Synthesis of a 3D photochromic coordination polymer with an interpenetrating arrangement: crystal engineering for electron transfer between donor and acceptor units

A new photochromic coordination network is constructed via the combination of viologen and carboxylate fragments. Close packing of the two-fold diamond-like interwoven mode creates electron transfer bridges for the acceptor and donor components. Radicals are generated upon photoirradiation and are accompanied by a color change from yellow to blue-green.