Caged structures have found wide application in a variety of areas, including guest encapsulation and catalysis. Although metal-based cages have dominated the field, anion-coordination-based cages are emerging as a new type of supramolecular ensemble with interesting host-guest properties. In the current work, we report a C3-symmetric tris-bis(urea) ligand based on the 2,4,6-triphenyl-1,3,5-triazine spacer, which assembles with phosphate anions to form an A4L4-type (A = anion, L = ligand) tetrahedral cage, 3, with unusually high packing coefficients (up to 99.5% for the best substrate). Cage 3 is able to adjust its size and shape (from 136 to 216 Å3) by bending of the triphenyltriazine plane. This allows it to accommodate relatively large guests. In the case of DABCO, inclusion within the cage allows the degree of methylation to be controlled and the monomethylated product to be isolated cleanly under conditions where mixtures of the mono- and dimethylated adduct are obtained in the absence of cage 3.

中文翻译：

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使用基于阴离子配位的四面体笼控制烷基铵客体的识别和反应性

笼状结构已广泛应用于各种领域，包括客体封装和催化。尽管基于金属的笼在该领域占据主导地位，但基于阴离子配位的笼正在成为一种具有有趣的主客体特性的新型超分子集合。在目前的工作中，我们报告了一种基于 2,4,6-triphenyl-1,3,5-triazine 间隔基的 C3 对称三双（脲）配体，它与磷酸根阴离子组装形成 A4L4 型（ A = 阴离子，L = 配体）四面体笼，3，具有异常高的堆积系数（最佳底物高达 99.5%）。Cage 3 能够通过弯曲三苯基三嗪平面来调整其大小和形状（从 136 到 216 Å3）。这使它能够容纳相对较大的客人。在 DABCO 的情况下，