s2 metal ions

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Short communication

Syntheses, crystal structures and fluorescent properties of three coordination polymers assembled from flexible bis-(imidazole-4,5-dicarboxylate) ligand and d10/s2 metal ions

T

Gang Yuana, , Chao Zhanga, Kui-Zhan Shaob, Wan-Li Zhoua, Xuan Weia, Feng-Chun Wanga, Zhong-Min Sub ⁎

a b

Faculty of Chemistry, Tonghua Normal University, Tonghua 134002, China Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, China

GRAPHICAL ABSTRACT

Three new coordination polymers were obtained by the self-assembly of a flexible bis-(imidazole-4,5-dicarboxylate) ligand (H4L) and d10/s2 metal ions. Complexes 1 and 2 exhibit isomorphic 2D layer-like fes network formed by interconnecting ring-like [M2(H2L)2] (M = Zn or Cd) MBBs, and complex 3 have a 3D framework with a seh-3,5-P21/c topology built by interconnected [Pb4(H2L)2] MBBs. Moreover, the purities, thermal stabilities and fluorescence properties of the complexes were investigated in detail.

ARTICLE INFO

ABSTRACT

Keywords: Imidazole-4,5-dicarboxylic acid d10 metal PbII complex Fluorescence MBB Topology

Three new coordination polymers, [Zn(H2L2)(H2O)]n (1), [Cd(H2L2)(H2O)]n (2) and {[Pb(H2L2)]n (3) (H4L = 1,1′-(propane-1,3-diyl)bis(1H-imidazole-4,5-dicarboxylic acid)) have been successfully prepared under hydrothermal conditions. Complexes 1 and 2 are isomorphic and exhibit 2D fes network constructed from interconnected ring-like [M2(H2L)2] (M = Zn or Cd) MBBs. Complex 3 displays a 3D covalent framework with seh3,5-P21/c net topology built by interconnected ring-like [Pb4(H2L)2] MBBs. Moreover, the thermal stability and fluorescent properties of these complexes were investigated in detail.

The past decade has witnessed the rapid development of coordination polymers (CPs) in both academic and industrial realms. As a promising inorganic–organic hybrid material, CPs not only possess diverse

⁎

structures and intriguing topological features, but also exhibit a variety of properties related to their compositions and structures [1–7]. Recently, the research on the fluorescent CPs has aroused much concern

Corresponding author. E-mail address: [email protected] (G. Yuan).

https://doi.org/10.1016/j.inoche.2018.12.011 Received 7 November 2018; Received in revised form 14 December 2018; Accepted 17 December 2018 Available online 19 December 2018 1387-7003/ © 2018 Elsevier B.V. All rights reserved.

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Fig. 1. (a) The coordination environment of ZnII ion in 1 with the thermal ellipsoids at 50% probability level. (b) The ring-like SBB in 1. (c) The 2D structure of 1. (d) Schematic description of the (3,3)-connected network of 1.

mainly because of their huge potential applications in lighting, display, biological imaging, chemical sensing, photocatalysis and non-linear optics [8–15]. Fluorescent CPs possesses the advantages of both inorganic and organic polymer fluorescence materials, such as higher molar extinction coefficient, larger Stokes shift, various and adjustable structures [16–19]. Recently, much of the works have focused on the fluorescent CPs containing d10/s2 metal ions owing to their unique luminescent characteristics resulting from the different electron configurations of metal centers. In general, the CPs based on d10 metal (CuI, AgI, ZnII and CdII) ions and ligands with chromophoric π-conjugated structures usually exhibit enhanced ligand-based fluorescence, which mainly because the closed-shell electron configuration of metal ions can effectively avoid d-d transitions [20,21]. While the CPs formed by πconjugated ligands bridging s2-metal (PbII) ions often emit fluorescence caused by ligand-to-metal charge transfer (LMCT) or metal-centered transitions [22,23]. In the preparation, choosing a well-designed organic linker with π-conjugated system to interact with specific metal ions has become one of the most effective and controllable strategy to obtain CPs materials with novel structures and excellent photoelectric properties [24–26]. As a multi-functional organic linker, imidazole-4,5dicarboxylic acid (H3IDC) has various coordination modes, excellent chelating coordinate capacity and suitable molecular size, which made it become an excellent candidate for assembling novel CPs with various architectures and interesting properties such as gas storage and separation, luminescence, drug release, magnetism, etc. [27–30]. Our interests focus on the CPs based on the derivative ligands of H3IDC, mainly considering that the organic linkers generated by different groups bridging two H3IDC molecules can assume many types of conformations which offer more possibilities to form complicated and

