Temperature-Dependent Superhydrophobic Functionalized Coordination Polymers (SFCPs) for Selective Adsorption of C2H4 over C2H6.

We prepared two new superhydrophobic functionalized coordination polymers (SFCPs) [Zn4(OH)2(BTMB)2(4,4'-Bipy)2]∞ ⊃ solvent, 1, and [Cd4(OH)2(BTMB)2(4,4'-Bipy)3]∞ ⊃ solvent, 2, by solvothermal methods. For 1, the single-crystal XRD structure revealed that it contains two crystallographically distinct Zn2+ ions with two different types of coordination geometries of 4 and 6, exhibiting a unique superhydrophobic behavior with microporosity. Compound 1 exhibits superhydrophobicity with a contact angle of 155.5° (at 30 °C), which is stable even at high temperatures, whereas for the SFCP 2, all of the Cd2+ ions have only 6-coordination and exhibit a superhydrophobic character at room temperature with a contact angle of 156.7°(at 30 °C). However, surprisingly, this superhydrophobic character is stable only up to 60 °C, above which it is converted to hydrophilic nature, in contrast to the SFCP 1. Moreover, in this study, we also report a selective gas adsorption study of two C2 gases with similar kinetic diameters (∼3.9 Å) of ethylene over ethane.