1795-01-3Relevant articles and documents
Role of Substituents at 3-position of Thienylethynyl Spacer on Electronic Properties in Diruthenium(II) Organometallic Wire-like Complexes
Roy, Sourav Saha,Chowdhury, Sabyasachi Roy,Mishra, Sabyashachi,Patra, Sanjib K.
, p. 3304 - 3313 (2020/09/09)
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.
Targeted and selective HOMO energy control by fine regulation of molecular planarity and its effect on the interfacial charge transfer process in dye-sensitized solar cells
Zhang, Fengyu,Wang, Ran,Wang, Yajun,Zhang, Xiaomin,Liu, Bo
, p. 6256 - 6264 (2019/04/04)
In terms of the in-depth development of organic dyes, targeted and selective energy control is becoming a more and more important objective. Herein, four indoline sensitizers based on D-π-A-π-A construction were designed and synthesized with exactly the same donor and acceptor segments. Their molecular planarity was regulated by introducing various side chains into donor bridges. Interestingly, along with an improvement of planarity at a donor bridge, the HOMO levels of the dyes lift gradually, and more importantly, their LUMO levels remain at around the same value. Besides, better molecular planarity is obviously preferred to obtain higher charge injection efficiency but, an overly planar molecule may cause an overly high HOMO level, leading to poor dye regeneration efficiency. Furthermore, an appropriate side chain also restrains charge recombination to some extent, while an overly large side chain gives more chance for I3- to recombine with charge in the conduction band. Accordingly, our results demonstrated that regulation of planarity at a donor bridge not only provides targeted and selective control of the HOMO of the dye, but also enable fine adjustment with multiple interfacial charge transfer processes. Molecular planarity deserves to play an important role in the design of organic dyes, providing a significant strategy for the further development of organic sensitizers.
Catalytic transformations of alkylthiophenes
Mashkina,Chernov
, p. 209 - 215 (2007/10/03)
The transformations of alkylthiophenes in the presence of amorphous aluminosilicate and decationated zeolite HNaY were studied. Substituted thiophenes with R = 2- and 3-Me, 2-Et, and 2-iso-Pr undergo dealkylation to thiophene with close rates, migration of the alkyl group from the 9α- to the β-position of the thiophene ring (or in the opposite direction with an elevated rate), and decomposition with H2S elimination. The dealkylation rate of 2-substituted thiophenes with a branched-chain radical (R = iso-Pr, terf-Bu) is much higher and the elimination rate with this radical is lower than those for normal-chain radicals; the isomerization step is virtually absent. Di-, tri-, and tetrasubstituted thiophenes with R = Et and iso-Pr undergo stepwise dealkylation, which is facilitated by an increase in the degree of substitution on the thiophene ring. Thiophene and its lower homologues can be obtained by the transformation of a mixture of high-molecular thiophenes. Copyright
The low affinity PCP sites in the rat cerebellum not only bind TCP-like but also BTCP-like structures
Espaze, Florence,Hamon, Jacques,Hirbec, Helene,Vignon, Jacques,Kamenka, Jean-Marc
, p. 323 - 331 (2007/10/03)
Congeners of the potent dopamine (DA) re-uptake inhibitor l-[1-(2- benzo[b]thiophenyl)cyclohexyl]piperidine (BTCP) are unexpectedly able to bind in the rat cerebellum, although this structure is devoid of dopaminergic nerve endings. In line with previous studies the hypothesis that they bind to low affinity PCP sites labelled with [3H]TCP in the rat cerebellum, even though they do not bind to the high affinity PCP sites in the forebrain, was considered. Analogues of l-[1-(2-thiophenyl)cyclohexyl]piperidine (TCP) and BTCP with a modified aromatic moiety and with O or S atoms substituted in the cyclohexyl ring were prepared and tested in competition experiments both in rat forebrain and cerebellum membranes labelled with [3H]TCP, and in rat striatum membranes labelled with [3H]BTCP. Results indicated that BTCP and congeners could bind to low affinity PCP sites labelled with [3H]TCP in the rat cerebellum with a decrease of the selectivity for the DA transporter. On the contrary, some TCP analogues displayed a very high selectivity for these low affinity sites: they might be important pharmacological tools to elucidate the nature and function at yet unknown of these sites. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
Thallium(III) Trifluoroacetate-Trifluoroacetic Acid in the Chemistry of Polythiophenes. 2. Treatment of 3-Alkylthiophenes and Electron Paramagnetic Resonance Results
Tormo, Jordi,Jesus Moreno,Ruiz, Jordi,Fajari, Lluis,Julia, Luis
, p. 878 - 884 (2007/10/03)
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.
Convergent synthetic routes to orthogonally fused conjugated oligomers directed toward molecular scale electronic device applications
Wu, Ruilian,Schumm, Jeffry S.,Pearson, Darren L.,Tour, James M.
, p. 6906 - 6921 (2007/10/03)
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.
STUDIES TOWARD ALKYLTHIOPHENE-2-CARBOXALDEHYDES. REDUCTION OF 3-ALKENYLTHIOPHENES WITH TRIETHYLSILANE/TRIFLUOROACETIC ACID. REGIOSELECTIVTY IN FORMYLATION REACTIONS OF ALKYLTHIOPHENES
Detty, Michael R.,Hays, David S.
, p. 925 - 938 (2007/10/02)
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.
Sulfonylureas: A new class of cancer chemotherapeutic agents
Mohamadi,Spees,Grindey
, p. 3012 - 3016 (2007/10/02)
This study summarizes the antitumor properties of a number of sulofenur thiophene analogs against subcutaneously implanted 6C3HED lymphosarcoma with structural modification of the aryl moiety of the sulfonamide portion of the diarylsulfonylureas. The spectrum of activity of N-(p-chlorophenyl)-N'-[(5- methoxy-2-thienyl)sulfonyl]urea in the HXGC3, VRC5, CX-1, and LX-1 cell lines is also presented.
A CONVENIENT SYNTHESIS OF 3-ALKYLTHIOPHENES
Pham, Chiem Van,Mark, Harry B.,Zimmer, Hans
, p. 689 - 696 (2007/10/02)
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.
