Luminescent detection by coordination polymers derived from a pre-organized heterometallic carboxylic building unit

A tetranuclear heterometallic complex [Li2Zn2(piv)(6)(py)(2)] (piv(-) = pivalate, py = pyridine) could be viewed as an 8-connected node or a dimer of 3-connected binuclear {LiZn(RCOO)(3)} carboxylate complexes. A solvothermal reaction of c with biphenyldicarboxylic acid (H(2)bpdc) results in two layered MOFs [{LiZn}(2)(bpdc)(3)(dma)(4)]center dot 3DMA center dot H2O (1a superset of DMA) and [{LiZn}(2)(bpdc)(3)(nmp)(4)]center dot 4NMP (1b superset of NMP) in dimethylacetamide (DMA) or N-methyl-2-pyrrolidone (NMP) solvents, respectively. The reaction of [Li2Zn2(piv)(6)(py)(2)] with H(2)bpdc and diazabicyclo[2.2.2]octane (dabco) in dimethylformamide (DMF) affords a 3D MOF [Li2Zn2(bpdc)(3)(dabco)]center dot 9DMF center dot 4H(2)O (2 superset of DMF) with an open structure. The frameworks in 1a and 1b are based on 3-connected binuclear nodes, connected through linear bpdc(2-) anions into a twofold interwoven honeycomb (hcb) layers, packed in ABAB manner. The tetranuclear units in 2 are connected by both bpdc(2-) and dabco into a 3D non-interpenetrated net with body-centered cubic (bcu) topology. The solvent molecules in both 1 and 2 could be substituted to various aromatic species, which nature affects the photoluminescence properties of the framework in a different way. For example, the substitution to nitrobenzene completely quenches the luminescence while the inclusion of benzyl alcohol, anisole, acetophenone into porous channels of 2 results in a marked shift of the emission peak maxima as well as an enhancement of the quantum yields. (C) 2018 Elsevier Ltd. All rights reserved.