Double‐bond photoswitching molecules typically can undergo trans→cis photoisomerization, but their photoisomerization mechanisms in the solid state have been rarely reported. Herein, the ...excited‐state evolutions of trans‐azobenzene (AB), trans‐stilbene (TS), and N‐benzylideneaniline (NBA) are studied to unveil the relationship between the double‐bond photoswitching molecules and the photoisomerization kinetics in the solution phase and in nanocrystal suspensions (NCS). The photoisomerization rate of NBA is the fastest among these three molecules in the solution phase due to its most apparent single‐bond feature of the central double bond in the S1 state. The free space ordered crystal configuration boosts the photoisomerization rates of AB and TS in NCS to be faster than that of the solution phase because the hindrance of the wrapping solvent is eliminated in the crystals. In contrast, when NBA is prepared into NCS, it becomes distorted into a nonplanar structure because of the asymmetrical C‐H···π interactions, resulting in NBA having a large spin‐orbital coupling (SOC) value which opens the intersystem crossing channel to generate the triplet state instead of undergoing photoisomerization in solution. Therefore, this work reveals that the crystal configuration and the molecular structure may critically determine the photophysical properties of photoswitching materials.
The nanocrystals of double‐bond photoswitching molecules exhibit totally different trans‐cis photoisomerization excited state evolution processes compared to the solutions phase of these molecules due to the crystal configuration and molecular structure critically determining the photophysical properties of photoswitching materials.
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.
This study reveals host–guest supramolecular complexes with dual long persistent luminescence (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 carrier along DPA strand in the supramolecular complexes is attributed to generate the ultralong TADF and RTP.
A novel supramolecular complex composed of diphenylacetylene (DPA) and α‐cyclodextrin (α‐CD) with dual ultralong thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence ...(RTP) is reported by Ming‐De Li and co‐workers in article number 2101337. The space charge transfer from host to guest and a long‐range charge transportation are responsibe for the unprecedented optical property.
Two positional isomers (regioisomers) through changing the substituted position of perylenetetracarboxylic diimide and benzanthrone moieties were designed and synthesized. These two regioisomers ...exhibit totally different aggregation behaviors. The
meta
(
bay
)-substituted product shows the aggregation-caused quenching feature as the fluorescence quantum yield in tetrahydrofuran-water mixtures is reduced by 80% with an increase in the water fraction of the medium from 0% to 60%. Interestingly, an aggregation-induced emission is observed for the
ortho
-substituted product as the fluorescence quantum yield is increased by nearly one order of magnitude with an increase in the water fraction. This fluorescence enhancement effect for the
ortho
-substituted product is because of the restriction of the intramolecular rotation between the perylene core and the benzanthrone substituent in the aggregated state. The
ortho
-substituted product also exhibits excellent two-photon absorption performance because the
ortho
-substitution retains the planarity of the perylene core and improves the intramolecular charge-transfer among the molecules. Moreover, the
ortho
-substituted product shows two-photon excited aggregation-induced emission, which has potential application in organic two-photon excited fluorescence imaging agents.
With
bay
- and
ortho
-substituted perylenetetracarboxylic diimide derivatives, one-photon and two-photon excited ACQ-to-AIE conversion is realized through simple positional isomerization.
Abstract
Photocatalytic conversion of diluted CO
2
into solar fuel is highly appealing yet still in its infancy. Herein, we demonstrate the metal‐node‐dependent performance for photoreduction of ...diluted CO
2
by constructing Ni metal–organic framework (MOF) monolayers (Ni MOLs). In diluted CO
2
(10 %), Ni MOLs exhibit a highest apparent quantum yield of 1.96 % with a CO selectivity of 96.8 %, which not only exceeds reported systems in diluted CO
2
but also is superior to most catalysts in pure CO
2
. Whereas isostructural Co MOLs is almost inactive in diluted CO
2
, indicating the performance is dependent on the metal nodes. Experimental and theoretical investigations show that strong CO
2
binding affinity of Ni MOLs is the crucial factor, which stabilizes the Ni‐CO
2
adducts and facilitates CO
2
‐to‐CO conversion.
PDF
