A germole-containing diacetylene, 1,1-diethynyl-2,3,4,5-tetraphenylgermole (2), was synthesized. Homopolymerization of 2 and its copolycyclotrimerization with 1-octyne were effected by TaCl5–Ph4Sn in toluene, producing completely soluble polymers (1) in moderate yields. The molecular structure of 1 was characterized by spectroscopic methods. The thermal stability of 1 was evaluated by thermogravimetric analysis, which detected virtually no weight loss when the polymers were heated to ∼350°C. These hyperbranched polymers were electronically conjugated as suggested by their strong absorption in the visible spectral region (λmax∼540 nm). Photoluminescence of the polymers was dramatically enhanced by cooling their solutions to low temperatures. Restricted intramolecular rotations of the phenyl rings upon the axes of the single bonds linked to the germole cores at the cryogenic temperatures might be responsible for this unique phenomenon of cooling-enhanced emission.
Tricyclic heteroaraomatic dye-based monomer containing NMe2 units, 6-bis(dimethylamino)acridine(p-cymene)dichlororuthenium (II), was used to prepare novel polyimides via a one-stage solution polycondensation due to their stability under a variety of oxidative and reductive conditions. The Ru(II) complex monomer was synthesized starting from [RuCl2(p-cymene)]2 and 3,6-bis(dimethylamino)acridine. A series of stable polyimides was synthesized from the Ru(II) complex of 3,6-bis(dimethylamino)acridine and various aromatic dianhyrides. The polymers had inherent viscosities ranging from 1.72 to 2.11 dL/g and were soluble in polar solvents. The glass transition temperatures were 192–278 °C, and the 10% weight loss temperatures were above 503–635 °C. Ruthenium-substituted polyimides were tested for catalytic activity in the furan formation reaction of (Z)-3-methylpent-2-en-4-yn-1-ol. The polymeric catalyst was added to (Z)-3-methylpent-2-en-4-yn-l-ol without a solvent and the pure furan was isolated by distillation under reduced pressure. The conversion of the starting, enynol, was determined by gas chromatography (GC).
The kinetics of ring opening polymerization of hexamethylcyclotrisiloxane, D3, and octamethylcyclotetrasiloxane, D4, in toluene initiated by protic borate complex H+ (H2O)3B(C6F5)4 have been studied. The reaction is first order in monomer and first order in initiator. Rate constants and activation parameters were determined. The formation of cyclic oligomers was followed. The kinetics of the formation of decamethylcyclopentasiloxane, D5, during the polymerization of D4 was in agreement with a back-biting mechanism. D3n cyclics (n = 2, 3,...) are exclusively formed during D3 polymerization by intramolecular reactions between the chain ends. The amount of generated D6 increases linearly with the monomer conversion in the range of the D3 conversion between 0 and 60% and is almost independent of temperature. Kinetic results are interpreted in terms of a mechanism involving cyclic tertiary trisilyloxonium ion transitory intermediates.
Mixed ligand complexes of Co II , Ni II and Cu II with dicarboxylic amino acids (aspartic, glutamic or H 2 ADA) as primary ligands and 8-hydroxyquinoline as a secondary ligand were prepared and characterized by elemental analysis, conductivity measurements, thermal analysis, cyclic voltammetry, and electronic and infrared (IR) spectroscopy. Cyclic voltammetry reveals a reversibility of the Cu II /Cu I couple, while the reactions of the Co II and Ni II complexes are irreversible. All complexes have a metal-to-ligand ratios of 1:1:1 and octahedral structures are suggested to be attained by interactions among both of the amino acids and 8-hydroxyquinoline anions with the metal ions. The reaction orders and activation energies have been computed by means of the Coats–Redfern and Horowitz–Metzger equations. The biological activity of selected complexes as anti-fungal agents has been tested.
An electrocatalytic dihydrogen oxidation was found to take place on an electrode coated with iron(III) ruthenocyanide (i.e., repeating unit cell structure: FeIII4[RuII(CN)6]3 or MFeIII[RuII(CN)6] and M = alkali metal counter ion) called ruthenium purple (RP). It was shown by voltammetric study that an electrocatalytic dihydrogen oxidation is induced on oxidizing the FeII ion in the cyanometallate. When the electrocatalysis characteristics of RP were investigated by voltammetry, especially in terms of the kinds of electrolyte used (K+ or Na+), RP exhibited a more efficient electrocatalysis in the K+ than in the Na+ electrolyte system. While a one-electron electro-oxidation of FeII to FeIII occurs, there is also a release of hydrated alkali metal cation(s) from the anionic RP (i.e., reduced RP) to compensate for charge. Moreover, cation transport through the cyanometallate network is more facile for the K+ electrolyte system (cf., size of hydrated cation: Na+ at 0.36 nm ≈ lattice channel of RP at 0.35 nm > K+ at 0.24 nm). Therefore, it was most probable that the present electrocatalysis is kinetically dominated by the electro-oxidation.
