On the control of secondary carbanion structure utilising ligand effects during directed metallation

• Andrew E. H. Wheatley,
• Jonathan Clayden,
• Ian H. Hillier,
• Alison Campbell Smith,
• Mark A. Vincent,
• Laurence J. Taylor and
• Joanna Haywood

Beilstein J. Org. Chem. 2012, 8, 50–60, doi:10.3762/bjoc.8.5

• ) (for 3-H) [23] or THF (for 4-H) [24] to yield 3/4-Lil·nL (n = 1, L = PMDTA; n = 3, L = THF). Notably, whereas the deptonation of 4-H in the presence of THF yielded the lateral lithiate as a tris(THF) solvate, the tridentate electron donor PMDTA was required to replicate this chemistry with 3-H

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• -IM-(π-A)2 (16), A-π-IM-(π-D)2 (17), A-π-IM-(π-A)2 (18), and D-π-IM-(π-D)2 (19). 4,5-Bis(4-nitrophenyl)imidazole was utilized as a suitable acceptor moiety and was further modified with a thiophene π-linker as an auxiliary electron donor (20). These basic push–pull imidazoles were mainly investigated

• of the π-linker, particularly in chromophores 53–57, caused β enhancement up to 320 × 10−30 esu (Table 8). This clearly demonstrates the beneficial role of the thiophene as a polarizable unit and auxiliary electron donor. A combination of fused phenanthroline-imidazole acceptor moiety, N,N

• interest for materials chemists due to their unique and tunable properties. In general, the imidazole-derived chromophores may possess two Y-shaped arrangements: One electron donor at C2 and two electron acceptors at C4/C5 or vice versa. Hence, according to the C4/C5 substitution, the entire imidazole

Equilibrium constants and protonation site for N-methylbenzenesulfonamides

• José A. Moreira,
• Ana M. Rosa da Costa,
• Luis García-Río and
• Márcia Pessêgo

Beilstein J. Org. Chem. 2011, 7, 1732–1738, doi:10.3762/bjoc.7.203

• -NO2 (3d), in aqueous sulfuric acid were studied at 25 °C by UV–vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pKBH+ values are −3.5 ± 0.2, −4.2 ± 0.2, −5.2 ± 0.3 and −6.0 ± 0.3 for 3a, 3b, 3c and 3d

• , respectively). The solvation parameter m* is always higher than 0.5 and points to a decrease in the importance of solvation on the cation stabilization as the electron-donor character of the substituent increases. Hammett plots of the equilibrium constants showed a better correlation with the σ+ substituent

• occurs on the sulfonyl oxygen atom, as such a structure may present resonance with the electron-donor substituents (Scheme 2). The fact that pKBH+ correlates better with σ+ (R = 0.9913) than with σ (R = 0.9681) also indicates protonation on the oxygen atom (Figure 4). Nevertheless, the curvature of the σ

Sexithiophenes as efficient luminescence quenchers of quantum dots

• Christopher R. Mason,
• Yang Li,
• Paul O’Brien,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2011, 7, 1722–1731, doi:10.3762/bjoc.7.202

• perfluoroalkyl groups for n-type semiconductors [12][13]. Previously, we reported the synthesis and properties of alkyl end-capped oligothiophenes 2 (Figure 1), which incorporate the ethylene dithiothiophene (EDTT) unit, including their performance as the electron donor material in a bilayer photovoltaic device

Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold–triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization

• Hideto Ito,
• Tomoya Harada,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2011, 7, 951–959, doi:10.3762/bjoc.7.106

• triethynylphosphine L1 in electron-donor ability [58], was slightly more effective than PPh3, but was far less effective than L1 (Table 1, entry 12). Bulky and strongly electron-donating ligands such as X-Phos and IPr were as effective as the electron-deficient ligand P(OPh)3 (Table 1, entries 13 and 14). Accordingly

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• towards early transition metals or metals in a higher oxidation state [53][54][55]. In recent years, our group has significantly expanded the use of these 2σ,4π-electron donor ligands in organometallic chemistry and homogeneous catalysis [56][57][58][59][60][61][62][63][64][65][66][67]. Their synthesis

Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

• César A. Urbina-Blanco,
• Xavier Bantreil,
• Hervé Clavier,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2010, 6, 1120–1126, doi:10.3762/bjoc.6.128

• complexes [26][27][28][29][30][31][32]. This method was initially developed by Tolman [33], using the average infrared frequency of CO in [Ni(CO)3L] complexes. This electronic parameter has become known as the Tolman electronic parameter (TEP) and has been used to quantify the electron donor ability of

