Stepwise Assembly of Silver(n-alkane)thiolates: An Example of Hierarchical or Cooperative Self-
Abstract -- In this paper, we show that the simple bulk phase synthesis of silver(n-alkane)thiolates, (AgS(CH2)nCH3), involving drop-wise addition of a silver salt to a solution containing equimolar amounts of long-chain alkanethiol and triethylamine, can be accurately described in terms of a hierarchical self-assembly process involving two major steps. First, strong coordination between Ag+ and RS- ions causes the organization of the inorganic constituents into domains of two-dimensional, quasi-hexagonally symmetric planes, with long aliphatic chains extending to either side of the inorganic lattice. Second, the three-dimensional complementary stacking of these organic-inorganic domains results in the formation of highly organized bimolecular chain assemblies. The characteristics of these assemblies as determined by a joint X-ray diffraction and infrared spectroscopy study14 support the proposed mechanism of hierarchical self-assembly. Evidence indicates that the initial coordination pattern of the Ag-S lattice controls the structure of the layered, bimolecular material, such as the formation of a three-dimensional network of one-dimensional channels, or corridors; and the all-trans chains extending vertically from the inorganic slabs. It is found that these features are independent of chain length, and our data are self-consistent for aliphatic chain lengths of 5, 6, 9, 11, 15, and 17 methylene units.
Adult/Continuing education, Community College, Higher education
Chemistry, General Science, Process Skills, Technology
Journal of Young Investigators