fantastic networks. In previous work, we reported a three-dimensional CdII-based CP built by a semi-rigid bis-(imidazole-4,5-dicarboxylate) ligand, and explored the coordination traits and configurations of the ligands as well as the structure and potential property of the resulting CP [31]. As an ongoing research to systematically investigate the selfassembly on the basis of ligands of this type, we design and synthesis a new flexible derivative ligand of H3IDC, namely 1,1′-(propane-1,3-diyl) bis(1H-imidazole-4,5-dicarboxylic acid) (H4L), by using an alkyl chain containing three carbon atoms to link two H3IDC molecules (see Supporting information). H4L ligand not only inherits the excellent coordination features of H3IDC, but also own more abundant coordination modes based on two IDC groups. In addition, two IDC groups of H4L can rotate and warp freely around the flexible alkyl chain to meet different configuration requirements. As far as we know, the complexes based on the flexible bis-(imidazole-4,5-dicarboxylate) ligands have rarely been reported. In this work, we reported the synthesis and characterization of three new CPs, namely, [Zn(H2L2)(H2O)]n (1), [Cd(H2L2)(H2O)]n (2) and {[Pb(H2L2)]n (3) built by H4L linking d10 or s2 metal ions. Both the complexes exhibit interesting 2D or 3D framework formed by interconnected ring-like MBBs. Furthermore, the thermal stability and solidstated fluorescence properties of complexes 1–3 were also studied. Complexes 1–3 were obtained by hydrothermal reactions of the corresponding M(NO3)2 (M = Zn, Cd or Pb) and flexible bis(imidazole4,5-dicarboxylate) ligand (H4L) in the presence of pyrazine [32]. The pyrazine molecules did not appear in the frameworks of the final complexes and they just acted as deprotonation agent. Compared with sodium hydroxide, the weak alkalinity of pyrazine makes the crystal quality of products better. These complexes are air stable, insoluble in common organic solvents, and can retain their crystalline integrity at 17

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two N atoms from three isolated H2L2− ligands, and one O atom from coordination water molecule to form slightly distorted octahedral coordination geometry. Each H2L2− anion serves as a tridentate ligand and displays a μ3-kN,O: kN′,O′: kO″ coordination mode (Scheme 1a) via bis-N,O-chelating and O-monodentate fashions to bridge three ZnII centers. In which, the carboxylic groups and the attaching aromatic rings are almost coplanar and the dihedral angle between two HIDC planes is about 60.84°. Two H2L2− ligands bridged two ZnII ions to afford a [Zn2(H2L)2] ring with the Zn···Zn distance of 10.726 Å (Fig. 1b). Each [Zn2(H2L)2] ring can be considered as a molecular building block (MBB). These ring-like MBBs further interconnect by the carboxylate O atoms and unsaturated ZnII site resulting to a 2D layer-like framework (Fig. 1c). The topology analysis method was accessed to simplify the structure by using the TOPOS program [33]. The overall framework can be defined as a new (3,3)-connected fes network with the Schläfli symbol of {4.82} by denoting the H2L2− ligand and ZnII ion as 3-connected nodes (Fig. 1d). When using Pb(NO3)2 as metal source, a new 3D framework with different ring-like MBB was obtained. Structure analysis reveals that crystal 3 crystallizes in the monoclinic system with space group of P21/ n. The asymmetric unit of 3 contains one PbII ion and one H2L2− anion. Each PbII ion adopts a pentagonal bipyramid coordination geometry bonded with four O atoms and two N atoms from five different H2L2− ligands (Fig. 2a). The H2L2− ligand adopts a μ5-kN,O: kO: kN′,O′: kO′: kO″ coordination mode (Scheme 1b) through bis-N,O-chelating and triO-monodentate fashions linking five metal ions. Similar to 1, all the atoms of each HIDC group are nearly coplanar and two HIDC planes of H2L2− ligand make a dihedral angle of 88.94°. Two H2L2− ligands connect two dinuclear Pb2 units to give rise to a ring-like [Pb4(H2L)2] MBB (Fig. 2b). Each [Pb4(H2L)2] MBB connects to the surrounding eight identical ones by sharing dinuclear Pb2 units and carboxylate O atom bridging to lead to a 3D framework (Fig. 2c). Topologically, each H2L2−

