Polycyclotrimers of 1,4-Diethynylbenzene, 2,6-Diethynylnaphthalene, and 2,6-Diethynylanthracene: Preparation and Gas Adsorption Properties

Hyperbranched partly cross-linked polycyclotrimers of 1,4-diethynylbenzene, 2,6-diethynylnaphthalene, and 2,6-diethynylanthracene, Pc(1,4-DEB), Pc(2,6-DEN), and Pc(2,6-DEA), respectively, are prepared using TaCl5/Ph4Sn catalyst. Brunauer-Emmett-Teller (BET) surface area, microporosity, and maximum sorption capacity for H-2 and CO2 decrease in the order of decreasing relative content of branching points in polycyclotrimers Pc(1,4-DEB) > Pc(2,6-DEN) > Pc(2,6-DEA), the highest values for Pc(1,4-DEB) being S-BET = 1299 m(2)g(-1),a(H2) = 1.26 wt% (100 kPa, 77 K), and a(CO2) = 10.8 wt% (100 kPa, 273 K). N-2 isotherms show that adsorption/desorption hysteresis occurs already at low equilibrium pressures. CO2 isotherms show that the time allotted to the measurement influences both the maximum adsorption capacity and the hysteresis upon desorption.