Supporting Information

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1 Supporting Information Facile Cucurbit[8]uril-Based Supramolecular Approach to Fabricate Tunable Luminescent Materials in Aqueous Solution Xin-Long Ni, * Shiyan Chen, Yaping Yang and Zhu Tao Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang, Guizhou , China longni333@163.com Table of Contents Materials and methods Figure S1 Synthesis of guest G1 Figure S2 Determination of pk a of G1 Figure S3 Fluorescence spectrum of G1 at different ph Figure S4 Results of fluorescence life time Figure S5 Results of fluorescence quantum yield Figure S6 Plausible host-guest model of G1 with 0.5 equiv of Q[8] host Figure S7 Normalized fluorescence spectrum of Q[8]/G1 Figure S8 Ratiometric fluorescence response of Q[8]/G1 Figure S9 ITC titration experiment Figure S10 Plausible color tuning mechanism of Q[8]/G1 Figure S11 Plausible complex models of Q[8]/G1 Figure S12 1 H NMR titration of G1 with Q[8] Figure S13 DLS and AFM data of Q[8]/G1 at ph 2.0 Figure S14 Fluorescence spectrum of G1/Q[8] at different concentration Figure S15 Different fluorescence behavior of HGIM from ACQ and AIE Figure S16 Fluorescence of G1 in the presence of β- and γ-cyclodextrin Figure S17 Host-guest interaction induced pk a shift Figure S18 Host-guest interaction of Q[8]/G1 switched by ph Figure S19 Plausible host-guest interaction of Q[8]/G1 at ph 7.2 Figure S20 UV vis absorption spectrum of Q[8]/G1 at ph 7.2 Figure S21 Fluorescence spectrum of Q[8]/G1 at ph 7.2 Figure S22 DLS data of Q[8]/G1 at ph 7.2 Figure S23 ITC titration experiment of Q[8]/G1 at ph 7.2 References S2 S3 S5 S6 S7 S10 S11 S12 S12 S12 S14 S14 S15 S16 S16 S17 S18 S18 S18 S19 S19 S19 S20 S20 S20 S1

2 Materials and methods The solvents and the reagents were purified and dried by usual methods prior to use. Reagents purchased from commercial suppliers were used as received. Cucurbit[8]uril 1 and 1,4-bis[2-(4-pyridyl)ethenyl]benzene 2 were prepared according to the published procedures. 1 H NMR spectra were measured on a Varian INOVA-400 spectrometer or Nippon Denshi JEOL FT-500 NMR with SiMe 4 as an internal reference. MALDI-TOF mass spectra were acquired on a time-of-flight mass spectrometer equipped with a nitrogen laser. UV-vis spectra were recorded on a Agilent-8453 spectrophotometer. Fluorescence spectra measurements were performed on a Varian Cary Eclipse fluorescence spectrophotometer equipped with a xenon discharge lamp. Fluorescence lifetime and quantum yield were obtained with an Edinburgh Instrument FLS 980 fluorospectrometer. Dynamic light scattering (DLS) experiments were carried out with Malvern Zetasizer Nano-ZS light scattering apparatus (Malvern Instruments, U.K.) at room temperature. Atomic force microscopy images were obtained on AFM (CSPM 5500) in tapping mode in air at room temperature. Isothermal titration calorimetry (ITC) was carried out using a Nano ITC (TA, USA), isothermal titration calorimeter at 25 o C, computer simulations were performed using the Nano ITC analyze software. S2

3 Synthesis of 4,4 -[(1E,1 E)-1,4-Phenylenebis(ethene-2,1-diyl)]bis(1-carboxyethyl pyridinium) bromide (G1) A mixture of 1,4-bis[2-(4-pyridyl)ethenyl]benzene (570 mg, 2.0 mmol) and Br-CH 2 CH 3 COOH (765 mg, 5.0 mmol) in DMF (6 ml) and was heated to 100 o C for 24 hours. Then the reaction mixture was cooled and an excess amount of acetone (100 ml) was added the solution. The precipitate was filtered and washed with petroleum ether and acetone to give rise to a yellow solid 791 mg (yield 67 %). 1 H NMR (500 MHz, DMSO- d6 ), δ (s, 2H, -COOH), (d, J=5 Hz, 4H), (d, J=5 Hz, 4H), (d, J = 15 Hz, 2H, vinyl-h), 7.87 (s, 4H), (d, J=15 Hz, 2H, vinyl-h ), (t, J=10 Hz, 4H), (t, J=15 Hz, 4H); MALDI-TOF: m/z calcd for C 26 H 26 N 2 O 2+ 4 : ; found: ; elemental analysis calcd (%) for C 44 H 54 N 2 Br 2 : C 52.90, H 4.44, N 4.75; found: C 52.75, H 4.58, N, Figure S1. 1 H NMR spectrum of G1 (500 MHz, DMSO- d6 ). S3

