English

• 1. INTRODUCTION

  Recently,metal-organic frameworks (MOFs) with appealingstructures and novel topology have become a hot research interest due to their tremendous potential applications in various fields,such as gas separation and storage^{[1, 2]},catalysis^{[3, 4]},luminescent material^{[5, 6]},and molecular magnetism^{[7, 8]}. Biphenyl-tetracarboxylic acid is one excellent type of organic ligands for synthesizing various MOFs for diverse coordination modes and supramolecular contacts,such as hydrogen bondingand π⋯π interactions^{[9, 10]}. Different from other biphenyl-tetracarboxylic acids reported previously^[11-17],2,3,3΄,5΄-biphenyltetra-carboxylic acid ligand which was chosen in this contribution has more distinct coordination geome-tries due to its low symmetry and remains largely unexplored. On the other hand,the metal component also plays an important role in the topology andphysical properties of the resulting framework. Especially,hetero-metal atoms with high and variable coordination numbersand poly carboxylate ligands which own versatile coordination modes provide unique opportunities for the discovery of unusual network topologies^[18]. In mixed metal Cd/M (M =alkali ions) carboxylate systems,the d¹⁰ configuration and softness of Cd(II) ion permit a host of coordina-tion numbers and geometries. Moreover,there are some reports showing that the alkali ions play a role in the self-assembly reactions.

  With the aim of understanding the coordination chemistry of this versatile ligand and preparing new materials with interesting structural topologies,we engage in the research of coordination polymers based on H₄bptc and mixed metal Cd/M,and have success-fully obtained a new 3D Cd/K hetero-nuclear mental coordination polymer 1. To the best of our knowledge,complex 1 has an unprecedented topology net with the Schlfli symbol of (6·8·8) ₂(6·6·8₂·8₂·12₆·12₆) .

  2. EXPERIMENTAL

  2.1. Materials and physical measurements

  H₄bptc was synthesized according to the litera-ture^[19]. Other starting materials were of reagent quality and obtained from commercial sourceswithout further purification. Elemental analyses (C,H) were carried out on a FLASH 2000 elemental analyzer. Fourier-transform infrared (FT-IR) spectra were collected in the solid state on a NICOLET 6700 FT-IR spectrometer (4000～400 cm^-1,resolution of 4 cm^-1,scanning number 70) . Thermogravimetric analysis (TGA) was performed on a SDT Q600 thermogra-vimetric analyzer from 30 to 900 ℃ at a heating rate of 10 ℃∙min^-1 (Al₂O₃ ceramic pan as a holder) under a flow of N₂ (rate of 40 ml∙min^-1) . Solid state lumi-nescence (emission and excitation) spectra in the visible ranges were measured at room temperature with an Edinburgh instrument FLS920 fluorescence spectrometer.

  2.2. Synthesis

  [K₂Cd₅(Hbptc)₄(H₂O)₁₂···12H₂O]n (1) : A mixture of Cd(NO₃) ₂···4H₂O (0.031 g,0.1 mmol) and H₄bptc (0.050 g,0.15 mmol) was dissolved in 10 mL of distilled water. The pH value was then adjusted to 6.0 with 2 M KOH solution and the resulting mixture was tra nsferred into a 25 mL Teflon-lined stainless-steel vessel,which was sealed and heated at 140 ℃ for 72 h,and then the reaction system was slowly cooled down to room temperature. Colorless prism-shaped crystals were filtered off and dried in air. Yield: (based on Cd) 47%. Elemental analysis (%): Anal. Calcd. for 1 (C₆₄H₇₆Cd₅K₂O₅₆) : C,32.28; H,3.32. Found: C,32.39; H,3.20. IR: ν (cm^-1) = 3345(b),1601(m),1537(s),1431(m),1361(s),1253(m),944(m),855(m),693(s),686(s).

  2.3. X-ray crystallography

  A suitable single crystal of 1 was mounted onto thin glass fibers in air. X-ray intensity data of compound 1 were collectedwith a Bruker SMART APEX CCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 296(2) K. A total of 53356 reflections were collected in the range of 1.90≤θ≤27.50 with 10613 unique ones (R_int = 0.0403) ,in which 7964 with I > 2σ(I) were observed and used in the succeeding refinements. Absorption corrections were applied using multi-scan technique and the structure was solved by direct methods with SHELXS-97^[20] and refined with SHELXL-97^[21] by full-matrix least-squares techniques on F². All non-hydrogen atoms were solved by direct methods and refined employing full-matrix least-squares on F² with anisotropic ther-mal parameters. An empirical absorption correction was applied using the SADABS program,while conventional refinement of compounds converged reasonably well. The hydrogen atoms of organic ligands were placed in the geometrically calculated positions^[22]. Selected bond lengths and bond angles are listed in Table 1 and hydrogen bonds are given in Table 2.

