The maximum generation g_max of a dendritic molecule denotes the value of the generation number g, above which such a compound cannot be synthesized without defects anymore due to steric constraints. For dendronized polymers (DPs), such a densely packed regime is entered far earlier (g_max ≈ 6) than it is for comparable dendrimers (g_max ≥ 10) because dendritic side chains are confined to a cylindrical rather than a spherical volume. We here report a long sought-after improvement to a key step in the divergent synthesis of high-g DPs which enabled obtaining the polymers of g = 6, 7, and 8. These DPs are of unprecedented dendritic perfection, and the representatives with g > 6 are to our knowledge the first molecules for which g_max has been surpassed. We suggest a straightforward parameter α which allows to assess whether any dendritic molecule is above g_max, given sufficiently efficient chemistry and the possibility of accurately determining the number of defects. Finally, we correlate gel permeation chromatography results and atomic force microscopic images with defect rates.

中文翻译：

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将合成推向树枝状大分子的最大生成范围

树状分子的最大生成量g _max表示生成数g的值，在该值以上，由于空间限制，不能再无缺陷地合成这样的化合物。对于树枝状聚合物（DPS），进入这样的密集堆积政权远远早（克_最大≈6）比它可比树枝状聚合物（克_最大值≥10）因为树突侧链被限制于圆柱形，而不是一个球形体积。我们在这里报告了长期寻求的改进方法，该改进方法是高g DP的不同合成中的关键步骤的关键步骤，从而能够获得g的聚合物= 6、7和8。这些DP具有前所未有的树突状完美性，据我们所知，g > 6的代表是第一个超过g _max的分子。我们建议一个简单的参数α ，如果化学足够有效并且可以准确确定缺陷数量，则可以评估树突状分子是否高于g _max。最后，我们将凝胶渗透色谱结果和原子力显微镜图像与缺陷率相关联。