Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• bridge and investigate its mixed-valence (MV) states by electrochemical and spectroelectrochemical methods. We found that the supporting electrolytes had unusual effects on potential splitting during electrochemical behavior, in which a smaller counteranion thermodynamically stabilized a MV cation more

• intervalence charge transfer characteristics of the zwitterionic MV state. Keywords: anion binding; electrochemistry; hydrogen bonding; triarylamine; urea; zwitterionic mixed valency; Introduction Mixed-valence (MV) compounds have received increasing attention from the viewpoint of fundamental research on

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• connected by a C=C double bond. The first oxidation converts one ring into an aromatic 6π-electron system, which is further stabilized by a mixed-valence resonance structure. The second oxidation yields two aromatic 1,3-dithiolium cations (2 × 6π electrons) which are connected by a C–C single bond. The

• so-called mixed-valence dimer (12) ●+. A mixed-valence dimer can be identified by splitting of the first TTF oxidation potential into two distinguishable waves. This change in redox behavior can be followed by electrochemical methods such as cyclic voltammetry. Another indication for a mixed-valence

• -type arrangement in the dimer [34]. Furthermore, the equilibrium between a paramagnetic monomer and a diamagnetic dimer makes the use of electron paramagnetic resonance (EPR) spectroscopy ideal to follow the dimerization process [36]. Mixed-valence and radical-cation interactions in the solid state are

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• increase in the viscosity of the solvent. According to these data, (1·−)H2 belongs to class III of Robin–Day classification [15] of mixed valence systems. Thus, the molecule does not have distinct catechol or semiquinone oxidation states for the dioxolene moieties on the termini, i.e., an additional

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• system to 2D with a significant contribution from S···S non-covalent interactions [26]. This gave a record transition temperature among TTF mixed valence ambient pressure superconductors in the salt κ-(BEDT-TTF)2Cu[N(CN)2]Br [27]. In an attempt to create macromolecular compounds with multi-electron redox

• polymer thin film revealed the splitting of the first oxidation wave during the cathodic run, which the authors attributed to a stepwise reduction from the aggregated radical cation to an intermediate mixed valence state, then further reduction to the neutral species. To decrease the difference in the

• and cathodic runs, was evident for all polymers, but clearest for 6c. This was assigned to the formation of a mixed valence state and aggregated cation radical [50]. The relative increase in the peak current during oxidation to the dication, compared to that of cation radical formation, was explained

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• nanostructures. Although radical cations derived from TTF oligomers strongly interact in solution to produce a mixed-valence dimer and π-dimer, it seems to be difficult to produce nanoobjects of radical cations different from those of neutral TTF oligomers. In some cases, however, radical cations form

• mixed-valence (MV) dyad (TTF/TTF)•+ and the dicationic dyad (TTF•+)2, so-called π-dimer, are formed in concentrated solution or at low temperature [61]. On the other hand, the synergy of either the fastener effect or π-expansion allows star-shaped C3-symmetric oligo-TTFs 22 and 23 to self-associate both

• /or S···H interactions in solution. Note that these K2 values of 23 in the neutral state are similar to that of the mixed valence dimer (TTF•+ + TTF) (K2 = 6.0 M−1) and much larger than that of the π-dimer (TTF•+ + TTF•+) (K2 = 0.6 M−1) described in the literature [61]. Strong self-association of 23

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• enantiopure and racemic salts excepting the space groups which were non-centrosymmetric and centrosymmetric, respectively. On the other hand, complete different solid-state packings may be observed in enantiopure and racemic forms of the same donor, as recently described for a series of mixed valence salts

• conductivity in enantiopure mixed-valence metallic salts formulated as [DM-EDT-TTF]2[ClO4] [11]. This is referred to as the electrical magnetochiral anisotropy (eMChA) effect. This effect, which translates the influence of chirality on the transport properties measured in a parallel magnetic field [12], was

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• distance within the clip and, consequently, the redox behavior of the receptor. Carried out at different concentrations in solution, electrochemical and spectroelectrochemical experiments provide evidence of mixed-valence and/or π-dimer intermolecular interactions between TTF units from two closed clips

• oxidation wave (Eapp0ox1 and Eapp0ox1’), suggesting the presence of intermolecular (between two clips) or intramolecular (within a clip) interactions between two TTF units (i.e., mixed valence and/or π-dimer) [41]. Eventually, the reversible two-electron process (i.e., 1 e− on each TTF+· unit) for the

• existence of intermolecular interactions and the formation of mixed-valence and radical cation dimer states. These results clearly demonstrated the presence of an intermolecular mixed-valence phenomenon. According to these first results, the following model could be proposed in agreement with the successive

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• were investigated by cyclic voltammetry, UV–vis–NIR and EPR absorption spectroscopical methods of the electrochemically generated oxidized species. The electron-accepting properties of the acetylenic cores were also investigated electrochemically. Keywords: alkynes; mixed valence; radiaannulene

• . Both polaronic structures behave as nearly independent and their weak interaction probably leads to the shift in the g-value. NIR absorptions of monocations. Finally, we wanted to examine, in more detail, the broad bands in the NIR region of the spectra of the mixed-valence radical cations. For this

• /CH2Cl2 1:4 using Fe(ClO4)3 as oxidizing agent). It is difficult to say if the long and weak absorption tail extending to almost 3000 nm observed in our experiment could be an IVCT absorption of the intermolecular mixed valence species, if present. The NIR absorptions of 4•+ and 8•+ disappeared upon

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• the Ru(II)–Ru(III) mixed-valence compound [(p-cymene)Ru(μ-Cl)3RuCl2(PCy3)], which was found to be an efficient promoter for atom transfer radical reactions under the adopted experimental conditions. Keywords: Grubbs catalyst; indenylidene ligands; Kharasch reaction; microwave heating; olefin

• -cymene)Ru(μ-Cl)3RuCl2(PCy3)] (7). This mixed valence Ru(II)–Ru(III) compound had already been isolated and fully characterized by Severin and co-workers when they investigated the reaction of ethylene complex 2 with carbon tetrachloride in toluene [4]. Yet, differences between the molecular structures

• 1 into mixed-valence bimetallic scaffold 7. This well-defined compound was an efficient promoter for the ATRC of intermediate 5 into the final product 6. Reaction of homobimetallic ruthenium–indenylidene complex 1 with ethylene. Schematic illustration of tandem assisted catalysis with complexes 1