  Table 1

  

  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) for Complex 1

  DownLoad: CSV

  Bond	Dist.	Bond	Dist.	Bond	Dist.
  Cd(1) -O(12)	2.286(3)	Cd(2) -O(9)	2.413(7)	Cd(3) -O(6)	2.645(8)
  Cd(1) -O(1W)	2.296(8)	Cd(2) -O(10)	2.445(7)	Cd(2) -O(4)	2.390(6)
  Cd(1) -O(3W)	2.304(9)	Cd(2) -O(3)	2.515(7)	Cd(3) -O(16)	2.483(7)
  Cd(1) -O(2W)	2.350(8)	Cd(3) -O(5)	2.240(7)	K(1) -O(4)	2.673(7)
  Cd(1) -O(2)	2.357(7)	Cd(3) -O(15)	2.296(7)	K(1) -O(6)	2.822(7)
  Cd(1) -O(1)	2.506(8)	Cd(3) -O(6W)	2.262(12)	K(2) -O(9)	2.692(7)
  Cd(1) -O(11)	2.529(7)	Cd(3) -O(4W)	2.284(14)	K(2) -O(16)	2.871(7)
  Cd(2) -O(4)	2.390(6)	Cd(3) -O(5W)	2.338(10)
  Angle	(°)	Angle	(°)	Angle	(°)
  O(12) #1-Cd(1) -O(1W)	141.1(3)	O(3W)-Cd(1) -C(24) #1	93.1(3)	O(9) #2-Cd(2) -O(3) #2	92.1(3)
  O(12) #1-Cd(1) -O(3W)	103.4(4)	O(2W)-Cd(1) -C(24) #1	92.9(3)	O(10) -Cd(2) -O(3) #2	81.5(3)
  O(1W)-Cd(1) -O(3W)	83.6(4)	O(2) -Cd(1) -C(24) #1	158.3(3)	O(10) #2-Cd(2) -O(3) #2	98.5(3)
  O(12) #1-Cd(1) -O(2W)	84.9(3)	O(1) -Cd(1) -C(24) #1	105.4(3)	O(4) #2-Cd(2) -O(3)	129.1(2)
  O(1W)-Cd(1) -O(2W)	87.6(3)	O(11) #1-Cd(1) -C(24) #1	26.6(2)	O(4) -Cd(2) -O(3)	52.7(2)
  O(3W)-Cd(1) -O(2W)	170.9(4)	O(4) #2-Cd(2) -O(4)	76.5(3)	O(9) -Cd(2) -O(3)	92.1(3)
  O(12) #1-Cd(1) -O(2)	131.5(2)	O(4) #2-Cd(2) -O(9)	125.6(3)	O(9) #2-Cd(2) -O(3)	86.5(3)
  O(1W)-Cd(1) -O(2)	85.7(3)	O(4) -Cd(2) -O(9)	131.4(3)	O(10) -Cd(2) -O(3)	98.5(3)
  O(3W)-Cd(1) -O(2)	91.3(4)	O(4) #2-Cd(2) -O(9) #2	131.4(3)	O(10) #2-Cd(2) -O(3)	81.5(3)
  O(2W)-Cd(1) -O(2)	85.7(3)	O(4) -Cd(2) -O(9) #2	125.6(3)	O(3) #2-Cd(2) -O(3)	178.2(3)
  O(12) #1-Cd(1) -O(1)	79.9(3)	O(9) -Cd(2) -O(9) #2	75.5(3)	O(5) -Cd(3) -O(15) #3	179.7(3)
  O(1W)-Cd(1) -O(1)	138.6(3)	O(4) #2-Cd(2) -O(10)	83.6(2)	O(5) -Cd(3) -O(6W)	90.6(4)
  O(3W)-Cd(1) -O(1)	92.5(4)	O(4) -Cd(2) -O(10)	95.7(2)	O(15) #3-Cd(3) -O(6W)	89.6(4)
  O(2W)-Cd(1) -O(1)	92.6(3)	O(9) -Cd(2) -O(10)	52.8(2)	O(5) -Cd(3) -O(4W)	88.2(4)
  O(2) -Cd(1) -O(1)	53.1(2)	O(9) #2-Cd(2) -O(10)	128.0(2)	O(15) #3-Cd(3) -O(4W)	91.5(4)
  O(12) #1-Cd(1) -O(11) #1	53.7(2)	O(4) #2-Cd(2) -O(10) #2	95.7(2)	O(6W)-Cd(3) -O(4W)	93.3(5)
  O(1W)-Cd(1) -O(11) #1	90.4(3)	O(4) -Cd(2) -O(10) #2	83.6(2)	O(5) -Cd(3) -O(5W)	89.6(3)
  O(3W)-Cd(1) -O(11) #1	82.5(3)	O(9) -Cd(2) -O(10) #2	128.0(2)	O(15) #3-Cd(3) -O(5W)	90.2(3)
  O(2W)-Cd(1) -O(11) #1	99.9(3)	O(9) #2-Cd(2) -O(10) #2	52.8(2)	O(6W)-Cd(3) -O(5W)	179.0(5)
  O(2) -Cd(1) -O(11) #1	173.0(3)	O(10) -Cd(2) -O(10) #2	179.2(3)	O(4W)-Cd(3) -O(5W)	87.7(5)
  O(1) -Cd(1) -O(11) #1	130.1(2)	O(4) #2-Cd(2) -O(3) #2	52.7(2)	O(5) -Cd(3) -O(16) #3	125.2(2)
  O(12) #1-Cd(1) -C(24) #1	27.1(2)	O(4) -Cd(2) -O(3) #2	129.1(2)	O(15) #3-Cd(3) -O(16) #3	55.1(2)
  O(1W)-Cd(1) -C(24) #1	115.9(3)	O(9) -Cd(2) -O(3) #2	86.5(3)	O(6W)-Cd(3) -O(16) #3	96.7(4)
  O(4W)-Cd(3) -O(16) #3	144.8(4)	O(5W)-Cd(3) -O(16) #3	82.4(3)	O(5) -Cd(3) -O(6)	53.2(2)
  O(15) #3-Cd(3) -O(6)	127.1(2)	O(6W)-Cd(3) -O(6)	85.1(4)	O(4W)-Cd(3) -O(6)	141.3(4)
  O(5W)-Cd(3) -O(6)	94.2(3)	O(16) #3-Cd(3) -O(6)	73.3(2)	O(4) #2-K(1) -O(4)	67.2(3)
  O(4) #2-K(1) -O(6) #2	92.8(2)	O(4) -K(1) -O(6) #2	159.3(2)	O(4) #2-K(1) -O(6)	159.3(2)
  O(4) -K(1) -O(6)	92.8(2)	O(6) #2-K(1) -O(6)	107.7(3)	O(9) #2-K(2) -O(9)	66.6(3)
  O(9) #2-K(2) -O(16)	158.6(2)	O(9) -K(2) -O(16)	92.6(2)	O(9) #2-K(2) -O(16) #2	92.6(2)
  O(9) -K(2) -O(16) #2	158.6(2)	O(16) -K(2) -O(16) #2	108.6(3)
  Symmetry codes: #1: x,y+1,z; #2: x,y-1,z; #3: -x+1,-y+1,-z+1

