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

• Published in: CrystEngComm Vol. 23; no. 7; pp. 164 - 1615
• Main Authors: Shi, Yong-Sheng, Yu, Qiang, Zhang, Jian-Wei, Cui, Guang-Hua
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 22.02.2021
• Subjects: Acetylacetone; Benzene; Crystallography; Cyclohexane; Ferric ions; Fluorescence; Ligands; Metal-organic frameworks; Selectivity; Zinc
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d0ce01619e

Four new Zn( ii ) metal-organic frameworks (MOFs): {[Zn(L1)(BTEC) 0.5 ]·3.1H 2 O} n ( 1 ), {[Zn(L2) 0.5 (BTEC) 0.5 ]·1.5H 2 O} n ( 2 ), {[Zn 2 (L3)(BTEC)(H 2 O)]·H 2 O} n ( 3 ), and {[Zn 2 (L4)(BTEC)]·H 2 O} n ( 4 ) were constructed by selecting N-containing linkers with the Zn( ii )/H 4 BTEC system (H 4 BTEC = 1,2,4,5-benzenetetracarboxylic acid, L1 = 1,4-bis(1-(pyridin-4-ylmethyl)-1 H -benzo[ d ]imidazol-2-yl)cyclohexane, L2 = 1,4-bis(1-(pyridin-4-ylmethyl)-1 H -benzo[ d ]imidazol-2-yl)butane, L3 = 1,5-bis(1-(pyridin-4-ylmethyl)-1 H -benzo[ d ]imidazol-2-yl)pentane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1 H -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 {4·8 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 BTEC 4− 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 Fe 3+ /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 Fe 3+ and acac in the naked eye range. Four Zn-MOFs with different topological types were synthesized and characterized, MOFs 1-4 have excellent sensitivity, selectivity, recyclability and structural stabilities for detecting acac/Fe 3+ in the naked eye range.