Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• -molecule electrical transport properties of a molecular wire containing a π-extended tetrathiafulvalene (exTTF) group and its charge-transfer complex with F4TCNQ. We form single-molecule junctions using the in situ break junction technique using a homebuilt scanning tunneling microscope with a range of

• carried out on the charge-transfer complex. Due to the fact we expected this species to have a higher conductance than the neutral molecule, we believe this supports the idea that the conductance of the neutral molecule is very low, below our measurement sensitivity. This idea is further supported by

• theoretical calculations. To the best of our knowledge, these are the first reported single-molecule conductance measurements on a molecular charge-transfer species. Keywords: break junction measurements; charge-transfer complex; DFT-based transport; molecular electronics; tetrathiafulvalene; Introduction

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT) transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a

• unit. Keywords: donor–acceptor systems; dye-sensitized solar cells; electrochemistry; intramolecular charge transfer; Knoevenagel reaction; tetrathiafulvalene; Introduction Dye-sensitized solar cells (DSSCs) have been intensively investigated as an alternative to silicon-based solar cells [1][2][3][4

• -donor (D) and an electron-acceptor (A) unit linked through a π-bridge, leading to a broad and intense optical absorption band in the visible spectral region due to an effective intramolecular charge transfer (ICT) from D to A units. To develop high-efficient DSSCs, a variety of organic donors [2][6][7

Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes

• Xiaofeng Lu,
• Jibin Sun,
• Shangxi Zhang,
• Longfei Ma,
• Lei Liu,
• Hui Qi,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 1043–1051, doi:10.3762/bjoc.11.117

• not afford the desired complexes. The complexes obtained thus far are intrinsically neutral [63], which means the charge transfer does not take place between Ar-S-TTF and fullerenes in the ground state. In this regard, the E1/21 values of Ar-S-TTFs would not affect the formation of co-crystals. On the

• Information File 1). To improve the functionality of the co-crystals, one interesting strategy would be the generation of itinerant carriers in the co-crystals, i.e., charge transfer between the donor and acceptor in the ground state. Conclusion In summary, we have prepared eleven donor–acceptor type co

Carboxylated dithiafulvenes and tetrathiafulvalene vinylogues: synthesis, electronic properties, and complexation with zinc ions

• Yunfei Wang and
• Yuming Zhao

Beilstein J. Org. Chem. 2015, 11, 957–965, doi:10.3762/bjoc.11.107

• materials and supramolecular assemblies [1][2][3][4][5], since the first discovery by Wudl and others in the early 1970s that TTF upon interactions with suitable electron acceptors could give rise to charge-transfer complexes exhibiting excellent metallic conductivity [6][7]. The remarkable electron

Synthesis and characterization of the cyanobenzene-ethylenedithio-TTF donor

• Sandrina Oliveira,
• Dulce Belo,
• Isabel C. Santos,
• Sandra Rabaça and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 951–956, doi:10.3762/bjoc.11.106

• unit to prepare new charge transfer salts where both the dipolar moment and the possibility of metal coordination and other interactions mediated by the cyano group can be further explored to obtain compounds with interesting properties. Experimental Materials and methods Elemental analyses of the

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

• . However, the electronic spectra of the chemically generated radical cations (TTF-bridge-TTF•+) were reported to show clear intramolecular intervalence charge-transfer (IVCT) absorption bands with broad maxima around 1300–1400 nm [6]. We have previously found that when separating two TTFs by a cross

• -energy bands to charge-transfer absorptions, which are usually observed in π-conjugated systems containing TTF donors and large acetylenic scaffolds that behave as electron acceptors [8][9][10]. The significant redshifts of the charge-transfer absorptions experienced for 8 and 2a relative to the

• absorption of all the compounds at λmax 779 nm (ε 210 M−1cm−1), but of significantly lower intensity than the charge-transfer absorptions of the TEE compounds. Electrochemistry The redox properties of the TTF-bridge-TTF molecules were investigated by cyclic voltammetry and differential pulse voltammetry in

