Studies of homologues are often useful for correlating material proper
ties to molecular structure. The liquid crystal 4-heptyl-4'-cyanobiphe
nyl (7CB) has received very little study, although the homologous 8CB
has been studied extensively by STM. Here we report several unusual pr
operties of 7CB monolayers on graphite, particularly the fact that ang
les between contacting domains of this liquid crystal were observed to
favor angles of 17 degrees rather than the expected 60 degrees angles
. This and other observations, coupled with an experimentally determin
ed unit cell of A = 3.85 +/- 0.37 nm, B = 1.10 +/- 0.10 nm, and Theta(
AB) = 92 +/- 6 degrees, lead us to propose an unusual monolayer struct
ure for 7CB, where only half of the molecules make the expected alkyl-
graphite contact in any domain. The 7CB monolayer shows great complexi
ty, including chirality effects and domain-domain interactions.