Topological Transformation of π‐Conjugated Molecules Reduces Resistance to Crystallization. Issue 32 (4th July 2017)

• Record Type: Journal Article
• Authors: Zhou, Cheng; Cui, Qiuhong; McDowell, Caitlin; Seifrid, Martin; Chen, Xiankai; Brédas, Jean‐Luc; Wang, Ming; Huang, Fei; Bazan, Guillermo C.
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 32(2017)
• Page Start: 9318
• Page End: 9321
• Publication Date: 2017-07-04
• Subjects: conjugated molecules -- crystallinity -- molecular topology -- organic semiconductors -- solubility; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201702646
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Two electronically delocalized molecules were designed as models to understand how molecular shape impacts the tradeoff between solubility and crystallization tendencies in molecular semiconductors. The more soluble compoundTT contains a non‐planar bithiophene central fragment, whereasCT has a planar cyclopentadithiophene unit. Calorimetry studies show thatCT can crystallize more easily thanTT . However, absorption spectroscopy shows that the initially amorphousTT film can eventually form crystals in which the molecular shape is significantly more planar. Two thermally reversible polymorphs forTT were observed by XRD and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) measurements. These findings are relevant within the context of designing soft semiconductors that exhibit high solubility and a tendency to provide stable organized structures with desirable electronic properties. Abstract : Molecular topological transformation : A molecule was designed that adopts a twisted, and therefore more soluble, conformation in solution. The molecule rearranges into a planar shape in the solid state and is able to form highly crystalline films. These transformations are fully reversible and encourage their applications as a new design element for producing organic semiconductors that are highly ordered and simple to process.