- Detrimental Ni(0) transfer in Kumada catalyst transfer polycondensation of benzo[2,1-b:3,4-b']dithiophene
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This article deals with the Kumada Catalyst Transfer Polycondensation (KCTP) of 4,7-dioctylbenzo[2,1-b:3,4-b']dithiophene (BDP-Oct) using Ni(II) catalyst or In/cat combination. A combination of MALDI MS, GPC, and 31P NMR spectroscopy is used to reveal the failure of the KCTP of this particular monomer. Intermolecular transfer reactions to monomer appeared to prevent the formation of polymer. This result is remarkable, since isomeric benzo[1,2-b:4,5-b']dithiophene polymerizes in a controlled way. The presence of a "non-aromatic double bond" in annulated monomers is discussed.
- Bedi, Anjan,De Winter, Julien,Gerbaux, Pascal,Koeckelberghs, Guy
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- Unusual Internal Electron Transfer in Conjugated Radical Polymers
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Nitroxide-containing organic radical polymers (ORPs) have captured attention for their high power and fast redox kinetics. Yet a major challenge is the polymer's aliphatic backbone, resulting in a low electronic conductivity. Recent attempts that replace the aliphatic backbone with a conjugated one have not met with success. The reason for this is not understood until now. We examine a family of polythiophenes bearing nitroxide radical groups, showing that while both species are electrochemically active, there exists an internal electron transfer mechanism that interferes with stabilization of the polymer's fully oxidized form. This finding directs the future design of conjugated radical polymers in energy storage and electronics, where careful attention to the redox potential of the backbone relative to the organic radical species is needed.
- Li, Fei,Gore, Danielle N,Wang, Shaoyang,Lutkenhaus, Jodie L
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- Linear and nonlinear optical properties of a quadrupolar carbo-benzene and its benzenic parent: The carbo-merization effect
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Herein, the optical properties of thiophene-functionalized quadrupolar carbo-benzenes and a benzenic parent, of generic structure Th–C[tbnd]C–[core]–C[tbnd]C–Th, Th = R2C4HS, are comparatively investigated. Beyond the previously unknown dioctylthienylethynylbenzene (core = p-C6H4, R = nOct), two bis-dialkylthienylethynyl-carbo-benzenes (core = C18Ph4, R = nOct, nBu) are envisaged for the unique “carbo-aromatic” character of the C18 macrocycle. The three targets were synthesized from the corresponding ethynylthiophenes in 47, 20 and 10% yield, respectively, then characterized by classical methods such as NMR spectroscopy, and X-ray crystallography for one of the carbo-benzenes. Regarding linear and nonlinear optical properties, our results show that the carbo-merization induces a significant shift to lower energies of the one-photon electronic excitations accompanied by an 8-fold increase of the molar extinction coefficient compared to the parent molecule. Intriguingly, these excitations lead to a broad band of photoluminescence comprising decay transitions of the type S1 → S0 but also of the type S2 → S0. This phenomenon of emission from higher excited states, which is contrary to Kasha's rule, is assigned to - or revealed by - a reduction of the internal conversion efficiency between S2 and S1. Two-photon induced transitions are also enhanced, the two-photon absorption cross-section (σ2PA) being in average five times larger for the carbo-benzenes than for their benzene parent in the wavelength range 650–950 nm, with a maximum of σ2PA = 1430 GM (1 GM = 10?50 cm4 s/photon). Beyond a moderate nonlinearity, this comparative study provides quantitative insights about the way carbo-merization or insertion of a π-conjugated macrocycle between chromophoric functions (here thiophene rings) can tune optical properties of organic molecules. The optical properties of the bis-dialkylthienylethynyl-carbo-benzenes are also discussed in regard of recent reports on organic chromophores based on other types of π-conjugated macrocyclic cores.
