Two Ag(I) coordination polymers derived from melamine and dicarboxylates: Syntheses, crystal structures and thermal stabilities Yun-Hua Li a,1 , Di Sun a,1 , Geng-Geng Luo b , Fu-Jing Liu a , Hong-Jun Hao a , Yi-Mei Wen a , Yang Zhao a , Rong-Bin Huang a,⇑ , Lan-Sun Zheng a a State Key Laboratory of Physical Chemistry of Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China b Institute of Materials Physical Chemistry, Huaqiao University, Xiamen, Fujian 361021, China article info Article history: Received 22 March 2011 Received in revised form 24 May 2011 Accepted 28 May 2011 Available online 2 June 2011 Keywords: Silver(I) Melamine Succinic acid Adipic acid AgAg interaction Kagomé lattice abstract Two mixed-ligand Ag(I) coordination polymers (CPs), [(NH 4 )Ag 3 (MA) 2 (suc) 2 ] n (1), [Ag 2 (MA) 2 (adip)- CH 3 OHH 2 O] n (2), (where MA = melamine, H 2 suc = succinic acid, H 2 adip = adipic acid) have been synthe- sized and structurally characterized by element analysis, IR and X-ray single-crystal diffraction. The CP 1 is a three-dimensional (3D) framework in which the MA acts as a tridentate ligand and suc 2 anion shows three types of coordination modes. Each Ag(I) ion acts as a 4-connected node to generate three- and six- membered cycles, as a result, the network can be simplified to be an overall multi-layered Kagomé topol- ogy. The CP 2 is a 2D single-layer structure constructed by tridentate MA ligands and adip 2 anions. The adjacent single-layers are inter-linked to form a double-layer 2D structure through the AgAg interac- tions. Two CPs structurally vary from 2D sheet to 3D framework, which indicates that the different dicar- boxylates and coordination modes of MA ligand have significant influence on the final structures. Moreover, the thermal stabilities of them were also discussed. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction Coordination polymer (CP) based upon the spontaneous self- assembly of transition metal ions and multifunctional organic ligands is a dynamic, thriving field that has drawn ever increasing research interests during the last few decades. The remarkable pro- gress in crystal engineering has provided a wide range of CPs with potential applications and novel topologies [1]. However, control- ling the unique orientation of organic ligand in CPs and thus predic- tion of the resulting structure represent appealing challenges. Some factors such as metal ions, the structure characteristics of polyden- tate organic ligand [2], pH value of the solution [3], the metal–ligand ratio [4], the temperature [5] and different solvent systems [6], intensively influence the resulting structures. Furthermore, the weak interactions also have a great influence, such as pp stacking interactions, hydrogen bonds and metalmetal interactions that can help to direct and stabilize the architectures [7]. Silver(I) ion has attracted enormous attention over the years due to their diverse coordination numbers and geometries as well as ability to form AgAg interaction. Organic ligands with carboxylic groups have been investigated extensively because they usually display various coordination modes and result in a variety of multidimensional frameworks [8]. Many studies have been focused on the both flexible aliphatic and aromatic carboxylate ligands, such as succinic acid, [9] adipic acid [10] and so on. On the other hand, amino-containing het- erocyclic N-donor ligands, such as 2-aminopyrazine, are versatile li- gands because of their established metal binding patterns including the ring nitrogen atom [11] and the exocyclic amino group [12], while the amino group can also interact with ligands or solvents through hydrogen bond. The MA is considered as an interesting li- gand due to the presence of three potential coordination sites as well as potential hydrogen bond donors. Considering the points aforementioned and our previous work [13], we continue to pay our attentions on the reaction of closed- shell d 10 Ag(I) with melamine and auxiliary dicarboxylates and investigate the influence of dicarboxylates on the resultant CPs as well as their potential properties. In this paper, we report the syntheses, crystal structures and thermal stabilities of two new mixed-ligand CPs, namely, [(NH 4 )Ag 3 (MA) 2 (suc) 2 ] n (1), [Ag 2 (MA) 2 (adip)CH 3 OHH 2 O] n (2), (MA = melamine, H 2 suc = succinic acid, H 2 adip = adipic acid) (Scheme 1). 2. Experimental 2.1. Materials and physical measurements All chemicals and solvents used in the syntheses were of analyt- ical grade and used without further purification. IR spectra were 0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2011.05.056 ⇑ Corresponding author. Fax: +86 592 2183074. E-mail address: rbhuang@xmu.edu.cn (R.-B. Huang). 1 These authors contributed equally to this work. Journal of Molecular Structure 1000 (2011) 85–91 Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc