How do substituent groups in the 5-position of 1,3-benzenedicarboxylate affect the construction of supramolecular frameworks?

Four 1,3-benzenedicarboxylic acid derivatives, with substituted R (OH, COOH, NO2, Me) groups at the 5-position, were employed to explore their effect on the construction of supramolecular assemblies. Four coordination polymers, [Zn(OH2)(5-HO-1,3-BDC)(1,4-bpeb)](n) (1), [Zn(1,3,5-HBTC)(1,4-bpeb)](n) (2), {[Zn(5-NO2-1,3-BDC)(1,4-bpeb)]center dot 2(H2O)(0.5)}(n) (3), and [Zn(5-Me-1,3-BDC)(1,4-bpeb)](n) (4) (1,4-bpeb - 1,4-bis[2-(4-pyridyl)ethenyl]benzene, 5-HO-1,3-BDC - 5-hydroxy-1,3-benzenedicarboxylate, 1,3,5-H3BTC = 1,3,5-benzenetricarboxylate, 5-NO2-1,3-BDC = 5-nitro-1,3-benzenedicarboxylate, 5-Me-1,3-BDC = 5-methyl-1,3-benzenedicarboxylate) were prepared by the hydrothermal reactions of Zn(NO3)(2)center dot 6H(2)O with 1,4-bpeb and 5-HO-1,3-H2BDC, 1,3,5-H3BTC, 5-NO2-1,3-H2BDC or 5-Me-1,3-H2BDC. All these compounds were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. The structure of 1 has a 3D H-bonded structure derived from linking 1D comb-like [Zn(OH2)(5-HO-1,3-BDC)(1,4-bpeb)](n) chains via intermolecular H-bonding interactions between the coordinated H2O molecule and 1,4-bpeb or one COO- group and between the OH group and the other COO- group. 2 has a 3D H-bonded net based on holding 2D [{Zn-2(1,3,5-HBTC)(2)}(4)](n) layers through intermolecular H-bonding interactions between 1,4-bpeb and the uncoordinated COOH group. 3 could be considered as a 6-fold interpenetrating 3D H-bonded supramolecular framework constructed by linking 2D [Zn-4(5-NO2-1,3-BDC)(4)(1,4-bpeb)(4)](n) networks through intermolecular H-bonding interactions between the water solvent molecules and the NO2 group. 4 has a 3-fold interpenetrating 3D framework in which each 2D (4,4) [Zn-4(5-Me-1,3-BDC)(4)(1,4-bpeb)(4)](n) network is interpenetrated by two other equivalent nets. The Schlafli symbols for the four supramolecular frameworks are 4(12)6(3), (4.6(2))(2)(4(2)6(6)8(7)), (6(3))(6(5)8) and 4(4)6(2), respectively. The thermal stability and photoluminescent properties of 1-4 were also investigated.