- Barba-Barba, Rodrigo M.,Chammam, Marwa,Ramos-Ortiz, Gabriel,Listunov, Dymytrii,Velusamy, Jayaramakrishnan,Rodriguez, Mario,Carriles, Ramon,Silva, Carlos,Duhayon, Carine,Kauffmann, Brice,Maraval, Valérie,Chauvin, Remi
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- Role of Substituents at 3-position of Thienylethynyl Spacer on Electronic Properties in Diruthenium(II) Organometallic Wire-like Complexes
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A series of organometallic complexes [Cl(dppe)2Ru?C≡C-(3-R?C4H2S)-C≡C?Ru(dppe)2Cl] (3-R-C4H2S=3-substituted thienyl moiety; R=?H, ?C2H5, ?C3H7, ?C4H9, ?C6H13, ?OMe, ?CN in 5 a–5 g respectively) have been synthesized by systematic variation of 3-substituents at the thienylethynyl bridging unit. The diruthenum(II) wire-like complexes (5 a–5 g) have been achieved by the reaction of thienylethynyl bridging units, HC≡C-(3-R-C4H2S)-C≡CH (4 a–4 g) with cis-[Ru(dppe)2Cl2]. The wire-like diruthenium(II) complexes undergo two consecutive electrochemical oxidation processes in the potential range of 0.0 - 0.8 V. Interestingly, the wave separation between the two redox waves is greatly influenced by the substituents at the 3-position of the thienylethynyl. Thus, the substitution on 3-position of the thienylethynyl bridging unit plays a pivotal role for tuning the electronic properties. To understand the electronic behavior, density functional theory (DFT) calculations of the selected diruthenium wire-like complexes (5 a–5 e) with different alkyl appendages are performed. The theoretical data demonstrate that incorporation of alkyl groups to the thienylethynyl entity leaves unsymmetrical spin densities, thus affecting the electronic properties. The voltammetric features of the other two Ru(II) alkynyl complexes 5 f and 5 g (with ?OMe and ?CN group respectively) show an apparent dependence on the electronic properties. The electronic properties in the redox conjugate, (5 a+) with Kc of 3.9×106 are further examined by UV-Vis-NIR and FTIR studies, showing optical responses in NIR region along with changes in “?Ru?C≡C?“ vibrational stretching frequency. The origin of the observed electronic transition has been assigned based on time-dependent DFT (TDDFT) calculations.
- Roy, Sourav Saha,Chowdhury, Sabyasachi Roy,Mishra, Sabyashachi,Patra, Sanjib K.
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p. 3304 - 3313
(2020/09/09)
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- Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
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Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
- Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
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supporting information
p. 1799 - 1802
(2019/01/25)
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- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
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The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
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- Oligothiophene-Bridged Conjugated Covalent Organic Frameworks
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Two-dimensional covalent organic frameworks (2D-COFs) are crystalline, porous materials comprising aligned columns of π-stacked building blocks. With a view toward the application of these materials in organic electronics and optoelectronics, the construction of oligothiophene-based COFs would be highly desirable. The realization of such materials, however, has remained a challenge, in particular with respect to laterally conjugated imine-linked COFs. We have developed a new building block design employing an asymmetric modification on an otherwise symmetric backbone that allows us to construct a series of highly crystalline quaterthiophene-derived COFs with tunable electronic properties. Studying the optical response of these materials, we have observed for the first time the formation of a charge transfer state between the COF subunits across the imine bond. We believe that our new building block design provides a general strategy for the construction of well-ordered COFs from various extended building blocks, thus greatly expanding the range of applicable molecules.
- Keller, Niklas,Bessinger, Derya,Reuter, Stephan,Calik, Mona,Ascherl, Laura,Hanusch, Fabian C.,Auras, Florian,Bein, Thomas
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supporting information
p. 8194 - 8199
(2017/06/27)
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- Cross-couplings of alkyl halides with heteroaromatic halides, in water at room temperature
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Zn-mediated, Pd-catalyzed cross-coupling reactions between heteroaromatic and alkyl halides can be done at room temperature in pure water using a commercially available Pd catalyst and PTS, a nanomicelle-forming amphiphile. Notably, zinc metal inserts selectively into a carbon sp3-halide bond, while palladium adds oxidatively to a carbon sp2-bond.
- Krasovskiy, Arkady,Thomé, Isabelle,Graff, Julien,Krasovskaya, Valeria,Konopelski, Paul,Duplais, Christophe,Lipshutz, Bruce H.
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experimental part
p. 2203 - 2205
(2011/05/05)
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- Cross-coupling reactions through the intramolecular activation of Alkyl(triorgano)silanes
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(Figure Presented) Cross-Si-ing the Jordan: Cross-coupling reactions of 2-(2-hydroxyprop-2-yl)phenylsubstituted alkylsilanes with a variety of aryl halides proceed in the presence of palladium and copper catalysts. The use of K3PO4 base allows for highly chemoselective alkyl coupling with both primary and secondary alkyl groups (Alk).
- Nakao, Yoshiaki,Takeda, Masahide,Matsumoto, Takuya,Hiyama, Tamejiro
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supporting information; scheme or table
p. 4447 - 4450
(2010/08/19)
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- Rapid solution and solid phase synthesis of monodisperse oligo[(1,4-phenyleneethynylene)-alt-(2,5-thiopheneethynylene)]s
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Monodisperse oligo[(1,4-phenyleneethynylene)-alt-(2,5-thiopheneethynylene)] s, new candidates for molecular wires, were rapidly synthesized via an iterative divergent/convergent doubling strategy in solution as well as on Merrifield's resin.
