Four dual-functional luminescent Zn(II)-MOFs based on 1,2,4,5-benzenetetracarboxylic acid with pyridylbenzimidazole ligands for detection of iron(III) ions and acetylacetone.

Four new Zn(II) metal–organic frameworks (MOFs): {[Zn(L1)(BTEC)0.5]·3.1H2O}n (1), {[Zn(L2)0.5(BTEC)0.5]·1.5H2O}n (2), {[Zn2(L3)(BTEC)(H2O)]·H2O}n (3), and {[Zn2(L4)(BTEC)]·H2O}n (4) were constructed by selecting N-containing linkers with the Zn(II)/H4BTEC system (H4BTEC = 1,2,4,5-benzenetetracarboxylic acid, L1 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)cyclohexane, L2 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)butane, L3 = 1,5-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)methyl)benzene). Structural analyses indicate that 1 exhibits a (3,4)-connected 2D 3,4L13 sheet. 2 manifests a rare (4,4,4)-connected 2D 4,4,4L10 layer. 3 displays an unprecedented (3,3,4,4,4)-connected 3D network based on the point symbol {4·82}2{42·6·83}2{42·6}2{42·82·102}{84·122} and 4 presents an unusual 4,4,4,6,6T3 3D network with a 5-node (4,4,4,6,6)-connected network. The structural variety of these Zn(II) MOFs demonstrates that different N-containing ligands can induce the BTEC4− linkers exhibiting various coordination modes, exerting a great influence on the final MOF frameworks. Further, MOFs 1–4 are favorable dual-functional fluorescent sensors for the detection of Fe3+/acetylacetone with high sensitivity and selectivity. To our knowledge, this is the first report of fluorescent MOFs based on L1–L4 ligands for the detection of Fe3+ and acac in the naked eye range. [ABSTRACT FROM AUTHOR]