Anion Helicates: Double Strand Helical Self-Assembly of Chiral Bicyclic Guanidinium Dimers and Tetramers around Sulfate Templates
Anion Helicates: Double Strand Helical Self-Assembly of Chiral Bicyclic Guanidinium Dimers and Tetramers around Sulfate Templates
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DOI：
10.1021/ja953243d
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发表时间：
1996-01
影响因子：
15
通讯作者：
J. Sánchez-Quesada;Christian Seel;P. Prados;J. de Mendoza;I. Dalcol;E. Giralt
中科院分区：
文献类型：
--
作者：
J. Sánchez-Quesada;Christian Seel;P. Prados;J. de Mendoza;I. Dalcol;E. Giralt
具有一级或二级结构螺旋性的合成分子可能与R-螺旋构象中的多肽有关。1另一方面，与双螺旋核酸有关的化合物产生于分子链的自发自组装，通常由金属模板(螺旋)推动。双链螺旋结构是由四面体、2个八面体、3个或非定向过渡金属形成的，而三链螺旋结构是由八面体配位金属或稀土元素形成的。6在这里，我们描述了第一个围绕阴离子折叠的双螺旋结构的例子。手性纯手性双环胍盐7已成功地用于羧酸盐(氨基酸)8或磷酸盐(核苷酸)的分子识别。9因此，设计了四胍盐1链(氯化物和硫酸盐)及其双胍前体2和3，用于络合和跨生物膜运输寡核苷酸。在我们的设计中，CH2SCH2间隔基团被选择来跨越磷酸二酯链中两个相邻的单阴离子之间的距离。在二价硫酸盐反离子的情况下，间隔基团太短，不能在垂直平面上将两个胍亚基包裹在单个阴离子周围。因此，1的两条链被迫以双螺旋结构折叠，这是由受体的手性施加的可预测的利手结构。此外，以及
Synthetic molecules possessing helicity derived from their primary or secondary structures could be related to polypeptides in the R-helix conformation. 1 On the other hand, compounds related to double-helical nucleic acids arise from the spontaneous self-assembly of molecular strands, usually promoted by metal templates (helicates). Double-stranded helicates have been reported with tetrahedral, 2 octahedral, 3 or nondirectional4 transition metals, whereas triple-stranded helices result from octahedral coordination metals5 or lanthanides. 6 Here, we describe the first example of a double-helical structure folding around anions.Enantiomerically pure chiral bicyclic guanidinium salts7 have been successfully employed for the molecular recognition of carboxylates (amino acids) 8 or phosphates (nucleotides). 9 Consequently, strands of tetraguanidinium salts 1 (chlorides and sulfates) as well as their diguanidinium precursors 2 and 3 were designed for the complexation and transport of oligonucleotides across biological membranes. In our design, the CH2SCH2 spacer unit was chosen to span the distance between two adjacent monoanions in the phosphodiester chain. In the case of a divalent sulfate counterion, the spacer is simply too short to wrap two guanidinium subunits in orthogonal planes around a single anion. Therefore, two strands of 1 are forced to fold in a double-helical structure of the predictable handedness imposed by the chiral nature of the receptor. In addition, and