Humidity- and Temperature-Tunable Multicolor Luminescence of

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Humidity and Temperature Tunable Multicolor Luminescence of Cucurbit[8]uril-based Supramolecular Assembly Tao Jiang, Xi Wang, Jie Wang, Guoping Hu, and Xiang Ma ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 27 Mar 2019 Downloaded from http://pubs.acs.org on March 27, 2019

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ACS Applied Materials & Interfaces

Humidity and Temperature Tunable Multicolor Luminescence of Cucurbit[8]uril-based Supramolecular Assembly Tao Jiang, Xi Wang, Jie Wang, Guoping Hu and Xiang Ma* Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai, 200237, China.

ABSTRACT: Fabrication of tunable luminescent materials by single luminophore is a challenge owning to the limit of emissive properties of mono-fluorophore. Herein, a type of temperature and humidity dual-responsive luminescent material based on host-guest supramolecular selfassembly was developed. Included into the cavity of cucurbit[8]uril (CB[8]) to form a 1:2 hostguest binding motif, the highly blue-emissive thiazolothiazole methyl-viologen (TMV) molecules were promoted to stack closely with dramatical luminescence decrease at 460 nm and rise of the dimer emission at 535 nm especially at high concentration in aqueous solution, which was demonstrated by fluorescence spectra, UV-Vis absorbance spectra, NMR, and ITC data. Accordingly, when printed on paper, the 1/2 CB[8]/TMV complex presented a reversibly humidity-dependent emissive behavior with luminescent color changing from greenish-yellow in wet to blue upon evaporation. Besides, the susceptibility of host-guest interaction endowed the CB[8]/TMV complexes with temperature-tunable emission which showed a considerably enhanced blue luminescence at higher temperature. Subsequently, a ratiometric temperature-

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responsive emitter with luminesce reversibly from pink to white and then to blue light at temperature ranging from 0 oC to 70 oC was fabricated by mixing CB[8]/TMV complex with thermal-sensitized emitting GSH-Au nanoclusters. These fine-tuning abilities endow the CB[8]/TMV supramolecular complex with promising applicable visual luminescent devices such as anti-counterfeiting labels and fluorescent thermometers.

KEYWORDS: host-guest self-assembly, cucurbit[8]uril, multicolor emission, white-light emission, gold nanocluster

INTRODUCTION Tunable luminescent materials have gained the extensive attention for their multiple optical characteristics and potential applications in fields such as light-emitting diodes,1 fluorescent probes and sensors,2,

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biological imaging,4,

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anti-counterfeiting,6 and so on. In particular,

tunable white-light emitting materials, which present RGB full-color or blue-yellow dual emission, have attracted considerable research attentions especially in light-emitting field for its superiority in intuitive observing from human visions.7 Furthermore, in consideration of the environmental compatibility of metalliferous luminescent complex and the costly and tedious synthesis procedures of organic chromophore, fabrication of multi-color emissive materials by mono-luminophore is a challenge because of its uniform molecular structure, which has been received much concern in recent years.8, 9 Generally, the approaches to tune multi-emissive chromophore, including adjusting pH,10 solvents,11 temperature,12 photo-irradiation,13-16 mechanical grinding17 and humidity,18 can be


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designed mainly by photophysical mechanisms such as energy transfer (ET),19 charge-transfer (CT, including inter- and intra-molecular ones),20 H- or J-aggregation,21 excited-state intramolecular proton transfer (ESIPT),22 vibration-induced emission (VIE),23 aggregationinduced emission (AIE)24 and fluo-phosphorescence dual-emission etc.25 As facile and noninvasive approaches, tuning temperature and humidity featured rapid response and can be applied on color-tunable visual devices such as luminescent temperature sensors,26, 27 humidity detectors 28 and fluorescent anti-counterfeiting.29 On the other hand, only a few literatures about tunable emission based on uniform organic fluorophore have been reported because of the difficulty for most chromophores with simple uniform π-conjugated structure in obtaining multiple excited-state pieces. Therefore, it’s a challenge to develop more tunable luminescent materials consisting of uniform chromophore by elaborating molecular design and valid modulatory approaches. Recently, the host-guest supramolecular interaction has been developed as a novel approach to fabricate tunable multi-color emissive materials in solids and solutions.30-33 In this case, macrocyclic molecules such as cucurbit[8]uril (CB[8]) and γ-cyclodextrin (γ-CD) are the most commonly used as host molecules because of their large cavity and excellent capacity to include specific luminescent guests.34-37 With inclusion of two specific guest luminophores, which is mainly driven by non-covalent interactions such as hydrophobic interaction, ion-dipolar interaction and H-bonding,38-40 CB[8] or γ-CD enables guest molecules to stack with each other orderly in limited space and subsequently generate a new red-shift fluorescent emission at Jaggregative or charge-transfer state.41,42 In addition, since the delicate and accessible characteristics of non-covalence, host-guest interaction is a facile and susceptible approach to tune the emissive behavior of guest chromophores by varying the ratio of host to guest and


