TY - JOUR
T1 - Adsorption of Carbon Dioxide on Unsaturated Metal Sites in M2(dobpdc) Frameworks with Exceptional Structural Stability and Relation between Lewis Acidity and Adsorption Enthalpy
AU - Yoo, Ga Young
AU - Lee, Woo Ram
AU - Jo, Hyuna
AU - Park, Joonho
AU - Song, Jeong Hwa
AU - Lim, Kwang Soo
AU - Moon, Dohyun
AU - Jung, Hyun
AU - Lim, Juhyung
AU - Han, Sang Soo
AU - Jung, Yousung
AU - Hong, Chang Seop
N1 - Funding Information:
This work was supported by the Korea CCS R and D Center (KCRC) grant funded by the Korea government (Ministry of Science, ICT and Future Planning (MSIP)) (NRF-2014M1A8A1049253, NRF-2014M1A8A1049256), by Basic Science Research Program (NRF-2015R1A2A1A10055658), and by PAL. W.R.L. was partly supported by a Korea University Grant, and J.P. was partly supported by NRF (NRF-2015R1D1A4A01018697). H.J and S.S.H acknowledge the financial support of the Korea Institute of Science and Technology (Grant No. 2E25372).
Publisher Copyright:
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2016/5/23
Y1 - 2016/5/23
N2 - A series of metal-organic frameworks (MOFs) M2(dobpdc) (M=Mn, Co, Ni, Zn; H4dobpdc=4,4′-dihydroxy-1,1′-biphenyl-3,3′-dicarboxylic acid), with a highly dense arrangement of open metal sites along hexagonal channels were prepared by microwave-assisted or simple solvothermal reactions. The activated materials were structurally expanded when guest molecules including CO2 were introduced into the pores. The Lewis acidity of the open metal sites varied in the order Mn<Co<Ni>Zn, as confirmed by C=O stretching bands in the IR spectra, which are related to the CO2 adsorption enthalpy. DFT calculations revealed that the high CO2 binding affinity of transition-metal-based M2(dobpdc) is primarily attributable to the favorable charge transfer from CO2 (oxygen lone pair acting as a Lewis base) to the open metal sites (Lewis acid), while electrostatic effects, the underlying factor responsible for the particular order of binding strength observed across different transition metals, also play a role. The framework stability against water coincides with the order of Lewis acidity. In this series of MOFs, the structural stability of Ni2(dobpdc) is exceptional; it endured in water vapor, liquid water, and in refluxing water for one month, and the solid remained intact on exposure to solutions of pH 2-13. The DFT calculations also support the experimental finding that Ni2(dobpdc) has higher chemical stability than the other frameworks.
AB - A series of metal-organic frameworks (MOFs) M2(dobpdc) (M=Mn, Co, Ni, Zn; H4dobpdc=4,4′-dihydroxy-1,1′-biphenyl-3,3′-dicarboxylic acid), with a highly dense arrangement of open metal sites along hexagonal channels were prepared by microwave-assisted or simple solvothermal reactions. The activated materials were structurally expanded when guest molecules including CO2 were introduced into the pores. The Lewis acidity of the open metal sites varied in the order Mn<Co<Ni>Zn, as confirmed by C=O stretching bands in the IR spectra, which are related to the CO2 adsorption enthalpy. DFT calculations revealed that the high CO2 binding affinity of transition-metal-based M2(dobpdc) is primarily attributable to the favorable charge transfer from CO2 (oxygen lone pair acting as a Lewis base) to the open metal sites (Lewis acid), while electrostatic effects, the underlying factor responsible for the particular order of binding strength observed across different transition metals, also play a role. The framework stability against water coincides with the order of Lewis acidity. In this series of MOFs, the structural stability of Ni2(dobpdc) is exceptional; it endured in water vapor, liquid water, and in refluxing water for one month, and the solid remained intact on exposure to solutions of pH 2-13. The DFT calculations also support the experimental finding that Ni2(dobpdc) has higher chemical stability than the other frameworks.
KW - Lewis acids
KW - carbon dioxide capture
KW - density functional calculations
KW - metal-organic frameworks
KW - solvothermal synthesis
UR - http://www.scopus.com/inward/record.url?scp=84968863274&partnerID=8YFLogxK
U2 - 10.1002/chem.201600189
DO - 10.1002/chem.201600189
M3 - Article
AN - SCOPUS:84968863274
SN - 0947-6539
VL - 22
SP - 7444
EP - 7451
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 22
ER -