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Two series of lanthanide-based metal–organic frameworks, namely {[Ln(BIPA-TC)0.5(DMA)2(NO3)]·DMA·H2O}n (1-Ln, Ln = Eu, Dy, Sm, Nd) and {[Ln2(BIPA-TC)1.5(DMA)3(H2O)2]·2DMA·2H2O}n (2-Ln, Ln = Eu, Dy, Sm, Nd), were successfully constructed via a solvent regulation strategy based on a π-electron rich tetra-carboxylate ligand (H4BIPA-TC). 1-Ln shows a 4-connected lvt topology with the point symbol of {42·84}, but 2-Ln displays a new 4,4,6-connected wxk1 topology with the point symbol of {43·83}4{46·66·83}2{86}. The solid-state luminescence property and the microporous nature of Eu-MOFs (1-Eu and 2-Eu) indicate that they can potentially be used as luminescent sensors. Fluorescence measurements indicate that Fe3+ exhibits the quenching effect for 1-Eu with the quenching efficiency of 93.1%. 2-Eu is the first MOF sensor for Mg2+ with the lowest detection limit of 1.53 × 10−10 mol L−1 and displays good recyclable capability. Simultaneously, in the presence of other metal ions (Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pd2+, Al3+, Cr3+and Fe3+), 2-Eu can maintain the selective sensing of Mg2+, indicating its potential for Mg2+ turn-on sensing. [ABSTRACT FROM AUTHOR]

A ligand with a flexible conformation can be obtained by modifying functional groups. We modified H4DCBA with –CH3/–CF3 groups to construct three Zr-MOFs; the torsion of the central benzene ring changes the topologies. The three Zr-MOFs showed high adsorption rates for Cr2O72−, and the CF3-functional groups enhanced the adsorption capacity of UPC-49 for Cr2O72−. [ABSTRACT FROM AUTHOR]

Nature gas plays an important part in daily life and petrochemical industry, but it always coexists with impurities of considerable amount, which hinders full utilization of methane and thus makes its purification an urgent issue to be addressed. Herein, via solvothermal reaction of N,N′-bis(3-methylbenzoic acid-4-yl)-1,4,5,8-naphthalenetetracarboxydiimide (H 2 L) and cadmium cation, we obtained a layer structure of [Cd 2 (L) 2 (H 2 O) 2 ]·4H 2 O (UPC-71) with sql/Shubnikov tetragonal plane net topology, where tiny pores are formed due to direct dense packing of layer by layer. After adding 1, 2-bis(4-pyridyl) ethane (BPEA) as ancillary ligand, a rare 8-fold interpenetrated framework, [Cd(L)(BPEA)]·4H 2 O (UPC-72), was obtained. Limited by their tiny pore volume, UPC-71 and UPC-72 both display somewhat small gas sorption capacities, but an obvious increase in the adsorption/separation performance can be observed in UPC-72 due to the effect of pore confinement strategy. In particular, the quantities of C 2 H 2 and CO 2 adsorbed are 1.54 and 0.83 ​mmol/g at ambient condition, and the IAST selectivities of C 2 H 2 /CH 4 and CO 2 /CH 4 are up to 20.1 and 4.7 for UPC-72. With the aid of GCMC simulation, we prove that there exist stronger binding interactions between C 2 H 2 and CO 2 with the active sites in UPC-72 , and thus enhances the separation selectivity. [Display omitted] • Two Cd-MOF (UPC-71 and UPC-72) were designed and synthesized. • Rare 8-fold interpenetrated structure is obtained via pore confinement strategy. • A new strategy is explored to improve adsorption/separation performance. • The IAST selectivities of UPC-72 exhibit a great improvement compared with UPC-71. • Interspersed behavior improved the sorption capacity effectively. [ABSTRACT FROM AUTHOR]

A ligand with a flexible conformation can be obtained by modifying functional groups. We modified H4DCBA with –CH3/–CF3 groups to construct three Zr-MOFs; the torsion of the central benzene ring changes the topologies. The three Zr-MOFs showed high adsorption rates for Cr2O72−, and the CF3-functional groups enhanced the adsorption capacity of UPC-49 for Cr2O72−. [ABSTRACT FROM AUTHOR]