US EPA

1039257 

Journal Article 

Coordination-chemistry control of proton conductivity in the iconic metal-organic framework material HKUST-1 

Jeong, NC; Samanta, B; Lee, CY; Farha, OK; Hupp, JT 

2012 

Yes 

Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 

134 

1 

51-54 

English 

22148287 

10.1021/ja2110152 

WOS:000301084200014 

HKUST-1, a metal-organic framework (MOF) material containing Cu(II)-paddlewheel-type nodes and 1,3,5-benzenetricarboxylate struts, features accessible Cu(II) sites to which solvent or other desired molecules can be intentionally coordinated. As part of a broader investigation of ionic conductivity in MOFs, we unexpectedly observed substantial proton conductivity with the "as synthesized" version of this material following sorption of methanol. Although HKUST-1 is neutral, coordinated water molecules are rendered sufficiently acidic by Cu(II) to contribute protons to pore-filling methanol molecules and thereby enhance the alternating-current conductivity. At ambient temperature, the chemical identities of the node-coordinated and pore-filling molecules can be independently varied, thus enabling the proton conductivity to be reversibly modulated. The proton conductivity of HKUST-1 was observed to increase by ~75-fold, for example, when node-coordinated acetonitrile molecules were replaced by water molecules. In contrast, the conductivity became almost immeasurably small when methanol was replaced by hexane as the pore-filling solvent.