Photochemistry of the π‐Extended 9,10‐Bis(1,3‐dithiol‐2‐ylidene)‐ 9,10‐dihydroanthracene System: Generation and Characterisation of the Radical Cation, Dication, and Derived Products

Abstract

Flash photolysis of bis[4.5-di(methylsulfanyl) 1,3-dithiol-2-ylidene]-9,10(-dihydroanthracene (1) in chloroform leads to formation of the transient radical cation species 1.+ which has a diagnostic broad absorption band at lambdamax approximately 650 nm. This band decays to half its original intensity over a period of about 80 micros. Species 1.+ has also been characterised by resonance Raman spectroscopy. In degassed solution 1.+ disproportionates to give the dication 1(2+), whereas in aerated solutions the photodegradation product is the 10-[4,5-di(methylsulfanyl) 1,3-dithiol-2-ylidene]anthracene-9(10 H)one (2). The dication 1(2+) has been characterised by a spectroelectrochemical study [lambdamax (CH2Cl2) = 377, 392, 419, 479 nm] and by an X-ray crystal structure of the salt 1(2-) (ClO4)2, which was obtained by electrocrystallisation. The planar anthracene and 1,3-dithiolium rings in the dication form a dihedral angle of 77.2 degrees; this conformation is strikingly different from the saddle-shaped structure of neutral 1 reported previously.

Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes

“…In the visible, the newly formed transient is characterized by a broad maximum at 680 nm. The latter resembles the radiolytically and photolytically generated fingerprint of the one electron-oxidized radical cation of exTTF 53,54 . In the NIR, appreciable blue shifts of the transient bleaching are detected, with minima that shift from 1,040 and 1,145 nm to 1,010 and 1,135 nm, respectively, followed by a broad transient between 1,150 and 1,600 nm.…”

Compactly Fused o‐Quinone‐Extended Tetrathiafulvalene‐o‐Quinone Triad – a Redox‐Amphoteric Ligand

“…The X‐ray study gives additional facts in favor of the charge‐separated structure 3 . The 1,3‐dithiole rings in 3 become essentially aromatic: the S9–C10 and S14–C10 bond lengths [1.680(4) and 1.696(6) Å, respectively] are comparable with those for TTF dications (1.670–1.690 Å), whereas in neutral TTF they should be longer (in the range 1.730–1.760 Å) 20–22. The C8–S9 and C15–S14 bonds are also slightly contracted compared with the values typical for the neutral form.…”

Self‐Assembled Cofacial Zinc–Porphyrin Supramolecular Nanocapsules as Tuneable 1O2 Photosensitizers

“…The redox‐controlled encapsulation of extended tetrathiafulvalene (exTTF) based switchable guest ( m ‐Py)exTTF in the cavity of 1 has been recently described . On the other hand, exTTF and superextended tetrathiafulvalene (sExTTF) derivatives are able to rapidly quench 1 O 2 produced by a photosensitizer by degradation into the corresponding quinone products, which makes them interesting 1 O 2 sensors. On this basis, we envisioned that the encapsulated ligand in the ( m ‐Py)exTTF ⊂ 1 suprastructure (Figure a) might react with the putative 1 O 2 produced at the Zn–porphyrin centers of 1 .…”