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• contrast, the spectrum of nitro-derivative 4d displays an additional strong absorption band centred at ca. 425 nm, arising most likely due to charge transfer from the electron-rich MPTTF moiety to the electron-deficient aromatic substituent. This absorption manifests itself in the dark red colour of 4d

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

• Longfei Ma,
• Jibin Sun,
• Xiaofeng Lu,
• Shangxi Zhang,
• Hui Qi,
• Lei Liu,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95

• -substituted tetrathiafulvalene derivatives (1–7) results in a series of charge-transfer (CT) complexes. Crystallographic studies indicate that the anions in the complexes, which are derived from CuBr2, show diverse configurations including linear [Cu(I)Br2]–, tetrahedral [Cu(II)Br4]2–, planar [Cu(II)2Br6]2

• : antiferromagnetic interaction; arylthio-substituted tetrathiafulvalenes; charge-transfer; crystal structure; magnetic property; Introduction Since firstly synthesized in 1970s [1], tetrathiafulvalene (TTF) and its derivatives have been intensively studied to explore functional organic materials [2]. Inspired by

• the discovery of highly conducting charge-transfer (CT) complex TTF·TCNQ [3] and the first organic superconductor (TMTSF)2X [4], the chemical modifications on TTF are traditionally aimed at the creation of organic conductors with various electronic ground states [5][6][7][8][9][10]. It has been well

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• potentials, these donor molecules with CF3 EWG can be involved in charge transfer complexes or cation radical salts, as reported here for the CF3-subsituted EDT-TTF donor molecule. A neutral charge transfer complex with TCNQ, (EDT-TTF-CF3)2(TCNQ) was isolated and characterized through alternated stacks of

• bond interactions [24][25][26][27]. Within such TTF derivatives, as reported by Bryce [28], an internal charge transfer (ICT) between the TTF and the EWG moieties increases the hydrophilicity of the TTF head groups and facilitates monolayer formation on the water surface for the preparation of Langmuir

• trifluoromethyl derivative 1c, we were also able to isolate a charge transfer complex with TCNQ and a cation radical salt with FeCl4−. The structures of both compounds will be described, and the geometrical evolutions of the TTF core upon oxidation analyzed by comparison with the structure of neutral 1c. Results

TTFs nonsymmetrically fused with alkylthiophenic moieties

• Rafaela A. L. Silva,
• Bruno J. C. Vieira,
• Marta M. Andrade,
• Isabel C. Santos,
• Sandra Rabaça,
• Dulce Belo and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

• /AgCl, typical of TTF donors at E11/2 = 279 V and E21/2 = 680 V for 1 and E11/2 = 304 V and E21/2 = 716 V in the case of 2. The single-crystal X-ray structure of 1 and of a charge transfer salt of 2, (α-mtdt)[Au(mnt)2] (3), are reported. Keywords: cyclic voltammetry; single-crystal X-ray diffraction

• charge transfer salt of 2, (α-mtdt)[Au(mnt)2] (3), (mnt = maleonitriledithiolate) could be obtained by electrocrystallization using standard conditions. Redox properties The redox properties of the donors 1 and 2 in solution were studied by cyclic voltammetry and the results are collected in Table 1

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• of the two different routes (to the Markovnikov or anti-Markovnikov addition products of styrene derivatives) results from the two types of photoinduced charge transfer initiated by the photoexcited catalyst (Scheme 1). If an electron-poor chromophore is applied, the first step that follows

• photocatalytic process. Back charge transfer to the photocatalyst closes the photocatalytic cycle and subsequent protonation yields the anti-Markovnikov-type addition product. In contrast, an electron-rich chromophore photoinduces an electron transfer onto the substrate. The corresponding radical anion is

• substrate 10. These results indicate that the initial charge transfer was the rate-limiting step of this photocatalytic process. The photocatalytic capability of PDI was representatively compared to that of 9-mesityl-10-methylacridinium perchlorate (MesAcr) which was applied by Nicewicz et al. for similar