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conditions such as pH, photo-irradiation and oxidation-reduction, which has excellent reversibility.43-45

Scheme 1. (a) Illustration of emissive host-guest dynamic self-assembled motifs of TMV with different equiv. of CB[8] in aqueous solution. (b) Schematic representation of dissociation and emission color change of 1/2 CB[8]/TMV patterns on paper in different humidity states under 365 nm irradiation. (c) Fabrication of thermo-mediated ratiometric fluorescent emitter by mixing diluted TMV/CB[8] solution with aqueous gold-nanoclusters (AuNCs) solution. To fabricate more multiple and tunable emissive materials with simple uniform π-conjugated chromophore, we herein elaborated a novel tunable emissive host-guest complex comprised of CB[8] and thiazolothiazole methyl-viologen fluorophore (TMV) with reversible response to humidity and temperature. Contributed to the specific molecular structure and highly efficient blue emission, TMV can be dynamically self-assembled with CB[8] in aqueous solution by two binding modes, which exhibit a different greenish-yellow emission derived from the closely stacking supramolecular TMV dimer of 1/2 host/guest motif and blue emission for


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supramolecular monomer of 1/1 one, respectively. Interestingly, when printed 1/2 CB[8]/TMV solutions on water-absorbing substrates such as paper and silica, the emission color was gradually changed from greenish-yellow to blue with the evaporation of water and reversibly turned back in watering conditions. Accordingly, we utilized this host-guest solution as fluorescent ink to print an alterable 2D-code pattern on paper, displaying a reversible yellow to blue emission color change under drying procedure. Besides, the susceptibility of host-guest interaction and free shuttle movement of TMV endowed the 1/2 CB[8]/TMV complex with temperature-tunable emission which presented a considerable enhanced blue luminescence with elevation of temperature. By mixing glutathione modified gold nanoclusters (GSH-AuNCs) that featured suppressed orange luminescence upon heating, a tunable multicolor temperaturedependent emitter was fabricated and presented a pink-white-blue emission color variation when temperature elevated from 0 to 70 oC. Those humidity and temperature dependent emissive properties granted the CB[8]/TMV supramolecular complex promising applications to visual luminescent devices such as anti-counterfeiting labels and ratiometric fluorescent thermometers. To our knowledge, this is the first example to fabricate humidity and temperature responsive emissive materials based on macrocyclic host-guest self-assembly and can attach more inspirations to fabricate new tunable luminescent materials (see Scheme 1). RESULTS AND DISCUSSION The Optical Properties of CB[8]/TMV Complexes. The molecule N, N’-dimethy 2,5-bis(4pyridinium) thiazolo[5,4-d] Thiazole Ditosylate (TMV) featuring high efficient blue emission (λem= 460 nm) was chosen as the guest due to its specific methyl-viologen-like molecular structure possessing planar hydrophobic aromatic rings and two positive charged terminals, thus providing hydrophobic effect and ion-dipolar interaction with CB[8]. Considering its slender


