RESUMEN
A dearomatization/aromatization strategy accesses the tetrahedral (crosslike) pentacene tetramer (tetrakis(4-((6,13-bis(TIPS-ethynyl)pentacen-2-yl)ethynyl)phenyl)silane). This molecular caltrop and one of its derivatives form amorphous thin films, demonstrating the impact of the 3D-tetramerization on the bulk morphology of the otherwise crystalline TIPS-pentacene.
RESUMEN
The synthesis and characterization of soluble azaiptycenes is reported. Optical and physical properties were studied and compared with those of the structurally consanguine azaacenes. Electrochemical experiments and quantum-chemical calculations revealed the electronic structure of the iptycene derivatives. Their crystallization behavior was examined. A highly fluorescent amorphous diazatetracene derivative was integrated into a simple organic light-emitting diode, showing enhanced performance compared with that of previously reported, structurally similar tetracenes.
RESUMEN
We report the successful synthesis of a series of ethynylated dioxadiazaacenes and investigate their properties. We developed a modular Cu-based catalytic procedure to build up [1,4]dioxino[2,3-b]pyrazine motifs starting from only a few building blocks. TIPS-acetylene-substituted benzene-1,2-diol and naphthalene-2,3-diol were reacted with 2,3-dichloropyrazine, 2,3-dichloroquinoxaline, and 2,3-dichlorobenzoquinoxaline to give a set of six novel and well-soluble dioxadiazaacenes. Different reaction conditions for the coupling were tested. Copper catalysis is most effective and gave the best yield of dioxadiazaacenes. The resulting azaoxaacenes were characterized in terms of optical and electronic properties and crystal packing.
Asunto(s)
Compuestos Aza/química , Compuestos Aza/síntesis química , Pirazinas/química , Alquilación , Catálisis , Cobre/química , Estructura Molecular , Teoría CuánticaRESUMEN
We have synthesized a series of ethynylated phenazines and their bis-triazolyl cycloadducts to serve as metal ion sensors. Binding of metal ions is achieved through coordination to the phenazine nitrogen atom and the triazole ring. To allow metal sensing in aqueous solution, the triazole units are substituted with water-soluble ethylene glycol chains. These phenazine cycloadducts exhibit a selective affinity for binding silver ions. Examination of the halogenated analogues reveals a lowering of the band gap and the corresponding bathochromic shifts in the absorption and emission spectra. The electron-withdrawing properties of these halogens also result in significantly decreased metal-binding activity of the phenazine cycloadducts.
Asunto(s)
Alquinos/química , Compuestos Organometálicos/síntesis química , Fenazinas/química , Fenazinas/síntesis química , Plata/química , Triazoles/química , Alquilación , Sitios de Unión , Ciclización , Estructura Molecular , Compuestos Organometálicos/química , Teoría CuánticaRESUMEN
Alkyne metathesis was effected by mixtures of Mo(CO)(6) and phenols at elevated temperatures based on an improved version of the method reported by Mortreux and Mori. When propynylated arenes are subjected to these reaction conditions, the formation of diarylalkynes is often quantitative and likewise allows the synthesis of alkyne-bridged macrocycles and polymers of high molecular weight. Alkyne metathesis made high-molecular weight poly[p-(dialkylphenylene)ethynylene]s (PPEs) accessible that show promise as active layers in organic semiconductor devices.
RESUMEN
Pd-catalyzed coupling of 1,2-diethynyl-3,4-(bistrimethylsilyl)cyclobutadienecyclopentadienylcobalt to a series of 1-iodo-2-(trimethylsilylethynyl)benzenes and 1-chloro-4-trimethylsilylbut-1-ene-3-yne is followed by desilylation with potassium carbonate. Cu(OAc)(2)-promoted oxidative ring closure leads to dehydro[14]annulenes and dehydro[14]benzoannulenes fused to a cyclobutadiene(cyclopentadienylcobalt) complex. Five of these fused dehydroannulenes were structurally characterized. (1)H NMR spectroscopy of the organometallic dehydro[14]annulenes incorporating the (bistrimethylsilyl)cyclobutadiene(cyclopentadienylcobalt) unit suggested that the aromaticity of the fused cyclobutadiene complex might be stronger than that of benzene according to the ring-current criterion.
RESUMEN
A nano-architectural system that has high variability while maintaining component specificity is described. Tetraphenylcyclobutadiene(cyclopentadienyl)cobalt complexes and phenyleneethynylene trimers were synthesized and subsequently modified with oligonucleotides utilizing standard phosphoramidite chemistry. The resulting oligonucleotide modified organics (OMOs) were characterized by UV-vis spectroscopy, fluorescence spectroscopy, and phosphate analysis. Hybridization of these OMOs resulted in a series of self-assembled oligomeric hybrids of varying length and topology. These hybrids were characterized by melting temperature, polyacrylamide gel electrophoresis, and fluorescence spectroscopy. This model system demonstrates the power of DNA to self-assemble modules of interest-independent of the module itself.
Asunto(s)
ADN/química , Oligonucleótidos/química , Compuestos Orgánicos/química , Compuestos Orgánicos/síntesis química , Polímeros/síntesis química , Polímeros/químicaRESUMEN
A series of photophysical measurements and semiempirical calculations were carried out with 1,4-bis(phenylethynyl)benzene in search of evidence on the effects of phenyl group rotation and chromophore aggregation of oligo- and poly(phenyleneethynylene)s. It is suggested that planarization gives rise to relatively modest shifts of ca. 20-30 nm, which preserve the vibronic structure of the monomer and retain a high emission quantum yield. In contrast, it is proposed that aggregation gives rise to larger shifts and loss of vibronic structure.
RESUMEN
Iterative target transformation factor analysis (ITTFA) was used to determine the spectra of the individual species generated during the oxidative p-doping of films of poly(para-phenyleneethynylene) (PPE). UV-visible spectra of PPE films on transparent electrodes were obtained in-situ during an anodic sweep. ITTFA identified 4 species present during the oxidation, which we assign as neutral polymer, polaron species, bipolaron species, and a species formed by further bipolaron reaction. The region of electrochemical stability for each of these species was identified and their potential-dependent profiles were obtained. This work is the first deconvolution of conjugated polymer spectroelectrochemistry.
Asunto(s)
Polímeros/análisis , Electroquímica , ElectrodosRESUMEN
Organometallic polymers were prepared by acyclic diyne metathesis (ADIMET) or by Pd-catalyzed coupling of 1,3-diethynylcyclobutadiene(cyclopentadienyl)cobalt with a suitably substituted diiodobenzene. The polymers obtained by Heck coupling show a degree of polymerization (Pn) of 20-60. The monomers for ADIMET were made by the Pd-catalyzed coupling of [1,3-bis(trimethylsilylethynyl)-2,4-bis(trimethylsilyl)cyclobutadiene](cyclopentadienyl)cobalt to 1-bromo-2,5-dialkyl-4-propynylbenzenes in the presence of KOH in yields of 40-48%. The monomers carry hexyl, ethylhexyl, and (S)-3,7-dimethyloctyl side chains. Polymerization of the propynylated monomers furnishes organometallic polymers with a Pn of up to 230 arylene-ethynylene units. The polymers were fully characterized by polarizing microscopy, transmission electron microscopy, circular dichroism, differential scanning calorimetry, and X-ray diffraction (XRD). They show nematic, lyotropic liquid crystalline phases as well as chiroptical properties from which aggregation in poor solvents and in the solid state can be concluded. Lamellar or irregular honeycomb-shaped morphologies in these organometallic polymers can be detected by electron microscopy.