An Interpenetrating Architecture Based on the Wells–Dawson Polyoxometalate and Ag^I···Ag^I Interactions

Abstract

Interpenetrating frameworks are described as architectures which cannot be separated except if one of the individual motifs is broken. 1 In their complicated architectures, supramolecular connections (such as electrostatic interaction, hydrogen bond, πÀπ stacking, and cationÀπ interactions) among the individual motifs endow them with structural flexibility, which is important in the applications of gas storage, conductivity, biological chemistry, and so on. 2 Interpenetration is a subclass of entangled system studied extensively and developed rapidly nowadays. Individual motifs of the interpenetrating architectures are from two-dimensional (2D) nets to three-dimensional (3D) frameworks, and the number of interpenetrating units varies from 2 to 10. 3 Ongoing research in interpenetration focuses on the introduction of functional groups with available characters.Polyoxometalates (POMs) are early transition metal oxide clusters composed of Mo, W, V, Nb, and so on. POMs show a wide variety of interesting structural motifs with different sizes and topologies. Besides the classical Keggin, WellsÀDawson, Anderson, Waugh, Silverton, and Lindqvist types, many new structures have been found, such as closed cages, Wheels, dimeric anions, and transition-metal-centered heteropolyoxometalates. 4 POMs are in the nanosize scale and have abundant surface oxygen atoms, which make them excellent inorganic building blocks. In addition, POMs bear versatile properties in such fields as catalysis, photochemistry, magnetism, electrochemistry, and biochemistry. 5,6 Accordingly, POM-based interpenetrating compounds will not only show aesthetic architectures but also possess both properties of flexibility of interpenetration and versatile functions of POMs. 7 However, to obtain such compounds is difficult as the nanosized POMs with a big steric hindrance would inhibit the formation of interpenetration.Ag þ ion is a prominent metal linker in the POM-based metal organic frameworks (MOFs), for it not only possesses abundant coordination modes such as linear, T-type, "seesaw", "squarepyramidal", "trigonal-bipyramidal" and octahedral geometries 8 but also is useful in the areas of catalysis, biological chemistry, and so on. 9 In addition, the argentophilicity of Ag þ ions may conduce the formation of {Ag 2 } 2þ dimers, which may play a key role in the expansion of multiple dimensional structures. {Ag 2 } 2þ dimers acting as linkers can be classified into unsupported and supported ones according to their coordination modes; that is, two Ag þ ions in an unsupported {Ag 2 } 2þ dimer are fused only by Ag I 3 3 3 Ag I interaction, while those in a supported {Ag 2 } 2þ dimer are connected not only by Ag I 3 3 3 Ag I interaction but also by

Synthesis, crystal structures, and photoluminescence of two silver(I) coordination polymers based on 2-sulfoterephthalic acid and N-donor ligands

“…The Ag-O bond distances vary from 2.283(3) to 2.509(3) Å , and the Ag-N bond lengths range between 2.190(3) and 2.330(4) Å . Both Ag-O and Ag-N bond lengths are well matched with those observed in similar complexes [10][11][12][13][14]29].…”

“…Silver(I) atoms can accommodate a wide variety of stereochemistries, with coordination numbers of two to six and versatile coordination geometries, including linear, T-shaped, square-planar, tetrahedral, square-pyramidal, trigonal-bipyramidal, and octahedral [10][11][12][13]. Furthermore, Ag(I) with a d 10 closedshell electronic configuration tends to form argentophilic interactions, which have an important influence on the formation of polymetallic clusters [14][15][16].…”

A survey of interactions in crystal structures of pyrazine-based compounds

“…A considerable number of flexible N-donor ligands have been used in POM-based metal-organic complexes Meng et al, 2009;Wang et al, 2010;Zhang et al, 2011;Taleghani et al, 2016). For example, two flexible bis-pyrazinebis-amide ligands are reacted with POM and it is seen that noncoordinated [PMo 12 O 40 ] 3À and [SiMo 12 O 40 ] 4À anions are trapped at the interface between adjacent wave-like chains of {[Cu(L1)] 2+ } n [L1 is N,N 0 -(propane-1,3-diyl)bis(pyrazine-2carboxamide)] cations via C-HÁ Á ÁO hydrogen bonds to create a 2D supramolecular architecture (Fig.…”

Three Silver(I) Coordination Polymers Constructed from Flexible Bis(benzimidazole) and Carboxylates Ligands

“…The supramolecular chemistry of Ag I coordination polymers represents a dynamic, thriving field, which abounds with various supramolecular forces such as metal–ligand, metal–π, and metal–metal interactions, hydrogen bonds, π–π stacking, and anion interactions 10–13. However, the complexes that depend on relatively weak cation ··· π interactions have been seldomly observed 14,15. Bis(benzimidazole) ligands contain both the imidazole ring and a larger conjugated π system, capable of acting as hydrogen‐bond donors and in π–π stacking interaction, but the skilful use of this type of ligands to construct complexes with Ag I ··· π interaction has been less investigated 16…”