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)]center dot 3.1H(2)O}(n )(1), {[Zn(L2)(0.5)(BTEC)(0.5)]center dot 1.5H(2)O)(n) (2), {[Zn-2 (L3)(BTEC)(H2O)]center dot H2O}(n) (3), and {(Zn-2(L4)(BTEC)]center dot 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-benzoknimidazol-2-yl)cyclohexane, L2 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzoknimidazol-2-Abutane, L3 = 1,5-bis(1-(pyridin-4-ylmethyl)-1HbenzoMimidazol-2-Apentane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzold1 imidazol-2-yOmethyl) 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 {4.8(2)}(2) {4(2).6.8(3)}(2) {4(2).6}(2) {4(2).8(2).10(2)}{8(4) .12(2)} 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.

Automated summary

Four new Zn(II) metal-organic frameworks were constructed by selecting N-containing linkers with the Zn(II)/H4BTEC system, exhibiting different structural features. These MOFs are favorable dual-functional fluorescent sensors for the detection of Fe3+/acetylacetone with high sensitivity and selectivity.