Lena Stefano, Brancolini Giorgia, Gottarelli Giovanni, Mariani Paolo, Masiero Stefano, Venturini Alessandro, Palermo Vincenzo, Pandoli Omar, Pieraccini Silvia, Samorì Paolo, Spada Gian Piero
Alma Mater Studiorum-Università di Bologna, Dipartimento di Chimica Organica A. Mangini, Via San Giacomo 11, 40126 Bologna, Italy.
Chemistry. 2007;13(13):3757-64. doi: 10.1002/chem.200601461.
We report on the synthesis and self-assembly of a guanosine derivative bearing an alkyloxy side group under different environmental conditions. This derivative was found to spontaneously form ordered supramolecular nanoribbons in which the individual nucleobases are interacting through H-bonds. In toluene and chloroform solutions the formation of gel-like liquid-crystalline phases was observed. Sub-molecularly resolved scanning tunneling microscopic imaging of monolayers physisorbed at the graphite-solution interface revealed highly ordered two-dimensional networks. The recorded intramolecular contrast can be ascribed to the electronic properties of the different moieties composing the molecule, as proven by quantum-chemical calculations. This self-assembly behavior is in excellent agreement with that of 5'-O-acylated guanosines, which are also characterized by a self-assembled motif of guanosines that resembles parallel ribbons. Therefore, for guanosine derivatives (without sterically demanding groups on the guanine base) the formation of supramolecular nanoribbons in solution, in the solid state, and on flat surfaces is universal. This result is truly important in view of the electronic properties of these supramolecular anisotropic architectures and thus for potential applications in the fields of nano- and opto-electronics.
我们报道了一种带有烷氧基侧基的鸟苷衍生物在不同环境条件下的合成与自组装。发现该衍生物能自发形成有序的超分子纳米带，其中单个核碱基通过氢键相互作用。在甲苯和氯仿溶液中观察到类凝胶液晶相的形成。对吸附在石墨 - 溶液界面的单层进行亚分子分辨扫描隧道显微镜成像，揭示了高度有序的二维网络。记录的分子内对比度可归因于构成分子的不同部分的电子性质，这已通过量子化学计算得到证实。这种自组装行为与5'-O-酰化鸟苷的自组装行为非常一致，5'-O-酰化鸟苷的特征也是由类似平行带的鸟苷自组装基序所决定。因此，对于鸟苷衍生物（鸟嘌呤碱基上没有空间位阻较大的基团）来说，在溶液、固态以及平面表面形成超分子纳米带是普遍现象。鉴于这些超分子各向异性结构的电子性质，这一结果对于纳米和光电子领域的潜在应用而言确实非常重要。
