Planar, Twisted, or Curved Extended Tetrathiafulvalenes with Polycyclic Aromatic Hydrocarbon Cores Featuring Five-Membered Rings.

Tetrathiafulvalene (TTF) and polycyclic aromatic hydrocarbons (PAHs) represent two distinct classes of redox-active chromophores. By merging these two classes in so-called extended tetrathiafulvalenes, new physico-chemical characteristics emerge. Here in this study, we summarize the properties of such PAH-extended TTFs for which the PAH core incorporates five-membered carbo-cyclic rings together with six-, seven-, and/or eight-membered rings.

Multistate Dihydroazulene-Spiropyran Dyads: Path-Dependent Switchings and Refinement of the "Meta-rule" of Photoactivity.

Multistate switches are interesting systems for a plethora of potential applications, such as for data storage involving many different states or for logic operations characterized by specific outputs. The main challenge is to achieve a precise control of accessibility to a specific state via a given sequence of multiple stimuli. Here, we have connected dihydroazulene (DHA) and spiropyran (SP) photoswitches in dyads to elucidate differences in optical and switching properties between ortho-, meta-, and para-phenylene-bridged dyads.

Synthesis and Properties of Acetylenic Scaffolds Modeling Segments of 6,6,12-Graphyne.

6,6,12-Graphyne is an all-carbon network formally generated by interspersing sp- and sp-hybridized carbon atoms between the carbon hexagons of graphene. Tetraethynylethene (TEE) is one structural unit that can be identified as bridging the benzene rings in 6,6,12-graphyne. Here we present the synthesis by stepwise Sonogashira couplings of TEE scaffolds that can be considered as small model systems of 6,6,12-graphyne segments.

Extended tetrathiafulvalene with a pentaleno[1,2-:4,5-']difluorene core - a donor-acceptor multi-redox system.

A novel extended tetrathiafulvalene was prepared by introducing the large pentaleno[1,2-:4,5-']difluorene as a central polycyclic aromatic hydrocarbon moiety. This compound behaved as a multi-redox system that could take reversibly six redox states (-1, 0, +1, +2, +3, +4). The compound exhibited strong absorptions in the visible region with an end-absorption almost reaching to 700 nm.

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units.

Large donor-acceptor scaffolds derived from polycyclic aromatic hydrocarbons (PAHs) with tunable HOMO and LUMO energies are important for several applications, such as organic photovoltaics. Here, we present a large selection of PAHs based on central indenofluorene (IF) or fluorene cores and containing various dithiafulvene (DTF) donor units that gain aromaticity upon oxidation and a variety of acceptor units, such as vinylic diesters, enediynes, and cross-conjugated radiaannulenes (RAs) that gain aromaticity upon reduction. In some cases, the DTF units are expanded by pyrrolo annelation.

Electronic Materials: An Antiaromatic Propeller Made from the Four-Fold Fusion of Tetraoxa[8]circulene and Perylene Diimides.

The synthesis of an antiaromatic tetraoxa[8]circulene annulated with four perylene diimides (PDI), giving a dynamic non-planar π-conjugated system, is described. The molecule contains 32 aromatic rings surrounding one formally antiaromatic planarized cyclooctatetraene (COT). The intense absorption (ϵ=3.

Dianthracenylazatrioxa[8]circulene: Synthesis, Characterization and Application in OLEDs.

A soluble, green-blue fluorescent, π-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material.