We present an investigation on the influence of benzoic acid, acetic acid, and water on the syntheses of the Zr-based metal-organic frameworks Zr-bdc (UiO-66), Zr-bdc-NH(2) (UiO-66-NH(2)), Zr-bpdc (UiO-67), and Zr-tpdc-NH(2) (UiO-68-NH(2)) (H(2) bdc: terephthalic acid, H(2) bpdc: biphenyl-4,4'-dicarboxylic acid, H(2) tpdc: terphenyl-4,4''-dicarboxylic acid). By varying the amount of benzoic or acetic acid, the synthesis of Zr-bdc can be modulated. With increasing concentration of the modulator, the products change from intergrown to individual crystals, the size of which can be tuned. Addition of benzoic acid also affects the size and morphology of Zr-bpdc and, additionally, makes the synthesis of Zr-bpdc highly reproducible. The control of crystal and particle size is proven by powder XRD, SEM and dynamic light scattering (DLS) measurements. Thermogravimetric analysis (TGA) and Ar sorption experiments show that the materials from modulated syntheses can be activated and that they exhibit high specific surface areas. Water proved to be essential for the formation of well-ordered Zr-bdc-NH(2) . Zr-tpdc-NH(2), a material with a structure analogous to that of Zr-bdc and Zr-bpdc, but with the longer, functionalized linker 2'-amino-1,1':4',1''-terphenyl-4,4''-dicarboxylic acid, was obtained as single crystals. This allowed the first single-crystal structural analysis of a Zr-based metal-organic framework.

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We present the synthesis and characterization of porous interpenetrated zirconium-organic frameworks (PIZOFs), a new family of metal-organic frameworks obtained from ZrCl(4) and the rodlike dicarboxylic acids HO(2)C[PE-P(R(1),R(2))-EP]CO(2) H that consist of alternating phenylene (P) and ethynylene (E) units. The substituents R(1),R(2) were broadly varied (alkyl, O-alkyl, oligo(ethylene glycol)), including postsynthetically addressable substituents (amino, alkyne, furan). The PIZOF structure is highly tolerant towards the variation of R(1) and R(2). This together with the modular synthesis of the diacids offers a facile tuning of the chemical environment within the pores. The PIZOF structure was solved from single-crystal X-ray diffraction analysis. The PIZOFs are stable under ambient conditions. PIZOF-2, the PIZOF prepared from HO(2)C[PE-P(OMe,OMe)-EP]CO(2)H, served as a prototype to determine thermal stability and porosity. It is stable up to 325 °C in air as determined by using thermogravimetry and powder X-ray diffraction. Argon sorption isotherms on PIZOF-2 revealed a Brunauer-Emmett-Teller (BET) surface area of 1250 m(2) g(-1) and a total pore volume of 0.68 cm(3) g(-1).

A novel porous coordination polymer (PCP), Zr-abdc, composed of Zr-based secondary building units (SBUs), [Zr 6 O 4 (OH) 4 ] 12+ , and 4,4Ј-azobenzenedicarboxylate (abdc 2-) linkers, has been synthesized by a modulated synthetic approach. In accord with the twelve-fold connecting SBU, Zrabdc has a topology similar to the PCP series UiO-66-UiO-68, which is proposed from single-crystal XRD and powder (P)XRD experiments. The linkers are strongly disordered, which made it impossible to determine the exact structure.

In this contribution we present a novel two-dimensional Zr-based metal-organic framework (MOF) which offers the possibility for delamination and post-synthetic photochemical modification at the linker molecule derived from benzophenone-4,4'-dicarboxylic acid (H bzpdc). The new Zr-bzpdc-MOF crystallizes in the orthorhombic system as crystals with rhombic shape. The structure was determined from single-crystal diffraction data. The MOF is stable up to 300 °C in air and exhibits a moderate BET surface area of 650 m g . The material can be obtained as thin sheets of a few nanometer thickness. Single crystals were modified post-synthetically, exploiting the intrinsic reactivity of the benzophenone group with C-H bond containing molecules. In this way, the surface properties of the MOF crystals (e.g., dispersibility in different solvents) can be changed drastically. Delamination and adaptation of the surface chemistry open up novel ways for shaping MOFs, for example, for the incorporation into polymer composites, and pave the way for various applications.