Tetraphenylethylene-Based Emissive Supramolecular Metallacages Assembled by Terpyridine Ligands

Abstract

Open AccessCCS ChemistryRESEARCH ARTICLE1 Aug 2020Tetraphenylethylene-Based Emissive Supramolecular Metallacages Assembled by Terpyridine Ligands Meng Li†, Shan Jiang†, Zhe Zhang, Xin-Qi Hao, Xin Jiang, Hao Yu, Pingshan Wang, Bin Xu, Ming Wang and Wenjing Tian Meng Li† State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Shan Jiang† State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Zhe Zhang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Xin-Qi Hao Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006 , Xin Jiang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Hao Yu State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Pingshan Wang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Bin Xu *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 , Ming Wang *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 and Wenjing Tian State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012 https://doi.org/10.31635/ccschem.020.201900109 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesTrack Citations ShareFacebookTwitterLinked InEmail We report the preparation and emission properties of tetraphenylethylene (TPE)-based metallacages with aggregation-induced emission (AIE) activities through coordination-driven self-assembly. Two supramolecular cages, [ Zn6LA3] and [ Zn6LB3], were assembled via TPE-decorated terpyridine (tpy) ligands, LA and LB, respectively, with Zn(II) ions. We performed a subtle change by introducing extra alkyne connectivity into LB to increase the degree of conjugation and geometric constraint, compared with LA. As a result, we obtained a highly emissive cage, [ Zn6LB3], even in a dilute solution. At a low temperature, the intramolecular rotation of TPE was further restricted, thus, resulting in a significant increase in fluorescence. Through mixing LA and LB, we obtained a series of hybrid cages, which also indicated that the emission was enhanced with highly abundant LB in the cages. Further, we studied the emission behaviors of the ligands and cages in solid state under external pressure. Upon gradual increase of the external pressure, the luminescence of [ Zn6LB3] increased initially, due to further rotation restriction, which was followed by quenching under 6.32 Gpa, owing to the tight packing of the supramolecules. The subsequent release of the pressure resulted in cage recovery of the emission. Download figure Download PowerPoint Introduction In the past two decades, aggregation-induced emission (AIE) studies have made significant progress in light-emitting materials,1–10 after Tang and co-workers11 first coined the concept of AIE in 2001. As a breakthrough study, the AIE phenomenon is completely opposite to the aggregation-caused quenching (ACQ) effect of conventional organic fluorophores. It is well documented that the aggregates of AIE-active molecules are able to block the thermal decay of nonluminescent substances in solution, leading to higher fluorescence efficiency than the single AIE molecule.12–19 Tetraphenylethylene (TPE) has been explored extensively as one of the iconic AIE fluorophores in terms of its fundamental emissive mechanism and its intriguing application.20 Within the TPE, free rotation of the phenyl rings led to fast nonradiative decay in a dilute solution. Among the TPE aggregates, due to the effect of restricting intramolecular motion, there is a hindrance of the path of nonradiative transitions and thus, induces fluorescence emission through radiation transitions.21–28 Specifically, owing to the largely twisted structure and the steric hindrance by phenyl rings, TPE derivatives often show distinct optical response under external stimuli, such as thermal energy and pressure applications. Based on such a distinct optical behavior, a series of TPE-related motifs have been introduced into supramolecular systems to target a variety of applications, including