- Li, Guorong,Wang, Xianhong,Li, Ji,Zhao, Xiaojiang,Wang, Fosong
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p. 2576 - 2582
(2007/10/03)
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- Synthesis of monodisperse oligo[(1,4-phenyleneethynylene)-alt-(2,5- thiopheneethynylene)]s
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The synthesis of monodisperse oligo[(1,4-phenyleneethynylene)-alt-(2,5- thioph-eneethynylene)]s using an iterative divergent/convergent doubling strategy based on Sonogashira coupling reaction was presented.
- Li, Guorong,Wang, Xianhong,Li, Ji,Zhao, Xiaojiang,Wang, Fosong
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p. 115 - 119
(2007/10/03)
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- Thallium(III) Trifluoroacetate-Trifluoroacetic Acid in the Chemistry of Polythiophenes. 2. Treatment of 3-Alkylthiophenes and Electron Paramagnetic Resonance Results
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The treatment of thiophene and 3-alkylthiophenes with thallium(III) trifluoroacetate (TTFA) in trifluoroacetic acid (TFA) gives insoluble and dark powdery solids with oxygen content and electrical conductivities ranging from 10-4 to 10-6 Ω-1 cm-1. Polar and short fractions are negligible. All of them show semiconductivity (10-3Ω-1 cm-1) when doped in iodine atmosphere. Electron paramagnetic resonance (EPR) spectra of either as-synthesized or I2-treated solids display characteristic single and broad lines (ΔHPP, 1.84-7.4 G) with Lorentzian shapes and g-values in the range 2.0028-2.0038. Infrared spectra show characteristic C-H out-of-plane deformations (780 cm-1 for polythiophene and 820-825 cm-1 for poly(3-alkylthiophenes)) in addition to a strong peak at 1650-1690 cm-1 which has not been conclusively assigned. EPR spectra of some disubstituted and tetrasubstituted 2,2′-bithiophene radical cations have been observed and their g-values and coupling constants assigned when the corresponding parent compounds are photolyzed with ultraviolet light in TFA. Photolysis of 3-alkylthiophenes in TFA in the EPR instrument gave the radical cations of 4,4′-dialkyl-2,2′-bithiophenes. In no case, were EPR signals of the isomeric 3,3′-dialkyl- or 3,4′-dialkyl-2,2′-bithiophene radical cations observed, indicating that dimerization of 3-alkylthiophenes occurs through the less sterically hindered 5-position. The presence of two doublet species corresponding to both conformers, syn and anti, in the radical cations is associated with a large barrier to rotation about the C(2)-C(2′) bond.
- Tormo, Jordi,Jesus Moreno,Ruiz, Jordi,Fajari, Lluis,Julia, Luis
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p. 878 - 884
(2007/10/03)
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- Rapid Syntheses of Oligo(2,5-thiophene ethynylene)s with Thioester Termini: Potential Molecular Scale Wires with Alligator Clips
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The syntheses of soluble oligo(3-ethyl-2,5-thiophene ethynylene)s via an iterative divergent/ convergent approach starting from 3-ethyl-2-(trimethylsilylethynyl)thiophene are described. The monomer, dimer, tetramer, octamer, and 16-mer were synthesized. The 16-mer is 100 A long in its minimized extended zigzag conformation. At each stage in the iteration, the length of the framework doubles. Only three sets of reaction conditions are needed for the entire iterative synthetic sequence: an iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling. The oligomers were characterized spectroscopically and by mass spectrometry. The optical properties are presented which show that at the octamer stage, the optical absorbance maximum is nearly saturated. The size exclusion chromatography values for the number average weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers verses the random coils of polystyrene. These differences become quite apparent at the octamer stage. Attachment of thiol end groups, protected as the thioacetyl moieties, was achieved. These serve as binding sites for adhesion to gold surfaces. In some cases, one end of the oligomeric chains were capped with a thiol group so that the surface attachments to gold could be studied. In other cases, thiol groups were affixed to both ends of the molecular chains so that future conduction studies could be done between proximal metallic probes. The rigid rod conjugated oligomers may act as molecular wires in molecular scale electronic devices, and they also serve as useful models for understanding analogous bulk polymers.
- Pearson, Darren L.,Tour, James M.