  Table 2

  

  Table 2.  Hydrogen Bond Parameters for Complex 1

  DownLoad: CSV

  D-H···A	d(D-H)	d(H···A)	d(D···A)	<(DHA)
  O(6W)-H(6W)···O(14) #1	0.84	2,52	3.088(11	125.5
  O(5W)-H(5W)···O(3) #8	0.84	2.25	2.767(12)	120.4
  O(5W)-H(5W)···O(2) #8	0.84	2.58	3.013(15)	113.6
  O(4W)-H(4W)···O(5) #5	0.84	2.45	2.88(3)	113.1
  O(4W)-H(4W)···O(4) #5	0.84	2.03	2.711(14)	138.0
  O(3W)-H(3W)···O(1) #6	0.84	2.29	2.971(9)	139.0
  O(2W)-H(2W)···O(15) #3	0.84	2.18	2.721(6)	122.4
  O(1W)-H(1W)···O(12) #3	0.84	1.92	2.712(7)	156.2
  O(7) -H(7) ···O(5) #1	0.84	1.84	2.644(6)	160.3
  Symmetry codes: #1: x,y+1,z; #3: -x+1,-y+1,-z+1; #5: -x+1,y+1,-z+1/2; #6: -x+3/2,y-1/2,z; #8: x,-y+2,z+1/2

