Folded-twisted mechanisms control dynamic redox properties, photophysics and electron transfer of anthanthrene-quinodimethanes.

The synthesis, electrochemical, spectroelectrochemical, photophysical and light induced electron transfer reactions in two new anthanthrene quinodimethanes have been studied and analyzed in the context of dynamic electrochemistry. Their properties are dependent on the interconversion between folded and twisted forms, which are separated by a relatively small energy range, thus allowing to explore their interconversion by variable temperature measurements. The photophysics of these molecules is mediated by a diradical excited state with a twisted structure that habilitates rapid intersystem crossing.

Extended Tetrathiafulvalene Multi-Redox Systems Incorporating 4,5-Dihydroazuleno[2,1,8-ija]azulene Cores.

The introduction of 4,5-dihydroazuleno[2,1,8-ija]azulene as a central core between two 1,4-dithiafulvene (DTF) units provides a novel class of extended tetrathiafulvalene (TTF) electron donors. Herein we present the synthesis of such compounds with the azulenoazulene further expanded by annulation to benzene, naphthalene, or thiophene rings. Moreover, unsymmetrical donor-acceptor chromophores with one DTF and one carbonyl at the central core are presented.

Synthesis of Contorted Polycyclic Aromatic Compounds via Alkyne Benzannulation on Zigzag-Edged Dibenzochrysene Derivatives.

Organic dyes are interesting building blocks for the preparation of organic semiconductors as they possess synthetic handles that can be used to functionalize them and, consequently, change their electronic properties. However, reactions to extend their π-conjugated framework through ring annulation have only been scarcely tested. Herein, we report the use of alkyne benzannulation on 2,8-dibromo-dibenzo[def,mno]chrysene (vat orange 3) and 2,9-dibromo-dibenzo[b,def]chrysene (vat orange 1) to extend the conjugation and reduce their bandgap.

Dibenzannulated -acenoacenes from anthanthrene derivatives.

A series of dibenzannulated phenyl-annulated [4,2]-acenoacenes have been synthesized in three straightforward steps from 4,10-dibromoanthanthrone (vat orange 3). The phenyl bisannulation of [4,2]-acenoacene provides extra stability by increasing the overall aromatic character of the molecules, and allows for a 45-80% increase of the molar extinction coefficient () compared to their [5,2]-acenoacene isomers. Depending on the substituents attached to the π-conjugated core, some derivatives exhibit strong aggregation in the solid state with association constant () up to 255 M, resulting in a significant broadening of the absorption spectrum and a substantial decrease of the bandgap value (more than 0.

Annulated Azuleno[2,1,8-ija]azulenes: Synthesis and Properties.

Non-alternant non-benzenoid hydrocarbons exhibit very different optical and electronic properties than their well-studied benzenoid analogues. However, preparing such structures with extended conjugation length, remains challenging. Herein, we report the synthesis and properties of azuleno[2,1,8-ija]azulene derivatives using a two-step sequence involving a four-fold aldol condensation between aromatic dialdehydes and readily available tetrahydropentalene-2,5-(1H,3H)-dione.

Pyrrole-Embedded Linear and Helical Graphene Nanoribbons.

Linear and helical graphene nanoribbons ( and ) bearing electron-rich pyrrole units have been synthesized by using the photochemical cyclodehydrochlorination (CDHC) reaction. The pyrrole units in the polymer backbone make the polymer electron-rich with moderate bandgap values and relatively high HOMO energy levels. The planarization of the pyrrole unit through cyclization yields a bandgap value almost 0.

Electron Acceptors Based on Cyclopentannulated Anthanthrenes.

We demonstrate the preparation of anthanthrene derivatives with fused five-membered rings. These new derivatives are prepared by a palladium catalyzed cyclopentannulation reaction from precursors derived from the low-cost dye Vat Orange 3 (4,10-dibromoanthanthrone). The new cyclopentaanthanthrene compounds possess reduced optical and electrochemical gaps (∼0.

Synthesis and Properties of Conjugated Polymers Based on a Ladderized Anthanthrene Unit.

Polycyclic aromatic hydrocarbons (PAHs) are interesting building blocks for the preparation of conjugated polymers due to their extended π surface and planar conformation. However, their use as comonomer in conjugated polymers often leads to nonplanar main chains as a consequence of high steric hindrance at the linking point. Herein, we report the synthesis of a ladderized anthanthrene unit using an sp carbon bridge.