Self-assembly and semiconductivity of an oligothiophene supergelator

• Pampa Pratihar,
• Suhrit Ghosh,
• Vladimir Stepanenko,
• Sameer Patwardhan,
• Ferdinand C. Grozema,
• Laurens D. A. Siebbeles and
• Frank Würthner

Beilstein J. Org. Chem. 2010, 6, 1070–1078, doi:10.3762/bjoc.6.122

• concentration of 5 x 10−5 M. Studies on blends of T1 with PCBM The fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a well-known n-type semiconductor and its blends with various electron-donor materials have been extensively used in solar cell devices [24]. The morphology of the blend

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• Ritesh Nandy Sethuraman Sankararaman Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India 10.3762/bjoc.6.112 Abstract Several 2-(phenylethynyl)triphenylene derivatives bearing electron donor and acceptor substituents on the phenyl rings have been synthesized. The

• show that the triphenylene chromophore can act either as an electron donor or as an electron acceptor in the ICT process, depending upon the nature of substituent on the phenyl ring. Derivatives 1e and 1g are potential candidates for use as solvent polarity probes. However, their performance is only

Differences between β-Ala and Gly-Gly in the design of amino acids-based hydrogels

• Andreea Pasc,
• Firmin Obounou Akong,
• Sedat Cosgun and
• Christine Gérardin

Beilstein J. Org. Chem. 2010, 6, 973–977, doi:10.3762/bjoc.6.109

• including, NMR, FT-IR, scanning electron microscopy, SAXS/WAXS. Results and Discussion Molecular design A hydrogelator generally contains three functional domains: a hydrogen or electron donor and acceptor domain as the main organiser, a hydrophilic domain to adjust the solubility in water or in organic

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• visible exhibiting blue or dark green colours, small band gaps and high charge carrier mobilities. They are suitable as electron donor in bulk heterojunction solar cells with PC60BM or PC70BM as electron acceptors to give maximum power conversion efficiencies of about 5%. In field-effect transistors they

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• at the 4 and 4′ positions led to only slight changes in the redox potentials. Keywords: dication; 4-DMAP; electron donor; electron transfer; radical cation; redox; reduction; Introduction Neutral organic compounds 1 and 4–10 (Figure 1) have attracted considerable attention as ground-state electron

• the conversion of an aryl radical to an aryl anion [39]. Whatever about the standard potentials, in practice, the formation of aryl anions is only observed when the electron donor has E1/2 = −1 V or is more negative [40]. In line with this, both the imidazole-derived donor 7 (E1/2 = −1.20 V vs SCE in

• the same potential (within 10 mV), so the increased flexibility does not benefit the two-electron donor 15 relative to 8. Taking the idea of flexible rotation between the two halves of the molecule to its limit, we prepared compound 20′ [27] (Figure 5) and determined its cyclic voltammetric behaviour

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• derivatives have been shown to be efficient emitters for OLED applications [2]. In these devices, the benzanthrone moiety acts as an electron accepting group, whereas the diarylamine group functions as an electron donor. The reaction of 1 with various organometallic reagents was studied by Allen in the 1970s

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• the presence of sacrificial electron donor substrates, such as aliphatic amines, flavins can photoreduce nitro arenes to anilines under blue light irradiation (Scheme 4). 4-Nitrophenyl phosphate was used as a substrate for photoreduction in water and in acetonitrile. The results summarized in Table 2

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• ], organic light-emitting diodes (OLED) [9] or functional polymers [10][11][12][13]. A typical push-pull chromophore consists of a polar A-π-D system with a planar π-system end-capped by a strong electron donor (D) and a strong electron acceptor (A). The π-conjugated system ensuring charge-transfer (CT

New diarylmethanofullerene derivatives and their properties for organic thin- film solar cells

• Daisuke Sukeguchi,
• Surya Prakash Singh,
• Mamidi Ramesh Reddy,
• Hideyuki Yoshiyama,
• Rakesh A. Afre,
• Yasuhiko Hayashi,
• Hiroki Inukai,
• Tetsuo Soga,
• Shuichi Nakamura,
• Norio Shibata and
• Takeshi Toru

Beilstein J. Org. Chem. 2009, 5, No. 7, doi:10.3762/bjoc.5.7

• -hexylthiophene) (P3HT) as the electron-donor and diarylmethanofullerene derivatives as the electron-acceptor material were examined. The {(methoxycarbonyl)phenyl[bis(octyloxy)phenyl]methano}fullerene showed power conversion efficiency as high as PCBM, but had higher solubility in a variety of organic solvents