2-Acrylamidosulfamethazine (ASM) was synthesized and characterized by elemental analyses and IR spectroscopy. Proton-monomeric ligand dissociation and metal-monomeric ligand stability constants of ASM with some metal ions were determined potentiometrically in 0.1 M KCl and 40% (v/v) ethanol–water mixture. In the presence of 2,2′-azobisisobutyronitrile as an initiator, the dissociation and stability constants of ASM were determined in polymeric form (PASM). The influence of temperature on the dissociation of ASM and the stability constants of their complexes in monomeric and polymeric forms were precisely studied. The pKH value of PASM was found to be higher than ASM, which indicates that the vinyl group in the monomeric form decreases the electron density on nitrogen and hence reduces the N–H bond strength. The stability constants of the metal complexes in polymeric form are higher than those of the monomeric form. This reveals that the ligand in a polymeric form may be considered as a better complexing agent.
A general survey of fluorinated phosphazene polymers starting from their synthesis in 1965 to recent times is presented. Various types of fluorinated phosphazenes are described depending on the way fluorine atoms are connected to the polyphosphazene skeleton. The characterization, properties and practical utilization of these compounds in different domains are critically discussed.
Anodic oxidation of Co, Ni, Cu, Zn, Cd and Sn metals in an anhydrous acetone solution of poly(azomethinethiosemicarbazone) (PATS) yields the PATS–metal complexes. Chemical and thermal analyses as well as FTIR and electronic spectral data are presented to confirm the formulation of the isolated materials. The spectral data show that the ligand polymer is coordinated to the metal ions via the thiol sulfur atom and the nitrogen of the azomethine group. Thermogravimetric measurements (TGA) and differential thermal analyses (DTA) were used to obtain the energy of decomposition of PATS and its metal polymer complexes. The DC electrical conductivity measurements of PATS and the polymer complexes as annealed and 5% iodine doped forms were measured in the range 300–500 K. The products gave electrical conductivities in the semi-conducting region that increased with temperature.
Reactions of Zr(OPr n )4 and Zr(OBu n )4 with 3-pentenoic acid (PA) in 1:1 molar ratio were studied in propanol and butanol solution at room temperature by the sol–gel process. The complexations were investigated by 13C{1H}, 1H-NMR and FTIR spectroscopy. The 13C{1H}, 1H-NMR and FTIR spectra showed that PA completely reacted with Zr(OPr n )4 and Zr(OBu n )4. The new products were hydrolyzed by water in a ratio of 1:4 (Zr(OR n )4/ H2O, R = propyl, butyl). The stability of hydrolyzed products was investigated spectroscopically. After hydrolysis, it was observed that no PA was released from the complexes, [Zr(OPr n )3(PA)] and [Zr(OBu n )3(PA)], under the reaction conditions.
This short review focuses on recent advances in the syntheses, characterization and structures of coordination and organometallic complexes of upper-rim functionalized calix[4]arenes that form either small oligomers or polymers. This field is very limited, presumably due to the lack of X-ray data or reliable characterization that demonstrates the presence of oligomers or polymers. Nonetheless, the few published works already clearly demonstrate the immense versatility of the calix[4]arene macrocycle as it forms polymeric materials via coordination bondings with transition metals.
Liquid silicone rubber with high thermal conductivity and effective electromagnetic interference (EMI) shielding properties was prepared. Silicone-based polymers were prepared by the equilibrium polymerization of cyclic siloxane and end-blockers. Magnesium ferrite nanoparticles having spinel magnetic properties were synthesized by the sol-gel method. A liquid silicone rubber (LSR) nanocomposite was prepared by compounding α,ω-vinyl poly(dimethyl/methylpenylsiloxane) prepolymer (VPMPS), α, ω-hydrogen poly(dimethyl/hydrogenmethylsiloxane) prepolymer (HPDHS), catalyst and magnesium ferrite, which was modified with the surface treating agent, 1,3-divinyltetramethyldisilazane (VMS). The microwave absorbing property and thermal conductivity for the LSR nanocomposite-containing magnesium ferrite ultrafine particles, which were modified with the surface treatment agent, exhibited 10∼14 dB of reflection loss at 1∼2 GHz and 1.33 w/mK.
Polymer complexes derived from cinnamaldehyde and 2-substituted aniline with Cu(II), Pd(II), Pt(II), UO2(II), Rh(III), Ru(III), and Pd(IV) have been synthesized and characterized by IR, electronic, EPR, 1H-NMR, and 13C-NMR spectra, as well as by elemental analysis, thermogravimetry, and magnetic susceptibility measurements. The important bands in the IR spectra and the main 1H- and 13C-NMR signals are assigned and discussed in relation to molecular structure. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters were evaluated. The complexes, [Ru(HL n )Cl3] n , are penta-coordinate; and, a trigonal-bipyramidal environment is commensurate for the Ru(III) ion. The presence of a coordinated water molecule in complex the Cu(II) complex (20) was demonstrated by thermogravimetry. The compounds, [N-(3-phenylacrylidene)-2-mercaptoaniline] (HL1) and cinnamaldehyde-2-aminophenol (HL2), act as monobasic and neutral bidentate ligands. The B-value suggests a strong covalency in the metal-ligand σ-bond. Tentative structures of the polymer complexes are proposed.
