Various generations of zero α,ω-alkylenediamine core poly(amidoamine) PAMAM dendrimers (tetra-amine terminated substrates, A4) were allowed to react with sub-stoichiometric amounts (i.e., 2.0 equivalents) of Boc anhydride to give product mixtures consisting of the symmetrical tetra-Boc product (B4) and four partial Boc protected adducts, namely, (1) the tri-(AB3), (2) di-geminal (A2B2), (3) di-vicinal (A2B2) and (4) mono-Boc (A3B) products. These unprecedented, regio-differentiated Boc cores possess emerging dendritic features and intrinsic “protect–deprotect” function. We refer categorically to these newly differentiated branched cores as differentiated dendroid templates (DDT's). These dendroid templates can be well resolved by thin layer chromatography (TLC). Gram quantities of these Boc adducts were purified using single pass silica gel column chromatography. These partial Boc protected, differentiated dendroid templates (AmBn, m/n = 1–3) were used as “protect–deprotect” functionalized starting substrates (i.e., regio-differentiated cores) for synthesizing higher generation libraries of regio-differentiated PAMAM dendrimers. In principle, the use of differentiated dendroid templates (i.e., regio-functionalized star-branched cores) should be expected to offer broad options for the systematic engineering and control of many diverse organic nanostructures as a function of size, shape and regio-chemistry.
使各代零α,ω-亚烷基二胺核聚(酰胺基胺)PAMAM树枝状聚合物(四胺封端的底物,A4)与亚
化学计量量(即,2.0当量)的
Boc酸酐反应,得到由以下组成的产物混合物对称四 Boc 产物 (B4) 和四个部分 Boc 保护的加合物,即 (1) 三 (AB3)、(2) 二联 (A2B2)、(3) 二邻 (A2B2) 和 (4) mono-Boc (A3B) 产品。这些前所未有的区域分化 Boc 核心具有新兴的树突特征和内在的“保护-去保护”功能。我们将这些新分化的分支核心明确称为分化树状模板(DDT)。这些树状模板可以通过薄层色谱(TLC)很好地解析。使用单程
硅胶柱色谱法纯化克数量的这些Boc加合物。这些部分 Boc 保护的分化树状模板(AmBn,m/n = 1-3)用作“保护-去保护”功能化起始底物(即区域分化核心),用于合成更高代的区域分化 PAMAM 树枝状聚合物文库。原则上,使用差异化的树状模板(即区域功能化的星形分支核)预计将为许多不同的有机纳米结构的系统工程和控制提供广泛的选择,作为尺寸、形状和区域
化学的函数。