Odd/even effect in self-assembly of chiral molecules at the liquid-solid interface: An STM investigation of coadsorbate control of self-assembly

Manipulation of the self-assembly of chiral 2-bromohexadecanoic acid by templates composed of coadsorbed achiral molecules has been investigated at the liquid-solid interface using scanning tunneling microscopy (STM). The template formed by the odd-numbered saturated fatty acid heptadecanoic acid induces coadsorption of R-2-bromo-hexadecanoic acid and S-2-bromo-hexadecanoic acid within a single domain. Specifically, heptadecanoic acid effects an intra-lamellar alternation of R and S-2-bromo-hexadecanoic acid molecules, which is further confirmed by studies of heptadecanoic acid with pure R-2-bromo-hexidecanoic acid. Templates formed by even-numbered acids such as hexadecanoic acid induce the segregation of R- and S-2-bromohexadecanoic acid into separate (R or S) domains.