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. 2020 Oct 21;12(42):47921-47938.
doi: 10.1021/acsami.0c12726. Epub 2020 Oct 12.

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

Pham Quoc Nhien  1 , Tu Thi Kim Cuc  1 , Trang Manh Khang  1 , Chia-Hua Wu  2 , Bui Thi Buu Hue  3 , Judy I Wu  2 , Brad W Mansel  4 , Hsin-Lung Chen  4 , Hong-Cheu Lin  1   5
Affiliations

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

Pham Quoc Nhien et al. ACS Appl Mater Interfaces. .

Abstract

A series of novel photo-switchable [2]rotaxanes (i.e., Rot-A-SP and Rot-B-SP 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. Upon UV/visible light exposure, both mono-fluorophoric rotaxanes Rot-A-SP and Rot-B-SP with the closed form (i.e., non-emissive SP unit) could be transformed into the open form (i.e., red-emissive merocyanine (MC) unit) to acquire their respective bi-fluorophoric Rot-A-MC and Rot-B-MC reversibly. The aggregation-induced emission (AIE) properties of bi-fluorophoric TPE combined with MC AIEgens of these designed rotaxanes and mixtures in semi-aqueous solutions induced interesting ratiometric photoluminescence (PL) and Förster resonance energy transfer (FRET) behaviors, which were further investigated and verified by dynamic light scattering (DLS), X-ray diffraction (XRD), and time-resolved photoluminescence (TRPL) measurements along with theoretical studies. Accordingly, in contrast to the model axle (Axle-MC) and the analogous mixture (Mixture-MC, containing the axle and macrocycle components in a 1:1 molar ratio), more efficient FRET behaviors and stronger red PL emissions were obtained from dual-AIEgens between a blue-emissive TPE donor (PL emission at 468 nm) and a red-emissive MC acceptor (PL emission at 668 nm) in both novel photo-switchable [2]rotaxanes Rot-A-MC and Rot-B-MC under various external modulations, including water content, UV/Vis irradiation, pH value, and temperature. Furthermore, the reversible fluorescent photo-patterning applications of Rot-A-SP in a powder form and a solid film with excellent photochromic and fluorescent behaviors are first investigated in this report.

