A Self‐Assembled Unit Comprising 12 Squaraine Dyes Built Up from Two Star‐Shaped Hexasquarainyl‐Benzene Molecules. Issue 11 (28th January 2019)

• Record Type: Journal Article
• Authors: Schreck, Maximilian H.; Röhr, Merle I. S.; Clark, Timothy; Stepanenko, Vladimir; Würthner, Frank; Lambert, Christoph
• Is Part Of: Chemistry. Volume 25:Issue 11(2019)
• Page Start: 2831
• Page End: 2839
• Publication Date: 2019-01-28
• Subjects: dyes/pigments -- exchange narrowing -- exciton coupling -- noncovalent interactions -- self-assembly; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201805685
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We describe the aggregate formation and optical properties of a star‐shaped hexaarylbenzene with six squaraine chromophores (=hexasquarainyl benzene). Comprehensive concentration‐dependence studies in acetone/CHCl3 mixtures reveal a strong propensity to form discrete dimeric aggregates with a high binding constant in excess of 10 6 m −1 . In this context, a large hypsochromic shift of almost 2700 cm −1 was found in the absorption spectrum, indicating H‐type exciton coupling. The aggregate band is characterised by a very small band width of only 560 cm −1, probably caused by exchange narrowing. Both experimental and computational methods were used to elucidate the supramolecular aggregate structure, which is assumed to consist of two stacked hexasquarainyl benzene monomers. Abstract : Concentration matters : Solvent‐ and concentration‐dependent self‐assembly of star‐shaped hexasquarainyl benzenes in well‐defined dimeric H‐type aggregates is described.