A multifunctional polyhedral metal−organic framework with a pcu network topology based on supramolecular building blocks can be constructed by the reaction of Eu(NO 3 ) 3 and pyridine-3,5-dicarboxylic acid (H 2 PDC). The basic Eu III paddlewheel nodes as secondary building units (SBUs) are connected by PDC ligands to generate nanosized metal−organic cuboctahedra (MOCs), which are further connected by sharing the paddlewheel SBUs to give rise to a three-dimensional primitive cubic network arrangement. The obtained metal−organic frameworks (MOFs) exhibit excellent catalytic activity toward the cyanosilylation of aromatic aldehydes and could be reused without loss of activity. In addition, they can also be considered as a fluorescent probe for nitrobenzene sensing based on luminescence quenching effects arising from host−guest interactions. This porous MOF combining catalytic and fluorescent properties could further meet the requirement as a multifunctional material.

La 1, Pr 2, Sm 3), [(CH 3 ) 2 NH 2 ][Ln 2 (PDC) 3 (HCOO)(H 2 O) 3 ]$2H 2 O (type II) (Ln ¼ Tb 4, Ho 5) and [Ln(HPDC) 3 (H 2 O) 2 ]$H 2 O (type III) (Ln ¼ Er 6, Lu 7) (H 2 PDC ¼ pyridine-3,5-dicarboxylic acid), have been successfully synthesized by the solvothermal reaction of pyridine-3,5-dicarboxylic acid (H 2 PDC) with the corresponding lanthanide nitrate. Compounds 1-3 are isomorphous and all crystallize in triclinic space group P 1, showing a 3D microporous framework of pcu topology with square channels along the b-axis.Isostructural compounds 4 and 5 show the same 2D layer network of (4,4)-grid in the monoclinic P2 1 /c space group. Isomorphic 6 and 7 crystallize in the monoclinic Cc space group and present 1D zigzag chains which expand to a 3D supramolecular structure through p/p stacking interactions. The structural diversity of these three classes of compounds may be attributed to the effect of lanthanide contraction. They were characterized by infrared spectra (IR), elemental analysis (EA), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and X-ray single crystal diffraction. Furthermore, the catalytic properties of these compounds were investigated and experiments revealed that compounds 1-3 show size-selective catalytic performance for cyanosilylation reactions and could be reused without losing their catalytic activity.

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