Metal-organic frameworks constructed from 2,4,6-tris(4-pyridyl)-1,3,5-triazine

摘要

Five new metal-organic frameworks based on 2,4,6-tris(4-pyridyl)-1,3,5-triazine (tpt) ligand have been hydrothermally synthesized. Reaction of tpt and AgNO3 in an acidic solution at 180 degrees C yields {[Ag(Htpt)(NO3)]NO3 center dot 4H(2)O}(n) (1). Ag(I) is trigonally coordinated by two pyridyl nitrogen and one nitrato oxygen to form a 1D zigzag chain. Reaction of tpt with CuSO4 affords {[Cu-2(tpt)(2)(SO4)(2)(H2O)(2)]center dot 4H(2)O}(n) (2). Copper(II) is bonded to two pyridyl nitrogen, two sulfato oxygen, and two water oxygen atoms to form an elongated octahedral geometry. Each H2O ligand bridges two copper(II), whereas sulfate bridges copper(II) via mu-1,3 and mu-1,1 fashions. The copper(II)-sulfate-H2O 2D layers are linked by bidentate tpt to form a 3D polymeric structure. Reaction of Cu(SO4)(2), tpt, and 1,2,4,5-benzenetetracarboxylic acid (H(4)btec) in the presence of piperidine gives [Cu(tpt)(H(2)btec)(1/2)](n) (3). Copper(I) is located in a trigonal-pyramidal coordination environment and coordinated by three pyridyl nitrogen of tpt in a plane, whereas a carboxylate oxygen is coordinated to the copper(I) axially. The tpt-Cu forms a layer, and the layers are linked through H(2)btec(2-) to form a 2D double-layered coordination polymer. Replacing CuSO4 with ZnI2 in the synthesis gives {[Zn(tpt)(btec)(1/2)]center dot H2O}(n) (4). Zinc(II) is in a distorted tetrahedral geometry and linked through bidentate tpt and exotetradentate btec(4-) to form a 2D coordination grid. Reaction of tpt with CuCN leads to the assembly of a 3D metal-organic framework [Cu-3(CN)(3)(tpt)](n) (5). Copper(I) is trigonally coordinated by one pyridyl nitrogen and two cyanides to form an intriguing honeycomb architecture. Luminescence study shows that 1, 3, 4, and 5 have blue fluorescence, which can be assigned to be ligand-centered emissions. Thermal analysis shows that all of these complexes are quite stable, and especially for 4, the framework is stable up to 430 degrees C.