Micropore Formation of [Zn 2 (Oxac) (Taz) 2 ]·(H 2 O) 2.5 via CO 2 Adsorption.

As-synthesized [Zn2 (Oxac) (Taz)2 ]·(H2 O)2.5 , referred to as ZOTW2.5 , was prepared from aqueous methanol solutions of Zn5 (CO3 )2 (OH)6 and two kinds of ligands of 1,2,4-triazole (Taz) and oxalic acid (Oxac) at 453 K for 12 h. The crystal structure was determined by the Rietveld method. As-synthesized ZOTW2.5 was pretreated at 383 K and 1 mPa for tpt h, ZOTWx (tpt h). ZOTWx (≥3h) showed a type I adsorption isotherm for N2 at 77 K having a saturation amount (Vs ) of 180 mg/g, but that pretreated shortly showed only 1/10 in Vs . CO2 was adsorbed at 303 K in sigmoid on nonporous ZOTWx (≤2h) and in Langmuir-type on ZOTWx (≥3h) to reach the adsorption amount of 120 mg/g at 700 Torr. N2 adsorption on ZOTWx (≤2h)deCO2 , degassed after CO2 adsorption on ZOTWx (≤2h), was promoted 5-fold from 180 mg/g on ZOTWx (tpt h) and ZOTWx (≥3h)deCO2 up to ca. 1000 mg/g. The interaction of CO2 and H2 O molecules in micropores may lead to a new route for micropore formation.