  3. RESULTS AND DISCUSSION

  3.1. Structure description

  Single-crystal X-ray diffraction reveals that com-plex1 crystallizesin orthorhombic group,Pbcn space group. As shown in Fig. 1,the asymmetric unit con-tains two K(I) ions,five Cd(II) ions of which three are crystallographically independent and another two are symmetrical,four Hbptc^3- ligands,twelvecoordinated water molecules and twelve lattice water molecules. TheHbptc^3- ligand shows the μ⁸-η³:η²:η³:η⁰ coordina-tion fashion as shown in Fig. 1. The dihedral angle between two phenyl rings is 54.112°,and the included angles of the four carboxyl groups (3′-,5′-,2-,3-COO-) towards the plane of the linking phenyl rings are 22.791°,6.356°,84.374° and 7.859°,respectively. Both K(1) and K(2) ions are four-coordinated with a distorted tetrahedral arrangement by four carboxylic oxygen atoms from four Hbptc^3- ligands. The K(1) -O(4) bond distance is 2.672(3) Å and K(1) -O(6) is 2.821(7) Å,while the distances between K(2) and O atoms (O(9) and O(16) ) are 2.691 and 2.871 Å,respectively. The angles around K range from 66.6(3) to159.3(2) Å. Both Cd(1) and Cd(3) ions are seven-coordinated by seven oxygen atoms from two Hbptc^3- ligands and three water molecules,exhibiting a slightly distorted pentagonal bipyramidal geometry singly; Cd(1) -O distances range from 2.283(3) Å to 2.528(3) Å and the Cd(3) -O ones are 2.239～2.646 Å. The O-Cd(1) -O angles are in the range of 53.20(8) ～ 173.0(12) ° while the O-Cd(3) -O angles change from 53.2(2) ° to 179.7(3) °. The Cd(2) ion is octa-coor-dinated with eight oxygen atoms from four Hbptc^3- ligands (Fig. 1) . The average Cd(2) -O distance is 2.441 Å and O-Cd(2) -O angles fall in the range of 52.8～131.4 Å. The nearest distance between K and Cd is 4.1034 Å (K(1) -Cd(2) ).

  Fig. 2 is a view of the 2D network from the b-direction. As shown in Fig. 2,one Cd(3) ion (purple),one K ion and one Cd(2) ion (yellow) constitute a [Cd3Cd2K] building block.Four [Cd3Cd2K]building blocks are linked by four Cd(1) ions (green) to form a cavity. In the whole molecule,the porosity is 35% as calculated by PLATON^[23]. As displayed in Fig. S1,if both C(2) and C(20) in the Hbptc^3- ligand are considered as a 3-connected node respectively,and Cd(2) as a 4-co nnected node,the whole 3D structure can be simplified as a novel 2-layer interpenetrating (3,4) -connected topological net with the Schlfli symbol of (6·8·8) ₂(6·6·8₂·8₂·12₆·12₆) (Fig. 3a and 3b). This new topological structure has not been documented yet,to the best of our knowledge.

  There are abundant hydrogen bonds in polymer 1. Lattice water molecules and coordinated water molecules play important roles in forming the 3D packing structure by H-bond. As shown in Table 2,there are three kinds of intermolecular hydrogen bonds in1: coordinated water molecules serve as H-donor andinteract with the carboxylate oxygen atoms with the hydrogen bond lengths falling in the 1.92～2.52 Å range; H-bond in which uncoordinated carboxylate group serves as H-donor and interacts with other carboxylate group oxygen atoms; In addition,some H-bonds exist between coordinated and lattice water molecules. As a result,these abundant hydrogen bonds link the structural units into a 3D network supramo-lecular architecture.

  Figure 1

  

  Figure 1.  Coordination mode of metal ions and the ligand for complex 1. All hydrogen atoms and lattice water molecules are omitted for clarity

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  Figure 2

  

  Figure 2.  View of the 2D network with large porosity along the b-axis (Green is Cd1,purple is Cd3 and yellow is Cd2)

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  Fig. 3a. View of the 3D topological network Fig. 3b.2-fold interpenetrating structure of polymer 1

  Figure 3a

  

  Figure 3a.  View of the 3D topological network

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  Figure 3b

  

  Figure 3b.  2-fold interpenetrating structure of polymer 1

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  3.2. IR spectra analysis

  IR spectra of complex 1 and free H₄bptc ligand were performed in the range of 4000～400 cm^-1 (Fig. S2) . Complex 1 shows the characteristic bands of carboxy-lic groups at 1627 ～ 1530 cm^-1 for the asymmetric vibration and at 1440～1310 cm^-1 for the symmetric vibration^{[24, 6]}. The broad band at 3500～3000 cm^-1 is attributed to the O-H vibration of water molecules containing H-bonds. The medium absorption band at 855 cm^-1 and strong absorption band at 770 ～ 670 cm^-1 can be ascribed to the bending vibrations of the aromatic C-H groups. The analysis of IR spectrum for complex 1 is in good agreement with the crystal structure considerations.

  3.3. Thermal gravimetric analysis

  To estimate the stability of the coordination archi-tecture,thermogravimetric analysis (TGA) was carried out under N₂ atmosphere with a heating rate of 10 ℃/min (Fig. 4) . TGA curve shows that compound 1 released twelvelattice water molecules in the range of 40～120 ℃ (calcd.9.08%,found.9.27%).From 120 to 350 ℃ ,the second weight loss of 9.86% is interpreted as the departure of 12 coordinated water molecules (calcd.9.08%). The major mass loss occurs in the temperature range of 350～610 ℃ with the loss of 55.76%,corresponding to the decomposition of the residual organic components of the compound (calcd.54.97%),in consistent with the crystal structure analysis. The residual organic components start to decompose after that,with a series of complicated weight losses that do not stop until the heating ends at 900 ℃.

