Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

• Diego M. Andrada,
• Nicole Holzmann,
• Thomas Hamadi and
• Gernot Frenking

Beilstein J. Org. Chem. 2015, 11, 2727–2736, doi:10.3762/bjoc.11.294

• = constant) of the product wave function. It comprises the destabilizing interactions between electrons of the same spin on either fragment. The orbital interaction ∆Eorb accounts for charge transfer and polarization effects [91]. The ∆Eorb term can be dissected into contributions from each irreducible

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

• Zhan-Jiang Zheng,
• Ding Wang,
• Zheng Xu and
• Li-Wen Xu

Beilstein J. Org. Chem. 2015, 11, 2557–2576, doi:10.3762/bjoc.11.276

• from binaphthol [27] (Scheme 10). Notably, this type of compound showed high selectivity over the recognition of I−, possibly due to the formation of a charge-transfer complex between the I− and the electron-deficient triazole ring. Bistriazoles formed through spacers Bistriazole synthesis with

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• nanomaterials is generally accepted to be the self-assembly of supermolecules, which is constructed through weak noncovalent interactions such as π–π stacking, van der Waals interactions, charge transfer and H-bonding interactions [3][4][5][6]. Generally speaking, H-bonding interactions are the key

• the fields of supramolecular and materials chemistry due to their great potential application in molecular electronics, for example, as switches and conductors [10][11][12][13][14]. As we all know, TTF derivatives can form charge transfer (CT) complexes with electron acceptors such as

• to explore the formation of the charge-transfer complexes. TTF derivates are representative electron donors, while TCNQ is a typical electron acceptor. When one equivalent of TCNQ was added to the solution of T1 in ethyl acetate, TCNQ radical anion species (TCNQ•−) and TTF radical cation species (TTF

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• mixtures, although I had been to Beijing for X-ray diffraction experiments at Peking University. We thus proposed that the two compounds formed 1:1 charge-transfer complexes (Scheme 1). Currently, this N···I interaction is termed as halogen bonding, which is widely used in supramolecular crystal

• of the TTF unit. Catenanes 6a and 6b are blue as a result of the charge-transfer complex between the TTF and bipyridinium units, whereas catenane 6c is orange, which is attributed to the charge-transfer complex between the dioxybenzene and bipyridinium units. Impressively, the three catenanes could

[2.2]Paracyclophane derivatives containing tetrathiafulvalene moieties

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

Beilstein J. Org. Chem. 2015, 11, 1917–1921, doi:10.3762/bjoc.11.207

• the rigid framework and the short distance between the two aromatic rings within the [2.2]paracyclophane unit. Besides investigations of the geometry and of transannular interactions, special attention has been paid to the ability of these compounds to form charge-transfer complexes [6][7][8][9]. A

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

• toward the synthesis of compounds with TTF donor units and subsequent investigation of their properties. Since the first discovery of the semiconducting properties of TTF and its cation radical [23], and the metallic behaviour of the TTF-TCNQ charge transfer complex [24], great attention was focused on

• circuit current density (Jsc) and low efficiency of the cell. Due to the possible presence of efficient interchain interactions between the TTF units and the PTV backbone (vide supra) in the film of polymer 39, another important factor that should be considered is photoinduced charge transfer

• 39. Photoinduced charge transfer from the TTF of polymer 39 to PC61BM. Electropolymerisation of 40 and 41 into polymers 45 and 46, respectively, and Stille polymerisation of 42 into polymer 47. The synthesis of polymer 48. The synthesis of TTF-sexithiophene system 51 and the structure of the parent

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• )-BEDT-TTF 2 were synthesized. Moreover, the preparations, crystal structure analyses, and electrical resistivity measurements of the novel achiral charge transfer salt θ21-[(S,S)-2]3[(R,R)-2]3(ClO4)2 and the chiral salt α’-[(R,R)-2]ClO4(H2O) were carried out. In the former θ21-[(S,S)-2]3[(R,R)-2]3(ClO4

• ohm cm with Ea = 140 meV for α'-[(R,R)-2]2ClO4(H2O), respectively. The variety of donor arrangements, θ21 and two kinds of α’-types, and their electrical conductivities of charge transfer complexes based upon the racemic and enantiopure (S,S)-2, and (R,R)-2 donors originates not only from the

• structures, and electrical resistivities of the achiral charge transfer complex θ21-[(S,S)-2]3[(R,R)-2]3(ClO4)2 and the chiral complex α’-[(R,R)-2]2ClO4(H2O), in comparison with those of α’-[(S,S)-2]2ClO4. The effects of introducing hydrogen bonds between hydroxymethyl groups of donors and ClO4− anions in

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• derivatives [1] has been initiated by the high electrical conductivity discovered in a chloride salt of TTF [2] and metallic behavior in the charge-transfer complex with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) [3]. These systems have played a major role for the preparation of molecular materials designed

• acceptor unit forming head-to-tail dimers. Moreover, the plane-to-plane distance between the donor and acceptor moieties is d = 3.39 Å, showing an evident overlap that is comparable to the reported intermolecular charge-transfer complexes [35]. This overlap develops along a-axis forming infinite columns

• dinitrophenylhydrazone group). As compared to ligand L1, L2 exhibits an additional absorption band around λ = 516 nm which is attributed to an intramolecular charge transfer (ICT) excitation from the TTF donor moiety to the dinitrophenylhydrazone accepting group. These results from a strong π-electronic delocalization

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• synthesis of indolophanes 90a–c by using the McMurry coupling [109]. Furthermore, they synthesized dioxastilbenophanes 91 and carried out charge transfer complexation studies which showed that these molecules form a complex with TCNE and TCNQ [110]. Due to the presence of nitrogen and sulfur atoms benzene

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• charge transfer (CT) from the TTF to the electron-deficient thiazole units, facilitated due to their planarity. The structural properties of each compound will be expanded upon in the theoretical calculations section. Solution-state cyclic voltammetry was employed to determine the highest occupied

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• been utilized in the formation of charge-transfer (CT) complexes for more than 40 years [21][22][23]. TTF (1) (Figure 1) is not aromatic according to the Hückel definition as its 14 π-electrons lack cyclic conjugation. Upon oxidation to the radical cation (2) and dication (3) states, a gain in

• -functionalised calix[4]arenes (which can bind to electron-deficient aromatics and form charge-transfer complexes) [29]. Alternative routes to N-arylated MPTTFs proceed through N-arylated (1,3)-dithiolo[4,5-c]pyrrole-2-ones or (1,3)-dithiolo[4,5-c]pyrrole-2-thiones (i.e. analogues of 6). In some cases these can

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