Issue 2, 2019

Amino-decorated bis(pyrazolate) metal–organic frameworks for carbon dioxide capture and green conversion into cyclic carbonates

Abstract

The novel Metal–Organic Frameworks (MOFs) M(BPZNH2) (M = Zn, Ni, Cu) were prepared from the reaction of the corresponding metal acetates M(OAc)2·nH2O and the organic linker 3-amino-4,4′-bipyrazole (H2BPZNH2) under solvothermal conditions. H2BPZNH2 was obtained straightforwardly from the reduction of the related nitro-compound using hydrazine as a reducing agent. The Zn(II) polymer is characterized by a 3D porous network featuring tetrahedral metallic nodes and bridging BPZNH22− anions defining the vertices and edges of square channels. The isostructural Ni(II) and Cu(II) MOFs show square-planar metallic nodes and bridging BPZNH22− spacers at the vertices and edges of the rhombic channels of a 3D porous framework. All the MOFs were characterized in the solid state [(VT)-PXRD, IR, TGA-DTG]. The textural property analysis revealed that they are micro–mesoporous materials with BET specific surface areas (SSAs) falling in the 100–400 m2 g−1 range. Zn(BPZNH2), showing the highest SSA (395 m2 g−1) and a prevalently microporous texture (micropore area = 69% of the accessible SSA), has been exploited as a CO2 capture material: at T = 298 K and pCO2 = 1 bar, the total gas uptake equals 3.07 mmol g−1 (13.5 wt% CO2). Its affinity for CO2 (isosteric heat of adsorption Qst = 35.6 kJ mol−1; CO2/N2 Henry selectivity = 17; CO2/N2 IAST selectivity = 14) is higher than that of its nitro-functionalized analogue and comparable to that of other amino-decorated MOFs from the literature. Finally, Zn(BPZNH2) was tested as a heterogeneous catalyst in the reaction of CO2 with activated epoxides bearing a –CH2X pendant arm (X = Cl: epichlorohydrin; X = Br: epibromohydrin) to give the corresponding cyclic carbonates at T = 393 K and pCO2 = 1 bar under green (solvent- and co-catalyst-free) conditions. A good conversion of 47% and a TOF of 3.9 mmol(carbonate) (mmolZn)−1 h−1 were recorded with epibromohydrin.

Graphical abstract: Amino-decorated bis(pyrazolate) metal–organic frameworks for carbon dioxide capture and green conversion into cyclic carbonates

Supplementary files

Article information

Article type
Research Article
Submitted
18 Sep 2018
Accepted
26 Dec 2018
First published
28 Dec 2018

Inorg. Chem. Front., 2019,6, 533-545

Amino-decorated bis(pyrazolate) metal–organic frameworks for carbon dioxide capture and green conversion into cyclic carbonates

R. Vismara, G. Tuci, N. Mosca, K. V. Domasevitch, C. Di Nicola, C. Pettinari, G. Giambastiani, S. Galli and A. Rossin, Inorg. Chem. Front., 2019, 6, 533 DOI: 10.1039/C8QI00997J

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