  3.4. Photoluminescence property

  The luminescent spectra of 1 and the free H₄bptc ligand were investigated in solid state at room temperature (Fig. 5) . The H₄bptc ligand displays an emission maximum at 410 nm upon excitation at 353 nm,which is probably caused by the π^*→π or π^*→n internal transitions. Compared with the emission band ofH₄bptc,complex 1 exhibits a distinct emission maximum at 424 nm upon excitationat 348 nm,and a remarkable red shift of 14 nm has been observed. The emissionband of complex 1 is neither ligand-to-metal charge transfer (LMCT) nor metal-to-ligand charge transfer (MLCT) since the Cd(II) and K(I) ions are difficult to reduce or oxidize due to the Cd(II) d¹⁰ configuration and K(I) 3s²3p⁶. Thus,the emission band can be attributed to the intra-ligand emission from the H₄bptc ligand^{[25, 26]}. The red shift is probably attributed to the effect of coordination environment around the Cd(II) ions decreasing the energy^[27].

  Figure 4

  

  Figure 4.  TGA curve of 1

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  Figure 5

  

  Figure 5.  Solid-state emission spectrum ofcomplex 1 and H₄bptc ligand

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  4. CONCLUSION

  In summary,we have prepared and characterized one novel 3D hetero-nuclear framework wi th 2-layer interpenetrating (3,4) -connected topological net based on [Cd3Cd2K] building block. The successful preparation of the title compound not only provides intriguing examples to chemical topology but also exhibits inimitable interpenetratingstructure. Further-more,the photoluminescence property of the polymer indicates that it may be a good candidate for lumine-scent material and can provideuseful help for further study.

• 1. [1]

     Suh M. P, Park H. J, Prasad T. K, Lim D. W. Hydrogen storage in metal-organic frameworks[J]. Chem. Rev., 2011, 112:  782-835.

  2. [2]

     Li J. R, Sculley J, Zhou H. C. Metal-organic frameworks for separations[J]. Chem. Rev., 2012, 112:  869-932. doi: 10.1021/cr200190s

  3. [3]

     Yoon M, Srirambalaji R, Kim K. Homochiral metal-organic frameworks for asymmetric heterogeneous catalysis[J]. Chem. Rev., 2011, 112:  .

  4. [4]

     Dhakshinamoorthy A, Garcia H. Catalysis by metal nanoparticles embedded on metal-organic frameworks[J]. Chem. Soc. Rev., 2012, 41:  5262-5284. doi: 10.1039/c2cs35047e

  5. [5]

     Cui Y. J, Yue Y. F, Qian G. D, Chen B. L. Luminescent functional metal-organic frameworks[J]. Chem. Rev., 2012, 112:  1126-1162. doi: 10.1021/cr200101d

  6. [6]

     Feng X, Feng Y. Q. ;Chen J. J, Ng S. W, Wang L. Y, Guo J. Z. Reticular three-dimensional 3d-4f frameworks constructed through substituted imidazole-dicarboxylate: syntheses, luminescence and magnetic properties study[J]. Dalton Trans., 2015, 44:  804-816. doi: 10.1039/C4DT02047B

  7. [7]

     Biswas S, Jena H. S, Adhikary A, Konar S. Two isostructural 3D lanthanide coordination networks (Ln = Gd3+, Dy3+) with squashed cuboid-type nanoscopic cages showing significant cryogenic magnetic refrigeration and slow magnetic relaxation[J]. Inorg. Chem., 2014, 53:  3926-3928. doi: 10.1021/ic4030316

  8. [8]

     Xu Z. Q, Meng W, Li H. J, Hou H. W, Fan Y. T. Guest molecule release triggers changes in the catalytic and magnetic properties of a Fe-parallel to-based 3D metal-organic framework[J]. Inorg. Chem., 2014, 53:  3260-3262. doi: 10.1021/ic500004s

  9. [9]

     Cook T. R, Zheng Y. R, Stang P. J. Metal-organic frameworks and self-assembled supramolecular coordination complexes: comparing and contrasting the design, synthesis, and functionality of metal-organic materials[J]. Chem. Rev., 2013, 113:  734-777. doi: 10.1021/cr3002824

  10. [10]

      Li R. F, Liu X. F, Zhang T, Zhang X. Y, Feng X. Hydrothermal syntheses, structures, and magnetic properties of two new Mn(II) complexes with biphenyl-2,3,3?,5?-tetracarboxylic acid[J]. J. Mol. Struct., 2014, 1075:  .

