Synthesis,Struchtres,and Properties Pof Metal-Organic Frameworks Based On Dicarboxyl And Bipyridy Mixedligands

Research interest in the assemblies of metal-organic frameworks (MOFs) has been rapidly expanding due to the construction of intriguing topological architectures and applications in the fields of luminescence, catalysis, gas absorption and magnetism. Major applications of MOFs are highly determined by structural characteristics, especially porosity. The pore size and shape within MOFs can be tuned by making use of framework interpenetration, self-catenation, supramolecular isomerism or interweaving. Recently, particular attention has been devoted to interpenetration, because the controlling and tuning of small pore/window sizes within MOFs is crucial to render the materials highly functional for specialized applications such as gas storage and separation of small gas molecules. In addition, according to the principle of crystal engineering, it is possible to achieve the rational design and synthesis of MOFs by selecting certain geometric metal ions and special structural characteristics of the organic ligands. Meanwhile, MOFs can be endowed with multifunctional properties by selecting functional metal ions and organic liagangs(ligands?) with functional groups.According to the principle of crystal engineering, we have focused our study on the synthesis, structures and multifunctional properties of MOFs by the selection of suitable dicarboxyl and bipyridy mixligands. The aim is to explore the effects of structural features and properties on the resulting MOFs, such as the metal ions, the structure of building blocks and organic ligands. In this paper, we choose ligands with different configurations to construct 15 MOFs. The corresponding structure and properties have been studied. These results will be introduced from the following aspects:(1) Six MOFs, [Zn₃(BPDC)₃(4-BPT)_1.5)]·1.5DMF (1), [Co₃(BPDC)₃(3-BPT)] (2), [Co_2.5(BPDC)_2.5(3-BPT)(DMF)] (3), [Cd(OBA)(3-BPT)] (4), [Zn₂(OBA)₂ 3- BPT)]·2.5DMF (5),[Co₂(OBA)₂(3-BPT)]·4DMF (6) (4-BPT = 4-amino-3,5- bis(4-pyridyl)-1,2,4-triazole, 3-BPT = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole, BPDC = biphenyl-4,4'-dicarboxylic acid, OBA = 4,4′-oxybis(benzoate)), have been prepared and structurally characterized by selecting n-BPT and BPDC/ OBA as the mixed ligands. Compound 1 exhibits threefold interpenetrated 6-connected pcu topology by linking {Zn₂(COO)₄} with 4-BPT and BPDC. Compound 2 presents a 2D structure with 6-connected topology by linking Co₃N₂(CO₂)₆ with 3-BPT and BPDC. Compound 3 shows a 3D structure with 8-connected topology with point symbol: (4².4.6⁴) by linking CoN₄(O)₂(COO)₁₀ with 3-BPT and BPDC. Compound 4 presents a 2D structure with (4, 4) topology. Compounds 5 and 6 exhibit a self-catenated 6-connected rob topology with the point symbol of (4⁸.6⁶.8) by linking {Zn₂(COO)₄}/{Co₂(COO)₄} with 3-BPT and OBA.(2) Six MOFs, [Zn₃(BPDC)₃(4-PYTZ)_1.5]·1.5DMF (7) , [Zn₃(BPDC)₃- (4-PYTZ)_1.5]·1.5DMF (8),[Zn₂(OBA)₂(4-PYTZ)]·2DMF (9),[Zn₂(OBA)₂- (3-PYTZ)·Zn₂(OBA)₂(DMF)₂]·7DMF (10),[Co₂(OBA)₂(3-PYTZ)₂]·DMF (11),[Cd₂(OBA)₂(3-PYTZ)₂] (12) (4-PYTZ = 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine) 3-PYTZ = 3,6-di(pyridin-3-yl)-1,2,4,5-tetrazine),have been prepared and structurally characterized by selecting n- PYTZ and BPDC/ OBA as the mixed ligands. Compounds 7 and 8 exhibit threefold interpenetrated 6-connected pcu topology by linking {Zn₂(COO)₄} with 4- PYTZ and BPDC. The structure of 9 is derived from a 2D double interpenetrated rhombic grid layer substructure, which is an interesting example of a self-catenated framework displaying a 6-connected uninodal framework with the point symbol of (4⁴.6¹⁰.8). Compound 10 is derived from a crosslinked threefold interpenetrated pts topology substructure, displaying a self-catenated 4, 6- connected binodal framework with the point symbol of (4².6².7²) (4².6⁸.7.8⁴). Compounds 11 and 12 present a 2D structure with 6-connected topology.(3) Three MOFs, [Zn₂(OBA)₂(DPNI)]·4DMF (13) , [Co₂(OBA)₂- (DPNI)]·1.5DMF (14), [Cd₂(OBA)₂(DPNI)]·2.5DMF (15) (DPNI = N,N′-di- (4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide) , have been prepared and structurally characterized by selecting DPNI and OBA as the mixed ligands. The structures of 13-15 are all derived from the rhombic grid layer substructure, which have the interesting example of self-catenated framework. Compound 13 exhibits a 6-connected roa topology with the point symbol of (4⁴.6¹⁰.8) by linking {Zn₂(COO)₄} with DPNI and OBA. Compounds 14 and 15 have the same 6-connected rob topology with the point symbol of (4⁸.6⁶.8).In summary, we have investigated the influence of changes cause by the metal ions, mixed ligands with different configurations, length of connection and flexible characteristic. We have prepared a series of MOFs with various topologies and studied their potential application. We believe that these results could facilitate the exploration of new MOFs with charming topologies and multifunctional properties.