If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Modulating MOFs

A postsynthetic modification provides control over the flexible “breathing” behavior of pores in metal-organic frameworks

by Stephen K. Ritter
November 23, 2009 | A version of this story appeared in Volume 87, Issue 47

Converting a MOF’s amine groups to amides permits controlled “breathing” of the pores.
Converting a MOF’s amine groups to amides permits controlled “breathing” of the pores.

By modifying amine groups in a metal-organic framework (MOF), Zhenqiang Wang and Seth M. Cohen of the University of California, San Diego, have shown that it’s possible to activate the “breathing” behavior of pores in the materials to selectively adsorb gases or other molecules. The finding marks the first time researchers have used a postsynthetic modification to trigger and control the flexibility of MOFs (J. Am. Chem. Soc., DOI: 10.1021/ja907742z). MOFs are porous materials with high surface areas that are ideal for catalysis, separation, sensing, and gas-storage applications. Most MOFs are rigid crystalline solids, but a small subset of the materials has unique flexible frameworks that permit the pores to open and narrow. Cohen’s group built a flexible MOF from zinc carboxylate units joined by 1,4-diazabicyclo[2.2.2]octyl groups in one direction and by 2-amino-1,4-benzenedicarboxylates in the other direction (Inorg. Chem. 2009, 48, 296). Wang and Cohen then treated the MOF with alkylanhydrides of various lengths (O[CO(CH2)nCH3]2) to form amide groups. The short-chain amide (n = 0) narrows the pores and the longer chain amides (n = 3–5) hold the pores open, but the medium-length chains (n = 1 or 2) are just right, creating a bistable framework that leads to controlled breathing.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.