  11. [11]

      Li H. H, Ma N, Li K. H. A 3D mesomeric supramolecular structure of a Cu(II) coordination polymer with 11?-biphenyl-22?33?-tetracarboxylic acid and 55 ′-dimethyl-22 ′-bipyridine ligands. J[J]. Inorg. Organomet. Polym. Mater., 2012, 22:  1320-1324. doi: 10.1007/s10904-012-9767-8

  12. [12]

      Yang Z, Liu J, Liang X. Q, Jiang Y, Zhang T, Han B, Sun F. X, Liu L. Two novel 2D metal-organic frameworks based on biphenyl-2,2?,6,6?- tetracarboxylic acid: synthesis, structures and luminescent properties[J]. Inorg. Chem. Commun., 2012, 16:  92-94. doi: 10.1016/j.inoche.2011.12.003

  13. [13]

      Tian D, Pang Y, Zhou Y. H, Guan L, Zhang H. A series of complexes based on biphenyl- 2,5,2?,5?-tetracarboxylic acid: syntheses, crystal structures, luminescent and magnetic properties[J]. CrystEngComm., 2011, 13:  957-966. doi: 10.1039/C0CE00281J

  14. [14]

      Pan Z. R, Xu J, Yao X. Q, Li Y. Z, Guo Z. J, Zheng H. G. Syntheses, structures, magnetic and photoluminescence properties of metal-organic frameworks based on aromatic polycarboxylate acids[J]. CrystEngComm., 2011, 13:  1617-1624. doi: 10.1039/C0CE00490A

  15. [15]

      Guo, S. Q.; Tian, D.; Zheng, X.; Zhang, H. A (3,4,10)-connected 3D sandwich-type metal-organic framework with trinuclear zinc(II) cluster and two kinds of discrete zinc(II) ions. Inorg. Chem. Commun. 2011, 14, 1876-1879.

  16. [16]

      Li B, Zang S. Q, Ji C, Hou H. W, Mak T. C. W. Syntheses, structures, and properties of silver-organic frameworks constructed with 1,1?-biphenyl- 2,2 ′,6,6 ′-tetracarboxylic acid[J]. Cryst. Growth. Des., 2012, 12:  1443-1451. doi: 10.1021/cg2015447

  17. [17]

      Zhang S, Xie G, Zou Y, Chen S, Gao S. Syntheses, structures, and magnetism of two coordination compounds with 3,3?,4,4?- biphenyltetracarboxylic acid and 1,10-phenanthroline[J]. J. Coord. Chem., 2012, 65:  1062-1070. doi: 10.1080/00958972.2012.666535

  18. [18]

      Du F. L, Zhao M. L, Long X. F, Du S. W. A new acentric heterometallic inorganic-organic hybrid framework with an unusual {Cd3Na4}n array: NLO and ferroelectric properties[J]. Inorg. Chem. Commun., 2013, 38:  39-42. doi: 10.1016/j.inoche.2013.10.011

  19. [19]

      Li R. F, Liu X. F, Zhang T, Wang L. Y, Ma L. F, Feng X. Two unique lanthanide-organic frameworks based on biphenyl-2,3,3?,5?-tetracarboxylic acid: syntheses, crystal structures and luminescence properties[J]. Polyhedron, 2015, 99:  238-243. doi: 10.1016/j.poly.2015.07.061

  20. [20]

      Sheldrick, G. M. SHELXS 97, Program for the Solution of Crystal Structure (University of Gottingen, Germany 1997).

  21. [21]

      Sheldrick, G. M. SHELXL 97, Program for the Refinement of Crystal Structure (University of Gottingen, Germany 1997).

  22. [22]

      Sheldrick, G. M. SADABS Siemens Area Correction Absorption Program (University of G?ttingen: G?ttingen, Germany 1994).

  23. [23]

      Spek, P. A. L. A Multipurpose Crystallographic Tool (Utrecht University, Utrecht, The Netherlands 2001).

  24. [24]

      Bellamy, L. J. The infrared spectra of complex molecules (John Wiley & Sons, New York 1958).

  25. [25]

      Zang S, Su Y, Li Y. Z, Lin J, Duan X, Meng Q, Gao S. Four 2D metal-organic networks incorporating Cd-cluster SUBs: hydrothermal synthesis, structures and photoluminescent properties[J]. CrystEngComm., 2009, 11:  122-129. doi: 10.1039/B806899B

  26. [26]

      Li, R. F.; Gu, Y. X.; Liu, X. F.; Feng, X.; Ma, L. F. Syntheses, structures, and properties of two zinc(II) metal-organic frameworks based on biphenyl- 2,3,3?,5?-tetracarboxylic acid and N-donor ancillary ligands. Z. Anorg. Allg. Chem. 2015, 641, 1114-1118.