fluorescence sensing,1,29,30 imaging,18,31 recognition,32 catalysis,33,34 and others. Thanks to the facile synthesis and rigid geometry, TPE and its derivatives exhibited remarkable compatibility for most of metalla-supramolecular systems. Currently, a series of discrete two-dimensional (2D) macrocycles, three-dimensional (3D) cages, and nanomaterials with well-defined sizes and shapes were constructed by coordination-driven self-assembly.35–50 In this field, Stang and co-workers51 reported the first TPE-based supramolecular cage, which brought about the recent flourishing of AIE-active metalla-supramolecular cages with tunable properties.52–54 Among most of these structures, the TPE moieties were either attached or embedded in the supramolecules, and their emissions still followed the classic AIE principle. Accordingly, high fluorescent efficiency was mainly observed in their aggregate state, in which the rotations of the benzene rings were restricted effectively.55 Nonetheless, in the solution state, as well as the isolated supramolecular cage scenario, these nonaggregate supramolecules were still nonemissive or weakly luminescent,47,48,50,54,56–60 which severely limited the application prospect of the TPE molecule. Herein, we intended to design and assemble discrete fluorescent supramolecules using the TPE motif with our goal of overcoming the limitation mentioned above to achieve high fluorescent efficiency in solution by extending the conjugation and rigidity of its building blocks. Accordingly, we report the self-assembly of two 2,2′:6″,2″-terpyridine (tpy)-based metallacages with tunable luminescence properties. The final discrete M6L3 cages were formed by the coordination between TPE-based tpy ligands and Zn(II). The structures of the supramolecules were characterized fully by NMR and mass spectrometry, and the optical properties were characterized by UV–vis, fluorescence, low-temperature emission, and high-pressure emission spectroscopy. Experimental Method Materials and methods All reagents were commercially available from Ark Pharm Inc. (Beijing, China) and Aladdin Bio-Chem Technology Co. Ltd (Shanghai, China) and were used without further purification. Compounds 2,49 3,50 7,61 and 862 were synthesized according to the reported methods. NMR spectra data were recorded on AVANCE 500-MHz (Bruker, Beijing, China) and 600-MHz NMR spectrometer (Bruker) in deuterated chloroform (CDCl3) and deuterated acetonitrile (CD3CN) with tetramethylsilane (TMS) as standard. Electrospray ionization mass spectrometry (ESI-MS) and traveling-wave ion mobility mass spectrometry (TWIM-MS) were recorded with a SYNAPT G2 tandem mass spectrometer (Waters, Milford, MA, United States). The UV–vis spectra were recorded with a UV2550 spectrophotometer (Shimadzu, Shanghai, China). The emission spectra were measured on a Shimadzu RF-5301 PC spectrometer (CCD) and Maya2000Pro optical fiber spectrophotometer (Ocean Insight, Shanghai, China). The solution-state quantum yields were determined by the FLS920 steady- and transient-state fluorescence spectrometer (Edinburgh Instruments Ltd., Livingston, United Kingdom). The high-pressure fluorescence spectra under hydrostatic conditions were measured using a fluorescence microscope (IX71, 50, NA = 0.5; Olympus, Beijing, China) equipped with a spectrometer (Horiba Jobin Yvon iHR320; Bensheim, Germany). The light source was a mercury lamp with an excitation wavelength of 365 nm. Synthesis of ligand LA Compound 3 (0.91 g, 1.872 mmol), compound 8 (0.3 g, 0.36 mmol), Pd(PPh3)2Cl2 (66 mg, 0.1 mmol), and Na2CO3 (1.0 g) were added into a Schlenk flask and degassed under nitrogen for three times. Next, 10 mL H2O and 30 mL THF were injected and stirred at 70 °C for 4 days. After cooling to room temperature, the reactants were extracted with CHCl3, and the crude product was purified by flash column chromatography with CHCl3: ethanol (50∶1, v/v) to obtain the ligand LA (0.47 g, 67% yield) as a yellow solid. 