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1,8-Bis(5-mercaptomethyl-2-thienyl)octane 1a, 1,8-bis(5'-mercaptomethyl-2,2'-bithienyl-5-yl)octane 1b, 1-(5-mercaptomethyl-2-thienyl)-4-(2-thienyl)butane 1c, 1,8-bis (2,2'-bithienyl-5-yl)octane 2, 1,12-dodecanedithiol 3, and 1,4-bis(mercaptomethyl) benzene 4 were prepared and their adsorption states on a gold single crystal surface were studied by using scanning tunneling microscopy under ultrahigh-vacuum condition. Two ordered phases were observed for the mercaptomethyl-thiophene derivatives 1: The first phase is composed of one-dimensional molecular rows with spacings smaller than those for other monothiols (Figure 1) and the second one has a previously unknown two dimensional honeycomb structure (Figure 2, Langmuir journal cover). In both of the two phases, the molecules were arranged with end-on configuration in which only one end thiol is attached to the gold substrate. The absence of the honeycomb structure for 3 and 4 suggests the important role of mercaptomethylthienyl moiety for the formation of the specific structures.
