122nd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation of Young Material Chemists
Room No. Room 322
Time THU 09:07-:
Code MAT.O-2
Subject Morphology-retained photo-conversion reaction of anthracene single crystal: a new approach for organic heterostructures
Authors Jinyoung Koo*, Hee Cheul Choi*
Department of Chemistry, Institute for Basic Scien, Pohang University of Science and Technology, Korea
Abstract The morphology of organic single crystal heavily affects its optical and electrical properties as these properties are determined by molecular arrangements in the crystal, and the morphologies generally reflect the molecular arrangements. In this presentation, we report the solid-state photo-conversion reaction of disk shape anthracene (AN) crystal into 9,10-anthraquinone (ANQ) and dipara-anthracene (DPA) crystals with the original crystal morphology retained. It should be noted that it is difficult to obtain such disk shape ANQ and DPA crystals by conventional crystallization methods, but they were realized by photo-conversion reaction of disk shape AN crystal. Time-dependent observation revealed the reaction mechanism as the photo-oxidation proceeded from the edge of the AN crystal due to oxygen diffusion while photo-dimerization occurs randomly. Interestingly, the electrical conductivity of photo-converted 9,10-anthraquinone (PC-ANQ) crystal is about five orders of magnitude higher than that of the starting AN crystal while the photo-converted dipara-anthracene (PC-DPA) crystal exhibits a decreased conductivity. Structural contributions to electrical conductivity differences were investigated by X-ray diffraction (XRD) and single crystal phase indexing, we revealed that the solid-phase photoreaction could induce molecular rearrangement. The remarkable advantage of solid-state photochemical reaction is that the reaction area is readily controlled by light irradiation area. By taking this advantage, we found a new approach to synthesize the lateral heterostructures (AN-ANQ, AN-DPA, and ANQ-DPA) by area-selective photoreaction using a chrome photomask.
E-mail comish@postech.ac.kr