Some ferrocene containing aromatic azo polyesters were prepared by condensing 1,1′-ferrocenedicarbonyl chloride with different azo groups containing aromatic diols, which were synthesized by diazotization coupling reaction from aromatic diamines. The polymeric products were separated as two portions on the basis of their solubility and subsequently characterized by their elemental analysis and FTIR spectral studies. Thermal properties of the products were measured by differential scanning calorimetry and thermogravimetry and the activation energies of pyrolysis were calculated using Horowitz and Metzger's method. The molecular weights of the soluble portions were determined by gel permeation chromatography (GPC) and these portions were also characterized by their inherent viscosities and UV-Vis spectroscopic studies.
The reaction of 1-(2,4,6-trimethylbenzyl)-3-(propyltriethoxysilane)imidazolidinium chloride, with the Pd(OAc)2 complex proceeded smoothly in DMSO to give the bis[1-(2,4,6-trimethylbenzyl)-3-(propyltriethoxysilane)imidazolidin-2-ylidene]dichloropalladium(II) complex that was grafted onto the surface of amorphous silica. The effects of various factors, such as reaction temperature and time, on the grafting efficiency was evaluated. Inorganic oxide particles that were modified with a carbene complex of palladium(II) were tested for catalytic activity in the Suzuki coupling reaction between phenylboronic acid and several aryl halides.
Kinetics of the anionic ring opening polymerization of octamethylcyclotetrasiloxane, D 4 , and hexamethylcyclotrisiloxane, D 3 , in toluene solution initiated by hexapyrrolidinediphosphazenium hydroxide, P 2 Pyr 6 + OH − were studied. Reactions are first order both in monomer and in initiator. The specific rate of the D 3 polymerization is higher than that of D 4 by about 2–3 orders of magnitudes. Activation energies are 18.1 kcal mol −1 for D 4 and 11 kcal mol −1 for D 3 . The back-biting reaction leading to decamethylcyclopentasiloxane, D 5 , was followed in the polymerization of D 4 . This reaction is retarded by the presence of monomer. The kinetics is interpreted in terms of a mechanism in which the active propagation center appears mostly as a monomer separated ion pair, which is also the intermediate in the propagation step.
Soluble cationic organoiron polynorbornenes with pendent hetarylazo side chains have been synthesized via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine)benzylideneruthenium(IV) dichloride (Grubbs' catalyst). The vibrantly colored organoiron polymers displayed weight average molecular weights between 24500 and 40900 and exhibited glass transition temperatures at 146 °C and 161 °C.
The reaction in dichloromethane at room temperature of the polyspirophosphazene copolymer {[NP(O2C12H8)]0.7[NP(OC5H4N)2]0.3} n (1) (O2C12H8=2,2′dioxybiphenyl) with [Ru2(η6-p-cymene)2Cl4] gives the polymer supported organometallic complex {[NP(O2C12H8)]0.7[NP(OC5H4N-Ru(η6-p-cymene)Cl2)2]0.3} n (2). Similarly the chiral phosphazene {[NP(O2C20H12)]0.9[NP(OC5H4N)2]0.1} n (3) (O2C20H12=R-2,2′-dioxy,1′1′-binaphthyl) reacts with the appropriate amount of the Ru precursor to give the related polymeric complex {[NP(O2C20H12)]0.9[NP(OC5H4N)(OC5H4N-Ru(η6-p-cymene)Cl2]0.1} n (4) as an orange solid. Carrying out the reaction of 3 with the Ru precursor in acetone at room temperature using 0.35 equivalents of Ru per pyridine site, gives the crosslinked yellow material with formula {[NP(O2C20H12)]0.9[NP(OC5H5N)2]0.1[Ru(η6-p-cymene)Cl2]0.07]} n (5), that may contain cationic [Ru(η6-p-cymene)Cl]+ units trapped in the rigid interior of a chiral network.
The usual sol–gel hydrolysis-condensation technique for the in-situ generation of reinforcing silica particles within an elastomer was recently modified by (i) controlling the required water of hydrolysis by simply absorbing it from the air, and (ii) generating the required catalyst in-situ from a tin salt. In the case of the silica, which is generated in poly(dimethylsiloxane) (PDMS), the technique had the advantages of producing well dispersed, highly reinforcing particles that did not significantly reduce the transparency of the composite. Applying the new technique to the in-situ generation of zirconia and titania in the same polymer also gave small well-dispersed particles, good reinforcement, and improved thermal stability. Although transparency was not maintained as well as in the case of the controlled hydrolysis producing silica, it was definitely better than that of composites prepared by the usual excess water method.
