Inorganic Chemistry, Vol.56, No.21, 13446-13455, 2017
Luminescent Cu4I4-Cu-3(Pyrazolate)(3) Coordination Frameworks: Postsynthetic Ligand Substitution Leads to Network Displacement and Entanglement
Six daughter complexes based on two-dimensional (2-D) luminescent Cu4I4-Cu(3)Pz(3) (Pz = pyrazolate) coordination networks, which exhibit an uncommon Cu4I4L3L' (L = pyridine; L' = acetonitrile, pyridine, pyrazine, 1,4-diazabicyclo[2.2.2] octane, triphenylphosphine, none) local configuration, were prepared through a postsynthetic modification method starting from a parent complex (L' = NH3). This work has successfully implemented the single-site substitution of Cu4I4-based coordination frameworks, which have rarely been reported for isolated Cu4I4-type compounds, by taking advantage of the solvent assisted ligand substitution strategy recently developed in metal organic framework (MOP) chemistry. Such a procedure not only resulted in the variation of local geometry in the Cu4I4 units but also led to interlayer network displacement and entanglement. Particularly, an interesting topological transformation (from 2-D to 2D -> 3-D interpenetration) occurred when linear bidentate linkers (e.g., pyrazine and 1,4-diazabicyclo[2.2.2]octane) are inserted between the 2-D layers. Moreover, the variation in the L' sites can effectively tune the emission colors, ranging from green to orange (lambda(max)(em) 540-605 rim at room temperature). The photoluminescence origins are tentatively assigned to be a mixture of (MLCT)-M-3 and (XLCT)-X-3, different from that of the well-studied isolated Cu4I4-type complexes.