  27. [27]

      Qiao J. Z, Zhan M. S, Hu T. P. One novel 3D tetranuclear cadmium coordination polymer based on 2,3?,4,5?-biphenyltetracarboxylic acid: synthesis, crystal structure and luminescence[J]. Inorg. Chem. Commun., 2015, 55:  157-160. doi: 10.1016/j.inoche.2015.03.019

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  Figure 1  Coordination mode of metal ions and the ligand for complex 1. All hydrogen atoms and lattice water molecules are omitted for clarity

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  Figure 2  View of the 2D network with large porosity along the b-axis (Green is Cd1,purple is Cd3 and yellow is Cd2)

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  Figure 3a  View of the 3D topological network

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  Figure 3b  2-fold interpenetrating structure of polymer 1

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  Figure 4  TGA curve of 1

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  Figure 5  Solid-state emission spectrum ofcomplex 1 and H₄bptc ligand

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  Table 1.  Selected Bond Lengths (Å) and Bond Angles (°) for Complex 1

  Bond	Dist.	Bond	Dist.	Bond	Dist.
  Cd(1) -O(12)	2.286(3)	Cd(2) -O(9)	2.413(7)	Cd(3) -O(6)	2.645(8)
  Cd(1) -O(1W)	2.296(8)	Cd(2) -O(10)	2.445(7)	Cd(2) -O(4)	2.390(6)
  Cd(1) -O(3W)	2.304(9)	Cd(2) -O(3)	2.515(7)	Cd(3) -O(16)	2.483(7)
  Cd(1) -O(2W)	2.350(8)	Cd(3) -O(5)	2.240(7)	K(1) -O(4)	2.673(7)
  Cd(1) -O(2)	2.357(7)	Cd(3) -O(15)	2.296(7)	K(1) -O(6)	2.822(7)
  Cd(1) -O(1)	2.506(8)	Cd(3) -O(6W)	2.262(12)	K(2) -O(9)	2.692(7)
  Cd(1) -O(11)	2.529(7)	Cd(3) -O(4W)	2.284(14)	K(2) -O(16)	2.871(7)
  Cd(2) -O(4)	2.390(6)	Cd(3) -O(5W)	2.338(10)
  Angle	(°)	Angle	(°)	Angle	(°)
  O(12) #1-Cd(1) -O(1W)	141.1(3)	O(3W)-Cd(1) -C(24) #1	93.1(3)	O(9) #2-Cd(2) -O(3) #2	92.1(3)
  O(12) #1-Cd(1) -O(3W)	103.4(4)	O(2W)-Cd(1) -C(24) #1	92.9(3)	O(10) -Cd(2) -O(3) #2	81.5(3)
  O(1W)-Cd(1) -O(3W)	83.6(4)	O(2) -Cd(1) -C(24) #1	158.3(3)	O(10) #2-Cd(2) -O(3) #2	98.5(3)
  O(12) #1-Cd(1) -O(2W)	84.9(3)	O(1) -Cd(1) -C(24) #1	105.4(3)	O(4) #2-Cd(2) -O(3)	129.1(2)
  O(1W)-Cd(1) -O(2W)	87.6(3)	O(11) #1-Cd(1) -C(24) #1	26.6(2)	O(4) -Cd(2) -O(3)	52.7(2)
  O(3W)-Cd(1) -O(2W)	170.9(4)	O(4) #2-Cd(2) -O(4)	76.5(3)	O(9) -Cd(2) -O(3)	92.1(3)
  O(12) #1-Cd(1) -O(2)	131.5(2)	O(4) #2-Cd(2) -O(9)	125.6(3)	O(9) #2-Cd(2) -O(3)	86.5(3)
  O(1W)-Cd(1) -O(2)	85.7(3)	O(4) -Cd(2) -O(9)	131.4(3)	O(10) -Cd(2) -O(3)	98.5(3)
  O(3W)-Cd(1) -O(2)	91.3(4)	O(4) #2-Cd(2) -O(9) #2	131.4(3)	O(10) #2-Cd(2) -O(3)	81.5(3)
