Ligand-Based Phase Control in Porous Molecular Assemblies

Functionalization of isophthalic acid ligands with linear alkoxide groups from ethoxy through pentoxy is shown to have a pronounced effect on both the synthesis of porous paddlewheel-based molecular assemblies and their resulting surface areas and gas adsorption properties. Shorter chain length is compatible with either tetragonal or hexagonal two-dimensional materials, with the hexagonal phase favored with longer chain length. Precise tuning of reaction conditions affords discrete molecular species that are soluble in a variety of organic solvents. The isolated porous molecules display BET surface areas ranging from 125 m2/g to 545 m2/g. The pentoxide-based molecular assembly shows considerable promise for the separation of hydrocarbons with average isosteric heats of adsorption of −48 and −31 kJ/mol for ethylene and ethane, respectively.将间苯二甲酸配体(isophthalic acid ligands)通过接枝从乙氧基(ethoxy)到戊氧基(pentoxy)的直链烷氧基(linear alkoxide groups)进行功能化，已被证实对多孔桨轮基分子组装体(porous paddlewheel-based molecular assemblies)的合成，以及其最终的比表面积与气体吸附性能均具有显著影响。较短的烷氧基链长可适配四方相(tetragonal)或六方相(hexagonal)二维材料，而较长链长则更有利于形成六方相。通过精准调控反应条件，可获得可溶于多种有机溶剂的离散分子实体(discrete molecular species)。所分离得到的多孔分子的BET比表面积(Brunauer-Emmett-Teller specific surface area)介于125 m²/g至545 m²/g之间。基于戊氧基的分子组装体在烃类分离领域展现出可观的应用前景，其对乙烯与乙烷的平均吸附等量热分别为-48 kJ/mol与-31 kJ/mol。