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molecular shape and positive charges, one CB[8] cavity can include two TMV guests with closely off-side stacking configuration and enable TMV to form supramolecular dimers such as excimers which feature a new longer-wavelength emission and different fluorescent lifetimes. To demonstrate this anticipation, the luminescent data of mixed aqueous TMV/CB[8] solutions with different molar ratios were characterized. As shown in Figure 1, with addition of less than 0.5 equiv. of CB[8] into the TMV solution, the emission intensity at λ460nm remarkably declined and a new large stokes-shift and broad emission with no vibrating structure at 535 nm generated which was observed distinctly in aqueous CB[8]/TMV=1/2 complex solution especially at high concentration (Figure 1a). Moreover, the lifetime of greenish-yellow fluorescence (4.59 ns) is also longer than the blue emission (1.8 ns, reported by Woodward et al.46) (shown in Figure S2). Unexpectedly, other than the previously reported CB[8]-based host-guest emissive motifs, the supramolecular self-assemblies presented an increasement of emissive intensity at 460 nm upon adding CB[8] to TMV in more than 0.5 equiv., indicating the disassembly of supramolecular dimer and formation of 1/1 TMV/CB[8] motif which featured a same blue emission as free TMV did (Figure 1c,d and Figure S1). Besides, the UV-Vis absorption spectra of TMV exhibited notable changes in the presence of CB[8] as well. As shown in Figure 1b, the maximum absorbent peak at 390 nm decreased remarkably and became narrow, sharp and generate slightly redshift after adding less than 0.5 equiv. of CB[8], which was ascribed to the suppression of rotation and vibration of TMV when included into the finite cavity of CB[8]. And similar changes were observed in absorption spectra of CB[7]/TMV complexes and pure TMV solid states as well (seen in Figure S3). Nevertheless, compared with CB[8]/TMV=1/2 inclusion complex, the λ390nm absorbance would increase mildly when adding excess equivalent of CB[8] with generating a new shoulder absorption peak at 415 nm which was increased with the


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equivalent of CB[8]. Based on these luminescence and absorption studies, we discreetly deduced that there existed two binding motifs, namely 1/2 and 1/1 complexes, in CB[8]/TMV supramolecular self-assembly. When the ratio of host is below 0.5, CB[8]/TMV complexes favor forming 1/2 inclusion model which promotes two TMV molecules to stack closely with each other in an “off-side” way to optimize the π-π stacking and charge-repulsive forces between guests. Therefore, the close stacked TMV remarkably quench their original blue emission and emerge a new greenish-yellow emission featuring redshift, broad, vibration-free structure and longer lifetime characteristics in fluorescent curves. On the other hand, an excess CB[8] will transform the assembled 1/2 complex into 1/1 one which exhibits similar highly efficient blue fluorescence as free TMV monomer does on account of the disassembly of closely-stacked TMV dimers. It should be noted that, different with the “first falling and then rising” tendency of fluorescence, the new emerged absorbent peak at 415 nm continues to rise with the addition of CB[8] even above 0.5 equivalent. We presumed that the new-generated absorbent peak resulted from the restricted configuration of TMV monomer in CB[8] cavity and confirmed by the reference absorbance experiment of CB[7]/TMV mixture, which could only form 1/1 host-guest complex for the limited cavity space, exhibiting hardly fluorescence decline at 460 nm and showing a new absorption at 415 nm as well (Figure S3 ).


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Figure 1. (a) Fluorescence emission spectra and (insert) photographs of TMV and 2/1 TMV/CB[8] in aqueous solutions under 365 nm UV light. The concentration of TMV in two samples is 1 mM. (b) UV-Vis absorption spectra and (c) Fluorescence emission spectra of diluted TMV/CB[8] solutions at different ratios at 298K. (d) Photographs of solution of TMV upon addition of increasing concentrations of CB[8] (0-3 equiv.) in aqueous solution under UV light at 365 nm. The concentration of TMV in b, c and d is 20 μM. All of the ratio value in above spectra are calculated by TMV/CB[8]. Binding Modes of CB[8] and TMV. Accordingly, NMR, ITC, Job’s plot and MALDI-TOFMS studies were carried out as well to further investigate the host-guest self-assemblies. As shown in Figure 2, when mixed with CB[8], two sets of protons (a and b) on pyridyl moiety of TMV shift upfield from 8.78 ppm to 8.67 ppm (marked as a’) and from 8.47 ppm to 8.32 ppm


