Tunable Nano-Bending Structures of Loosened/Tightened Lassos with Bi-Stable Vibration-Induced Emissions for Multi-Manipulations of White-Light Emissions and Sensor Applications.

The first tunable nano-bending structures of [1]rotaxane containing a single-fluorophoric N,N'-diphenyl-dihydrodibenzo[a,c]phenazine (DPAC) moiety (i.e., [1]RA) are developed as a loosened lasso structure to feature the bright white-light emission [CIE (0.

Controllable Aggregation-Induced Emission and Förster Resonance Energy Transfer Behaviors of Bistable [2] Daisy Chain Rotaxanes for White-Light Emission and Temperature-Sensing Applications.

Bistable [2] daisy chain rotaxanes with respective extended and contracted forms of 2 and 2 containing a blue-emissive anthracene () donor and orange-emissive indandione-carbazole () acceptor were successfully synthesized via click reaction. Tunable-emission bistable [2] daisy chain rotaxanes with fluorescence changes from blue to orange, including bright-white-light emissions, could be modulated by the aggregation-induced emission (AIE) characteristics and Förster resonance energy transfer (FRET) processes through altering water fractions and shuttling processes (i.e.

Dual and sequential locked/unlocked photo-switching effects on FRET processes by tightened/loosened nano-loops of diarylethene-based [1]rotaxanes.

The self-trapping nano-loop structures of [1]rotaxanes exhibited multiple Förster resonance energy transfer (FRET) patterns dual and sequential locking/unlocking of pH-gated and UV exposure processes. As a tightened and constrained nano-loop in the acidic condition, dithienylethene (DTE) unit was locked in the highly bending open form to forbid ring closure upon UV irradiation.

Dual and Sequential Locked/Unlocked Photochromic Effects on FRET Controlled Singlet Oxygen Processes by Contracted/Extended Forms of Diarylethene-Based [1]Rotaxane Nanoparticles.

Manipulations of singlet oxygen ( O ) generations by the integration of both aggregation-induced emission luminogen (AIEgen) photosensitizer and photochromic moieties have diversified features in photodynamic therapy applications. Through Förster resonance energy transfer (FRET) pathway to induce red PL emissions (at 595 nm) for O productions, [1]rotaxane containing photosensitive tetraphenylethylene (TPE) donor and photochromic diarylethene (DAE) acceptor is introduced to achieve dual and sequential locked/unlocked photoswitching effects by pH-controlled shuttling of its contracted/extended forms. Interestingly, the UV-enabled DAE ring closure speeds follow the reversed trend of DAE self-constraint degree as: contracted < extended < noninterlocked forms in [1]rotaxane analogues, thus FRET processes can be adjusted in contracted/extended forms of [1]rotaxane upon UV irradiations.

Designs and Applications of Multi-stimuli Responsive FRET Processes in AIEgen-Functionalized and Bi-fluorophoric Supramolecular Materials.

Materials capable of displaying strong ratiometric fluorescence with Förster resonance energy transfer (FRET) processes have attracted much research interest because of various chemosensor and biomedical applications. This review highlights several popular strategies in designing FRET-OFF/ON mechanisms of ratiometric fluorescence systems. In particular, the developments of organic and polymeric FRET materials featuring aggregation-induced emission-based luminogens (AIEgens), supramolecular assemblies, photochromic molecular switches and surfactant-induced AIE/FRET mechanisms are presented.

Controllable FRET Behaviors of Supramolecular Host-Guest Systems as Ratiometric Aluminum Ion Sensors Manipulated by Tetraphenylethylene-Functionalized Macrocyclic Host Donor and Multistimuli-Responsive Fluorescein-Based Guest Acceptor.

The novel multistimuli-responsive monofluorophoric supramolecular polymer and pseudo[3]rotaxane consisted of the closed form of nonemissive fluorescein guest along with TPE-based main-chain macrocyclic polymer and TPE-functionalized macrocycle hosts, respectively. By the combination of various external stimuli, these fluorescent supramolecular host-guest systems could reveal interesting photoluminescence (PL) properties in DMF/HO (1:1, v/v) solutions, including bifluorophoric host-guest systems after the complexation of Al ion, i.e.

Highly Efficient Förster Resonance Energy Transfer Modulations of Dual-AIEgens between a Tetraphenylethylene Donor and a Merocyanine Acceptor in Photo-Switchable [2]Rotaxanes and Reversible Photo-Patterning Applications.

A series of novel photo-switchable [2]rotaxanes (i.e., and before and after shuttling controlled by acid-base, respectively) containing one spiropyran (SP) unit (as a photochromic stopper) on the axle and two tetraphenylethylene (TPE) units on the macrocycle were synthesized via click reaction.

Multi-Stimuli Responsive FRET Processes of Bifluorophoric AIEgens in an Amphiphilic Copolymer and Its Application to Cyanide Detection in Aqueous Media.

A novel amphiphilic aggregation-induced emission (AIE) copolymer, that is, , consisting of -isopropylacrylamide (NIPAM) as a hydrophilic unit and a tetraphenylethylene-spiropyran monomer () as a bifluorophoric unit is reported. Upon UV exposure, the close form of non-emissive spiropyran (SP) in can be photo-switched to the open form of emissive merocyanine (MC) in in an aqueous solution, leading to ratiometric fluorescence of AIEgens between green TPE and red MC emissions at 517 and 627 nm, respectively, via Förster resonance energy transfer (FRET). Distinct FRET processes of can be observed under various UV and visible light irradiations, acid-base conditions, thermal treatments, and cyanide ion interactions, which are also confirmed by theoretical studies.