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Star‐Shaped Conjugated Molecules with Oxa‐ or Thiadiazole Bithiophene Side Arms
Author(s) -
Kotwica Kamil,
Kostyuchenko Anastasia S.,
Data Przemyslaw,
Marszalek Tomasz,
Skorka Lukasz,
Jaroch Tomasz,
Kacka Sylwia,
Zagorska Malgorzata,
Nowakowski Robert,
Monkman Andrew P.,
Fisyuk Alexander S.,
Pisula Wojciech,
Pron Adam
Publication year - 2016
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.201600984
Subject(s) - electrochromism , alkyl , molecule , materials science , supramolecular chemistry , photochemistry , monomer , conjugated system , electrochemistry , homo/lumo , oxadiazole , carbazole , molecular electronics , crystallography , monolayer , polymer , chemistry , nanotechnology , electrode , organic chemistry , composite material
Star‐shaped conjugated molecules, consisting of a benzene central unit symmetrically trisubstituted with either oxa‐ or thiadiazole bithiophene groups, were synthesized as promising molecules and building blocks for application in (opto)electronics and electrochromic devices. Their optical ( E g (opt)) as well as electrochemical ( E g (electro)) band gaps depended on the type of the side arm and the number of solubilizing alkyl substituents. Oxadiazole derivatives showed E g (opt) slightly below 3 eV and by 0.2 eV larger than those determined for thiadiazole‐based compounds. The presence of alkyl substituents in the arms additionally lowered the band gap. The obtained compounds were efficient electroluminophores in guest/host‐type light‐emitting diodes. They also showed a strong tendency to self‐organize in monolayers deposited on graphite, as evidenced by scanning tunneling microscopy. The structural studies by X‐ray scattering revealed the formation of supramolecular columnar stacks in which the molecules were organized. Differences in macroscopic alignment in the specimen indicated variations in the self‐assembly mechanism between the molecules. The compounds as trifunctional monomers were electrochemically polymerized to yield the corresponding polymer network. As shown by UV/Vis‐NIR spectroelectrochemical studies, these networks exhibited reversible electrochromic behavior both in the oxidation and in the reduction modes.