored. Herein, a photocatalytic cascade radical cyclization of LBRs with vinyldiazo reagents through sequential B─N/C─N bond formation is described. The reaction starts with the addition of LBRs (Lewis base–boryl radicals) at diazo site, followed by intramolecular radical cyclization to access a wide range of important boron‐handled pyrazoles in good to excellent yields. Control experiments, together with detailed mechanism studies well explain the observed reactivity. Further studies demonstrate the utility of this approach for applications in pharmaceutical and agrochemical research. [ABSTRACT FROM AUTHOR]

"D-A pairs" as the basic "micro-stacking units" in cocrystals guarantee strong donor-acceptor interactions and excellent photothermal performance. Dynamics of excited states, mechanochemistry, integer-charge-transfer, intermolecular hydrogen bond, photo-thermal conversion Keywords: dynamics of excited states; mechanochemistry; integer-charge-transfer; intermolecular hydrogen bond; photo-thermal conversion EN dynamics of excited states mechanochemistry integer-charge-transfer intermolecular hydrogen bond photo-thermal conversion 1 1 1 07/25/23 20230721 NES 230721 B The Front Cover b shows integer-charge-transfer cocrystals are self-assembled via multiple intermolecular hydrogen bonds with one electron transferred from donor to acceptor unit for high-efficiency (~87 %) NIR photothermal conversion. [Extracted from the article]

An anion-counterion strategy is proposed to construct organic mono-radical charge-transfer cocrystals for near-infrared photothermal conversion and solar-driven water evaporation. Ionic compounds with halogen anions as the counterions serve as electron donors, providing the necessary electrons for efficient charge transfer with unchanged skeleton atoms and structures as well as the broad red-shifted absorption (200-2000 nm) and unprecedented photothermal conversion efficiency (~90.5 %@808 nm) for the cocrystals. Based on these cocrystals, an excellent solar-driven interfacial water evaporation rate up to 6.1±1.1 kg ⋅ m -2  ⋅ h -1 under 1 sun is recorded due to the comprehensive evaporation effect from the cocrystal loading in polyurethane foams and chimney addition, such performance is superior to the reported results on charge-transfer cocrystals or other materials for solar-driven interfacial evaporation. This prototype exhibits the great potential of cocrystals prepared by the one-step mechanochemistry method in practical large-scale seawater desalination applications., (© 2024 Wiley-VCH GmbH.)

A new phosphine-catalyzed reaction of α-substituted allenes with aryl imines, in stark contrast to classic cycloaddition reactions, has been developed. This reaction delivers valuable highly functionalized itaconimides with excellent stereoselectivities by a new «un-cyclizing» reaction mode involving β'-carbon of α-substituted allenes. Moreover, the present «un-cyclizing» reaction can also be carried out in a one-pot fashion and scaled up to the gram scale by using aryl aldehydes, without the need to isolate the aryl imines. Mechanistic studies and control experiments reveal the crucial role of H 2 CO 3 for the present reaction mode. In addition, density functional theory (DFT) calculations were performed to understand the possible mechanism., (© 2023 Wiley-VCH GmbH.)

We report an approach for the synthesis of benzothiophene motifs under electrochemical conditions by the reaction of sulfonhydrazides with internal alkynes. Upon the formation of a quaternary spirocyclization intermediate by the selective ipso -addition instead of an ortho -attack, the S-migration process was rationalized to lead to the products. Computational studies revealed the selectivity and the compatibility of drug molecules showcased the potential application of the protocols., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)