A Highly Ordered Quantum Dot Supramolecular Assembly Exhibiting Photoinduced Emission Enhancement

Abstract

Multicomponent supramolecular assembly systems enable the generation of materials with outstanding properties, not obtained from single‐component systems, via a synergetic effect. Herein, we demonstrate a novel supramolecular coassembly system rendering highly ordered quantum dot (QD) arrangement structures formed via the self‐assembly of azobenzene derivatives, where the photocontrollable photoluminescence (PL) properties of the QDs are realized based on photoisomerization. Upon mixing the assembled azobenzene derivatives and QDs in apolar media, a time‐evolution coaggregation into hierarchical nanosheets with a highly ordered QD arrangement structure occurs. Upon photoirradiation, the nanosheets transform into ill‐defined aggregates without arranged QDs together with enhancing the PL intensity. In days, the photoirradiated coaggregates undergo recovery of the PL properties corresponding to the arranged QDs through thermal isomerization.

One‐Dimensionally Arranged Quantum‐Dot Superstructures Guided by a Supramolecular Polymer Template

“…Importantly, the distance between arranged csQDs is small due to the interdigitation between the ligands on csQD and/or dipole-dipole interactions between csQDs. [5,23] This arrangement is different from the previously reported adhesion-based arrangement of supramolecular assemblies and QDs, in which QDs were randomly adsorbed on the assemblies. [29][30][31] The arranged csQDs were observed via TEM even upon decreasing the concentration of csQDs ([csQD]: [1] = 0.26 : 500 to [csQD]: [1] = 0.033 : 500, [1] = 150 μM; Figures 3k,l and S16).…”

“…This result further supports the arrangement mechanism of csQD s via the interdigitation between the original ligands on the csQD and those on another csQD and subsequent adhesion of the csQD to SP (Figure 3m). [23,32] Furthermore, as the 1D‐arranged csQD s on one SP have adhesion sites for another SP at the other sides, the 1D‐arranged csQD s can be covered by not only one SP but also multiple SPs.…”

“…An exception is the use of templates to form 1D assemblies of QDs. [17] Several research groups succeeded in fabricating 1D-arranged QDs by mixing dispersed QDs with appropriate templates comprising adhesion groups for QDs, such as molecular assemblies of a double-crossover DNA, [18] an amphiphilic block copolymer [19][20] and small organic molecules produced by our group, [21][22][23] and inorganic nano-sized substrates. [24] However, pure inter-QD interactions in 1D-arranged QDs have not been reported because of the presence of electronic and excitonic interactions between the arranged QDs and their templates and the absence of closely arranged QDs.…”

Thiolate-Assisted Route for Constructing Chalcogen Quantum Dots with Photoinduced Fluorescence Enhancement

“…Thus, different PL materials with high photostability such as semiconductor quantum dots (QDs), , graphene/carbon QDs, , silicon-based nanodots, − and aggregation-induced emission luminogens (AIEgens) − have been developed. Nevertheless, fluorescent probes with photoinduced fluorescence enhancement (PFE) behavior where fluorescence intensity increases with irradiation time have been rarely reported for bioimaging. − …”

Insights into the Effect of Trans-to-Cis Photoisomerization of a Co-coordinated Stilbene Derivative on the Luminescence of Di-β-diketonate Lanthanide Complexes

“…Photoinduced trans-to-cis isomerization is the reversible conversion of trans isomers to cis isomers under a certain light wavelength. , Isomers with different molecular structures have different physical and chemical properties (including magnetic, optical, and electrical properties), which can be controlled by illumination. This feature is widely used in biochemistry, pharmacology, and supramolecular chemistry. − Much research has been conducted on the photoinduced trans-to-cis isomerization of various azobenzene and stilbene derivatives. In addition, we have studied a series of lanthanide β-diketonate complexes functionalized with azobenzene, finding that azobenzene groups attached to lanthanide β-diketonate complexes were stable in both solution and the solid state, exhibiting the reversible trans-to-cis photoisomerization properties of azobenzene and good fatigue resistance. ,,, The introduction of electron donor substituents is not conducive to improving the photoisomerization quantum yield and photoisomerization rate .…”