The synthesis of linear and star-shaped oligomers containing cationic and neutral organoiron groups in their structures was achieved by reaction of cationic arene complexes of cyclopentadienyliron containing terminal hydroxyl groups with 1,1′-ferrocenedicarbonyl chloride or ferrocene carboxylic acid. The use of chloroarene complexes allowed for the formation of triiron complexes that were subsequently polymerized via nucleophilic aromatic substitution with various oxygen- and sulfur-based dinucleophiles. The corresponding polyethers and thioethers were isolated in good yields and these materials exhibited excellent solubilities in polar organic solvents. Cyclic voltammetric investigations revealed that the cationic iron centers pendent to the polymer backbones underwent reversible reduction steps, while the neutral iron centers within the polymer backbones underwent reversible oxidation steps. Photolysis of these polymers resulted in the removal of the cationic cyclopentadienyliron moieties pendent to the polymer backbones. Thermogravimetric analysis (TGA) revealed that the cationic iron complexes were cleaved from the polymers at approximately 210 °C. Differentials scanning calorimetry (DSC) revealed that the glass transition temperatures of the cationic polymers occurred at higher temperatures than their neutral analogs. 相似文献
Summary: 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.
Organoiron macromolecules containing azo dye moieties prepared in this study. 相似文献
The 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. 相似文献
This communication is focused on the controlled design of star‐shaped aromatic ethers with pendent cyclopentadienyliron moieties. A trimetallic core was prepared, which was then reacted with a number of oligomeric ether complexes to give star‐shaped polymers with six, nine, twelve and fifteen pendent cationic cyclopentadienyliron moieties. Cyclic voltammetric studies showed reduction of the iron centers between –0.99 and –1.41 V. Thermogravimetric analysis showed that loss of the metallic moieties occurred between 225 and 284°C. 相似文献
The synthesis of sulfone-containing monomers with pendent cationic cyclopentadienyliron (CpFe+) moieties has been accomplished via nucleophilic aromatic substitution of dichloroarene complexes with a number aliphatic dithiols. These complexes were further oxidized using m-CPBA to give the sulfone-based monomers. Polymerization of the sulfone-based monomers with O-containing nucleophiles produced the sulfone-based polymers. Direct nucleophilic aromatic substitution of dichloroarene complexes with dinucleophiles allowed for the formation of organoiron sulfide-based polymers. Oxidation of these polymers led to the formation of sulfone polymers with the pendent iron moieties. The organometallic monomers and polymers were found to be more soluble in polar solvents in comparison to their organic analogues. 相似文献
A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non‐polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of polymer amphiphilicities was surveyed by pairing a cationic oxanorbornene with eleven different non‐polar monomers and varying the comonomer feed ratios. Their properties were tested using antimicrobial assays and copolymers possessing intermediate hydrophobicities were the most active. Polymer‐induced leakage of dye‐filled liposomes and microscopy of polymer‐treated bacteria support a membrane‐based mode of action. From these results there appears to be profound differences in how a polymer made from FA monomers interacts with the phospholipid bilayer compared with copolymers from segregated monomers. We conclude that a well‐defined spatial relationship of the whole polymer is crucial to obtain synthetic mimics of antimicrobial peptides (SMAMPs): charged and non‐polar moieties need to be balanced locally, for example, at the monomer level, and not just globally. We advocate the use of FA monomers for better control of biological properties. It is expected that this principle will be usefully applied to other backbones such as the polyacrylates, polystyrenes, and non‐natural polyamides. 相似文献
The synthesis of cationic organoiron polymers with azobenzene moieties in their side chains has been accomplished via nucleophilic aromatic substitution and ring-opening metathesis polymerization (ROMP) reactions. Polyaromatic ethers and thioethers with azobenzene moieties in their side chains were functionalized with different chromophores to yield yellow-, orange- and red-colored polymers. Polynorbornenes with azobenzene-containing side chains were isolated following ROMP of their monomeric analogs. All of the organoiron polymers were soluble in polar organic solvents and underwent reversible electrochemical reduction processes. Photobleaching of the azobenzene-containing polymers was achieved in the presence of hydrogen peroxide. The metallated polymers had glass transition temperatures approximately 50 to 80°C higher than their organic analogs. 相似文献
