Organometallic strategies for the synthesis of conjugated oligomers

: In this account we report our contribution to the synthesis of conjugated oligomers with defined structure. The targets of our work are oligoenes, oligophenylenevinylenes, also with fluorinated vinylene units, oligophenylenes and oligomers with thiophene-arylene or thiophene-anthraquinone units. The synthetic strategies developed in our research group are based on transition-metal catalyzed coupling reactions

Synthesis of conjugated oligomers and polymers: the organometallic way

Results of special interest in the field of organometallic chemistry directed towards the synthesis of conjugated oligomers and polymers are reviewed. Methodologies widely employed in the synthesis of well-defined molecules and based on the transition metal catalyzed coupling reactions of various organometallic (B, Sn, Si, Mg and Zn) reagents have been more recently extended to build up polyor oligo-meric conjugated molecular architectures. Although the focus of the present work is on transition metal cross-coupling or homo-coupling processes, other useful organometallic routes, such as metathesis reactions and acetylene polymerization, have also been dealt with. Owing to their higher versatility with respect to the nonorganometallic processes commonly used for the synthesis of these materials, the approaches presented allow the realization of more complex molecular structures, which are nowadays required in many electronic and optoelectronic applications. The use of organometallic strategies has been discussed from a synthetic organic chemist’s point of view, and advantages and limitations of the different methodologies reviewed have been highlighted. Some attention has also been paid to the properties of the resulting materials and to their dependence on the procedure followed and the framework obtained

Iron-catalyzed cross-coupling reaction of aryl Grignard reagents with bis(2-bromovinyl)benzenes

Fe(acac)3 has been used as the catalyst in cross-coupling reactions of aryl Grignard reagents with 1,4-bis(2- bromovinyl)benzenes affording bis(2-arylvinyl)benzenes. Effects of alkoxy substituents on both reactants and of the temperature on the reaction outcome are investigated

Third-order nonlinear optical properties of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dialkoxy-1,4-phenylenevinyl ene)s, a novel class of push-pull substituted PPVs

A series of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dioctyloxy-1,4-phenylenevin ylene)s containing variable ratios of tetrafluorophenylenevinylene and dialkoxyphenylenevinylene repeating units has been synthesized via the Stille cross-coupling reaction in order to investigate the influence on the Χ(3) of the simultaneous presence of electron-deficient and electron-rich aromatic monomers in the PPV backbone. Third-order nonlinear optical properties of the resulting materials have been studied in chloroform solutions at λ=1064 nm using the picosecond Z-scan technique. The nonlinear refractive index has been found to be negative, strongly dependent on the copolymer composition, and as high as (-10±2)×10-12 cm2/W

Synthesis of oligoarylenevinylenes with fluorinated double bonds

Oligoarylenevinylenes with fluorine atoms in the vinylene units and side-chains with a range of polarities bonded to the aryl rings, have been synthesized via a methodology based on the Stille cross-coupling reaction. All compounds were stereoselectiveIy synthesized with trans double bonds

Vibrational spectroscopic study of a push-pull substituted fluorinated poly(p-phenylenevinylene) copolymer

In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroelectrochemistry during oxidation (p-doping) and reduction (n-doping) as well as photoinduced infrared spectroscopy of a random copolymer of 2,3,5,6-tetrafluoro-1,4-phenylenevinylene and 2,5-dioctyloxy-1,4-phenylenevinylene [co(TFPV-DOPV)] is presented. The infrared active vibration (IRAV) patterns obtained during electrochemical oxidation (p-doping) and reduction (n-doping) are different. The copolymer shows photoinduced IRAV bands that are similar to those obtained during electrochemical reduction (n-doping) in contrast to most of the other conjugated polymers which show similarities with oxidation (p-doping) IRAV bands. To our knowledge this is the only p- and n-dopable polymer with different IRAV patterns of charge carriers of both signs, and a similarity between n-doping and photodoping IRAV bands