Scheme 1. Coordination modes of H2L2− ligands in complexes 1–3.

ambient conditions for a considerable length of time. The phase purities of bulk samples were identified by powder X-ray diffraction analysis (Figs. S3–S5). Single-crystal X-ray diffraction analysis reveals that complexes 1 and 2 are isostructural with two-dimensional (2D) framework containing a ring-like basic unit of [M2(H2L)2]. Thus, as an example, only the structure of 1 is described here in detail. Crystal 1 crystallized in orthorhombic space group Pbca with the asymmetric unit consists of one ZnII ion, one H2L2− ligand and one coordination water molecule. As shown in Fig. 1a, each Zn center is surrounded by three O atoms and

Fig. 2. (a) The coordination environment of PbII ions in 3 with the thermal ellipsoids at 50% probability level. (b) The ring-like SBB in 3. (c) The 3D framework of 3. (d) Schematic description of the 2D (3,5)-connected network of 3. 18

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to the intraligand π* → π or π* → n transitions. Complex 1–3 exhibit emission peaks at 416 (λem = 320 nm) for 1, 417 nm (λem = 325 nm) for 2, and 470 nm (λem = 334 nm) for 3, respectively. Complex 1 and 2 have similar emission spectra as H4L ligand, which shows that their fluorescence is mainly attributed to intraligand emissions. The enhanced emission intensities for 1 and 2 may be attributed to the coordination between ligands and metal centers, which effectively increases the rigidity of the ligands and reduces the energy loss due to radiationless decay. As for the emission of complex 3, its wavelength is red shifted by 53 nm as compared to the emission of the free H4L ligand. Thus, the nature of red-shifted emission band may be ascribed to the ligand-to-metal charge transfer (LMCT) between the π systems and the p orbitals of PbII ions similar to those observed in PbII complexes [37,38]. The CIE (Commission Internationale de L'Eclairage) diagram is widely used to examine all the possible colors by combining three primary colors, in which the chromaticity coordinates x and y are used for ascertaining the accurate emission colors of the as-synthesized materials. On the basis of the corresponding photoluminescence spectra of ligand and complexes, their CIE diagram has been drawn (Fig. 3b). All the emissions of H4L ligand and three complexes can be described as blue luminescence with CIE coordinates of (0.16, 0.14) for H4L, (0.17, 0.16) for 1, (0.16, 0.13) for 2, (0.19, 0.28) for 3, respectively. In conclusion, we have prepared three complexes by using a new flexible H3IDC derivative ligand (H4L) with double HIDC groups. In three complexes, the H4L displays μ3- and μ5-bridging modes, respectively. Three complexes exhibit 2D layer and 3D framework constructed from interconnected ring-like MBBs. They possess high stabilities and display blue fluorescent emissions originating from the intraligand or ligand-to-metal electron transitions. The works about other derivate ligands of H3IDC by using alkyl chain containing two or four carbons atoms to link two IDC groups is currently ongoing in our labs. Acknowledgements This work was financially supported by Youth Foundation of Department of Science and Technology of Jilin Province (20160520172JH), Science and Technology Research Foundation of the “13th 5-year Plan” Program of Jilin Education Department (JJKH20170433KJ and JJKH20170434KJ). Fig. 3. (a) Emission spectra of the H4L ligand and complexes 1–3 in the solid state at room temperature. Inset: Fluorescence photograph for sample powders of H4L ligand and three CPs under UV illumination (λex = 365 nm). (b) CIE chromaticity coordinates of the H4L ligand and complexes 1–3.

