Structure and catalytic activity of a penta-silver supramolecular cluster through hydrogen bonding and 2,2 0 -bipyridine Safaa El-din H. Etaiw ⇑ , Mohamed M. El-bendary Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt article info Article history: Received 21 February 2015 Received in revised form 27 May 2015 Accepted 4 June 2015 Available online 2 July 2015 Keywords: Silver cyanide Coordination polymer 2,2 0 -Bipyridine Spectra Catalytic activity abstract Colorless crystals of the coordination polymer (CP) [Ag 5 (CN) 5 (2,2 0 -bpy) 2 ] n , 1 were obtained by the reac- tion of AgNO 3 , 2,2 0 -bipyridine (2,2 0 -bpy) and KCN. The crystal structure of 1 consists of 1D-puckered AgCN chains which are decorated by 2,2 0 -bpy molecules. These chains form 2D-fused deformed six-mem- bered rings; [Ag 4 (CN) 2 (2,2 0 -bpy) 2 ] creating wide voids capable to accommodate the 2,2 0 -bpy molecules. 3D-network structure is created via H-bonds, p–p stacking and Ag–Ag interaction. The structure of the CP 1 was characterized by IR, UV–Vis, TGA, NMR spectra and X-ray single crystal analysis. The CP 1 was used as heterogeneous catalyst for the oxidative discoloration of methylene blue dye (MB) by H 2 O 2 . Ó 2015 Elsevier B.V. All rights reserved. 1. Introduction The rational design and synthesis of novel, discrete and poly- meric metal–organic hybrid frameworks have remained an impor- tant research focus in recent years [1–3], due to their fascinating coordination architectures and their potential applications in vari- ous fields, including gas storage, conductivity, catalysis, photo- chemistry, fluorescence, magnetism, corrosion inhibitions and antitumor activity [4–10]. The synthesis of such coordination poly- mers (CPs) is highly influenced by numerous factors such as the solvent system, temperature, counter ions with different bulk or coordination abilities, template, metal/ligand ratio and even pH [11–12]. Besides these aspects, non-covalent interactions such as hydrogen bonding, p–p interactions, and metal–metal interactions play an important role in the construction of supramolecular struc- tures [13]. Among these polymers, the Ag(I) coordination polymers are of great interest because the Ag–donor atom bond shows the high lability and the resulting Ag(I) coordination polymers can generally be crystallized allowing investigation by X-ray diffrac- tion [14,15]. On the other hand, Ag(I) ions are known to show a tendency to form silver–silver bonds which could be used to con- trol supramolecular structure and dimensionality [16]. Silver(I) is good candidate as a soft acid favoring coordination to soft bases such as ligands containing halogens, sulfur and nitrogen atoms. The inorganic cyanide group is a potential bridging ligand, its silver(I) coordination polymer not yet well documented [17,18]. Detailed structural information on AgCN was unavailable until the appearance of a report on its vibrational spectroscopy and the determination of the crystal structure using powder neutron diffraction data [19]. Also, only a few examples of silver(I) pseudo-halide coordination polymers with nitrogen bases have been previously reported [17,20]. Here we report the synthesis and structural characterization of [Ag 5 (CN) 5 (2,2 0 -bpy) 2 ] n , 1 from the simple reaction of AgCN and 2,2 0 -bpy ligand in H 2 O/acetonitrile/NH 3 media at room tempera- ture. Further, we report on the crystal packing effects, namely metal–ligand, Ag–Ag, H-bonds, and p–p stacking interactions, which may have an effect on the formation and stability of the CP 1. Furthermore, the CP 1 was used as heterogeneous catalyst for the oxidative discoloration of methylene blue dye (MB) by dilute solution of hydrogen peroxide as oxidant. 2. Experimental 2.1. Materials and physical measurements All chemicals and solvents used in this study were of analytical grade supplied by Aldrich or Merck and used as received. MB dye (98% purity) was received from B.D.H. Chemicals Ltd and used as received. Microanalyses (C, H, N) were carried out with a Perkin Elmer 2400 automatic elemental analyzer. The IR spectra were recorded on Perkin Elmer 1430 Ratio Recording Infrared http://dx.doi.org/10.1016/j.ica.2015.06.020 0020-1693/Ó 2015 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +20 01149442423. E-mail addresses: safaaetaiw@hotmail.com, safaaetaiw@science.tanta.edu.eg (S.E.H. Etaiw). Inorganica Chimica Acta 435 (2015) 167–173 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica