Unusual room temperature CO2 uptake in a fluoro-functionalized MOF: insight from Raman spectroscopy and theoretical studies

Abstract

We herein report an unusual CO₂ adsorption behavior in a fluoro-functionalized MOF {[Zn(SiF₆)(pyz)₂]·2MeOH}_n (1) with a 1D channel system, which is made up of pyrazine and SiF₆²⁻ moieties. Surprisingly, desolvated 1 (1′) adsorbs higher amounts of CO₂ at 298 K than at 195 K, which is in contrast to the usual trend. Combined Raman spectroscopic and theoretical studies reveal that slanted pyrazine rings in 1′ with an angle of 17.2° with respect to the (200) Zn(II)–Si plane at low temperature block the channel windows and thus reduce the uptake amount.