The group of Takashi UEMURA at the University of Tokyo has used porous metal complexes (MOF) consisting of metal ions connected in regular nano-sized spaces to separate modified and non-modified polyethylene glycol. Using MOF with a pore size of 0.57 nm as the adsorbent, PEG with unmodified terminal group OH was efficiently incorporated into the pores, while PEG modified with trityl groups (size = 0.72 nm) at the terminal was not adsorbed at all. Interestingly, the method worked even with PEG with more than several hundred repeating units, which could be separated at a purity of 99% or more from a mixture of modified and unmodified PEG.

JST news release, September 13, 2018