4 Fluorescence lifetime measurements: Fluorescence lifetime measurements were obtained using the time-correlated single photon counting (TCSPC) method with an Edinburgh Instrument FLS 980 fluorospectrometer at 25 o C. The excitation source was a nitrogen nanosecond flash lamp. In the present work, 405 nm diode laser (~65.5 ps, Maximum flicker frequency 20 MHz) was used as the excitation source and a microchannel plate photomultiplier tube (R928P-PMT) was used for fluorescence detection. Decay time data analysis was made with the method of nonlinear last square iterative reconvolution. The quality of the fit was estimated by the reduced chi-square χ 2 and the autocorrelation function of the residuals. Absolute emission quantum yield measurements: Emission quantum yield (Φ) measurements were carried out using Edinburgh instrument model FLS980 equipped with 450W Xenon arc lamp at 25 o C. Quantum yield of the samples were calculated based on the absolute method using integrating sphere of diameter 15 cm coated with tetrafluoroethylene after standardization. The performance of the integrating sphere was verified by using rhodamine B as test sample. The absolute quantum yield was calculated for rhodamine B first and compared with its literature value (0.21) in water, which matched very well. It was assumed that light falling to tetrafluoroethylene coating are scattered perfectly (100%). Sample holder is kept in the centre of sphere and scattered light was collected by detector through two windows: one for entrance of exciting light and another for collection of scattered/emitted light. Emission quantum yield (Φ) is related to number of photons absorbed (α) and number of photons emitted by the sample (ε) as where, I emission is emission spectrum of sample, I solvent is the spectrum of light used to excite only solvent (water) and I sample is the spectrum of light used for exciting sample in solvent. In the present case samples were excited at 398 nm and emission spectrum were collected from 420 nm to 750 nm with minimum slit width. All spectrums were corrected with the correction factor for the integrating sphere before calculation of the S4

5 quantum yields. ph titrations: The pk a value was measured using the Rex model PHSJ-5 digital ph meter (Leici, China). Generally, The ph of G1 solutions ( mol L 1 ) were adjusted to ph = 2 with aqueous HCl (0.5 mol L 1 ), and afterwards they were titrated with a sodium hydroxide solution ( to 1.0 mol L 1 ) at 25 o C. The titrant was added discontinuously at constant ionic strength (0.15 M KCl), and the amount added at each step varied between and 0.1 ml. The ph change was of the order of 0.1 at each titration step. During one titration, between 80 and 100 different ph values were measured. The pk a value of sample was then calculated by RefinementPro software (Sirius Analytical Instruments Ltd., Forest Row, UK). Figure S2. ph titration of an aqueous solution (3.0 ml, M) of G1 with a normalized volume of NaOH ( M). The pk a value of sample was calculated to be Advanced Chemistry Development (ACD/Labs) Software V12.01 ( ACD/Labs) revealed that the calculation pk a of the carboxylic acid groups of G1 is Determination of ratio [HA]/[A - ]: With equation Considering an obtained pk a of 4.52 for G1, several [HA] values were calculated at distinct ph values (Table S1) S5

6 Table S1: Calculated mole fraction [HA]/[A - ] of G1 Figure S3. Fluorescence spectrum of G1 (10.0 μm) at different ph values (λ ex = 398 nm). S6

