Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P R China E-mail : CLBAI@infoc3.icas.ac.cn Fax : 86-10-62557908 Manuscript received 10 October 2000 A series of N-9-alkyladenines, which can self-assemble through hydrogen bonding networks, have been synthesized. N-9- Dodecyladenine and N-9-tetradecyladenine have been characterized by X-ray crystallography and direct observation using scanning tunnelling microscopy (STM).