149 research outputs found
Highly coloured organometallic thermoplastics: Polymers incorporating azo dyes.
No full textInterest in organometallic polymers is due to their applications as chem. sensors, electrocatalysts, modified electrodes and photo-active mol. devices. The incorporation of organometallic moieties into the backbone of org. mols. has modified the optical, magnetic and thermal properties of these systems. These types of materials are known to display liq. crystallinity, ferromagnetism, as well as nonlinear optical and catalytic properties. Recently interest in polymers contg. azo dyes in their side chains or backbones has grown due to their liq. cryst., nonlinear optic properties. This research group has prepd. a no. of classes and types of organometallic polymers contg. azobenzene or hetrayl azo dyes. In these polymers the azo dyes were incorporated into either the side chains or backbones. Here, a review of the synthetic methodol., spectroscopic anal., and phys. characterizations of these materials will be discussed
Neutral and cationic cyclopentadienyliron macromolecules containing arylazo chromophores.
No full textSummary: A new class of macromolecules containing neutral and cationic organoiron moieties with arylazo chromophores in their backbones has been prepared. Photolysis of these polymers resulted in the removal of the cationic iron moieties leading to new polyferrocenes with azo dyes in their backbones. UV-vis studies showed λmax around 419 nm in DMF with a bathochromic shift to around 530 nm upon the addition of HCl
Azo dye functionalized oligomers and polymers containing neutral and cationic cyclopentadienyliron complexes.
No full textRecently, we have focused on the synthesis of monomeric and polymeric cationic organoiron functionalized with azo dyes. In this presentation we will describe the synthesis of novel polyferrocene incorporating azo dyes and pendent cyclopentadienyliron cations. Condensation of 1,1'-ferrocenedicarbonyl chloride with azo dyes functionalized arene cyclopentadienyliron complexes resulted in the isolation of neutral/cationic organoiron oligomers contg. azo dyes. Polymn. of these oligomers with sulfur dinucleophiles allowed for the isolation of polymers contg. iron in and pendent to their backbones, these polymers displayed excellent soly. in polar solvents. Photolytic demetallation of these polymers resulted in the isolation of polyferrocenes contg. azo dye moieties in their backbones. UV-vis studies showed a λmax around 430 nm in DMF, upon addn. of 10 % HCl a bathocromic shift to higher wavelength, λmax around 525 nm, was obsd. due to the formation of azonium ion
Ferrocence-based polymers containing azo groups in their backbone: Synthesis, electrochemical and thermal analysis.
No full textFerrocene-based monomers were prepd. via the reaction of cationic chloroarene cyclopentadienyliron complex cations with 1,1'-ferrocene dicarbonyl chloride. These monomers were then reacted with O-, S- and N- contg. dinucleophiles to give the polymeric materials with neutral iron moieties in the backbone and pendent cationic cyclopentadienyliron moieties. Photolytic demetallation gave the title organometallic polymers in good yields. Electrochem. studies showed that the neutral iron moieties were oxidized at 0.89 V while the cationic species were reduced at -1.42 V. Thermal anal. and mol. wt. detn. were preformed using TGA, DSC, and GPC. The synthetic methodol., characterization, and spectral properties will be discussed
"Third Generation"-Type Functional Tris(2-pyridyl)borate Ligands and their Transition-Metal Complexes
No full textPhenyltris(2-pyridyl)borates (Tpyb) are a promising class of tripodal “scorpionate”-type ligands with potential utility in the development of transition metal complexes with interesting optical, electronic or magnetic properties, and as building blocks to metallosupramolecular polymers. We report here a new class of “third generation”-type Tpyb ligands that contain different functional groups attached to the boron-bound aryl moiety. The synthesis, characterization and metal ion complexation behavior of ligands with iodo and trimethylsilyl groups is discussed. The electrochemical and absorption characteristics of the corresponding low-spin Fe(II) and Ru(II) complexes are compared. We demonstrate the further elaboration of the iodo derivatives with alkynes via Sonogashira-Hagihara coupling, a process that proceeds with high yield for the Fe(II) and Ru(II) complexes, but not for the free ligand. The borylation of the silyl-substituted Ru(II) complex with BBr3 was also investigated. In addition to the expected borylation product, Ru(Tpyb-Bpin)2, the replacement of one (major product) or two phenyl groups is observed, suggesting that electrophilic borylation occurs at both the C(Ph)-Si and the C(Ph)-B aromatic carbons. The successful attachment of a range of different functional groups at the periphery of the Tpyb metal complexes is expected to provide opportunities to access new polymeric materials via C-C coupling or click-type reactions.Peer reviewe
Redox-active η6-arene-η5cyclopentadienyliron-containing macromolecules.
