Water-Stable In(III)-Based Metal-Organic Frameworks with Rod-Shaped Secondary Building Units: Single-Crystal to Single-Crystal Transformation and Selective Sorption of C2H2 over CO2 and CH4.
Inorg Chem
; 56(4): 2188-2197, 2017 Feb 20.
Article
em En
| MEDLINE
| ID: mdl-28165753
ABSTRACT
Three new water-stable In(III)-based metal-organic frameworks, namely, [In3(TTTA)2(OH)3(H2O)]·(DMA)3 (BUT-70, DMA = N,N-dimethylacetamide), [In3(TTTA)2(CH3O)3] (BUT-70A), and [In3(TTTA)2(OH)3] (BUT-70B), with rod-shaped secondary building units (SBUs) and an new acrylate-based ligand, (2E,2'E,2â³E)-3,3',3â³-(2,4,6-trimethylbenzene-1,3,5-triyl)-triacrylate (TTTA3-) were obtained and structurally characterized. BUT-70A and -70B were generated in a single-crystal to single-crystal transformation fashion from BUT-70 through guest exchange followed by their removal. The solvents used for guest exchange were methanol and dichloromethane, respectively. Single-crystal structure analyses show that the guest exchange and removal process is accompanied by the substitution of coordinated water molecules of In(III) centers with uncoordinated carboxylate O atoms of TTTA3- ligands. Moreover, hydroxyl groups bridging two In(III) centers are also replaced by methoxyl groups in the transformation from BUT-70 to -70A. Overall, three metal-organic frameworks (MOFs) are constructed by infinite chains consisting of corner-sharing InO4(OR)2 (R = H or Me) octahedral entities, which are interconnected by TTTA3- ligands to form three-dimensional frameworks. Unlike most reported MOFs with infinite chains as SBUs, such as well-known MIL-53 and M-MOF-74, which have one-dimensional channels along the chain direction, the BUT-70 series contain two-dimensional intersecting channels. The Brunauer-Emmett-Teller surface area and pore volume of BUT-70A were estimated to be 460 m2 g-1 and 0.18 cm3 g-1, respectively, which are obviously lower than those of BUT-70B (695 m2 g-1 and 0.29 cm3 g-1). Gas adsorption experiments demonstrated that BUT-70A and -70B are able to selectively adsorb C2H2 over CO2 and CH4. At 1 atm and 298 K, BUT-70A uptakes 3.1 mmol g-1 C2H2, which is 3.6 times that of the CO2 uptake and 7.2 times that of the CH4 uptake. Compared with BUT-70A, BUT-70B presents an even higher C2H2 uptake of 3.9 mmol g-1 at the same conditions, but slightly lower Ideal Adsorbed Solution Theory C2H2/CO2 and C2H2/CH4 selectivities.
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01-internacional
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MEDLINE
Idioma:
En
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Inorg Chem
Ano de publicação:
2017
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Article