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(marked as b’) respectively as a result of shielding effect of CB[8] cavity; on the other hand, the methyl protons c featuring a little downfield shift to c’ upon host-guest inclusion indicates that the methyl group is located on the outside of CB[8]. Likewise, all protons of CB[8] shift upfield as well attributed to the shielding effect of aromatic moiety of TMV. In addition, the original 1HNMR signals of methyl-pyridyl moiety completely disappear when the ratio of CB[8]/TMV is beyond 1/2, indicating that all TMV molecules have been included into CB[8] cavities. These results were further validated by diffusion-ordered spectroscopy (DOSY) spectrum and isothermal titration calorimetry (ITC) test. As shown in Figure S4, DOSY signals at diffusion rate of 4.82 × 10−10 m2s−1 were observed in 5 mM CB[8]/TMV=1/2 D2O solution and at 6.75 × 10−10 m2s−1 in TMV solutions in the same concentration. In addition, ITC experiment presented a binding constant Ka=(4.04 ± 0.54) × 106 M−2 at the binding ratio of 1:2, demonstrating that stable 1/2 complexes had been formed in CB[8]/TMV solutions (Figure S5). Nevertheless, the chemical shift of protons c shifts downfield when CB[8] is less than 0.5 equiv. and conversely upfield back to original value upon addition more CB[8], suggesting an alteration of the inclusion behavior between CB[8] and TMV. Notably, all the a’, b’ and c’ proton signals only feature one peak, demonstrating a dynamic inclusion behavior between TMV and CB[8]. The TMV guest could move more frequently in the host cavity because of its longer aromatic moiety than traditional guests such as methyl-viologen. On account of the poor solubility of CB[8], it is hard to observe the diffusion signals of 1/1 complex in DOSY experiments. And the dynamic inclusion interaction probably accounted for the only 1:2 binding constant demonstrated by ITC data because of the more free movement and easier dissociation between TMV and CB[8] in 1:1 binding model compared with the 1:2 one. Nevertheless, the 1:1 CB[8]/TMV assembly complex was demonstrated by Job’s plot study that presented two binding ratios, namely 1:1 and 2:1 for


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TMV/CB[8] (Figure S6) and MALDI-TOF-MS spectrum indicating a mass peak of [TMV/CB[8]]+ specie at m/z=1654.8092 (calculated: 1654.5549) (Figure S7).

Figure 2. 1H NMR titration of CB[8]/TMV complexes in D2O at 298 K. 1:1, 1:1.5, 1:2 and 1:3 represent the ratio of CB[8]/TMV. Characters a-e and a’-c’ represent the resonance signals for the TMV before and after being included into CB[8], respectively.

Figure 3. (a) Normalized fluorescence spectra and (b) 1931 CIE chromaticity coordinate of 1/2 aqueous CB[8]/TMV solution at concentrations from 10 μM to 1 mM. The dash arrows represent


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the changing tendency of fluorescence spectra. Excitation wavelength is 365 nm. (c) Photographs of three typical 1/2 CB[8]/TMV samples at 1 mM, 0.1 mM and 0.01mM, respectively. Top: under natural light; Bottom: under 365 nm light in dark. Water Mediated Emission Color Change. We observed that the 1/2 CB[8]/TMV complex presented concentration-dependent color emission, that is, blue-white color fluorescence at low concentrations (below 0.05 mM) while greenish-yellow color luminescence at relative high concentrations (above 0.1 mM) (see Figure 3). This property is attributed to the dynamic selfassembly between TMV and CB[8] and difference of concentration-sensitivity between the original blue emission (from free TMV monomers) and the emerging greenish-yellow emission (from closely-stacked supramolecular dimers). The free TMV monomers exhibited strong aggregation-caused-quenching (ACQ) and slight red-shift effects (see Figure S8) while the supramolecular dimers formed by host-guest interaction showed a relative insensitive luminescence to concentration even above 0.1 mM. Attributed to the dynamic inclusion interaction and high emissive efficiency of TMV, the blue emission at 460 nm is still existed even at 1mM. When dropped the 0.1 mM aqueous 1/2 complex solution onto water-absorbed materials such as paper and silica, obvious yellow color fluorescence could be observed directly in wet state due to the inspissation effect of absorbent materials. The 460 nm fluorescence peak of 1/2 CB[8]/TMV dramatically declined when dropping the complex solution on silica, which was presumed to concentration effect of water-absorbing silica. As shown in Figure 4, the greenlish-yellow emission would gradually transfer into blue one when evaporated paper or silica and could change back when dropped water on it. The fluorescent spectra of 1/2 silica/TMV/CB[8] in different humidity show a considerable rise of luminescent intensity at 460 nm under evaporation. As a reference, the pure silica/TMV powders just presented a slight


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emissive intensity variation at 460 nm under different humidity (Figure 4b). A proposed explanation to this humidity-dependent emission is that water can dramatically prompt the assembly of TMV and CB[8] because of the hydrophobic driven force of host-guest interactions and then the TMV dimers of host-guest complex are dissociated into highly blue emissive free TMV when water is evaporated. To demonstrate this presumption, solid UV-Vis absorbance study of silica/TMV/CB[8] was conducted, as shown in Figure 4c, the absorption peak of dry solids causes a blue shift and features a similar absorption curve with pure TMV, indicating the dissociation of TMV/CB[8] after evaporating water. Notably, despite TMV exhibits a strong ACQ effect in aqueous solutions, solid materials such as paper and silica can serve as rigid matrix to disperse TMV molecules. As a result, there still exists a considerable blue fluorescence of TMV after printing solutions on paper. Attributed to this distinct humidity-dependent emissive property, we utilized 1/2 TMV/CB[8] solutions as fluorescent ink to print a two-dimensional code pattern (linked to some website) on a paper sheet, which presented blue fluorescence in dry state and yellow one under treatment of watering while the pure TMV ink hardly exhibited any emission color change under the same conditions (as shown in Figure 4d). Moreover, the greenish-yellow emissive pattern would be gradually changed back with continuous evaporation. The water-dependent optical behavior provided the TMV/CB[8] complex with access to applications such as anti-counterfeiting labels and secret writing, to our knowledge, this is the first humidity-responsive emissive motif based on macrocyclic host-guest self-assembly.


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Figure 4. Fluorescence spectra of 1/2 CB[8]/TMV complex (a) and free TMV aqueous solution (b) mixed with silica powders at different humidity. Insert: Character “E” written with 1/2 CB[8]/TMV complex (a) and free TMV (b) aqueous ink on paper in original wet state (down) and after drying 5 min by a blower (top). (c) Solid absorbance spectra of TMV and 1/2 CB[8]/TMV complex in silica. (d) Photographs of fluorescent 2D Code printed with 1/2 CB[8]/TMV ink under dry and wet procedures. The excitation and irradiation light are at 365 nm uniformly. Temperature-dependent Optical Characteristics. Ascribed to the susceptibility of supramolecular interactions, we presumed that the fluorescent intensity of 1/2 CB[8]/TMV complex could be remarkably influenced by temperature. Figure 5a indicates that the intensity of blue emission at 460 nm gradually increases with temperature elevation from 0 oC to 60 oC accompanied by the decline of emission at 535 nm. Accordingly, the intensity of λ460nm at 60 oC rises by 178% than the ones at 0 oC while pure TMVs hardly exhibit obvious changes with the increase of temperature (see Figure S9). UV-Vis spectra indicated considerable changes upon


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heating CB[8]/TMV solutions. As shown in Figure S10, both 1/1 and 1/2 host/guest mixed with aqueous solution featured an nearly unchanged absorption at 390 nm and evidently enhanced absorption at 415 nm when elevated temperature from 20 oC to 60 oC, indicating that closelystacking 1/2 CB[8]/TMV complex has transformed into loose ones with weakening π-π interactions because the TMV could move more freely in the cavity of CB[8] upon heating and thus exhibited similar optical characteristics with the 1/1 complex.

Figure 5. Fluorescence spectra of (a) 1/2 CB[8]/TMV complex (50 μM, λex= 390 nm) and (b) GSH-AuNCs (0.5 mg/ml, λex = 400 nm) at different temperatures. Insert: Correlative emissive intensity of 460 nm of CB[8]/TMV complex (a) and 600 nm of AuNCs aqueous solution (b) variation with temperature. To take advantage of the temperature-dependent emission of CB[8]/TMV complexes, glutathione-ligand gold nanoclusters (GSH-AuNCs) with similar excited wavelength and orange emission at 600 nm was utilized to fabricate a thermo-tunable white-light emissive material via simple mixing. The synthesis of GSH-AuNCs, a type of ultrasmall nanoclusters (< 2 nm, Figure S11) presenting relatively high effective Au(I) emission, was according to a method previously reported by Luo et.al.47 In addition, we found that these orange-emitting AuNCs featured an enhanced luminescent behavior under low temperature conditions (see Figure 5b) and exhibited a rapid declining emission upon heating. Although there have existed disputes about the specific


