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Temperature-Stable Compelled Composite Superhydrophobic Porous Coordination Polymers Achieved via an Unattainable de Novo Synthetic Method

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posted on 29.09.2018, 00:00 authored by Koya Prabhakara Rao, Masakazu Higuchi, Jettiboina Suryachandram, Susumu Kitagawa
We demonstrate a new de novo synthetic methodology to achieve high-temperature-stable compelled composite superhydrophobic porous coordination polymers (PCPs). These new PCPs were achieved based on coordination capabilities of first-row transition metal ions such as Co2+, Ni2+, and Zn2+. The obtained composite PCPs containing a [Zn2M2O]6+ (M = Co or Ni) bimetallic cluster core with open metal sites (OMSs) exhibited distinct isosteric heats of adsorption and surface areas due to the difference in their open metal Lewis acidic sites of solvent-free state. Additionally, these composite PCPs exhibit remarkable superhydrophobic properties with contact angles of 159.3° and 160.8° respectively for Zn–Co and Zn–Ni analogues. This superhydrophobic surface survives even at high temperature for longer time periods. As projected, these new composite PCPs exhibit better surface area and heats of adsorption compared to the PESD-1 (Zn) analogue due to a larger number of OMSs. Moreover, they display selective adsorption toward aromatic solvents such as benzene and toluene over aliphatic solvents such as cyclohexane due to corrugated and terminated aromatic hydrocarbon moieties toward the interactive surface. They also exhibit oil spill cleanup from the water surface in the powder form as well as pellet form up to 385 wt %. This study certainly offers a roadmap for designing and engineering new composite superhydrophobic porous materials for better water and thermal stability along with OMSs. This type of PCP exhibits a wide range of applications especially in catalysis, separation technology, and securing environmental problems such as oil spill cleanup in seawater.