Silver(I) Coordination Polymers Containing Heteroditopic Ureidopyridine Ligands:  The Role of Ligand Isomerism, Hydrogen Bonding, and Stacking Interactions

Abstract

New silver (I) coordination polymers has been successfully designed and synthesized using heteroditopic ureidopyridine ligands 1 and 2 via a combination of coordinations bonds, hydrogen bonding, and pi-pi stacking interactions. This study shows an example of the orientation of the pyridine nitrogen relative to the urea moiety (4-substituted, 1, or 3-substituted, 2), used to control the packing of resulting crystalline coordination polymers. The ureidopyridine ligands present some flexibility because of the conformational rotation around the central urea moiety. The co-complexation of the silver(I) cation by two pyridine moieties and of the PF(6)(-) counteranion by the urea moiety results in the formation of discrete [1(2)Ag](+)PF(6)(-), (3) and [2(2)Ag](+)PF(6)(-), (4) complexes presenting restricted rotation around the central urea functionality. The geometrical information contained in the structures of ligands 1 and 2 and the heteroditopic complexation of silver hexafluorophosphate are fully exploited in an independent manner resulting in the emergence of quasi-rigidly preorganized linear and angular building blocks of 3 and 4, respectively. Additional pi-pi stacking contacts involving interactions between the pi-donor benzene and the pi-acceptor pyridine systems reinforce and direct the self-assembly of the above-described combined structural motifs in the solid state. Accordingly, linear and tubular arrays of pi-pi stacked architectures are generated in the solid state by synergistic and sequential metal ion complexation, hydrogen bonding, and pi-pi stacking interactions.

Ion-fuelled L-Phenylalanine controlled pumping by hybrid membrane materials

“…High values of K p and K 2 indicate strong association via H-bonding, while high values of the ratio K p /K 2 are related to the cooperativity of the self-association process. Calculation of the association constants revealed that the strength of the self-association of compound 1 and the process cooperativity are both decreased, when compared with the values determined for the bis-aromatic compound 1 [37] (Fig. 3a).…”

“…moieties known to bind metal cations (i.e. Li + ) [36] and the anions, respectively [37,38]; (2) the supramolecular guiding interaction is the urea head-to-tail H-bond association, [35,38] reminiscent with the amide moiety's H-bonding in proteins, (3) the ureidopyridyl residues are covalently bonded to triethoxysilyl groups allowing to transcribe the self-organized superstructures into the hybrid materials by sol-gel process [13,14]. 1 H NMR dilution experiments showed the strong downfield shifts of NH alif (Dd = 0.82 ppm) or NH arom (Dd = 2.2 ppm) protons upon increasing concentration of 1, which is indicative of self-association through the intermolecular hydrogen bonding in CDCl 3 (Fig.…”

Bis(μ-trifluoromethanesulfonato-κ2O:O′)bis[aqua(1,4,7,10,13,16-hexaoxacyclooctadecane-κ6O)barium(II)] bis(trifluoromethanesulfonate)

“…For biological and related applications, see: Dougherty (1996); Meyer et al (2003); Ma & Dougherty (1997). For examples of tubular superstructures, see: Barboiu et al (2003); Blondeau et al (2005); Fromm & Bergougnant (2007).…”

Metallacycles or coexistence of isomeric metallacycle and chain: Anion-dependent luminescent Ag complexes of a flexible diaminotriazine–imidazole ligand

“…In the L ligand, the DAT group can donate up to three H-bonding acceptors and four H-bonding donors, also, both the triazine ring and the imidazole ring have the p-interaction abilities. It is expected that the L ligand could involve in strong supramolecular interactions with other components, such as counteranions and solvents, which may exert profound effects in the self-assembly process and the architectures of the final products, especially in the Ag(I) system due to the modest stereochemical preferences of the Ag(I) ion [36][37][38][39][40].…”