Two calix[4]arene tetracarboxylates, [calix[4]arene tetraacetate (K(4)CTA) and calix[4]arene tetrabenzoate (K(4)CTB)] as their potassium salts, have been prepared. Employing these as precursors, two Ag(I) coordination polymers incorporating calix[4]arene units have been successfully prepared and their X-ray crystal structures have been determined. In these, the CTA and CTB derivatives are linearly bound to two and four silver atoms, respectively, to generate unusual tubular nanostructures. A comparative NMR study was undertaken to investigate the nature of the metal ion blocking of the tube as observed in the CTA-derived structure. The thermal properties for both coordination polymers were also examined.
Calix[4]bis(thiacrown-5) (L) with 1,3-alternating conformation was employed as a strong dinucleating ligand for the soft metal ions AgI and CuI. The reaction of L with AgPF6 afforded a discrete endo-coordinated disilver(I) complex 1, [Ag2L](PF6)2. In contrast, mixed products (2a + 2b) consisting of 3D networks were obtained from the reaction of L and CuI; 2b linked with a Cu4I4 cubane unit was shown to generate photoluminescence, while 2a linked with a Cu2I2 rhomboid unit does not.
[reaction: see text] Calix[4]thiacrowns with hetero-L(1) and a homodonor set (L(2)) were synthesized and characterized by X-ray analysis. From the reaction of L(2) with AgPF(6), disilver complex [Ag(2)(L(2))](PF(6))(2) (1) was isolated. By comparing 1,3-alternate conformations of L(2) and 1, we found a considerable decrease of dihedral angles of two opposite aromatic rings upon complexation. This finding can be explained in terms of the "chopsticks process", which illustrates how Ag(+)-arene pi-coordination occurs. Heterobinuclear complexation of L(1) in solution was also observed.
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