Shape- and size-controlled synthesis of coordination polymer {[Cu(en)2][KFe(CN)6]}n nano/micro-crystals

In the last decade, chemists have devoted their efforts and enormous attention to coordination polymers (CP) with infinitely extended structures due to their intriguing properties and potential applications in catalysis [1], gas storage [2, 3], nonlinear optics [4], molecular magnet [5], and molecular recognition and separations [6, 7]. Recently, CP nanocrystals, nanosized coordination polymers with finite repeating units, have aroused a growing interest due to their special properties distinctive from conventional bulk CP [8]. Up to now, the CP nanocrystals of Prussian blue analogies [9–11] have been intensively studied and various nanocrystals including nanoparticles, nanocubes, nanorods, and nanotubes have been successfully synthesized. However, it still remains a key research challenge to fabricate CP nano/micro-crystals with controlled shape and size, although some works have been demonstrated by several groups [12–16] in the past 3 years. This new class of materials promises to advance nanoscience into the realm of coordination polymers and thereby circumvent the nominal composition limitations generally ascribed to nanoparticles [17]. The novel crystal structure of {[Cu(en)2][KFe(CN)6]}n using [Cu(en)2] 2? as a template and K as a connecting unit was reported in previous studies [18]. We now present the morphology and size control on the nanoand microcrystals of the complex, and the results may refer a new approach for the synthesis of CP with an organic ligand.