Synthesis of Hierarchically Porous HKUST-1 MOF: Use of C14-6-14, a Cationic Gemini Surfactant, as Soft-Template†

Presence of hierarchical connectivity between the meso- and micro- scale pores in a material, greatly facilitate the use of available active sites in the porous space for many important applications. Here, we present a strategy of using a soft template based assemblies of a gemini surfactant, C14-6-14, to introduce mesopores in one of the well-known metal organic framework (MOF), HKUST-1. A combination of certain synthetic parameters are adopted in this work, to induce variations in the nucleation and crystal growth conditions that are crucial to achieve a wide range of hierarchical porosity (HP). We demonstrate the presence of HP, through N(2)gas sorption, TEM and a dye uptake study. The soft-templation mechanism, has been probed through DLS, zeta potential and confocal imaging studies. The observed HP structure, where the mesoporous channels separate the embedded MOF clusters from the surrounding MOF matrix, is unique due to the formation of vesicle like assembly of C(14-6-14)and their utilization as soft templates. For our prepared samples, we have calculated hierarchy factor (HF), a value that can be used to assess and compare the HP quantitatively.