  O(2W)-Cd(1) -O(2)	85.7(3)	O(4) -Cd(2) -O(9) #2	125.6(3)	O(3) #2-Cd(2) -O(3)	178.2(3)
  O(12) #1-Cd(1) -O(1)	79.9(3)	O(9) -Cd(2) -O(9) #2	75.5(3)	O(5) -Cd(3) -O(15) #3	179.7(3)
  O(1W)-Cd(1) -O(1)	138.6(3)	O(4) #2-Cd(2) -O(10)	83.6(2)	O(5) -Cd(3) -O(6W)	90.6(4)
  O(3W)-Cd(1) -O(1)	92.5(4)	O(4) -Cd(2) -O(10)	95.7(2)	O(15) #3-Cd(3) -O(6W)	89.6(4)
  O(2W)-Cd(1) -O(1)	92.6(3)	O(9) -Cd(2) -O(10)	52.8(2)	O(5) -Cd(3) -O(4W)	88.2(4)
  O(2) -Cd(1) -O(1)	53.1(2)	O(9) #2-Cd(2) -O(10)	128.0(2)	O(15) #3-Cd(3) -O(4W)	91.5(4)
  O(12) #1-Cd(1) -O(11) #1	53.7(2)	O(4) #2-Cd(2) -O(10) #2	95.7(2)	O(6W)-Cd(3) -O(4W)	93.3(5)
  O(1W)-Cd(1) -O(11) #1	90.4(3)	O(4) -Cd(2) -O(10) #2	83.6(2)	O(5) -Cd(3) -O(5W)	89.6(3)
  O(3W)-Cd(1) -O(11) #1	82.5(3)	O(9) -Cd(2) -O(10) #2	128.0(2)	O(15) #3-Cd(3) -O(5W)	90.2(3)
  O(2W)-Cd(1) -O(11) #1	99.9(3)	O(9) #2-Cd(2) -O(10) #2	52.8(2)	O(6W)-Cd(3) -O(5W)	179.0(5)
  O(2) -Cd(1) -O(11) #1	173.0(3)	O(10) -Cd(2) -O(10) #2	179.2(3)	O(4W)-Cd(3) -O(5W)	87.7(5)
  O(1) -Cd(1) -O(11) #1	130.1(2)	O(4) #2-Cd(2) -O(3) #2	52.7(2)	O(5) -Cd(3) -O(16) #3	125.2(2)
  O(12) #1-Cd(1) -C(24) #1	27.1(2)	O(4) -Cd(2) -O(3) #2	129.1(2)	O(15) #3-Cd(3) -O(16) #3	55.1(2)
  O(1W)-Cd(1) -C(24) #1	115.9(3)	O(9) -Cd(2) -O(3) #2	86.5(3)	O(6W)-Cd(3) -O(16) #3	96.7(4)
  O(4W)-Cd(3) -O(16) #3	144.8(4)	O(5W)-Cd(3) -O(16) #3	82.4(3)	O(5) -Cd(3) -O(6)	53.2(2)
  O(15) #3-Cd(3) -O(6)	127.1(2)	O(6W)-Cd(3) -O(6)	85.1(4)	O(4W)-Cd(3) -O(6)	141.3(4)
  O(5W)-Cd(3) -O(6)	94.2(3)	O(16) #3-Cd(3) -O(6)	73.3(2)	O(4) #2-K(1) -O(4)	67.2(3)
  O(4) #2-K(1) -O(6) #2	92.8(2)	O(4) -K(1) -O(6) #2	159.3(2)	O(4) #2-K(1) -O(6)	159.3(2)
  O(4) -K(1) -O(6)	92.8(2)	O(6) #2-K(1) -O(6)	107.7(3)	O(9) #2-K(2) -O(9)	66.6(3)
  O(9) #2-K(2) -O(16)	158.6(2)	O(9) -K(2) -O(16)	92.6(2)	O(9) #2-K(2) -O(16) #2	92.6(2)
  O(9) -K(2) -O(16) #2	158.6(2)	O(16) -K(2) -O(16) #2	108.6(3)
  Symmetry codes: #1: x,y+1,z; #2: x,y-1,z; #3: -x+1,-y+1,-z+1

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  Table 2.  Hydrogen Bond Parameters for Complex 1

  D-H···A	d(D-H)	d(H···A)	d(D···A)	<(DHA)
  O(6W)-H(6W)···O(14) #1	0.84	2,52	3.088(11	125.5
  O(5W)-H(5W)···O(3) #8	0.84	2.25	2.767(12)	120.4
  O(5W)-H(5W)···O(2) #8	0.84	2.58	3.013(15)	113.6
  O(4W)-H(4W)···O(5) #5	0.84	2.45	2.88(3)	113.1
  O(4W)-H(4W)···O(4) #5	0.84	2.03	2.711(14)	138.0
  O(3W)-H(3W)···O(1) #6	0.84	2.29	2.971(9)	139.0
  O(2W)-H(2W)···O(15) #3	0.84	2.18	2.721(6)	122.4
  O(1W)-H(1W)···O(12) #3	0.84	1.92	2.712(7)	156.2
  O(7) -H(7) ···O(5) #1	0.84	1.84	2.644(6)	160.3
  Symmetry codes: #1: x,y+1,z; #3: -x+1,-y+1,-z+1; #5: -x+1,y+1,-z+1/2; #6: -x+3/2,y-1/2,z; #8: x,-y+2,z+1/2

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