Regioselective Cyclopolymerization of 1,7-Octadiynes
摘要:
The regioselective cyclopolymerization of two structurally different 1,7-octadiynes, i.e. of 1,4-dihexyloxy-2,3-dipropargylbenzene (M1) and (R,R)/(S,S)-4,5-bis(trimethylsilyloxy)-1,7-octadiyne (M2) has been achieved with the modified Grubbs-Hoveyda-type metathesis initiator Ru(NCO)(2) (IMesH(2))(=CH-(2-(2-PrO)C6H4)) (I1, IMesH(2) = 1,3-dimesitylimidazolidin-2-ylidene) and with a series of Schrock initiators in the presence of quinuclidine, yielding conjugated polymers consisting virtually exclusively of 1,2-cyclohex-1-enylenvinylene units. In contrast to I1, Mo(N-2,6-(2-Pr)(2)C6H3) (CHCMe2Ph)(OCHMe2)(2) (I3) allows for establishing a living polymerization with M2 in the presence of quinuclidine. The structure of the polymers, which represent highly soluble and stable poly(acetylene) analogues, Was confirmed by comparing the C-13 NMR shifts of model compounds with those of the corresponding polymer. Poly(ene)s that are virtually solely based on six-membered repeat units show a bathochromic shift in UV-absorption compared to poly(ene)s based on six- and seven-membered rings.
Synthesis of Novel Highly Soluble <i>N</i>-(3,5-Di-<i>tert</i>-butylbenzyl)-monopyrrolo-tetrathiafulvalene Derivatives
作者:Andreas Denhof、Jens Cordes、Vladimir A. Azov
DOI:10.1080/10426507.2010.524175
日期:2011.5.1
Abstract Highly soluble bis-(2-cyanoethyl)-protected derivative (11) of monopyrrolo-tetrathiafulvalene containing a bulky 3,5-di-tert-butylbenzyl solubilizing group has been synthesized and characterized. It was successfully employed to prepare two aromatic conjugates of monopyrrolo-tetrathiafulvalenes (TTFs) and is proposed to be used for preparation of TTF-containing molecular tweezers.
Redox responsive molecular tweezers with tetrathiafulvalene units: synthesis, electrochemistry, and binding properties
作者:Maciej Skibiński、Rafael Gómez、Enno Lork、Vladimir A. Azov
DOI:10.1016/j.tet.2009.10.052
日期:2009.12
Several new molecular tweezers with tetrathiafulvalene (TTF) arms as well as mono-TTF derivatives bearing 3,5-di-tert-butylbenzylthio groups to provide enhanced solubility were prepared starting from a bis-cyanoethyl-protected tetrathiafulvalene derivative. The X-ray crystallographic analysis of 3 and 7a showed highly distorted TTF groups and absence of close TTF-TTF contacts in the crystalline state. Comparative cyclic voltammetry (CV) measurements demonstrated that through space distance-dependent TTF-TTF interactions take place in the TTF-containing molecular tweezers, leading to electronic pairing with formation of mixed valence [TTF](2)(+center dot) species and splitting of the first oxidation wave. TTF-containing molecular tweezers were successfully tested as receptors for several electron-deficient substances. (C) 2009 Elsevier Ltd. All rights reserved.
作者:Adam, Martin、Enkelmann, Volker、Raeder, Hans-Joachim、Roehrich, Joerg、Muellen, Klaus
DOI:——
日期:——
Reaction of C<sub>60</sub> with Sultines: Synthesis, Electrochemistry, and Theoretical Calculations of Organofullerene Acceptors
作者:Beatriz M. Illescas、Nazario Martín、Carlos Seoane、Enrique Ortí、Pedro M. Viruela、Rafael Viruela、Antonio de la Hoz
DOI:10.1021/jo9706436
日期:1997.10.1
The [4 + 2] cycloaddition reaction of o-quinodimethanes, generated in situ from 4,5-benzo-3,6-dihydro-1,2-oxathiin 2-oxides (10a,b, 13, and 19) (sultines), to [60]fullerene is described. Sultines are readily accesible from the commercially available rongalite and smoothly generate o-quinodimethanes, by extrusion of sulfur dioxide, which are efficiently trapped by the active dienophile C-60. The cycloadducts formed (21a-d) were further oxidized to the respective p-benzoquinone-containing fullerenes 23a-c. The temperature dependent H-1 NMR spectra show a dynamic process of the methylene protons. The activation free energy determined for the boat-to-boat inversion (11.3-11.6 kcal/mol) is remarkably lower than that obtained for other related carbocyclic or heterocyclic analogues. Semiempirical PM3 calculations show that the geometrical features and not the electronic properties of the organic addend in 23 are responsible for the low activation energy barriers. A linear correlation is found between the activation energy barriers and the length of the C62-C63 bond. The electrochemical properties of 23a-c have been rationalized on the basis of DFT-B3P86/3-21G calculations. The attachment of the first electron in the reduction process takes place in either the C-60 cage or the organic addend depending upon the nature of the substituents on the p-benzoquinone ring, which controls the relative energy of the LUMO of the p-benzoquinone moiety. A full agreement between the theoretical predictions and the electrochemical measurements is found.