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8 Figure S4. (a) Fluorescence decay traces of G1 (10.0 μm) at 475 nm (λ ex = 398 nm) in aqueous solution (ph 2.0). (b-d) Fluorescence decay traces of G1 (10.0 μm) at 575 nm (λ ex = 398 nm) in aqueous solution (ph 2.0) upon addition of 0.2, 0.5, and 1.0 equiv of Q[8] host, respectively. (e) Fluorescence decay traces of G1 (1.0 μm) at 575 nm (λ ex = 398 nm) in aqueous solution (ph 2.0) upon addition of 1.0 equiv of Q[8] host. (f) Fluorescence decay traces of G1 (0.1 mm) at 575 nm (λ ex = 398 nm) in aqueous solution (ph 2.0) upon addition of 1.0 equiv of Q[8] host. (g-h) Fluorescence decay traces of G1 (10.0 μm) at 575 nm (λ ex = 398 nm) in aqueous solution (ph 7.2) upon addition of 0.2, 0.5, and 1.0 equiv of Q[8] host, respectively. In this experiment, G1 displays fast decay kinetics with contribution from a lifetime of 0.13 ns (100%). At ph 2.0, upon addition of Q[8] host to 0.2 equiv, the excited state decay kinetics of G1 displayed a long lifetime of ns (23.42 %) with a major contribution from a short component of 0.15 ns (76.58). This result indicated that the white-light is obtained by the mixture emission of free G1 and the Q[8]/G1 dimer complex. With increase in the concentrations of Q[8] host to 0.5 equiv, the excited state decay kinetics of G1 displayed a long lifetime of ns (75.39 %) with a minor contribution from a short component of 4.91 ns (24.61). Further gradual increase in the concentrations of Q[8] host to 1.0 equiv, the excited state decay kinetics of G1 displayed a major lifetime of ns (88.47 %) with a minor contribution from a short component of 1.55 ns (11.53). Generally, due to the encapsulation of G1 in Q[8] cavity, some of these relaxation processes are severely hindered by the hydrophobic cavity, which therefore allowing the lifetime to be measured in the ns time domain. On the other hand, according to Figure 2a, although the absorption of Q[8]/G1 complexes (as acceptor absorption) located in the higher energy area, the spectral overlap between the G1 emission and the host-guest interaction including dimer complexes absorption suggests that they may still can act as donor-acceptor couple for excitation energy transfer. In particular, because of the reversible assembly of G1 with Q[8], there are still some free G1 existed in the solution even in the presence of high concentration of Q[8]. Therefore, the major long lifetime can be attributed to the independent emission of the Q[8]/G1 complex, the minor relative short lifetime ascribed to the energy transfer of uncomplex G1 emission to the Q8/G1 complexes. S8

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10 Concentration of G μm 0.1 mm 1.0 μm sample a b c d e f Q[8]/G1 (mole ratio) Φ f(abs) (%) Figure S5. (a) Absolute fluorescence quantum yield (Φ f(abs) ) of G1 (10.0 μm) (λ ex = 398 nm) in aqueous solution (ph 2.0). (b-d) Absolute fluorescence quantum yield (Φ f(abs) ) of G1 (10.0 μm) (λ ex = 398 nm) in aqueous solution (ph 2.0) after addition of 0.2, 0.5 and 1.0 equiv of Q[8] host. (e) Absolute fluorescence quantum yield (Φ f(abs) ) of G1 (1.0 mm) (λ ex = 398 nm) in aqueous solution (ph 2.0) after addition of 1.0 equiv of Q[8] host. (f) Absolute fluorescence quantum yield (Φ f(abs) ) of G1 (1.0 μm) (λ ex = 398 nm) in aqueous solution (ph 2.0) after addition of 1.0 equiv of Q[8] host. Fluorescence quantum yield (Φ f(abs) ) of G1 increased up on encapsulation by the Q[8] host in aqueous solution is mainly attributed to (i) Q[8] host shielding the guest (G1) from quenchers (e.g., oxygen and the polar water molecule); 3 (ii) Q[8] host providing a restricted environment and affected the structure and electronic distributions of G1. 4 S10

11 (a) (b) Figure S6. (a) X-ray crystal structure 5 showing two trans-1,2-bis(4-pyridyl)ethylene dihydrochloride molecules aligned in a slipped antiparallel orientations (J-dimer) within Q[8] cavity. The two antiparallel aromatic guests have a distance about 3.9 Å in Q[8] cavity indicative of an extensive π π interaction was formed. (b) The encapsulation of the G1 in the Q[8] cavity was examined computationally with PM3 calculations, and all plausible structures were optimized. The energy-minimized structures for the Q[8]/G1 confirmed the antiparallel orientations (J-dimer) of G1 in the Q[8] cavity with a linear distance 3.63 nm. The results of (a) and (b) confirmed that the photophysical property changes of G1 upon addition of Q[8] host can be ascribed to the extensive π π interactions or intermolecular orbital overlap between G1 homodimers in the Q[8] cavity. S11

