Extended triphenylenes: synthesis, mesomorphic properties and molecularly resolved scanning tunneling microscopy images of hexakis(dialkoxyphenyl)triphenylenes and dodeca(alkoxy)tris(triphenylenylene)s
作者:Tetsuo Yatabe、Martha A. Harbison、Johann Diedrich Brand、Manfred Wagner、Klaus Müllen、Paolo Samorí、Jürgen P. Rabe
DOI:10.1039/b001162m
日期:——
Palladium-catalyzed cross-coupling between 3,4-dialkoxyphenylboronic acids (1a–d) and 2,3,6,7,10,11-hexabromotriphenylene (2) provided 2,3,6,7,10,11-hexakis[3,4-bis(alkoxy)phenyl]triphenylenes, C18H6[C6H3(OCnH2n + 1)2]6 where n = 6, 8, 10, and 12 (3a–d). Cyclodehydrogenation of the aryl-substituted triphenylenes 3a–d using ferric chloride oxidation followed by methanol reduction produced 6,6′,6″,7,7′,7″,10,10′,10″,11,11′,11″-dodecaalkoxy-2,3′:3,2″:2′,3″-tris(triphenylenylene)s, C54H18(OCnH2n + 1)12 where n = 6, 8, 10, and 12 (4a–d). The mesomorphic properties of the compounds 3a–d and 4a–d were investigated by differential scanning calorimetry (DSC) measurements, polarizing microscopy, and wide angle X-ray diffraction (WAXD). The triphenylenes 3a–d exhibited a columnar mesophase in the range of 111–126, 85–104, 74–103, and 47–101 °C, respectively. Upon oxidation of the moiety, the columnar mesophases shift to higher temperatures and exist in a much broader range of temperatures: for the tris(triphenylenylene)s 4a–d, they have been observed in the range of 180–430, 150–370, 120–322, and 104–306 °C, respectively. Finally, the self-assembly at the interface between a solution of 4c and a graphite substrate has been studied by scanning tunneling microscopy. Molecularly resolved imaging revealed a highly ordered monolayer exhibiting a two-dimensional hexagonal lattice.
在钯催化下,3,4-二烷氧基苯硼酸(1a-d)与 2,3,6,7,10,11-六溴三亚苯(2)发生交叉偶联,生成 2,3,6,7,10,11-六[3,4-双(烷氧基)苯基]三亚苯,C18H6[C6H3(OCnH2n + 1)2]6,其中 n = 6、8、10 和 12(3a-d)。先用三氯化铁氧化,再用甲醇还原,使芳基取代的三亚苯基 3a-d 环氢化,生成了 6,6′,6″,7,7′,7″,10,10′,10″,11,11′,11″-十二烷氧基-2,3′:3,2″:2′,3″-三(三亚苯)s,C54H18(OCnH2n + 1)12,其中 n = 6、8、10 和 12 (4a-d)。通过差示扫描量热法(DSC)测量、偏光显微镜和广角 X 射线衍射(WAXD)研究了 3a-d 和 4a-d 化合物的介观性质。三亚苯基 3a-d 分别在 111-126、85-104、74-103 和 47-101 ℃ 范围内呈现柱状介相。当分子被氧化时,柱状介相会转移到更高的温度,并在更宽的温度范围内存在:三(三亚苯)4a-d 的柱状介相分别在 180-430、150-370、120-322 和 104-306 ℃ 范围内观察到。最后,我们利用扫描隧道显微镜研究了 4c 溶液与石墨基底之间界面的自组装。分子分辨成像显示出一个高度有序的单层,呈现出二维六边形晶格。