Paddlewheel SBU based Zn MOFs: Syntheses, Structural Diversity, and CO? Adsorption Properties.

ABSTRACT: Four Zn metal?organic frameworks (MOFs), {[Zn?(2,6-ndc)?(2-Pn)]·DMF}n (1), {[Zn?(cca)?(2-Pn)]·DMF}n (2), {[Zn?(thdc)?(2-Pn)]·3DMF}n (3), and {[Zn?(1,4-ndc)?(2-Pn)]·1.5DMF}n (4), were synthesized from zinc nitrate and N,N'-bis(pyridin-2-yl)benzene-1,4-diamine (2-Pn) with naphthalene-2,6-dicarboxylic acid (2,6-H?ndc), 4-carboxycinnamic acid (H?cca), 2,5-thiophenedicarboxylic acid (H?thdc), and naphthalene-1,4-dicarboxylic acid (1,4-H?ndc), respectively. MOFs 1?4 were all constructed from similar dinuclear paddlewheel {Zn?(COO)?} clusters and resulted in the formation of three kinds of uninodal 6-connected non-interpenetrated frameworks. MOFs 1 and 2 suit a topologic 4?·6?-net with 17.6% and 16.8% extra-framework voids, respectively, 3 adopts a pillared-layer open framework of 4?·6?·8-topology with sufficient free voids of 39.9%, and 4 features a pcu-type pillared-layer framework of 412·6³-topology with sufficient free voids of 30.9%. CO? sorption studies exhibited typical reversible type I isotherms with CO? uptakes of 55.1, 84.6, and 64.3 cm³ g-1 at 195 K and P/P? =1 for the activated materials 1', 2', and 4', respectively. The coverage-dependent isosteric heat of CO? adsorption (Qst) gave commonly decreased Qst traces with increasing CO? uptake for all the three materials and showed an adsorption enthalpy of 32.5 kJ mol-1 for 1', 38.3 kJ mol-1 for 2', and 23.5 kJ mol-1 for 4' at zero coverage.

SUBMITTER: Lin TR 

PROVIDER: S-EPMC6401755 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature