Organic cocrystals that combine two or more organic molecules give people an efficient way to construct functional molecular crystals. In particular, the multi-component crystals are of great important because of their novel or enhanced optoelectronic properties.
Besides, organic cocrystals can display promising luminescent features, for example, a series of luminescent microtubes can be assembled by Tetracyanobezene(TCNB)-based charge-transfer (CT) complexes due to the CT transition between donors and acceptors. Thus, integrating appropriate arene-perfluoroarene (AP) pairs into two-component cocrystals may also potentially generate novel optical and/or electronic properties.
Recently, a research group led by Prof. HU Wenping from Institute of Chemistry of Chinese Academy of Sciences (ICCAS) reported a simple and available method to build doped organic cocrystals with tunable emission colors. The study was published on Angew. Chem Int. Ed. as cover paper.
They developed two luminescent organic cocrystals, i.e. pyrene-octafluoronaphthalene (pyrene-OFN) and pyrene-1,2,4,5-tetracyanobezene (pyrene-TCNB), with different optical properties due to their different intermolecular interaction modes, such as CT and AP interactions.
Unexpectedly, white-light emission (WLE) can be obtained by inducing appropriate doping TCNB rate into a pyrene-OFN matix. In the supramolecular cocrystal system, an efficient energy transfer process from pyrene-OFN to pyrene-TCNB occur due to their well-matched spectra and desirable energy D/A distance.
The present competitive intermolecular interaction strategy can be further applied to the fabrication of more complicated organic light-harvesting systems.

Schematic illustration of the doping strategy of between pyrene-TCNB and pyrene-OFN (Image by HU wenping)

Contact:
Prof. HU Wenping
Institute of Chemistry, Chinese Academy of Sciences
 Email: huwp@iccas.ac.cn