Exceptional chemical and thermal stability of zeolitic imidazolate frameworks

doi:10.1073/pnas.0602439103

Exceptional chemical and thermal stability of zeolitic imidazolate frameworks

*Department of Chemistry and Biochemistry, Center for Reticular Materials Research at California NanoSystems Institute, University of California, Los Angeles, CA 90095;
^‡Department of Chemistry Education, Seoul National University, Seoul 151-748, Korea;
^§Institute for Chemical Physics, School of Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China; and
^¶Department of Chemistry, Arizona State University, Tempe, AZ 85287

Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved May 22, 2006
↵ ^†K.S.P., Z.N., and A.P.C. contributed equally to this work. (received for review March 24, 2006)

Abstract

Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m²/g), high thermal stability (up to 550°C), and remarkable chemical resistance to boiling alkaline water and organic solvents.

Footnotes

^‖To whom correspondence should be addressed. E-mail: yaghi{at}chem.ucla.edu
Author contributions: O.M.Y. designed research; K.S.P., Z.N., A.P.C., J.Y.C., R.H., F.J.U.-R., and H.K.C. performed research; Z.N., A.P.C., and M.O. analyzed data; and Z.N., A.P.C., M.O., and O.M.Y. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: Atomic coordinates for all ZIFs (12 structures) have been deposited in the Cambridge Structural Database, Cambridge Crystallographic Data Centre, Cambridge CB2 1EZ, United Kingdom (CSD reference nos. 602535–602546).
↵ ** The compounds having the same framework composition and structure as ZIF-7 and -8 were published in refs. 9 and 10, respectively. We note that we used a completely different and more efficient method to prepare these compounds. In particular, ZIF-8 was prepared solvothermally within 24 h, whereas the synthesis of the same structure reported in ref. 10 required a very long reaction time (1 month).
↵ †† Since our work was completed, a Langmuir surface area of 1,400 m²/g was reported for a material having the same framework composition and structure as ZIF-8 (10).
Abbreviations:

Abbreviations:

IM,

imidazolate;

ZIF,

zeolitic IM framework;

PhIM,

benzimidazolate;

MeIM,

2-methylimidazolate;

DMF,

N,N-dimethylformamide;

MOF,

metal–organic framework;

TGA,

thermal gravimetric analysis;

PXRD,

powder x-ray diffraction.