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A hexanuclear CdII metal-organic framework (1) based on 4-(1H-pyrazole-4-carboxamido)benzoic acid (H2L) and featuring a three-dimensional microporous framework was synthesized. Notably, 1 shows a unique fluorescence-quenching response toward Fe3+ ions with high selectivity and sensitivity (Stern-Volmer constant KSV = 2.07 × 104 M-1). The response is attributable to the coaction of absorption competition and energy-transfer (ET) mechanism. Furthermore, spectral analysis indicates that the energy-transfer mechanism makes the dominant contribution to the fluorescence quenching of 1. [ABSTRACT FROM AUTHOR]

In order to elucidate the effect of the structure on stability and gas adsorption performance, three porous Zn(II) metal-organic frameworks, NKU-106, NKU-107, and NKU-108, have been constructed. NKU-106 and NKU-107 assembled from acylamide functionalized tetracarboxylate ligand exhibit low stability and thereby poor gas adsorption ability. However, when one isophthalate moiety of the tetracarboxylate ligand is replaced with a pyrazole group, and the resulting NKU-108 shows improved thermal and chemical stability as well as good adsorption capacities with respect to CO2 and C2 hydrocarbons. This result demonstrates that coordination group optimization is an effective strategy to improve the stability and gas adsorption properties of metal-organic frameworks (MOFs) and thus provides very valuable information for future design and synthesis of porous MOFs for practical application. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are typically built by assembly of metal centres and organic linkers, and have emerged as promising crystalline materials in a variety of fields. However, the stability of MOFs is a key limitation for their practical applications. Herein, we report a novel Sr2+-MOF [Sr4(Tdada)2 (H2O)3(DMF)2] (denoted as NKU-105, NKU=Nankai University; H4Tdada=5,5'-((thiophene-2,5-dicarbonyl) bis(azanediyl))diisophthalic acid; DMF=N, N-dimethylformamide) featuring an open square channel of about 6 Å along the c-axis. Notably, NKU-105 exhibits much outstanding chemical stability against common organic solvents, boiling water, acids and bases, relative to most MOF materials. Furthermore, NKU-105 is an environment-friendly luminescent material with a bright cyan emission. This article is part of the themed issue 'Coordination polymers and metal-organic frameworks: materials by design'. [ABSTRACT FROM AUTHOR]

In this paper, two 3D anionic metal-organic frameworks, [(CH3CH2)2NH2]·[Zn(BTC)1/3(PyC)]·1/2CH3CN·2H2O (NKU-102) and [(CH3CH2)2NH2]·[Zn2(BTC) (PyC)]·1.5H2O·DEF (NKU-103), were constructed from the same reaction system at different temperature. Though both are of anionic framework, NKU-102 possesses a sealed 3D framework based on octahedral cage and shows negligible adsorption capacity of organic dyes, whereas NKU-103 features an open triangular microchannel surrounded by two types of helical chains, and thus exhibits outstanding size-selective adsorption toward small cationic organic dyes. [ABSTRACT FROM AUTHOR]