Appendix A. Supplementary material Crystallographic data for the structural analysis have been deposited to the Cambridge Crystallographic Data Centre, CCDC No. 1868231−1868233 for complexes 1–3. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www. ccdc.cam.ac.uk/data_request/cif. Supplementary data to this article can be found online at https://doi.org/10.1016/j.inoche.2018.12.011.

ligand bridging three dinuclear Pb2 units can be viewed as a 3-connected node and each Pb2 unit connecting with another two Pb2 units and three H2L2− ligands can be denoted to a 5-connected node. Based on the above simplification, the framework of 3 can be defined as a 2nodal (3,5)-connected seh-3,5-P21/c net with the schläfli symbol of (4.62)(4.67.82) (Fig. 2d). Thermogravimetric analyses (TGA) of 1–3 were also carried out to examine their thermal stability (Fig. S6). The TGA curves of 1–3 show that all they have one-step obvious weight losses. Complexes 1 and 2 are thermally stable to 240 and 234 °C, respectively, and then successively decomposes corresponding to the removal of a coordination water molecule and organic component. The anhydrous framework of 3 maintains stability up to 280 °C, and then decomposes above this temperature. Considering that the complexes constructed with d10/s2 metal ions and organic π-conjugate ligands usually have shown excellent fluorescent properties with potential to become promising candidates for fluorescent materials [34–36]. Therefore, the solid-state fluorescence of organic ligand and complexes 1–3 were investigated at room temperature (Fig. 3a). The free H4L ligand displays photoluminescence with an emission maxima at 417 nm (λex = 320 nm), which can be assigned

References [1] T.R. Cook, Y.−.R. Zheng, P.J. Stang, Metal−organic frameworks and self-assembled supramolecular coordination complexes: comparing and contrasting the design, synthesis, and functionality of metal−organic materials, Chem. Rev. 113 (2013) 734–−777. [2] W. Lu, Z. Wei, Z.Y. Gu, T.F. Liu, J. Park, J. Park, J. Tian, M. Zhang, Q. Zhang, T. Gentle III, M. Boscha, H.C. Zhou, Tuning the structure and function of metal–organic frameworks via linker design, Chem. Soc. Rev. 43 (2014) 5561–5593. [3] L. Carlucci, G. Ciani, D.M. Proserpio, T.G. Mitina, V.A. Blatov, Entangled two dimensional coordination networks: a general survey, Chem. Rev. 114 (2014) 7557–7580. [4] L. Meng, K. Liu, C. Liang, X. Guo, X. Han, S. Ren, D. Ma, G. Lia, Z. Shi, S. Feng, Three 3D metal coordination polymers based on triazol-functionalized rigid ligand: synthesis, topological structure and properties, J. Solid State Chem. 258 (2018) 56–63. [5] Q. Yue, X. Liu, W.−.X. Guo, E.−.Q. Gao, Structural diversity and magnetic properties of Co(II)/Mn(II)/Ni(II) coordination polymers constructed from an unsymmetrical tetracarboxylic acid and varying N-donor ligands, CrystEngComm 20 (2018) 4258–−4267. [6] K.−.X. Shang, J. Sun, D.−.C. Hu, X.−.Q. Yao, L.−.H. Zhi, C.−.D. Si, J.−.C. Liu,

19

Inorganic Chemistry Communications 100 (2019) 16–20

G. Yuan et al.

[7]

[8]

[9] [10] [11] [12]

[13] [14]

[15] [16] [17]

[18]

[19] [20]

[21]

[22] [23] [24]

