The Effects of Microenvironment Polarity and Dendritic Branching of Aliphatic Hydrocarbon Dendrons on the Self-Assembly of 2-Ureido-4-pyrimidinones
作者:Chun-Ho Wong、Lai-Sheung Choi、Sui-Lung Yim、Kwun-Ngai Lau、Hak-Fun Chow、Sin-Kam Hui、Kong-Hung Sze
DOI:10.1002/asia.201000359
日期:——
hydrocarbon‐based G1–G3 dendritic 2‐ureido‐4‐pyrimidinones (UPy) (S‐Gn)2 and (L‐Gn)2, differing from one another by the distance between the branching juncture to the urea end, were prepared and characterized. These hydrocarbon dendrons were also appended to a p‐aminonitrobenzene solvatochromic chromophore in order to probe their microenvironment polarity. While positive solvatochromism was observed which
基于脂族烃基的G1-G3树突状2‐脲基‐4‐嘧啶酮(UPy)(S‐G n)2和(L‐G n)2的两个系列,在分支结点到基点之间的距离互不相同。制备并表征了尿素端。这些烃树枝状分子也被附加到p-氨基硝基苯溶剂化发色团,以探测其微环境极性。尽管观察到了正溶剂溶剂变色,这表明生色团可接近溶剂,但是从G1到G3树突的微环境极性之间没有显着差异。通过1 H NMR光谱检查了树突状UPy衍生物的自组装行为和互变异构偏好。DDAA互变异构体的二聚常数(K dim *)在25和50°C的CDCl 3中在10 7 M -1不变,这与带有其他非极性取代基的UPy化合物相当。此外,K的下限(S-G n)2和(L-G n)2系列的DADA互变异构形式的dim *被确定分别为CDCl 3中的10 6和10 5 M -1。发现树突分支连接点与UPy单元的更近距离可导致对二聚态的去稳定作用。因此,(L-G n)2二聚体比(S-G