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• potential utility to detect fluoride. Based on the aforementioned UV–vis, spectrofluorimetric and 1H NMR studies, the possible mechanism of F− recognition by BIP was proposed and illustrated in Scheme 2. On binding of F−, the isomerization of BIP was restricted, which enhanced the intramolecular charge

• transfer interaction between the assembly of binding sites with F− to the chromophore [1]. With further addition of F−, intermolecular hydrogen bond formation disturbed the intramolecular hydrogen bonding and destroyed the geometrically restricted conformation [2], at the same time, the new geometrically

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• with the discovery of the salt of 1 with 7,7,8,8-tetracyanoquinodimethane (2, TTF-TCNQ) in 1973 [4]. Since then, studies have been focused on the syntheses of donor TTF analogues and investigations of the physical properties of their charge-transfer (CT) salts with various acceptors for applications

• charge transfer salts. The physical and electronic properties of their solid states were investigated [13][25][47][48][49]. We attempt here to provide a summary of the synthesis of differently functionalized and extensively π-electron delocalized conjugated TTF core dithiin- and thiophene-fused donor

• % yields. The fully unsaturated tetraphenyl analogue 52 of ET was obtained in 90% yield by a coupling reaction of 51, which was obtained by converting the thione group of 48 to its corresponding oxo form in 85% yield, in hot triethyl phosphite, yielding 52 in 90% yield (Scheme 7). A charge transfer salt 54

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• DNA was used to study photoinducible charge transfer processes [87]. Upon attachment to the DNA chain the phenanthridinium base (E, Figure 9) was efficiently intercalated into the DNA oligonucleotide, not disturbing the position of adjacent basepairs nor the complementary oligonucleotide strand

• (DNA3-XY and DNA4-XY) from the EB chromophore showed an enhanced fluorescence quenching compared to the matched duplexes [91]. Among many studies of charge transfer in DNA, several applying ethidium bromide, revealed an unexpected complexity of the process, pointing out the importance of the DNA/EB

• complex flexibility on the efficiency of the transfer. A study of comparatively flexible DNA/EB complex, EB covalently attached to the 5’-end of oligonucleotides, in detail described the rate and distance dependencies of charge transfer through DNA [92][93]. A more rigid type of EB-binding, whereby the EB

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• rutin (rutin@TiO2) shows an electron injection into the conduction band of TiO2 as the result of a direct molecule-to-band charge transfer (MBCT) within the surface-formed, colored, charge-transfer complex of titanium(IV) [21]. TiO2 with an adsorbed chromium(III) anionic complex [CrF5(H2O)]2– acts as a

Selenium halide-induced bridge formation in [2.2]paracyclophanes

• Laura G. Sarbu,
• Henning Hopf,
• Peter G. Jones and
• Lucian M. Birsa

Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266

• systems and their ability to form charge-transfer complexes [4][5][6][7]. Much attention is also being paid to the development of new functionalized [2.2]paracyclophanes that can be used in asymmetric synthesis [8], while the formation of new bridges, particularly functionalized ones, has been somewhat

Microsolvation and sp²-stereoinversion of monomeric α-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR

• Rudolf Knorr,
• Monika Knittl and
• Eva C. Rossmann

Beilstein J. Org. Chem. 2014, 10, 2521–2530, doi:10.3762/bjoc.10.263

• charge at C-α of 4 (Scheme 2) into the α-aryl π-orbital system. The resulting negative lithiation NMR shifts Δδ = δ(4) − δ(8a) for 13C-4 and 4-H (entries 2 and 3, Table 1) point to a significant charge transfer [9][11] from C-α to C-4 of 4&3THF. The full set of Δδ values of 4 in the two THF solutions is

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• ). This suggests that the intramolecular charge transfer between 1 and 2 units of 1/4 molar ratios is relatively weak. Moreover, the smaller red shift from a dilute solution compared to the solid-state of 4a and 4b polyrotaxanes corroborated the beneficial effect of TMS-β-CD and TMS-γ-CD encapsulations on

