DESIGN AND FUNCTION OF THE SELF-ASSEMBLED NANO-RINGS

为了通过Ag^+和柔性芳胺配体的结合来构建纳米尺寸的多边形或多面体，我们决定使用N，N '-双（4-吡啶基）苄胺（1）。通过MMFF对配体1进行构象分析后，用B3 LYP/3- 21 G方法计算得到配体1最稳定构象的N <（1）>-N <（2）>-N <（3）>夹角约为109.7°，与配体1的X射线结构完全一致。通过Ag^+诱导的~ 1H-NMR和UV-VIS维斯滴定实验研究了Ag^+与1在溶液中的化学计量关系。两种滴定结果均表明配体1与Ag^+在溶液中形成（1：1）_n络合物。将等摩尔量的配体1溶于乙腈中，AgOTf溶于甲醇中，在氮气保护下，得到1-AgOTf固体配合物。两天后，单晶定量沉淀。用FAB-MS研究了配合物中配体1与Ag^+离子的化学计量比。FAB-MS还表明， ...更多信息 配合物中配体1与Ag^+之间的y为（1：1）_n。在90 K下测量了1-AgOTf配合物的X射线晶体学。该配合物是一个包含六个OTf离子的离散环状六聚体（1：Ag^+ = 6：6），六聚体呈六边形。在建筑群的中心有一个巨大的洞穴。由于腔中原子的无序性，在90 K时腔中的溶剂原子没有被指定。腔体直径约为20 μ m（Ag-Ag间距为21.2 μ m，N_（2）>-N_（2 '）>间距为21.7 μ m）。有趣的是，六边形不是平面的，而是形成一个椅子构象，有点像环己烷的椅子形式。N_（2）>原子位于椅型结构的角上。配合物中N_（1）>-N_（2）>-N_（3）>和N_（1）>-Ag-N_（3 '）>键角分别为109.7°和170°。中心的纳米椅与一侧的六个纳米椅重叠，两侧共有十二个纳米椅。这些纳米椅相互堆叠，形成蜂窝状的空腔。参与重叠位点的原子由球-棒模型显示。有两种面对面的π-π堆积（吡啶-吡啶堆积：黄-蓝，苯-苯堆积：黄-红）位点。碳-碳距离和Ag^+-Ag^+距离分别为3.26-3.67和3.41 μ m。这些碳-碳距离和Ag^+-Ag^+距离与前面描述的无限网络系统中观察到的距离相当。在该复合物中，没有观察到Ag^+-p相互作用。Stang等人报道，在使用Pd^2+和Pt^2+离子的自组装体系中，具有109.5°角的角双齿配体形成五边形、三角形双齿酰亚胺、金刚烷或立方八面体，并且六方大环体系需要具有120°角的角双齿配体。少

In order to construct the nano-sized polygons or polyhedra by the combination of Ag^+ and flexible aromatic amine ligands, we decided to use N, N'-bis(4-pyridyl)benzylamine (1). B3LYP/3-21G calculations after the conformation analysis by MMFF of 1 showed that the N_<(1)>-N_<(2)>-N_<(3)> angle of the most stable conformer is about 109.7°, which is exactly the same as that of X-ray structure of ligand 1. The Ag^+ induced ^1H-NMR and UV-VIS titration experiments were carried out in order to investigate the stoichiometry between Ag^+ and 1 in solution. Both titration results suggest that ligand 1 forms a (1:1)_n complex with Ag^+ ion in solution. A solid 1-AgOTf complex was obtained by mixing equimolar amount of ligand 1 in CH_3CN and AgOTf in CH_3OH in an N_2 atmosphere. After two days, single crystals precipitated quantitatively. The stoichiometry between ligand 1 and Ag^+ ion in the complex was studied by FAB-MS using m-nitrobenzyl alcohol. The FAB-MS also suggests that the stoichiometr … More y between ligand 1 and Ag^+ in the complex is (1:1)_n. The X-ray crystallography of 1-AgOTf complex was measured at 90K. The complex is a discrete cyclic hexamer (1:Ag^+ = 6:6) including six OTf ions and the hexamer is in the form of a hexagon. There is a large cavity in the center of the complex. Because of the disorder of atoms in the cavity, the solvent atoms in the cavity were not specified at 90K. The diameter of the cavity is about 20Å (Ag-Ag distance: 21.2Å and N_<(2)>-N_<(2')> distance: 21.7Å). Interestingly, the hexagon is not planer, but forms a chair conformation somewhat like the chair-form of cyclohexane. The N_<(2)> atoms are at the corners of the chair structure. The N_<(1)>-N_<(2)>-N_<(3)> and the N_<(1)>-Ag-N_<(3')> bond angles in the complex are 109.7° and 170°, respectively. A nano chair at the center overlaps with six nano chairs from one side, and a total twelve nano chairs from both sides. The nano chairs stack on each other and make honeycomb-like cavities. The atoms that participate overlapped sites are shown by ball-and-stick models. There are two kinds of face-to-face π-π stacking (pyridine-pyridine stacking: yellow-blue, benzene-benzene stacking: yellow-red) sites. The carbon-carbon distances and Ag^+-Ag^+ distances are 3.26-3.67 and 3.41Å, respectively. These carbon-carbon and Ag^+-Ag^+ distances are comparable to those observed in the infinite network systems described previously. In this complex, Ag^+-p interactions were not observed. Stang et al. reported that the angular bidentate ligands having 109.5° angles form pentagon, trigonal bipyramide, adamantanoid or cuboctahedron in self-assembly systems using Pd^<2+> and Pt^<2+> ions, and hexagonal macrocyclic systems need angular bidentate ligands having 120° angles. Less