12 Figure S7. Normalized fluorescence emission spectrum of a solution of G1 (10.0 µm) with Q[8] (0 2.0 equiv). Figure S8. (a, b) Ratiometric response of G1 (10.0 µm, ph 2.0) switched by the Q[8] host. (c) The related coordinates data from CIE chromaticity diagram. ITC measurements: All microcalorimetric titrations were performed in aqueous solution at atmospheric pressure and K in a thermostated and fully computer-operated isothermal calorimetry (TA, U.S.A.). Each solution was degassed and thermostated by a ThermoVac accessory before the titration experiment. Twenty-five successive injections were made for each titration experiment. A constant volume (10 ml per injection) of host solution in a ml syringe was injected into the reaction cell ( ml) charged with a guest molecule solution in the same aqueous solution. A representative titration curve is shown in Figure S9. As can be seen from Figure S9, each titration of Q[8] into the sample cell gave an apparent reaction heat caused by the formation of an inclusion complex between Q[8] and G1. The reaction heat decreases after each injection of Q[8] because less and less guest molecules are available to form inclusion complexes. A control experiment was carried out in each run to determine the dilution heat by injecting an aqueous solution of the host into a pure aqueous solution containing no guest molecules. The dilution heat determined in these control experiments was subtracted from the apparent reaction heat measured in the titration experiments to give the net reaction heat. The net reaction heat in each run was analyzed by using the Independent model and S12

13 Multiple Site model (ORIGIN software, Microcal Inc.) to simultaneously compute the binding stoichiometry (N), complex stability constant (K a ), standard molar reaction enthalpy (ΔH ), and standard deviation from the titration curve. Generally, the first point of the titration curve was disregarded, as some liquid mixing near the tip of the injection needle is known to occur at the beginning of each ITC run. Knowledge of the complex stability constant (K a ) and molar reaction enthalpy (ΔH ) enabled calculation of the standard free energy (ΔG ) and entropy changes (ΔS ) according to ΔG = RT Ln K a =ΔH TΔS where R is the gas constant and T is the absolute temperature A typical curve fitting result for the complexation of Q[8] with G1 in aqueous solution (ph 2.0) is shown in Figure S9, which also evaluated by considering the following complexation equilibria Figure S9. (a) ITC titration curve fitted by Independent model indicated that a molar ratio of 0.5 of Q[8]/G1 was observed at the beginning of the titration when there was an excess of G1 around (K a = (9.47 ± 0.56) 10 6 M 2 ). (b) With continued addition of Q[8] into the G1 solution, a second transition appeared in the ITC titration curve, and fitted by Multiple Site model. The result suggested that a head to tail polymer was formed with mole ratio of 1:1 (Q[8]/G1). K 1 (K a ) and K 2 (K b )were found to be 2.91 ± M 2 and 9.99 ± M 3, respectively. S13

14 Figure S10. Plausible mechanism of color tuning of Q[8] based host-guest interaction in aqueous solution. Figure S11. Plausible host-guest interaction procedure of Q[8] with G1 in aqueous solution (ph 2.0). S14

15 Figure S12. 1 H NMR titration spectrum of G1 (1.0 mm, D 2 O, ph 2.0) upon addition of increasing concentrations of Q[8] (0-1.0 equiv) at 298 K. In the procedure of Q[8] ratio from 0.6 to 1.0, a new set of protons on the Q[8] host (H 1, H 2, and H 3, green color) appeared in the spectrum, which can be attributed to the Q[8] host interaction with different moiety of G1 (OPV and N substituted propionic acid, respectively). This result clearly suggested that the polymeric chains was formed by the two different Q[8]-based host-guest interaction (A and B). S15

16 Figure S13. DLS data of G1 (10.0 µm) with 1.0 (a) and 0.5 equiv of Q[8] (b) in aqueous solution (ph 2.0) at 298 K. (c) AFM image of the Q[8]/G1 system. The AFM sample was prepared by applying a 10.0 µm Q[8]/G1 (1:1, mole ratio) solution (ph 2.0) onto a newly clipped mica foundation, which was then air dried. The sample was analyzed in tapping mode. A linear 1D nanowire is clearly visualized by the AFM image. Figure S14. Changes in the fluorescence emission spectrum of G1 (a) (1.0 µm) and (b) (0.1 mm) upon addition of increasing concentrations of Q[8] (0 2.0 equiv) in aqueous solution at ph 2.0. S16