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p. 1376 - 1387
(2007/10/03)
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- Convergent synthetic routes to orthogonally fused conjugated oligomers directed toward molecular scale electronic device applications
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This paper describes the synthetic organic phase of a project directed toward the construction of molecular scale electronic devices. Outlined is a convergent synthetic route to orthogonally fused conjugated organic oligomers. The final systems are to have a potentially conducting chain fused perpendicularly to a second potentially conducting chain via a a bonded network. One of the core segments synthesized is based on a spirobithiophene moiety with a central silicon atom. It is formed by a zirconium-promoted bis(bicyclization) of a tetrapropargylsilane. The second core is a 9,9′-spirobifluorene system. Terminal halide groups provide the linkage points for further extension of the chains via Pd-catalyzed or Pd/Cu-catalyzed cross coupling methods. All four branching arms are affixed to the core in a single operation, thus making the syntheses highly convergent. In the cases of the larger functionalized systems, alkyl substituents on the thiophenes afford soluble materials. In order to prepare the molecules with > 50 A lengths, an iterative divergent/convergent approach had to be utilized for the construction of oligo(thiophene-ethynylene) branching arms. Organopalladium-catalyzed procedures are used extensively for the syntheses of the orthogonally fused compounds.
- Wu, Ruilian,Schumm, Jeffry S.,Pearson, Darren L.,Tour, James M.
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p. 6906 - 6921
(2007/10/03)
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- STUDIES TOWARD ALKYLTHIOPHENE-2-CARBOXALDEHYDES. REDUCTION OF 3-ALKENYLTHIOPHENES WITH TRIETHYLSILANE/TRIFLUOROACETIC ACID. REGIOSELECTIVTY IN FORMYLATION REACTIONS OF ALKYLTHIOPHENES
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Reduction of 2- or 3-alkenylthiophenes with Et3SiH/CF3CO2H in CH2Cl2 gives the corresponding 2- or 3-alkylthiophene in >90percent isolated yield.The regioselectivity of various Vilsmeier formylations of 3-alkylthiophenes was found to be a function of increasing steric bulk in the 3-alkyl substituent and in the Vilsmeier reagent.The regioselectivty of formylations of 3-alkylthiophenes by initial lithiation with butyllithium in ether followed quenching with DMF is independent of the presence or absence of TMEDA.
- Detty, Michael R.,Hays, David S.
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p. 925 - 938
(2007/10/02)
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- Side-chain Effects on the Fragmentation Behaviour of Alkylthiophenes
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The processes leading to the fragment ions formed from alkylthiophene molecule ions by benzylic cleavage without and with transfer of one hydrogen from the side-chain to the ring and the influence of additional methyl groups on the relative importance of these two fragmentation reactions were investigated.
- Lange, D.,Budzikiewicz, H.
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p. 432 - 438
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 3-ALKYLTHIOPHENES
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The known procedures for the synthesis of 3-alkylthiophenes are rather lengthy or involved.By using the NiDPPP++ catalyzed cross-coupling method between 3-bromothiophene and Grignard reagents derived from alkyl halides a number of 3-alkylthiophenes have been prepared in a one-step reaction in good to excellent yields.
- Pham, Chiem Van,Mark, Harry B.,Zimmer, Hans
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p. 689 - 696
(2007/10/02)
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- NICKEL-PHOSPHINE COMPLEX-CATALYZED GRIGNARD COUPLING-II; GRIGNARD COUPLING OF HETEROCYCLIC COMPOUNDS
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A general, versatile method for alkylation and arylation of haloheterocyclic compounds is reported.In the presence of a catalytic quantity of , where dppp stands for Ph2P(CH2)3PPh2, bromothiophenes, halopyridines, haloquinoline, and haloisoquinolines reacted with alkyl and aryl Grignard reagents at room temperature or at ether refluxing temperature to give the cross-coupling products.The coupling reactions has been applied to the synthesis of isoquinoline alkaloids.Reactivities of 2-thienyl and 2-pyridyl Grignard reagents have also been examined.
- Tamao, K.,Kodama, S.,Nakajima, I.,Kumada, M.,Minato, A.,Suzuki, K.
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p. 3347 - 3354
(2007/10/02)
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- Regiospecific Synthesis of 3-Alkylfuranes and 3-Alkylthiophenes via Organoboranes
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The reaction of bromide or iodide with ate-complexes obtained from trialkylboranes and 3-lithiofuran or 3-lithiothiophene gives the corresponding 3-alkylfurans or 3-alkylthiophenes in good yields, respectively.
- Akimoto, Itaru,Sano, Masahiro,Suzuki, Akira
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p. 1587 - 1588
(2007/10/02)
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