Vinyl ethers containing tricarbonyl(14-η4-1,3-pentadiene)-ruthenium(0) and -iron(0) species were prepared utilizing selective dienylation with penta-dienylpotassium and were polymerized with cationic initiators to give high molecular weight polymers. The diene-metal moieties were converted into tricarbonyl(13-η3-allyl)metal species by protonation with dry HCl. Tricarbonyl(3-allyl-14-η4-1,3-pentadiene)iron(0) also undergoes cationic polymerization but the presence of its isomer, tricarbonyl(3-propenyl-14-η4-1,3-pentadiene)iron(0) inhibits the polymerization. 相似文献
The electronic properties of conjugated polyelectrolytes (CPEs) with poly(fluorene-co-phenylene) backbones and different counterions and charges have been investigated using absorption and ultraviolet photoelectron spectroscopy (UPS). The optical energy band gap of CPEs depends mainly on their conjugated backbone and are nearly insensitive to the charges or counterions. UPS measurements reveal that electron injection from Au to polymers with cationic groups is more efficient than for the neutral and anionic counterparts. The vacuum levels of CPEs were also shifted toward higher or lower binding energy, relative to that of Au, depending on the charge and counterion presence, and provide insight into the general alignment of dipoles at the metal/organic interface. 相似文献
The synthesis and the solution behavior of rigid, rodlike cationic polyelectrolytes having (i) poly(p-phenylene) backbones and (ii) main chains composed of 4,4“-bis(2,2′:6′,2”-terpyridine)2′,5′-dihexyl-p-terphenyl moieties and ruthenium(II) centers are presented. All these polymers are shown to have a homogeneous constitution and degrees of polymerization of up to Pn ≈ 70. Their solution properties were analyzed using viscosimetry, small-angle X-ray scattering (SAXS) and osmometry. Pronounced polyelectrolyte effects were found in salt-free solutions using viscosimetry. Small-angle X-ray scattering demonstrated directly the strong correlation of the counterions and the macroions. The osmotic coefficients measured in salt-free solution as function of polyelectrolyte concentration were found to be lower than predicted by the cell model. 相似文献
Organoiron polynorbornene containing arylazo or hetarylazo dye chromophores has been prepared via ring opening metathesis polymerization using Grubbs' catalyst. The obtained polymers were isolated as brightly colored materials and displayed good solubility in polar organic solvents. The colors of these polymers were affected by the nature of the incorporated azo chromophores. Thermogravimetric analysis of these materials showed that the cleavage of the cyclopentadienyliron (CpFe+) moieties was between 225 and 231 °C, while the degradation of the polymer backbones occurred between 400 and 450 °C. UV-vis studies in DMF showed that the organoiron polymers containing arylazo dyes exhibit wavelength maxima around 425 nm. However, the replacement of these arylazo moieties with hetarylazo dyes displayed substantial bathochromic shifts in the λmax values (≈ 511 nm). 相似文献
Dynamic covalent polymers (DCPs) offer opportunities as adaptive materials of particular interest for targeting, sensing and delivery of biological molecules. In this view, combining cationic units and fluorescent units along DCP chains is attractive for achieving optical probes for the recognition and delivery of nucleic acids. Here, we report on the design of acylhydrazone-based DCPs combining cationic arginine units with π-conjugated fluorescent moieties based on thiophene-ethynyl-fluorene cores. Two types of fluorescent building blocks bearing neutral or cationic side groups on the fluorene moiety are considered in order to assess the role of the number of cationic units on complexation with DNA. The (chir)optical properties of the building blocks, the DCPs, and their complexes with several types of DNA are explored, providing details on the formation of supramolecular complexes and on their stability in aqueous solutions. The DNA-templated formation of DCPs is demonstrated, which provides new perspectives on the assembly of fluorescent DCP based on the nucleic acid structure. 相似文献
Hyperbranched polymers form a novel class of materials that are employed as components of resin formulations. They are appreciated for their low intrinsic viscosities, which is ascribed to their spherical shape. It was envisaged to devise pigment dispersants with hyperbranched moieties as structural elements. Commercially available hyperbranched polymers with polyester, polyesteramide and polyethylene imine backbones were chemically modified to develop a range of disperants with core- and shell-type pigment anchoring mechanisms. Both the shell- and core-type anchoring principles generally can be used for pigment dispersion and stabilisation at a low viscosity level. 相似文献
This paper describes our recent work dealing with novel polymerization methods of allene and propargyl derivatives. By the radical, cationic, and living coordination polymerizations, polymers bearing exomethylene moieties in the side chain could be obtained. The polymers obtained could undergo the cationic crosslinking reaction. As step-growth polymerizations, spontaneous copolymerizations, polyadditions with dithiols, and coupling polymerizations using palladium catalyst are also described. 相似文献