17 Figure S15. Fluorescence photographs 6 of solutions/suspensions of (A) aggregation-caused quenching (ACQ) with a typical example of N,N-dicyclohexyl-1,7-dibromo-3,4,9,10-perylenetetracarboxylic diimide in THF solution, (B) aggregation-induced emission (AIE) with a typical example of hexaphenylsilole in THF-water with different water contents. (C) host-guest induced emission (HGIE) with a typical example of Q[8]/G1 (1:1) in dilute and high concentrations in water. The results demonstrated HGIE has highly fluorescence emissions at both low- and high-concentration due to the hydrophobic cavity based host-guest interaction and is very different from ACQ and AIE. In particular, the noncovalent interaction bearing switchability and reversibility led to the HGIE based fluorescent materials have a wide application sensors and materials. S17

18 Figure S16. Fluorescence emission spectrum changes of G1 (10.0 µm) upon addition of increasing concentrations of β- and γ-cyclodextrin (0-4.0 equiv) in aqueous solution at ph 2.0. Figure S17. pk a value of Q[8]-G1 (1:1) in aqueous solution by monitoring the absorption change of G1 (10.0 µm) at λ = 405 nm upon ph variation. 7 Figure S18. Plausible host-guest interaction of Q[8] with G1 which switched by the ph (ph < 2.0, head to tail polymer (A type); ph > 7.0, J-dimer (B type); 2.0< ph < 7.0, (mixture of A+B)). S18

19 Figure S19. Plausible ph controlled host-guest interaction of Q[8] with G1 in aqueous solution. Figure 20. UV vis absorption spectrum of G1 (10.0 µm) at increasing concentrations of Q[8] (0-3.0 equiv) in aqueous solution (ph 7.2) (left); right: curve of A vs. nq[8]/ng1 for the absorption peak at 395 and 405 nm, respectively. The changes and results indicated that Q[8]/G1 is 1:2 molar ratio. Figure S21. Fluorescence spectral changes G1 at increasing concentrations of Q[8] (0-3.0 equiv) in aqueous solution (ph 7.2). Compared to Fig. 2a, the fluorescence enhancement of G1 at 580 nm indicative of only 1:2 complex of Q[8]/G1 was formed even at high concentration of Q[8]. S19

20 Figure S22. DLS results for G1 (10.0 µm) with 1.0 equiv of Q[8] in water (ph 7.2) at 298 K. Data represent the hydrodynamic diameters (D h ) is 4.18 nm which consistent with the linear diameter of J-dimer complex of Q[8]/G1 (3.63 nm, Figure S6). Figure S23. Microcalorimetric titration data and fitting curves (HEPES buffer solution, 10 mm, ph 7.2) at K; Q[8] (0.2 mm) titrated into G1 (0.02 mm) in aqueous solution. References (1) Kim, J.; Jung, I. S.; Kim, S. Y.; Lee, E.; Kang, J. K.; Sakamoto, S.; Yamaguchi, K.; Kim, K. J. Am. Chem. Soc. 2000, 122, (2) Ichimura, K.; Watanabe, S. J. Polym. Sci., Polym. Chem. Ed. 1982, 20, (3) (a) Marquez, C.; Huang, F.; Nau, W. M. IEEE Trans. Nanobiosci. 2004, 3, (b) Freitag, M.; Gundlach, L.; Piotrowiak, P.; Galoppini, E. J. Am. Chem. Soc. 2012, 134, (4) Choudhury, S. D.; Mohanty, J.; Pal, H.; Bhasikuttan, A. C. J. Am. Chem. Soc. 2010, 132, (5) Pattabiraman, M.; Natarajan, A.; Kaliappan, R.; Magueb, J. T.; Ramamurthy, V. Chem. Commun. 2005, (6) Hu, R.; Leung, N. L. C.; Tang, B. Z. Chem. Soc. Rev. 2014, 43, (7) Mohanty, J.; Bhasikuttan, A. C.; Nau, W. M.; Pal, H. J. Phys. Chem. B 2006, 110, S20