No full textThere has been tremendous interest in organoiron macromols. This interest stems from their application as chem. sensors, electrocatalysts, modified electrodes and photo-active mol. devices. Herein, we report the synthesis and characterization of a no. of different classes of organoiron macromols. contg. η6-arene-η5-cyclopentadienyliron complexes, and ferrocene. The electrochem. behavior of these materials has been investigated and showed the redn. of the cationic iron moieties and the oxidn. of the ferrocene moieties. The synthesis properties and the electrochem. studies of these iron-contg. macromols. will be presented
Synthesis of iron-containing polymers with azo dyes in the backbones or side chains.
No full textThe synthesis of cationic cyclopentadienyliron-containing polymers with pendent azobenzene chromophores was accomplished via metal-mediated nucleophilic aromatic substitution reactions. All of the desired polymers were isolated as vibrantly coloured materials and displayed excellent solubility in polar aprotic solvents. Cationic and neutral cyclopentadienyliron polymers incorporating azo dyes in the backbone were also prepared. Reactions of azo dyes with dichlorobenzene complexes allowed for the isolation of cationic cyclopentdienyliron (CpFe+) complexes with azo dye chromophores. These complexes were then reacted with 1,1′-ferrocenedicarbonyl chloride to produce the trimetallic monomers with terminal chloro groups. These monomers contained two pendent CpFe+ cations and a neutral iron moiety in the backbone. Nucleophilic substitution reactions of these monomers with oxygen and sulfur containing dinucleophiles gave rise to a new class of polymeric materials. The pendent CpFe+ moieties could also be cleaved from the polymer backbones using photolysis to afford novel ferrocene based polymers. The UV-vis spectra of the organoiron monomers and polymers display similar wavelength maxima however incorporating azobenzene chromophores with electron-withdrawing substituent into the polymer chains resulted in bathochromic shifts of the λmax values
Highly colored organometallic thermoplastics
No full textPrepn. of organoiron monomers that contain one or more azo dye functionalities was performed. It was found that the resulting organoiron complex contained multiple azo dyes functionalities. Very good yields of organoiron polymers contg. multiple dyes were obtained for the nucleophilic arom. substitution reactions of complex compd. with O- or S-contg. dinucleophiles. These materials were found to be thermally stable, and characterization of these materials displayed unique photophys. and electrochem. properties.Source type: Electronic(1
Near-edge x-ray absorption fine structure spectroscopy study of the photolytic process in poly(Phenyl thioether) with pendant iron moieties.
No full textThe near-edge x-ray absorption fine structure (NEXAFS) spectra of poly(Ph thioether) polymers with pendant Fe(Cp) iron moieties have been recorded at the carbon 1s, iron 2p, and phosphorus 1s and 2p edges. This study shows that soln. photofragmentation of the organometallic polymer causes the removal of iron moieties and the prepn. of the corresponding org. polymer: poly(Ph thioether). Spectroscopic characterization of poly(Ph thioether) prepd. in this manner indicates the presence of iron oxide, likely Fe2O3, and hexafluorophosphate counterion trapped in the demetalated polymer matrix. A photolytic examn. of the solid phase poly(Ph thioether)-Fe(Cp) organometallic polymer shows that irradn. of this polymer in air leads to the formation of poly(Ph thioether) and Fe2O3, while irradn. in vacuum leads to formation of iron species with a lower oxidn. state. The ability to probe the oxidn. state of this metal species is relevant to understanding how demetalation conditions affect the properties of the polymer.Source type: Electronic(1
Substituent effects in the iron 2p and carbon 1s edge near-edge x-ray absorption fine structure spectroscopy of metal arene complexes and polymers.
No full textWe have examined the electronic structure of a series of metal arene monomers and polymers by
near-edge X-ray absorption fine structure spectroscopy. We observe that electron-donating or -withdrawing
substituents have a measurable effect on some features in the NEXAFS spectra of these species. However,
more significant changes are observed that arise from strong π*-conjugation between the arene ligand
(benzene or cyclopentadienyl) and substituents bonded to this ligand. Spectral features observed in the
iron 2p and carbon 1s NEXAFS spectra were assigned with the aid of EHMO and DFT calculationsCopyright (C) 2012 American Chemical Society (ACS). All Rights Reserved.; Section Code: 29-12; CA Section Cross-references: 22, 36, 73; CODEN: ORGND7; CAS Registry Numbers: 12176-31-7; 12288-80-1; 32757-45-2; 32992-68-0; 33086-63-4; 33435-42-6; 35640-39-2; 89031-72-1; 99685-98-0; 153294-58-7; 156952-16-8; 1141428-77-4 Role: PEP (Physical, engineering or chemical process), PRP (Properties), PROC (Process) (substituent effects in iron 2p and carbon 1s edge NEXAFS of cationic (η5-cyclopentadienyl)iron(substituted η6-benzene) sandwich complexes and their polymers)Source type: Electronic(1
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