Second generation silver(I)-mediated imidazole base pairs

• Susanne Hensel,
• Nicole Megger,
• Kristina Schweizer and
• Jens Müller

Beilstein J. Org. Chem. 2014, 10, 2139–2144, doi:10.3762/bjoc.10.221

• increased charge transfer capability [10][11] and DNA-based logic gates [12][13]. Applying the concepts of coordination chemistry, a wide range of metal-specific ligands have been incorporated successfully into nucleic acids and nucleic acid derivatives. Most recently, even coordination patterns of the [2

Lateral ordering of PTCDA on the clean and the oxygen pre-covered Cu(100) surface investigated by scanning tunneling microscopy and low energy electron diffraction

• Stefan Gärtner,
• Benjamin Fiedler,
• Oliver Bauer,
• Antonela Marele and
• Moritz M. Sokolowski

Beilstein J. Org. Chem. 2014, 10, 2055–2064, doi:10.3762/bjoc.10.213

• metal surfaces, the interaction strength of PTCDA increases from physisorption to stronger chemisorption from Au over Ag to Cu. On the (111) surfaces, this is reflected by the decreasing adsorption heights [4][5][6] and the increasing charge transfer from the metal into the former lowest unoccupied

Theoretical study of the adsorption of benzene on coinage metals

• Werner Reckien,
• Melanie Eggers and
• Thomas Bredow

Beilstein J. Org. Chem. 2014, 10, 1775–1784, doi:10.3762/bjoc.10.185

• framework that can be substituted with functional groups. The bonding between the surface and the adsorbate is an interplay between electrostatic interaction, including charge transfer (CT) to the surface, and covalent contributions [9][10][11]. In addition, it was found that dispersion interaction plays a

• differ for the potential curve we give only one adsorption distance d. Adsorption energies Eads are calculated according to the supramolecular approach: Eads = E(system) − E(surface) − E(adsorbate). A Bader analysis [48][49] was performed in order to study the net charge transfer between the surfaces and

• confirms that the surface–adsorbate interaction is dominated by dispersion interaction. Nevertheless we also calculated the charge transfer between benzene and the metal surfaces on the basis of a Bader analysis in order to investigate electrostatic contributions to the interactions. For the Cu(111), Ag

Proton transfers in the Strecker reaction revealed by DFT calculations

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 1765–1774, doi:10.3762/bjoc.10.184

• complex 1. The reaction begins with the addition of NH3 to the carbonyl carbon of acetaldehyde to form a Mulliken charge-transfer complex 2. This complex was firstly proposed here. In 2, the C–O bond is elongated to1.345 Å, which has an alkoxide character and the complex is not stable in the gas phase

Influence of perylenediimide–pyrene supramolecular interactions on the stability of DNA-based hybrids: Importance of electrostatic complementarity

• Christian B. Winiger,
• Simon M. Langenegger,
• Oleg Khorev and
• Robert Häner

Beilstein J. Org. Chem. 2014, 10, 1589–1595, doi:10.3762/bjoc.10.164

• well as van der Waals, electrostatic and charge transfer interactions that can lead to a thermodynamically favourable association [8]. It is an important interaction in biological systems, drug receptor interactions, materials sciences, and supramolecular chemistry [8][9][10][11][12]. Such interactions

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• ), used as a base in the AT reaction) probably reacted first with carbontetrachloride to produce a charge-transfer complex (this type of interaction was confirmed by refractometric titration). However, in this reaction the trichloromethylphosphonate, which would result from the reaction of the anion CCl3

• − with chlorophosphate, was never observed because CCl3− probably reacted as a base in the presence of dialkylphosphite (Scheme 3-ii). This experiment indicates that the basicity/nucleophilicity of the amine has an impact on the first step of the mechanism (a charge-transfer complex was not observed with

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• diazonium ions to give highly electrophilic aryl cations. Moreover, arenediazonium salts are known to form weak charge-transfer complexes with solvent molecules whose absorption tails into the visible range [30]. These observations support the notion that the use of broad-band visible irradiation indeed can