A New Strategy for the Synthetic Assembly of Inorganic–Organic Silver(I)-Polyoxometalate Hybrid Structures Employing Noncovalent Interactions between Theobromine Ligands

Abstract

A new strategy for the synthesis of inorganic−organic silver(I)-polyoxometalate materials was developed. The approach takes advantage of the ability of purine bases to build strong networks using them as ligands to silver(I). Its major experimental strong point is the facile preparation of target compounds from aqueous solutions from basic starting materials. Proof of concept was accomplished by using theobromine as the purine base. Seven new compounds containing silver(I) theobromine building blocks were characterized by single crystal X-ray diffraction: [Ag(thb) 2 ]ClO 4 (2), [Ag(thb) 2 (H 2 O)]ClO 4 (3), [Ag(thb) 2 ] 2 (H 4 V 10 O 28 )•3H 2 O (4), [Ag(thb) 2 ] 2 (Cr 2 O 7 )•0.5H 2 O (5), [Ag(thb) 2 (H 2 O)] 2 (H 3 O)[Ag(β-Mo 8 O 26 )]•4H 2 O (6), [Ag(thb)] 2 [Ag(Cr(OH) 6 Mo 6 O 18 )]•2H 2 O (7), and [Ag(thb) 2 ] 2 (H 3 O) 4 [Ni(OH) 6 Mo 6 O 18 ](CO 3 )•13H 2 O ( 8) (thb = theobromine). The purity of compounds 2−7 was confirmed by powder X-ray diffraction and elemental analysis. They were also characterized by IR and UV/vis spectroscopy and thermal analysis (DTA/TG). The main structural traits in all of the polyoxometalate containing compounds are coordination polymers running along the direction of one of the crystallographic axes. These chains are interconnected by a framework of strong hydrogen bonds and stacking interactions. The thermodynamic rationalization of these crystal structure landscapes is thoroughly discussed.

Wenn sich Kompetenzen ergänzen

“…The intramolecular interactions can be self‐pairing of thb molecules by hydrogen bonding (Figure 1). The amide‐to‐amide thb dimers are quite frequently encountered in materials containing these organic molecules 6,7. The donor‐acceptor distances between the amide‐N atom and carbonyl‐O atom are 2.797(8) and 2.852(7) Å, respectively, which is consistent with hydrogen bonds of medium strength 8…”

“…We have recently developed a strategy, in which purine bases are used as Ag + ligands in the synthesis of organoamine‐silver(I)‐POM materials 6. This experimental approach was employed exclusively in water and with theobromine as the representative purine base.…”

“…In order to scrutinize the influence of solvent and starting material on the reaction outcome we performed similar reactions in benzonitrile (PhCN). Theobromine (thb) was used as the organoamine ligand of choice, as it builds networks of non‐covalent interactions quite easily and thus aids crystallization 6…”

Polyoxotungstates in Molecular Boxes of Purine Bases

“…To the best of our knowledge, only structures of caffeinium decavanadate and of a hybrid of adenosine and the Strandberg anion were described and discussed [13][14][15]. We recently published two further articles within the area, describing materials consisting of theobromine silver(I) complexes and POMs [16,17]. In the present work we discuss three new compounds consisting of protonated purine bases and polyoxotungstates focusing on their unusual and aesthetically appealing crystal structures.…”

A Versatile Polyoxovanadate in Diverse Cation Matrices: A Supramolecular Perspective

“…The modern chemical research on polyoxometalates (POMs)-based solid state materials fascinates synthetic chemists because of their potential applications in diverse research areas, such as, catalysis (Vazylyev et al, 2005; Hill, 2007; Zhou et al, 2014; Lechner et al, 2016; Mukhopadhyay et al, 2018), medicinal chemistry (Pope and Müller, 1991; Liu et al, 2012; Xie et al, 2018), and materials science (Guo et al, 2000; Rao et al, 2011; Kulikov and Meyer, 2013; Omwoma et al, 2015; Walsh et al, 2016). Among these, the area of polyoxovanadate (henceforth, POV) based materials have received special attention due to not only their diverse topologies (Miiller et al, 1990; Klemperer et al, 1992; Chen et al, 2005), structural (Miiller et al, 1987; Koene et al, 1999) and electronic properties (Müller et al, 1997) but also their fascinating versatile industrial applications, e.g., catalysis (Gao and Hua, 2006) and materials applications (Khan et al, 2003; Arumuganathan and Das, 2009; Chen et al, 2018).…”