• [19]. These first reduction potential data showed that the diarylmethanofullerene derivatives can be a better electron acceptor than PCBM [27]. Photovoltaic Devices A series of solar cells was fabricated with P3HT as the electron-donor and diarylmethanofullerene derivatives as the electron-acceptor

Synthesis and redox behavior of new ferrocene- π-extended- dithiafulvalenes: An approach for anticipated organic conductors

• Abdelwareth A. O. Sarhan,
• Omar F. Mohammed and
• Taeko Izumi

Beilstein J. Org. Chem. 2009, 5, No. 6, doi:10.3762/bjoc.5.6

• Abstract A number of new ferrocene-π-extended-dithiafulvalenes were successfully synthesized as new electron donor compounds. The chemical structures and electrochemical behaviors of these compounds were investigated using several spectroscopic methods. The synthesis of these compounds was achieved using

• characterized a donor-acceptor dyad system involving tetrathiafulvalene (TTF) as electron donor attached by a flexible spacer to perylene derivatives as electron acceptor [5]. They have shown that the fluorescence of the tetrathiafulvalene–perylene derived dyad can be reversibly modulated by the transformation

• was extensively recognized [6][7]. For instance, π-extended-dithiafulvalenes have been successfully used as multi-electron donor moieties with high electrical conductivities in the preparation of new charge transfer (CT) complexes [8][9]. However, a number of modifications of the TTF framework have

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• , employing tetrathiafulvalene (TTF, 4a, Scheme 1) as electron donor. A number of functionalised heterocycles [5][6][7][8][9][10][11][12][13][14][15][16][17] such as dihydrobenzofurans, indolines and indoles have been synthesized using this methodology and the radical-polar methodology has been employed

• available and economically attractive tetrakis(dimethylamino)ethylene (TDAE, 1). This paper describes the results of our investigations on reactions of TDAE as a neutral organic electron donor with arenediazonium salts. TDAE (1), has been widely exploited as a strong electron donor [21][22][23][24][25][26

• electron donor. Additionally, we have described the utility of the aryl radicals in the construction of indolines and indoles by intramolecular radical cyclization of aryl radicals onto appropriately placed alkenes bearing terminal radical leaving groups. The presence of a suitable radical leaving group

Inversion symmetry and local vs. dispersive interactions in the nucleation of hydrogen bonded cyclic n-mer and tape of imidazolecarboxamidines

• Sihui Long,
• Venkatraj Muthusamy,
• Peter G. Willis,
• Sean Parkin and
• Arthur Cammers

Beilstein J. Org. Chem. 2008, 4, No. 23, doi:10.3762/bjoc.4.23

• weaker electron donor, agrees with previous studies of competitive solid state hydrogen bonding [19]. Rotamer/tautomer 4 was not observed in the crystalline phases, providing further control and predictability. Crystallization requires non-equilibrium conditions to progress [20][21]; however, predictions

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• at the ortho and para position. This means the inductive electron-withdrawing effect compromises the attack of the electrophile, but is counterbalanced, to some extent, by the capacity of the ether oxygen to act through resonance as an electron donor. This antagonistic behavior is well known for

Hydrogen bonding patterns in the cocrystals of 5-nitrouracil with several donor and acceptor molecules

• Reji Thomas,
• R. Srinivasa Gopalan,
• G. U. Kulkarni and
• C. N. R. Rao

Beilstein J. Org. Chem. 2005, 1, No. 15, doi:10.1186/1860-5397-1-15

• cocrystals of I with other electron donor compounds such as piperazine, N,N'-dimethylpiperazine, 3-aminopyridine and diazabicyclo [2.2.2]octane. Crystallographic structures of the cocrystals so obtained have revealed interesting changes in the hydrogen bonding pattern of I in the presence of other molecules

• (14A)...O(12), 2.400(3) Å). The pyridine molecules make linear N-H...N, (H(12A)...N(21), 1.810(3) Å) and C-H...O, (H(23A)...O(11), 2.216(4) Å) bonds with the nitrouracil molecules. Pyridine being a strong electron donor, it is not surprising that the characteristic hydrogen-bonded dimeric structure

Towards practical biocatalytic Baeyer- Villiger reactions: applying a thermostable enzyme in the gram- scale synthesis of optically- active lactones in a two-liquid- phase system

• Frank Schulz,
• François Leca,
• Frank Hollmann and
• Manfred T. Reetz

Beilstein J. Org. Chem. 2005, 1, No. 10, doi:10.1186/1860-5397-1-10

• effective stoichiometric sacrificial electron donor, resulted in significantly decreased stability of both enzymes used. The maximum concentration of isopropanol under which both enzymes show optimal activity was found to be 5% (v/v). In order to enhance conversion, we added surplus reducing equivalents in