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emissive mechanism of AuNCs, a considerable explanation of this temperature-dependent characteristic, according to previously reported studies,48 is deduced. The orange emission at 600 nm, originating from Au(I)–thiolate complexes on the AuNCs surface, is susceptible to external conditions such as thermal motion of ligands because of the long lifetime of excited states (Figure S12). Accordingly, a temperature-dependent white-light emitting aqueous solution was constructed by mixing the 1/2 CB[8]/TMV complex and GSH-AuNCs solutions with final concentration at 6×10-6 M and ~0.5 mg/mL respectively under room temperature. As shown in Figure 6, despite a certain degree of quenching in hybrids (Figure S13), the emission of room temperature white-light emissive solution gradually went pink color when cooled down to approximately 0 oC and turned into blue color when heated up to 70 oC. The CIE 1931 chromaticity diagram indicates that the coordinates change from (0.40, 0.39) to (0.19, 0.20) smoothly with temperature ranging from 0 oC to 70 oC, and the coordinates for the white-light emission at 40 oC are (0.33, 0.33) (QY=2.37%) demonstrating a standard white-emission. Besides, as shown in Figure 7a, the ratio of I460nm/I600nm featured an increasing change with temperature ranging from 0 oC to 70 oC. In addition, the cyclic temperature-controlled emission test demonstrated a good reversibility of emissions at 460 nm and 600 nm through the heatingcooling procedure between 0 oC and 70 oC for more than ten times. These sensitive fluorescent color change and good reversibility enable CB[8]/TMV & GSH-AuNCs hybrid to fabricate selfreferencing optical thermometry for visual temperature detection.


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Figure 6. (a) Photo luminescence spectra and (b) Corresponding 1931 CIE chromaticity coordinate of CB[8]/TMV(6 μM) and AuNCs (0.5 mg/ml) hybrid at temperatures from 0 oC to 70 oC. (c) Photographs of hybrid at temperatures from 10 oC to 70 oC under 365 nm UV light.


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Figure 7. (a) Ratio of emission intensity at 460 nm and 600 nm of CB[8]/TMV & AuNCs hybrid variation with temperature. Cyclic temperature-controlled emissive test of hybrid between


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10 oC and 60 oC. The luminescence intensity variation with cycles at 460 nm (b) and 600 nm (c) (excited at 365 nm). CONCLUSION In summary, we have developed new host-guest complexes based on CB[8] with highly blue emissive TMV featuring a new-generated greenish-yellow luminescence from closely stacking supramolecular dimers, which was prompted by the inclusion of two TMVs into the cavity of CB[8]. Moreover, the 1/2 aqueous CB[8]/TMV solution presented a concentration-dependent emissive behavior, that is, blue-white emission at concentrations below 0.05 mM while greenishyellow one at concentrations above 0.1 mM. Attributed to the dynamic characteristic of hostguest interaction, the 1/2 CB[8]/TMV complex reversibly featured a humidity responsive emission upon absorption in hydrophilic substrates and a temperature-dependent luminescence in aqueous solution, respectively. When printed on paper, the CB[8]/TMV pattern presented a greenish-yellow emission in wet and blue fluorescence under evaporation. Since the elevation of temperature also promoted the 1/2 complex to emit strong blue fluorescence, we fabricated a thermal-regulated emitter by mixing GSH-AuNCs that presented temperature-dependent emission in contrary to the complex. The ratiometric fluorescence colors varied from pink to blue with temperature ranging from 0 oC to 70 oC with good reversibility and presented standard white light at 40 oC. Above all, our study have extended the fabrication methods of controlled luminescent materials by tuning the assembly of host and guest, and these fine-tuning abilities endow the CB[8]/TMV supramolecular complex to serve as visual luminescent devices such as anti-counterfeiting labels and fluorescent thermometers. EXPERIMENTAL SECTION


