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A Self‐Assembled Unit Comprising 12 Squaraine Dyes Built Up from Two Star‐Shaped Hexasquarainyl‐Benzene Molecules
Author(s) -
Schreck Maximilian H.,
Röhr Merle I. S.,
Clark Timothy,
Stepanenko Vladimir,
Würthner Frank,
Lambert Christoph
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805685
Subject(s) - hypsochromic shift , chromophore , benzene , context (archaeology) , j aggregate , aggregate (composite) , monomer , molecule , exciton , chemistry , supramolecular chemistry , absorption (acoustics) , photochemistry , materials science , crystallography , physics , optics , nanotechnology , organic chemistry , quantum mechanics , paleontology , composite material , fluorescence , biology , polymer
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/CHCl 3 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.