Walker Samuel E, Chant William, Thoonen Shannon, Tuck Kellie L, Turner David R
School of Chemistry, Monash University, Clayton, VIC, 3800, Australia.
Chemistry. 2024 Apr 25;30(24):e202400072. doi: 10.1002/chem.202400072. Epub 2024 Mar 15.
Self-assembling systems in nature display remarkable complexity with assemblies of different sub-units to generate functional species. Synthetic analogues of such systems are a challenge, often requiring the ability to bias distributions that are under thermodynamic assembly control. Using lantern-type MOCs (metal-organic cages) as a prototypical self-assembling system, herein we explore the role that steric bulk plays in controlling the exchange rate of ligands in paddlewheel-based assemblies, and thus the stability of cages, in competitive self-assembling scenarios. The effective lifetime of the lantern-type MOCs varies over an order of magnitude depending on the steric bulk proximal to the metal nodes with lifetimes of the cages ranging from tens of minutes to several hours. The bulk of the coordinating solvents likewise reduces the rate of ligand exchange, and thus yields longer-lived species. Understanding this subtle effect has implications for controlling the stability of complex assemblies in competitive environments with implications for guest release and application.
自然界中的自组装系统通过不同亚基的组装展现出非凡的复杂性，从而生成功能性物种。此类系统的合成类似物颇具挑战性，通常需要具备改变处于热力学组装控制下的分布的能力。以灯笼型金属有机笼（MOC）作为典型的自组装系统，在此我们探究了空间位阻在基于桨轮的组装体中控制配体交换速率进而控制笼稳定性方面所起的作用，这是在竞争性自组装情形下进行的研究。灯笼型MOC的有效寿命根据金属节点附近的空间位阻不同而变化超过一个数量级，笼的寿命从几十分钟到几小时不等。配位溶剂的量同样会降低配体交换速率，从而产生寿命更长的物种。理解这种微妙效应对于在竞争性环境中控制复杂组装体的稳定性具有重要意义，这对客体释放及应用也有影响。
