Pyridine Linker Research Articles

Comparative electrochemistry and electrocatalytic activities of cobalt, iron and manganese phthalocyanine complexes axially co-ordinated to mercaptopyridine self-assembled monolayer at gold electrodes

Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards l-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.

Pyridine linker pyrazolyl palladium complexes: Synthesis, characterization and ethylene polymerization activity

A series of pyrazolyl compounds with 2,6-pyridinedicarbonyl linker, {RR′pz(CO)} 2py, R = R′ = t Bu ( L1); R = R′ = Me ( L2); R = R′ = H ( L3), R = H, R′ = Me ( L4) has been prepared from the reaction of 2,6-pyridinedicarbonyl chloride with the appropriate pyrazole and a mild base. Ligands L1– L3 reacted with Pd(NCMe) 2Cl 2 to form mononuclear complexes while the reaction with L4 produced an intractable product. Complexes 1 and 2 were tested for their catalytic activities for the polymerization of ethylene after activation with methylaluminoxane (MAO). Active polymerization catalysts were formed in situ with MAO and that catalyzed the polymerization of ethylene to high-density linear polyethylene. The effects of co-catalyst concentration and temperature are reported. The optimum co-catalyst to catalyst ratio is 3000:1 and catalyst activity decreases above 40 °C due to catalyst deactivation.

Dioxygen Binding to a Simple Myoglobin Model in Aqueous Solution

Reversible binding of dioxygen occurs in aqueous solution to a myoglobin model composed of a porphinato iron(II) compound and a per-O-methylated β-cyclodextrin dimer with a pyridine linker (see picture). The dioxygen affinity of this system is 17.5±1.7 Torr and the half-life of the O2 adduct is 30.1 h in phosphate buffer at pH 7 and 25 °C.