1H NMR conditions: (500 MHz, CDCl3, 300 K); characterization, δ (ppm): 8.73 (s, 8H, tpy-H3',5'), 8.66 (m, 16H, tpy-H6,6" and tpy-H3,3"), 7.89–7.83 (m, 8H, tpy-H4,4"), 7.80 (d, J = 2.3 Hz, 4H, Ha), 7.61 (d, J = 8.2 Hz, 4H, Hb), 7.47 (d, J = 8.0 Hz, 8H, Hd), 7.31 (d, J = 6.3 Hz, 8H, tpy-H5,5"), 7.24 (d, J = 8.2 Hz, 8H, He), 7.04 (d, J = 8.6 Hz, 4H, Hc), 4.05 (t, J = 6.3 Hz, 8H, Hf), 1.74 (t, J = 7.5 Hz, 8H), 1.46–1.38 (m, 8H), 1.17 (m, 16H), 0.75 (t, J = 7.1 Hz, 12H). 13C NMR conditions: (125 MHz, CDCl3, 300 K); characterization, δ (ppm): 156.57, 155.77, 155.08, 149.10, 148.49, 142.64, 140.21, 138.28, 136.63, 133.50, 132.03, 129.10, 128.57, 128.36, 126.14, 123.46, 121.98, 121.17, 112.57, 68.68, 31.56, 29.19, 25.81, 22.38, 13.94. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) characterization, (m/z): Calcd for [C134H120N12O4-e]+ 1960.96. Found: 1960.95. Synthesis of ligand LB Compound 5 (0.14 g, 0.2 mmol), compound 7 (0.5 g, 1.2 mmol), Pd(PPh3)4 (46 mg, 0.04 mmol), CuI (6.0 mg, 0.032 mmol) were added into a Schlenk flask. After degassing under nitrogen for three times, an anhydrous THF (20 mL) and triethylamine (10 mL) were added into the Schlenk flask. Then the mixture was stirred at 70 °C for 4 days. After cooling to room temperature, the mixture was extracted with CHCl3, and the crude product was purified by flash column chromatography with CHCl3: ethanol (100: 3, v/v) and the ligand LB were obtained (0.27 g, 65% yield) as a yellow solid. 1H NMR conditions: (500 MHz, CDCl3, 300 K); characterization, δ (ppm): 8.72 (s, 8H, tpy-H3',5'), 8.70 (d, J = 4.5 Hz, 8H, tpy-H6,6"), 8.67 (d, J = 7.5 Hz, 8H, tpy-H3,3"), 7.87 (td, J = 7.7, 1.9 Hz, 8H, tpy-H4,4"), 7.77 (d, J = 2.2 Hz, 4H, Ha), 7.53 (dd, J = 8.5, 2.1 Hz, 4H, Hb), 7.37–7.32 (m, 16H, tpy-H5,5" and Hd), 7.06 (d, J = 8.1 Hz, 8H, He), 6.98 (d, J = 8.7 Hz, 4H, Hc), 4.06 (t, J = 6.2 Hz, 8H, Hf), 1.74 (m, 8H), 1.45–1.39 (m, 8H), 1.16 (m, 16H), 0.75 (t, J = 7.0 Hz, 12H). 13C NMR conditions: (125 MHz, CDCl3, 300 K); characterization, δ (ppm): 156.45, 155.17, 149.12, 147.58, 142.88, 140.90, 136.68, 133.86, 133.33, 131.47, 131.07, 128.47, 123.55, 121.97, 121.81, 121.17, 115.59, 112.15, 89.78, 88.67, 68.64, 31.53, 29.08, 25.78, 22.36, 13.93. MALDI-TOF MS characterization, (m/z): Calcd for [C142H120N12O4-e]+ 2056.96. Found: 2056.95. Synthesis of cage [Zn6LA3] The solution of Zn(NO3)2·6H2O (2.3 mg, 7.6 μmol) dissolved in MeOH (3 mL) was accurately added into another solution of ligand LA (7.5 mg, 3.8 μmol) in CHCl3 (1.0 mL), then the mixture was heated at 50 °C for 10 h. After cooling to room temperature, 40 mg NH4PF6 was added and bright yellow precipitate was observed, washed twice with water, and a yellow solid product was obtained in 91% yield. 1H NMR conditions: (500 MHz, CD3CN, 300 K); characterization, δ (ppm): 9.02 (s, 8H, tpy-H3',5'), 8.52 (d, J = 8.2 Hz, 8H, tpy-H3,3"), 8.16 (s, 4H, Ha), 7.97 (d, J = 8.8 Hz, 4H, Hb), 7.83 (t, J = 8.0 Hz, 8H, tpy-H4,4"), 7.75 (m, 16H, tpy-H6,6" and Hd), 7.40 (m, 12H, Hc and He), 6.97 (t, J = 6.5 Hz, 8H, tpy-H5,5"), 4.28 (s, 8H, Hf), 1.92–1.84 (m, 8H), 1.50 (m, 8H), 1.29–1.19 (m, 8H), 1.05 (m, 8H), 0.57 (t, J = 7.4 Hz, 12H). 13C NMR conditions: (125 MHz, CD3CN, 300 K); characterization, δ (ppm): 156.14, 154.60, 148.78, 147.89, 147.79, 142.46, 140.91, 137.54, 137.42, 132.88, 131.33, 130.50, 130.09, 128.89, 127.06, 125.90, 125.83, 124.30, 122.98, 113.34, 68.90, 31.35, 29.07, 25.81, 22.21, 13.13. ESI-MS characterization: (m/z): 1458.9 [M-5PF6−]5+ (calcd m/z: 1458.9), 1191.6 [M-6PF6−]6+ (calcd m/z: 1191.6), 1000.7 [M-7PF6−]7+ (calcd m/z: 1000.7), 857.5 [M-8PF6−]8+ (calcd m/z: 857.5), 746.1 [M-9PF6−]9+ (calcd m/z: 746.1) and 657.0 [M-10PF6−]10+ (calcd m/z: 657.0). Synthesis of cage [Zn6LB3] The solution of Zn(NO3)2·6H2O (2.1 mg, 7.0 μmol) in MeOH (3 mL) was added accurately into another solution of ligand LB (7.2 mg, 3.5 μmol) in CHCl3 (1.0 mL), then the mixture was heated at 50 °C for 10 h. After cooling to room temperature, 35 mg NH4PF6 was added and bright yellow precipitate was observed. The product was washed twice with water, and a yellow solid was obtained in 90% yield. 