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Pillared paddle-wheel-based metal-organic framework (MOF) materials are an attractive target as they offer a reliable method for constructing well-defined, multifunctional materials. A drawback of these materials, which has limited their application, is their tendency to form catenated frameworks with little accessible volume. To eliminate this disadvantage, it is necessary to investigate strategies for constructing non-catenated pillared paddle-wheel MOFs. Hydrogen-bonding substituents on linkers have been postulated to prevent catenation in certain frameworks and, in this work, we present a new MOF to further bolster this theory. Using 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid, BPDC-(NH2)2, linkers and dipyridyl glycol, DPG, pillars, we assembled a MOF with pcu topology. The new material is non-catenated, exhibiting large accessible pores and low density. To the best of our knowledge, this material constitutes the pcu framework with the largest pore volume and lowest density. We attribute the lack of catenation to the presence of H-bonding substituents on both linkers.

[Display omitted] • Flexible ligand strategy was first proposed to prepare MOFs with simultaneous large-pore and antenna effect emission. • Flexible –CH 2 -O- group can tune the energy level of ligand. • Different diffusion dynamics was observed for MOFs with different pore sizes. • The relative specific surface area affected the linear response range. • L1-Eu MOF sensor realized the ratiometric fluorescence detection of PO 4 3- and ATP. Polycyclic aromatic ligands improve the pore size of metal–organic frameworks (MOFs), but their big π-conjugation structure forbids energy transfer for antenna effect emission. Thus, large-pore and antenna effect are a dilemma even their combination could improve the efficiency of MOFs. Herein, we construct a flexible ligand, 1,3,5-tris(5-methoxy-1,3-benzene dicarboxylic acid)benzene (L1) by attaching three isophthalic acids (L2) to a benzene ring through flexible –CH 2 -O- bonds. L1 retains the optical properties of L2 for antenna effect and expands the molecular size for MOFs with large pore. Single-crystal result of the MOFs obtained with L1 and Eu3+, Tb3+, or Gd3+ reveals the aperture of 18 Å and the density of 1.2 g/mL. L1 excites Eu3+ and Tb3+ ions for their antenna effect emission. The –CH 2 -O- group tunes the energy transfer for dual-emission at 360 and 623 nm from L1 -Eu MOF under single excitation of 290 nm. The dual-emission is used for ratiometric fluorescence detection of phosphate (PO 4 3-) and adenosine-5′-triphosphate (ATP). We reveal the effect of porous structure of MOFs on the response speed and range. The pore size affects the target entrance as L1 -Eu MOF shows faster response to PO 4 3- and ATP than L2 -Eu MOF. Moreover, fast diffusion dynamics of a target is observed in large-pore MOFs for good linear response. The relative specific surface area affects the linear range as a narrower range was observed for ATP than PO 4 3-. Thus, flexible ligand is effective to expand the aperture, improve optical properties, and study the response mechanism for the extensive applications of MOFs. [ABSTRACT FROM AUTHOR]

Abstract: A mesoporous MCM-48 membrane with three-dimensional (3D) accessible pore structures has been prepared on a large-pore α-Al2O3 ceramic tube by adopting the pore-prefilling method. [Copyright &y& Elsevier]

Pillared paddle-wheel-based metal-organic framework (MOF) materials are an attractive target as they offer a reliable method for constructing well-defined, multifunctional materials. A drawback of these materials, which has limited their application, is their tendency to form catenated frameworks with little accessible volume. To eliminate this disadvantage, it is necessary to investigate strategies for constructing non-catenated pillared paddle-wheel MOFs. Hydrogen-bonding substituents on linkers have been postulated to prevent catenation in certain frameworks and, in this work, we present a new MOF to further bolster this theory. Using 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid, BPDC-(NH2)2, linkers and dipyridyl glycol, DPG, pillars, we assembled a MOF with pcu topology. The new material is non-catenated, exhibiting large accessible pores and low density. To the best of our knowledge, this material constitutes the pcu framework with the largest pore volume and lowest density. We attribute the lack of catenation to the presence of H-bonding substituents on both linkers. [ABSTRACT FROM AUTHOR]