A 2D Substitutional Solid Solution through Hydrogen Bonding of Molecular Building Blocks.

Two-dimensional (2D) molecular self-assembly allows for the formation of well-defined supramolecular layers with tailored geometrical, compositional, and chemical properties. To date, random intermixing and entropic effects in these systems have largely been associated with crystalline disorder and glassy phases. Here we describe a 2D crystalline self-assembled molecular system that exhibits random incorporation of substitutional molecules.

Supramolecular ordering in oligothiophene-fullerene monolayers.

Scanning tunneling microscopy (STM) of monolayers comprising oligothiophene and fullerene molecular semiconductors reveals details of their molecular-scale phase separation and ordering with potential implications for the design of organic electronic devices, in particular future bulk heterojunction solar cells. Prochiral terthienobenzenetricarboxylic acid (TTBTA) self-assembles at the solution/graphite interface into either a porous chicken wire network linked by dimeric hydrogen bonding associations of COOH groups (R(2)(2) (8)) or a close-packed network linked in a novel hexameric hydrogen bonding motif (R(6)(6) (24)). Analysis of high-resolution STM images shows that the chicken wire phase is racemically mixed, whereas the close-packed phase is enantiomerically pure.

Synthesis, polymerization, and unusual properties of new star-shaped thiophene oligomers.

Terthienobenzene (TTB, 6) was prepared through a new, high yield route along with pi-extended derivatives 10 and 11. Electropolymerization of tris-EDOT derivative 11 results in a highly stable cross-linked conjugated polymer that shows polaron confinement between the TTB units as confirmed by UV-vis-NIR spectroelectrochemistry and EPR.