5976–5984. [25] P. Ju, E. Zhang, L. Jiang, Z. Zhang, X. Hou, Y. Zhang, H. Yang, J. Wang, A novel microporous Tb-MOF fluorescent sensor for highly selective and sensitive detection of picric acid, RSC Adv. 8 (2018) 21671–21678. [26] J. Zhu, P.M. Usov, W. Xu, P.J. Celis-Salazar, S. Lin, M.C. Kessinger, C. LandaverdeAlvarado, M. Cai, A.M. May, C. Slebodnick, D. Zhu, S.D. Senanayake, A.J. Morris, A new class of metal-cyclam-based zirconium metal−organic frameworks for CO2 adsorption and chemical fixation, J. Am. Chem. Soc. 140 (2018) 993–1003. [27] F. Nouar, J. Eckert, J.F. Eubank, P. Forster, M. Eddaoudi, Zeolite-like metal-organic frameworks (ZMOFs) as hydrogen storage platform: lithium and magnesium ionexchange and H2-(rho-ZMOF) interaction studies, J. Am. Chem. Soc. 131 (2009) 2864–2870. [28] R. Ananthoji, J.F. Eubank, F. Nouar, H. Mouttaki, M. Eddaoudi, J.P. Harmon, Symbiosis of zeolite-like metal–organic frameworks (rho-ZMOF) and hydrogels: composites for controlled drug release, J. Mater. Chem. 21 (2011) 9587–9594. [29] Y.–.F. Li, D. Wang, Z. Liao, Y. Kang, W.–.H. Ding, X.–.J. Zheng, L.–.P. Jin, Luminescence tuning of the Dy–Zn metal–organic framework and its application in the detection of Fe(III) ions, J. Mater. Chem. C 4 (2016) 4211–4217. [30] S. Zhang, W. Shi, P. Cheng, The coordination chemistry of N-heterocyclic carboxylic acid: a comparison of the coordination polymers constructed by 4,5-imidazoledicarboxylic acid and 1H-1,2,3-triazole-4,5-dicarboxylic acid, Coord. Chem. Rev. 352 (2017) 108–150. [31] G. Yuan, K.–.Z. Shao, X.–.R. Hao, Y.–.R. Pan, Z.–.M. Su, Synthesis, structure, and photoluminescent property of a trinuclear CdII complex based on semi-rigid bis (imidazole-4,5-dicarboxylate) ligand, Inorg. Chem. Commun. 42 (2014) 15–19. [32] Synthesis of 1. A mixture of Zn(NO3)2·6H2O (0.2 mmol, 59.4 mg), H4L(0.1 mmol, 35.2 mg), pyrazine (0.4 mmol, 32 mg) and H2O (16 mL) was sealed in a 23 mL Teflon-lined stainless steel vessel and heated at 140 °C for 72 hours. The reaction mixture was slowly cooled to room temperature at a rate of 10 °C/h, and the colorless block crystals were obtained with the yield of 47% (based on Zn). Elemental analysis (%) for 1, Calcd: C, 36.00; H, 2.78; N, 12.91; found: C, 35.67; H, 2.19; N, 12.46. IR (KBr, cm−1): 3489 (m), 3108 (m), 3019 (w), 2999 (w), 2339 (w), 1712 (s), 1516 (s), 1276 (s), 1182 (m), 1157 (s), 993 (s), 880 (m), 815 (w), 800 (w), 773 (s), 735 (w), 663 (s), 527 (m), 499 (m). Synthesis of 2. The preparation of 2 was similar to that of 1 except that Zn(NO3)2·6H2O was used instead of Cd(NO3)2·4H2O. The colorless block crystals of 2 were obtained with the yield of 50% (based on Cd). Elemental analysis (%) for 2, Calcd: C, 32.48; H, 2.51; N, 11.65; found: C, 31.93; H, 2.10; N, 11.88. IR (KBr, cm−1): 3402 (s), 3129 (m), 3104 (m), 2999 (w), 1701 (m), 1508 (s), 1343 (m), 1276 (s), 1153 (s), 992 (s), 879 (m), 815 (w), 799 (w), 775 (s), 727 (m), 662 (s), 535 (s), 501 (s). Synthesis of 3. The preparation of 3 was similar to that of 1 except that Zn(NO3)2·6H2O was used instead of Pb(NO3)2. The colorless block crystals of 3 were obtained with the yield of 43% (based on Pb). Elemental analysis (%) for 3, Calcd: C, 28.01; H, 1.80; N, 10.05; found: C, 27.53; H, 2.32; N, 10.46. IR (KBr, cm−1): 3430 (m), 3142 (w), 3110 (m), 1716 (m), 1560 (s), 1504 (s), 1460 (s), 1390 (s), 1320 (w), 1279 (s), 1147 (m), 1077 (m), 1011 (m), 843 (m), 771 (m), 650 (w), 637 (m), 614 (w), 539 (w), 516 (m). [33] (a) Net topology was calculated by the TOPOS program, in: V.A. Blatov (Ed.), TOPOS, A Multipurpose Crystallochemical Analysis with the Package, Samara State University, Russia, 2004A TOPOS software is available for download at http:// www.topos.samsu.ru. [34] D. Chisca, L. Croitor, O. Petuhov, O.V. Kulikova, G.F. Volodina, E.B. Coropceanu, A.E. Masunov, M.S. Fonari, Tuning structures and emissive properties in a series of Zn(II) and Cd(II) coordination polymers containing dicarboxylic acids and nicotinamide pillars, CrystEngComm 20 (2018) 432–447. [35] A.M.P. Peedikakkal, H.S. Quah, S. Chia, A.S. Jalilov, A.R. Shaikh, H.A. Al-Mohsin, K. Yadava, W. Ji, J.J. Vittal, Near-white light emission from lead(II) metal−organic frameworks, Inorg. Chem. 57 (2018) 11341–11348. [36] J.−.X. Li, Z.−.B. Qin, Y.−.H. Li, G.−.H. Cui, Sonochemical synthesis and properties of two new nanostructured silver(I) coordination polymers, Ultrason. Sonochem. 48 (2018) 127–135. [37] X. Wang, K. Zhang, L. Lv, R. Chen, W. Wang, B. Wu, Homochiral coordination polymers based on amino acid-functionalized isophthalic acid: synthesis, structure determination, and optical properties, Cryst. Growth Des. 18 (2018) 1799–1808. [38] J.−.X. Li, Y.−.F. Li, L.−.W. Liu, G.−.H. Cui, Luminescence, electrochemical and photocatalytic properties of sub-micron nickel(II) and cobalt(II) coordination polymers synthesized by sonochemical process, Ultrason. Sonochem. 41 (2018) 196–205.

Six Ln(III) coordination polymers with a semirigid tetracarboxylic acid ligand: bifunctional luminescence sensing, NIR-luminescent emission and magnetic properties, Cryst. Growth Des. 18 (2018) 2112–2120. C. Zhao, L. Zhao, M. Zhang, Syntheses, characterizations and luminescence properties of four novel coordination polymers based on 4,4′-(phenylazanediyl)dibenzoic acid with two rigid N-donor imidazol ligand, Inorg. Chim. Acta 469 (2018) 136–143. R. Jiang, M. Liu, T. Chen, H. Huang, Q. Huang, J. Tian, Y. Wen, Q. Cao, X. Zhang, Y. Wei, Facile construction and biological imaging of cross-linked fluorescent organic nanoparticles with aggregation-induced emission feature through a catalystfree azide-alkyne click reaction, Dyes Pigments 148 (2018) 52–60. L. Mao, Y. Liu, S. Yang, Y. Li, X. Zhang, Y. Wei, Recent advances and progress of fluorescent bio-/chemosensors based on aggregation-induced emission molecules, Dyes Pigments 162 (2019) 611–623. X. Zhang, K. Wang, M. Liu, X. Zhang, L. Tao, Y. Chen, Y. Wei, Polymeric AIE-based nanoprobes for biomedical applications: recent advances and perspectives, Nanoscale 7 (2015) 11486–11508. X. Zhang, X. Zhang, B. Yang, M. Liu, W. Liu, Y. Chen, Y. Wei, Polymerizable aggregation-induced emission dye-based fluorescent nanoparticles for cell imaging applications, Polym. Chem. 5 (2014) 356–360. X. Zhang, X. Zhang, B. Yang, M. Liu, W. Liu, Y. Chen, Y. Wei, Fabrication of aggregation induced emission dye-based fluorescent organic nanoparticles via emulsion polymerization and their cell imaging applications, Polym. Chem. 5 (2014) 399–404. D. Li, Q. Zhang, X. Wang, S. Li, H. Zhou, J. Wu, Y. Tian, Self-assembly of a series of thiocyanate complexes with high two-photon absorbing active in near-IR range and bioimaging applications, Dyes Pigments 120 (2015) 175–183. J. Su, J. Zhang, X. Tian, M. Zhao, T. Song, J. Yu, Y. Cui, G. Qian, H. Zhong, L. Luo, Y. Zhang, C. Wang, S. Li, J. Yang, H. Zhou, J. Wu, Y. Tian, A series of multifunctional coordination polymers based on terpyridine and zinc halide: secondharmonic generation and two-photon absorption properties and intracellular imaging, J. Mater. Chem. B 5 (2017) 5458–5463. D. Li, S.−.H. Yu, H.−.L. Jiang, From UV to near-infrared light-responsive metal–organic framework composites: plasmon and upconversion enhanced photocatalysis, Adv. Mater. 30 (2018) 1707377. J. Mei, N.L.C. Leung, R.K. Kwok, J.W.Y. Lam, B.−.Z. Tang, Aggregation-induced emission: together we shine, united we soar, Chem. Rev. 115 (2015) 11718–−11940. Y.−.X. Zhu, Z.−.W. Wei, M. Pan, H.−.P. Wang, J.−.Y. Zhang, C.−.Y. Su, A new TPE-based tetrapodal ligand and its Ln(III) complexes: multi-stimuli responsive AIE (aggregation-induced emission)/ILCT(intraligand charge transfer)-bifunctional photoluminescence and NIR emission sensitization, Dalton Trans. 45 (2016) 943–950. Z. Long, M. Liu, R. Jiang, Q. Wan, L. Mao, Y. Wan, F. Deng, X. Zhang, Y. Wei, Preparation of water soluble and biocompatible AIE-active fluorescent organic nanoparticles via multicomponent reaction and their biological imaging capability, Chem. Eng. J. 308 (2017) 527–534. C.-X. Chen, Z.-W. Wei, Y.-N. Fan, P.-Y. Su, Y.-Y. Ai, Q.-F. Qiu, K. Wu, S.-Y. Yin, M. Pan, C.-Y. Su, Visualization of anisotropic and stepwise piezofluorochromism in an MOF single crystal, Chem 4 (2018) 2658–2669. R. Wang, L. Liu, L. Lv, X. Wang, R. Chen, B. Wu, Synthesis, structural diversity and properties of Cd–MOFs based on 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate and N-heterocyclic ancillary ligands, Cryst. Growth Des. 17 (2017) 3616–3624. D.−.C. Zhang, X. Li, A Zn(II) complex with large channels based on 3′-nitro-biphenyl-3,5,4′-tricarboxylic acid: synthesis, crystal structure, fluorescent sensing of ATP, ADP, GTP, and UTP in aqueous solution and drug delivery, CrystEngComm 19 (2017) 6673–6680. Y.–.F. Kang, J.–.Q. Liu, B. Liu, W.–.T. Zhang, Q. Liu, P. Liu, Y.–.Y. Wang, Series of Cd (II) and Pb(II) coordination polymers based on a multilinker (R,S-)2,2′-bipyridine3,3′-dicarboxylate-1,1′-dioxide, Cryst. Growth Des. 14 (2014) 5466–5476. X.–.Y. Lin, P. Yang, J. Chen, M.–.H. Liu, C. Lin, Solvothermal synthesis, crystal structure and photoluminescence property of a 3D lead(II) coordination polymer based on terephthalic acid, Chin. J. Struct. Chem. 35 (2016) 61–68. A. Dey, S.K. Konavarapu, H.S. Sasmal, K. Biradha, Porous coordination polymers containing pyridine-3,5-bis(5-azabenzimidazole): exploration of water sorption, selective dye adsorption and luminescent properties, Cryst. Growth Des. 16 (2016)

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