The impact of interplay between electronic and steric effects on the synthesis and the linear and non-linear optical properties of diketopyrrolopyrrole bearing benzofuran moieties. Issue 5 (16th February 2017)

• Record Type: Journal Article
• Authors: Purc, Anna; Koszarna, Beata; Iachina, Irina; Friese, Daniel H.; Tasior, Mariusz; Sobczyk, Krzysztof; Pędziński, Tomasz; Brewer, Jonathan; Gryko, Daniel T.
• Is Part Of: Organic chemistry frontiers. Volume 4:Issue 5(2017)
• Page Start: 724
• Page End: 736
• Publication Date: 2017-02-16
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/c6qo00869k
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : Benzofuran has been proven to be the versatile substituent for tuning the optics of diketopyrrolopyrroles. Abstract : An in-depth investigation of the reaction of substituted salicylaldehydes with chloroacetonitrile led to the development of new conditions for the synthesis of 2-cyanobenzofurans. The crucial improvement lies in the use of phase-transfer catalysis in the second step, i.e., intramolecular aldol type condensation. In a two-step process, the reactants were transformed into a library of 3, 6-bis(benzofuran-2-yl)diketopyrrolopyrroles. We show that the presence of a methyl group in a position adjacent to the cyano functionality only slightly decreased the yield of diketopyrrolopyrroles (to 30–57%). An analysis of the relationship between the degree of polarization/planarization of aryl-diketopyrrolopyrroles and their one- and two-photon spectroscopic properties is reported. Careful design of the desired dyes and enhanced control of their ability to assume a planar molecular structure resulted in interesting photophysical properties, such as absorption and emission in the so-called biological window. Despite having less promising linear spectroscopic properties, the deplanarized molecules possess pretty strong two-photon absorbing properties. Placing methyl groups at adjacent positions to the linkage between benzofuran and the DPP core caused the formation of yellow-emitting dyes with almost quantitative fluorescence quantum yield, moderate Stokes shift and reasonable two-photon absorption cross-sections.