Synthesis of Well-Defined Tower-Shaped 1,3,5-Trisubstituted Adamantanes Incorporating a Macrocyclic Trilactam Ring System
journal contributionposted on 20.02.2004, 00:00 by Quan Li, Changshu Jin, Pavel A. Petukhov, Aleksey V. Rukavishnikov, Tatiana O. Zaikova, Avinash Phadke, Donald H. LaMunyon, Melissa D. Lee, John F. W. Keana
We describe the synthesis of two novel well-defined tower-shaped 1,3,5-trisubstituted adamantanes 30 and 33 that incorporate a macrocyclic trilactam ring system. Each nanoscale molecule has a broad tripodal base consisting of three identical sulfur-containing termini as the tripod feet, 4-acetylsulfanylmethylphenyl units in the case of 30 and 3,5-bis(acetylsulfanylmethyl)phenyl units in the case of 33. The sulfur atoms are designed to bind the molecules trivalently to the apex of a gold-coated commercial AFM tip through formation of three S−Au bonds. The rigid adamantane-derived head unit with a single hydrogen atom at the apex is designed to scan the sample. Molecules 30 and 33 are synthesized from 1,3,5-triethynyladamantane by a series of Sonogashira coupling reactions involving terminal alkynes and aryl iodides. A macrocyclic trilactam unit is included for added rigidity. We demonstrate that molecule 30 is sufficiently large and rigid to be visualized by a conventional AFM tip. These nanoscale molecules may also find application as chemically well-defined nanoscale objects for calibration of AFM tips.