title: Self-assembly of silver(i) and bis-bidentate N,N-donor ligands: from a tetranuclear complex to coordination polymers.
abstract: The supramolecular self-assembly structures of one tetranuclear silver(i) complex and three silver(i) coordination polymers derived from bis-bidentate imino-pyridine ligands and their reduced N-methyl derivatives are discussed. Six new ligands were synthesised, and the X-ray structural analysis of L(1), L(2) and L(5) with silver(i) ions indicated the formation of 1D coordination polymers, namely {[AgL(1)]BF(4)}(n) (1), {[AgL(2)]ClO(4)}(n) (2), and {[AgL(5)]ClO(4).H(2)O}(n) (5), whereas ligand L(4) led to a tetranuclear complex {[AgL(4)]ClO(4)}(4) (4). L(1) is the Schiff-base derived from the condensation of alpha,alpha'-diamino-m-xylene and pyridine-2-carboxaldehyde and L(4) that resulting from the reaction of 2-(4-aminophenyl)ethylamine with 6-methyl-pyridine-2-carboxaldehyde, while L(2) and L(5) are the reduced N-methyl derivatives. The structural determination shows achiral syndiotactic polymers for 1 and chiral isotactic for 2 and 5. The 1D coordination chains of 1 are stabilised by intramolecular pi-pi stacking interactions between the phenyl ring of a spacer with the pyridine of a symmetry related adjacent ligand, while the crystal packing of 5 show inter-chain pi-pi interactions. Compound 4 comprises discrete tetranuclear [AgL(4)](4)(4+) complex cations and the rhomboid disposition of the metal ions leads to a globular arrangement of the silver(i) complex. The results provide an insight about the effect of ligand spacer length and flexibility in stabilising the metallo-supramolecular architecture.
authors: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, India. ictkp@iacs.res.in.
authors: Partha
authors: P
authors: Halder
authors: Ennio
authors: E
authors: Zangrando
authors: Tapan Kanti
authors: TK
authors: Paine