1H NMR conditions: (500 MHz, CD3CN, 300 K); characterization, δ (ppm): 9.00 (s, 8H, tpy-H3',5'), 8.58 (d, J = 8.6 Hz, 8H, tpy-H3,3"), 8.15 (s, 4H, Ha), 8.10–8.02 (m, 8H, tpy-H4,4"), 7.87–7.75 (m, 12H, tpy-H6,6" and Hb), 7.43 (s, 8H, Hd), 7.39–7.25 (m, 12H, tpy-H5,5" and Hc), 7.18 (d, J = 8.2 Hz, 8H, He), 4.28 (s, 8H, Hf), 1.88 (s, 8H), 1.49 (s, 8H), 1.26 (s, 8H), 1.08 (m, 8H), 0.70–0.52 (m, 12H). 13C NMR conditions: (125 MHz, CD3CN, 300 K); characterization, δ (ppm): 156.72, 153.74, 149.05, 147.99, 147.89, 141.23, 131.32, 130.85, 127.46, 127.36, 125.79, 124.23, 124.13, 122.98, 121.62, 115.67, 113.36, 89.15, 88.65, 69.09, 31.31, 28.93, 25.75, 22.22, 13.15. ESI-MS characterization: (m/z): 1516.6 [M-5PF6−]5+ (calcd m/z: 1516.6), 1239.7 [M-6PF6−]6+ (calcd m/z: 1239.7), 1041.8 [M-7PF6−]7+ (calcd m/z: 1041.8), 893.5 [M-8PF6−]8+ (calcd m/z: 893.5), 778.1 [M-9PF6−]9+ (calcd m/z: 778.1), 685.8 [M-10PF6−]10+ (calcd m/z: 685.8), and 610.3 [M-11PF6−]11+ (calcd m/z: 610.3). Results and Discussion Preparation and characterization of ligands and supramolecules In coordination-driven self-assembly, tpy has been widely used as powerful building block to construct rigid supramolecular architectures.63–66 In this study, tpy-based ligands, LA and LB, were prepared through Suzuki and Sonogashira couplings, as shown in Figure 1. Both LA and LB were designed with TPE core to afford strong emission properties. By contrast with LA, LB contained additional alkyne connectivity to increase the rigidity of the structure. These two ligands were assembled with Zn(NO3)2·6H2O in a precise 1∶2 stoichiometric ratio in a solvent mixture of CHCl3/MeOH at 50 °C for 10 h, followed by addition of an excess ammonium hexafluorophosphate (NH4PF6) salt to give yellow precipitate products (yields: 91% for [ Zn6LA3] and 90% for [ Zn6LB3]). Figure 1 | Synthesis of the ligands LA, LB, and self-assembly of the complexes [Zn6LA3] and [Zn6LB3]. Download figure Download PowerPoint These ligands and complexes were characterized by 1H NMR ( Supporting Information Figures S1, S5, S9, and S14), 13C NMR ( Supporting Information Figures S2, S6, S10, and S15), 2D correlation spectroscopy (2D-COSY) ( Supporting Information Figures S3, S4, S7, S8, S11, S12, S16, and S17), 2D diffusion-ordered NMR spectroscopy (2D-DOSY) ( Supporting Information Figures S13 and S18), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) ( Supporting Information Figures S19 and S20), ESI-MS ( Supporting Information Figures S21 and S22) and TWIM-MS. First, the 1H NMR spectroscopy documented the formation of highly symmetrical metallacages (Figure 2). Compared with their respective ligands, the cages, [ Zn6LA3] and [ Zn6LB3], displayed broadened peaks of all the protons, suggesting the formation of large complexes due to the slow tumbling motion67 on the NMR time scale. 3′,5′ protons of [ Zn6LA3] shifted downfield (∼0.29 ppm), compared with the signal of LA, while the protons at 6,6″ position of tpy were significantly shifted upfield (∼ 0.91 ppm) due to the electron shielding effect68 (Figure 2a). For [ Zn6LB3], the signals of 3′,5′ protons shifted downfield (∼ 0.28 ppm), and 6,6″ protons shifted upfield (∼ 0.95 ppm) (Figure 2b). Collectively, such NMR results suggested the formation of discrete metalla-supramolecules rather than the random polymers attained by tpy-Zn(II) coordination. Second, molecular simulations using the Materials Studio software showed that the diameters of complexes [ Zn6LA3] and [ Zn6LB3] were 2.9 and 3.6 nm, respectively. To prove the size of the simulated structures, we measured the real molecular size by DOSY. The signal bands of complexes [ Zn6LA3] and [ Zn6LB3] were observed at the logarithm of diffusion coefficient (log D) = –9.34 and –9.48, respectively. Accordingly, the experimental diameters of [ Zn6LA3] and [ Zn6LB3], calculated via the Stokes–Einstein equation, were 2.7 and 3.6 nm, which proved the formation of simulated discrete supramolecular structures ( Supporting Information Figures S13 and S18). Figure 2 | 1H NMR spectra (500 MHz). (a) LA in CDCl3 and cage [Zn6LA3] in CD3CN. (b) LB in CDCl3 and cage [Zn6LB3] in CD3CN. Download figure Download PowerPoint ESI-MS and TWIM-MS were used to validate further the molecular compositions of the metallacages.63,69 For cage [ Zn6LA3], only one set of peaks with different charge states (5+ to 10+) were observed with successive loss of the corresponding PF6− counterions (Figure 3a). The experimental molecular weight (MW) obtained was 8006.0 Da, which matched well with the formula of [(C134H120N12O4)3Zn6(PF6)12]. The experimental isotope pattern of each charge state was consistent with the theoretical simulation ( Supporting Information Figure S21). Moreover, all the different charge states revealed by TWIM-MS spectrum had narrow drift time distribution, which indicated that no overlapping isomers or structural conformers were generated (Figure 3b).63,69–76 For cage [ Zn6LB3], the experimental MW obtained was 8294.0 Da, corresponding to the formula of [(C142H120N12O4)3Zn6(PF6)12]. Also, there was only one prominent set of signals for the multicharged entities from 5+ to 11+ shown in the ESI-MS spectrum (Figure 3c). Each peak was in an excellent agreement with the corresponding theoretical isotope pattern ( Supporting Information Figure S22). Moreover, the cage [ Zn6LB3] displayed a narrowly distributed band of signals in TWIM-MS, which verified the successful formation of a discrete metallacage (Figure 3d). Figure 3 | (a) ESI-MS and (b) 2D TWIM-MS plot of [Zn6LA3]. (c) ESI-MS and (d) 2D TWIM-MS plot of [Zn6LB3]. Download figure Download PowerPoint Photophysical studies of ligands and supramolecules in solution With the well-defined supramolecular cages in hand, we systematically characterized the ligands and supramolecules by UV-vis and fluorescence spectroscopy. By the spectra of LA and [ Zn6LA3], the band of LA mainly from the of TPE and Compared to LA, [ Zn6LA3] had an enhanced peak at 300 nm, which have from the charge after coordination (Figure In the fluorescence spectrum of LA, the emission band at nm, to the tpy the emission of TPE is observed (Figure suggesting that the rotation of TPE in LA The quantum efficiency fluorescence of LA is Nonetheless, the fluorescence of the prepared supramolecular cage [ Zn6LA3] significantly with an emission peak at (Figure to the restricted rotation of TPE by coordination. the of the molecular led to an intramolecular charge resulting in the of the emission It is there was a strong emission of tpy in the after the ligand was with the its energy was to the through and via nonradiative which resulted in fluorescence The quantum efficiency of [ Zn6LA3] only even had a strong Figure 4 | (a) and spectra of TPE, LA, and [Zn6LA3] in acetonitrile = nm, = (b) and spectra of LB and [Zn6LB3] in acetonitrile = nm, = spectra of (c) [Zn6LA3] and (d) [Zn6LB3] in acetonitrile = 365 nm, = Download figure Download PowerPoint Moreover, by introducing additional alkyne connectivity into the building the optical spectra of LB and [ Zn6LB3] (Figure were completely different from the LA series shown in Figure The of LB and [ Zn6LB3] were mainly to the TPE, and state in the UV–vis in which the of TPE at was significantly In the fluorescence spectrum of LB and [ Zn6LB3] (Figure the emission of LB of two one at from the tpy and the peak at is to TPE The quantum efficiency fluorescence increased to due to the of the alkyne which increased the rigidity and the the twisted of the and resulting in enhanced to [ Zn6LA3], the emission peak of [ Zn6LB3] at is to In the emission of the tpy is by after coordination with Zn(II). the quantum efficiency of [ Zn6LB3] is and 4.5 as high as that of [ As a subtle change in by introducing an alkyne into the to increase the emission of supramolecular cages in dilute solution we performed the low-temperature fluorescence spectra on the two cages by these supramolecules in acetonitrile solution to a state, using nitrogen at state limited the intramolecular rotation of TPE and led to a significant increase in the fluorescence (Figure and Further, we studied the fluorescence of the hybrid supramolecular cages by mixing LA and LB at for self-assembly. LA and LB were assembled in a ratio of with the Zn(II) the ESI-MS data exhibited the formation of a series of hybrid supramolecular cages rather than [ Zn6LA3] or [ Zn6LB3] via a of the supramolecules, [ Zn6LA3], [ [ [ Zn6LB3] (Figure 5 and Supporting Information Figures As shown in the fluorescence spectra of with different of LA and LB (Figure the quantum of these hybrid systems increased with the of LB (Figure These results that the ligand LB, which has a higher degree of is for the emission of TPE than LA, and this even in an of of the hybrid cages. Figure 5 | (a) ESI-MS of self-assembly of LA and LB in a ratio of ESI-MS experimental data and theoretical isotope of (b) (c) (d) Download figure Download PowerPoint Photophysical studies of ligands and supramolecules in the we to the emission of ligands and the supramolecules to external hydrostatic pressure in the The and spectra in the solid state were under hydrostatic pressure as shown in Supporting Information Figure and Figure high pressure ( Supporting Information Figure the emission wavelength of LA from to and the emission wavelength of [ Zn6LA3] also from to ( Supporting Information Figures and the emission of LA and [ Zn6LA3] at pressure. due to the molecular packing that enhanced the and under high pressure with the fluorescence Moreover, the fluorescence of LA and [ Zn6LA3] with the of the pressure ( Supporting Information Figures and Figure 7 | of pressure on ligand and their supramolecular emission for (a) LB, at pressure, (b) LB, gradual pressure of (c) LB and (d) [Zn6LB3] emission for pressure, pressure, and gradual pressure = 365 Download figure Download PowerPoint for ligand LB, the emission was as pressure increased from to (Figure also as in Figure We also this to the packing leading to the fluorescent emission in this the fluorescence of [ Zn6LB3] increased significantly under low hydrostatic pressure from to (Figure the pressure was increased above to 6.32 which the fluorescence to which is also displayed as in Figure the pressure was increased above to 6.32 which the fluorescence to for [ Zn6LB3], the pressure have further limitation on the rotation of TPE moieties leading to the energy loss through transitions with the subsequent increase in emission efficiency at from to the hand, the pressure to increase 6.32 molecular packing have to the pressure, the emission of LB and [ Zn6LB3] was at and nm, respectively. Upon the corresponding fluorescence of LB and [ Zn6LB3] to at and at 6.32 the pressure was the fluorescence of LB and [ Zn6LB3] to an and the corresponding emission wavelength was to the state (Figure and Figure | (a) spectra and (b) quantum yields in acetonitrile of ligands LA, LB assembled in different = nm, = Download figure Download PowerPoint We have prepared two TPE-based metallacages through the coordination-driven self-assembly of tpy ligands and Zn(II) Through introducing additional alkyne on LA, the ligand LB with a high degree of rigidity and conjugation was able to assemble into a highly emissive cage [ Zn6LB3] in dilute solution. The quantum of these two complexes were for [ Zn6LA3] and for [ These results to the luminescence of metalla-supramolecules with AIE-active which our design of emissive supramolecules with properties. Further, we studied the emission properties of ligands and their respective supramolecules in the by the external pressure. Through subtle of these structures, we in supramolecular cages with enhanced emission and luminescence our into supramolecular AIE and the of Supporting Information Supporting Information is of The no of We the from the of and for the of Jilin for and the