Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

• Jaume García-Amorós and
• Dolores Velasco

Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113

• -chromophore and the thermal cis-to-trans isomerisation, the kinetics and mechanism are also discussed as a key point for reaching azoderivatives endowed with fast thermal back-isomerisation kinetics. Keywords: kinetics; light-controlled materials; molecular switches; photochromic switches; push–pull

• substitution (type-I), that is, bearing a push–pull configuration. Secondly, kinetic studies of different azophenolic systems (type-II) will be presented, since these azoderivatives exhibit a fast thermal back reaction due to their capability to establish an azo-hydrazone tautomeric equilibrium. Both type-I

• the millisecond time scale, based on chromophores with a push–pull configuration The electronic spectra of the stable trans isomer of type-I azoderivatives 1–4, display a high-intensity band peaking at ca. 355 nm, corresponding to the π→π* transition, and a weak broad-band signal at ca. 450 nm

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

• Jiri Kulhanek Filip Bures Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, CZ-53210, Czech Republic 10.3762/bjoc.8.4 Abstract Research activities in the field of imidazole-derived push–pull systems featuring

• made in the development and the investigation of new organic push–pull systems. In contrast to inorganic materials, the advent of dipolar (hetero)organic materials with readily polarizable structure was stimulated by their relative ease of synthesis, well-defined structure, chemical and thermal

• robustness, possibility for further modification, and facile property tuning. Hence, heteroaromatic push–pull chromophores have been targeted and investigated as active components of optoelectronic devices, organic light-emitting diodes (OLED), photovoltaic cells, semiconductors, switches, data-storage

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

• hexafluoro-tert-butoxide, OCCH3(CF3)2, proved to be essential for creating active catalysts [74], indicating that successful catalyst design in this system relies on establishing a push-pull situation in a similar fashion present in Schrock–Hoveyda olefin metathesis catalysts (Scheme 4) [10] and also in an

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

• use as building blocks in Suzuki–Miyaura or Sonogashira coupling reactions. Keywords: boronic acid; donor/acceptor; linker; Sonogashira reaction; property tuning; push-pull; Suzuki–Miyaura reaction; Introduction Development of new organic compounds with improved and advanced properties is one of the

• most important goals of modern material chemistry. Organic chemists steadily attempt to design and synthesize novel and well-defined organic push-pull systems with prospective applications as chromophores for nonlinear optics (NLO) [1][2][3][4][5], dyes [6], electronic and photonic devices [7][8

• ], 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

Aroylketene dithioacetal chemistry: facile synthesis of 4-aroyl- 3-methylsulfanyl- 2-tosylpyrroles from aroylketene dithioacetals and TosMIC

• H. Surya Prakash Rao and
• S. Sivakumar

Beilstein J. Org. Chem. 2007, 3, No. 31, doi:10.1186/1860-5397-3-31

• -naphthoyl/ferrocenoyl/pyrenoyl scaffolds on C-4 of the pyrrole ring. In this transformation, the AKDTAs behave as a 3-(methylsulfanyl)-1-aryl-2-propyn-1-one (ArCOC≡CSMe) equivalent. Competition experiments clearly showed that the cycloaddition of TosMIC to "push-pull" alkenes like AKDTAs is slower compared

• -unsaturated carbonyl compounds with two electron-donating alkylsulafanyl groups on one end and an electron-withdrawing aroyl group at the other end of the double bond, i.e., they are "push-pull" alkenes. Depending on the nucleophile and the reaction conditions either 1,2- or 1,4-necleophilc additions on 1 are

• excellent yield. [8][9][10] Similarly, the reaction of TosMIC with activated alkynes afford trisubstituted pyrroles. However, the scope of pyrrole synthesis via cycloaddition of TosMIC to the "push-pull" alkenes is not well explored. We reasoned that, in the event of cycloaddition taking place between