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Materials and Methods. All reagents were purchased from Sigma-Aldrich or TCI Chemicals and used without further purification. TMV and AuNCs was synthesized according to the published procedures.39, 40 Solvents were purified according to standard laboratory methods. 1H NMR, 13C NMR and diffusion-ordered spectroscopy (DOSY) spectra were recorded on a Brüker AV-400 spectrometer. The experiments were performed at room temperature in deuterated solvent. Chemical shifts were shown in ppm relative to TMS and the solvent residual peak was used as the internal standard. The electronic spray ionization (ESI) high-resolution mass spectra were tested on a HP 5958 mass spectrometer, and also a BIFLEIII matrix-assisted laser vario desorption/ionization time of fight mass spectrometry (MALDI-TOF MS) instrument was applied. UV-Vis absorption spectra were performed on a Varian Cray 500 spectrophotometer. Fluorescence spectra and Quantum yields were determined by using HORIBA FluoroMax-4 spectrometer. Fluorescent lifetime was carried out using a Life Spec-Red spectrometer. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Full experimental details, NMR, UV−Vis, fluorescence spectrum, fluorescence lifetime, ITC experiment, MALDI-TOF MS, TEM and control experiments.

AUTHOR INFORMATION Corresponding Author *Email: [email protected] Notes


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The authors declare no competing financial interest.

ACKNOWLEDGMENT We gratefully acknowledge the financial support from NSFC/China (21788102, 21722603, 21871083, and 21476075), Shanghai Municipal Science and Technology Major Project (Grant No.2018SHZDZX03), the Innovation Program of Shanghai Municipal Education Commission (2017-01-07-00-02-E00010), Programme of Introducing Talents of Discipline to Universities (B16017) and the Fundamental Research Funds for the Central Universities. REFERENCES (1) Park, Y. I.; Postupna, O.; Zhugayevych, A.; Shin, H.; Park, Y. S.; Kim, B.; Yen, H. J.; Cheruku, P.; Martinez, J. S.; Park, J. W.; Tretiak, S.; Wang, H. L. A New pH Sensitive Fluorescent and White Light Emissive Material through Controlled Intermolecular Charge Transfer Chem. Sci. 2015, 6, 789-797. (2) Zhu, H.; Fan, J.; Du, J.; Peng, X. Fluorescent Probes for Sensing and Imaging within Specific Cellular Organelles Acc. Chem. Res. 2016, 49, 2115-2126. (3) Chen, L.; Ye, J.-W.; Wang, H.-P.; Pan, M.; Yin, S.-Y.; Wei, Z.-W.; Zhang, L.-Y.; Wu, K.; Fan, Y.-N.; Su, C.-Y. Ultrafast Water Sensing and Thermal Imaging by a Metal-Organic Framework with Switchable Luminescence Nat. Commun. 2017, 8, 15985. (4) He, X.; Zhao, Z.; Xiong, L.-H.; Gao, P. F.; Peng, C.; Li, R. S.; Xiong, Y.; Li, Z.; Sung, H. H. Y.; Williams, I. D.; Kwok, R. T. K.; Lam, J. W. Y.; Huang, C. Z.; Ma, N.; Tang, B. Z. RedoxActive AIEgen-Derived Plasmonic and Fluorescent Core@Shell Nanoparticles for Multimodality Bioimaging J. Am. Chem. Soc. 2018, 140, 6904-6911. (5) Peng, H.-Q.; Sun, C.-L.; Niu, L.-Y.; Chen, Y.-Z.; Wu, L.-Z.; Tung, C.-H.; Yang, Q.-Z. Supramolecular Polymeric Fluorescent Nanoparticles Based on Quadruple Hydrogen Bonds Adv. Funct. Mater. 2016, 26, 5483-5489. (6) Li, D.; Yang, X.; Yan, D. Cluster-Based Metal–Organic Frameworks: Modulated Singlet– Triplet Excited States and Temperature-Responsive Phosphorescent Switch ACS Appl. Mater. Interfaces 2018, 10, 34377-34384. (7) Mukherjee, S.; Thilagar, P. Organic White-Light Emitting Materials Dyes Pigm. 2014, 110, 2-27. (8) Zhu, L.; Ang, C. Y.; Li, X.; Nguyen, K. T.; Tan, S. Y.; Ågren, H.; Zhao, Y. Luminescent Color Conversion on Cyanostilbene-Functionalized Quantum Dots via In-situ Photo-Tuning Adv. Mater. 2012, 24, 4020-4024.


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TOC picture of the manuscript.


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Humidity- and Temperature-Tunable Multicolor Luminescence of

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