Keywords: Förster resonance energy transfer (FRET); aggregation-induced emission (AIE); photo-switchable [2]rotaxane; spiropyran; tetraphenylethylene.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1.
Figure 1.
Partial 1H NMR spectra (300 MHz, 298 K, CD3CN) of (a) TPE-Cy-TPE, (b) Rot-A-SP, and (c) Axle-SP.
Figure 2.
Figure 2.
Partial 1H NMR spectra (300 MHz, 298 K, CD3CN) of (a) Rot-A-SP, (b) deprotonation of Rot-A-SP with 1 equiv. of DBU, (c) reprotonation of Rot-A-SP with 2 equiv. of TFA, and (d) mechanically interlocked and shuttling motion of AIE photo-switchable [2]rotaxane under acid/base conditions.
Figure 3.
Figure 3.
(a) PL spectra and (b) relative emission intensities of Rot-A-SP (50 μM) vs different water fractions and DLS results of (c) Rot-A-SP and (d) Rot-B-SP in H2O/THF solvents (90% H2O, v/v). (insets) Fluorescence photo-images of Rot-A-SP solutions in pure THF (left) and H2O/THF (90% H2O, v/v) (right) solvents under a UV lamp, λex of 365 nm and λem of 468 nm.
Figure 4.
Figure 4.
Time-dependent PL spectra of (a) Rot-A-SP, (c) Rot-B-SP, and (e) Mixture-SP in H2O/THF solvents (90% H2O, v/v) upon UV exposure (0–90 s) and schematic illustrations of energy transfer (ET) processes from TPE to MC units of (b) Rot-A-SP, (d) Rot-B-SP, and (f) Mixture-SP via ET processes after UV exposure. (insets) Photo-images of photoluminescence color changes (after 90 s of UV exposure). Concentration of 50 μM and λex of 365 nm.
Figure 5.
Figure 5.
PL spectra and relative emission intensities of (a,b) Rot-A-MC, (c,d) Rot-B-MC, and (e,f) Mixture-MC vs different water fractions. (insets) Fluorescence photo-images of (b) Rot-A-MC, (d) Rot-B-MC, and (f) Mixture-MC in pure THF (left) and H2O/THF (90% H2O, v/v) (right) under a UV lamp. Concentration of 50 μM and λex of 365 nm.
Figure 6.
Figure 6.
PL spectra and relative PL intensities of (a,b) Rot-A-MC, (c,d) Rot-B-MC, and (e,f) Mixture-MC in H2O/THF solvent (90% H2O, v/v) at various pH values. (insets) PL photo-images of (b) Rot-A-MC, (d) Rot-B-MC, and (f) Mixture-MC at different pH values. Concentration of 50 μM and λex of 365 nm.
Figure 7.
Figure 7.
PL spectra and relative PL intensities of (a,b) Rot-A-MC, (c,d) Rot-B-MC, and (e,f) Mixture-MC in H2O/THF solvent (90% H2O, v/v) at various temperatures (20–60 °C). (insets) PL photo-images of (b) Rot-A-MC, (d) Rot-B-MC, and (f) Mixture-MC at different temperatures. Concentration of 50 μM and λex of 365 nm.
Figure 8.
Figure 8.
Optimized structures of (a) Rot-A-MC and (b) Rot-B-MC and (c) molecular orbital energies of MC and TPE units in Rot-A-MC involved in the electronic transition. See the Supporting Information for the full list of absorptions.
Figure 9.
Figure 9.
Molecular orbital energies of MC and TPE units in Rot-B-MC involved in the electronic transition. See the Supporting Information for the full list of absorptions.
Figure 10.
Figure 10.
Photo-images of Rot-A-SP in (a) powder form (top: naked-eye and bottom: PL observation) and (b) coated cellulosic papers (top: naked-eye and bottom: PL observation) under UV/sunlight and Vis/heating processes, (c) PL emission color changes of a PMMA film blended with Rot-A-SP (0.5 wt %) under various UV exposure times, and (d) photo-patterning features of photochromic and multicolor fluorescent inks based on Rot-A-SP under UV/sunlight and Vis/heating processes.
Scheme 1.
Scheme 1.
Synthetic Routes for Axle-SP, Rot-A-SP, Rot-A-MC, Rot-B-SP, and Rot-B-MC
See this image and copyright information in PMC

References

    1. Stoddart JF Mechanically Interlocked Molecules (MIMs)-Molecular Shuttles, Switches, and Machines (Nobel Lecture). Angew. Chem., Int. Ed. 2017, 56, 11094–11125. - PubMed
    1. Fu H-G; Chen Y; Liu Y Multistimuli-Responsive and Photocontrolled Supramolecular Luminescent Gels Constructed by Anthracene-Bridged Bis(dibenzo-24-crown-8) with Secondary Ammonium Salt Polymer. ACS Appl. Mater. Interfaces 2019, 11, 16117–16122. - PubMed
    1. Arumugaperumal R; Srinivasadesikan V; Raju MVR; Lin MC; Shukla T; Singh R; Lin H-C Acid/Base and H2PO4− Controllable High-Contrast Optical Molecular Switches with a Novel BODIPY Functionalized [2]Rotaxane. ACS Appl. Mater. Interfaces 2015, 7, 26491–26503. - PubMed
    1. Inthasot A; Tung S-T; Chiu S-H Using Alkali Metal Ions to Template the Synthesis of Interlocked Molecules. Acc. Chem. Res. 2018, 51, 1324–1337. - PubMed
    1. Bruns CJ; Frasconi M; Iehl J; Hartlieb KJ; Schneebeli ST; Cheng C; Stupp SI; Stoddart JF Redox Switchable Daisy Chain Rotaxanes Driven by Radical-Radical Interactions. J. Am. Chem. Soc. 2014, 136, 4714–4723. - PubMed