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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]

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]

Long persistent luminescence (LPL) can store light energy in excited states and gradually release it as light. Organic host–guest systems provide a good platform for LPL, and single‐color LPL is often achieved while multicolor LPL is challengeable. Here host–guest supramolecular complexes are presented with dual LPL emissions: thermally activated delayed fluorescence (TADF) (≥100 ms) and room temperature phosphorescence (RTP). A space charge transfer from α‐cyclodextrin to diphenylacetylene (DPA) with long‐range transportation (2.32 mm) carrier along DPA strand in the supramolecular complexes is attributed to generate the TADF and RTP. Fortunately, these supramolecular complexes are readily fabricated from α‐cyclodextrin and DPA or DPA derivatives. The gradient color is observed after removing UV excitation. Furthermore, the hydrophobic property inside α‐cyclodextrin makes the LPL appear by water shedding and disappear by organic solvent infiltration, showing the character of a "switch." This host–guest space charge transfer strategy paves a way to design LPL materials. [ABSTRACT FROM AUTHOR]

By utilizing the bipolarity of 1,2‐diphenylphenanthroimidazole (PPI), two types of asymmetrical tripartite triads (PPI‐TPA and PPI‐PCz) were designed with triphenylamine (TPA) and 9‐phenylcarbazole (PCz). These triads are deep‐blue luminescent materials with a high fluorescence quantum yield of nearly 100 %. To trace the photophysical behaviors of these triads, their excited‐state evolution channels and interchromophoric interactions were investigated by ultrafast time‐resolved transient absorption and excited‐state theoretical calculations. The results suggest that the electronic nature, asymmetrical tripartite structure, and electron–hole distance of these triads, as well as solvent polarity, determine the lifetime of intramolecular charge transfer (ICT). Interestingly, PPI‐PCz triads show anti‐Kasha ICT, and the charge‐transfer direction among the triads is adjustable. For the PPI‐TPA triad, the electron is transferred from TPA to PPI, whereas for the PPI‐PCz triad the electron is pushed from PPI to PCz. Exploration of the excited‐state ICT in these triads may pave the way to design better luminescent materials in the future. [ABSTRACT FROM AUTHOR]