Pradeep Mathur

Biomimetic sensor for certain catecholamines employing copper(II) complex and silver nanoparticle modified glassy carbon paste electrode.

A dimeric Cu(II) complex [Cu(μ(2)-hep)(hep-H)](2)·2ClO(4) (1) containing bidentate (hep-H=2-(2-hydroxyethyl)pyridine) ligand was synthesized and characterized by single crystal X-ray diffraction studies. Each Cu-ion in 1 is in a distorted square pyramidal geometry. Further 1 along with silver nanoparticles (SNPs) have been used as modifier in the construction of a biomimetic sensor (1-SNP-GCPE) for determining certain catecholamines viz., dopamine (DA), levodopa (l-Dopa), epinephrine (EP) and norepinephrine (NE) using cyclic voltammetry, chronocoulometry, electrochemical impedance spectroscopy and adsorptive stripping square wave voltammetry (AdSSWV). Finally, the catalytic properties of the sensor were characterized by chronoamperometry. Employing AdSSWV, the calibration curves showed linear response ranging between 10(-6) and 10(-9)M for all the four analytes with detection limits (S/N=3) of 8.52×10(-10)M, 2.41×10(-9)M, 3.96×10(-10)M and 3.54×10(-10)M for DA, l-Dopa, EP and NE respectively. The lifetime of the biomimetic sensor was 3 months at room temperature. The prepared modified electrode shows several advantages such as simple preparation method, high sensitivity, high stability, ease of preparation and regeneration of the electrode surface by simple polishing along with excellent reproducibility. The method has been applied for the selective and precise analysis of DA, l-Dopa, EP and NE in pharmaceutical formulations, urine and blood serum samples.

Biomimetic sensor for certain phenols employing a copper(II) complex.

A new dimeric Cu(II) complex [Cu(mu(2)-hep)(hep-H)](2).2PF(6) (1) containing a bidentate (hep-H = 2-(2-hydroxyethyl)pyridine) ligand was synthesized and characterized by single crystal X-ray diffraction studies. Each Cu ion in 1 is in a distorted square pyramidal geometry. Further 1 is used as a modifier in the construction of a biomimetic sensor for determining phenols [phenol (Phe), resorcinol (Res), hydroquinone (HQ), and catechol (Cat)] in phosphate buffer by using cyclic voltammetry (CV), chronocoulometry, electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). DPV has been proposed for trace determination of Phe and Res while SWV for HQ and Cat. The method has been applied for the selective and precise analysis of Phe in commercial injections, Res in hair coloring agents, HQ in photographic developers and cosmetics, and Cat in tea samples and guarana tablets. The calibration curves showed a linear response ranging between 10(-6) and 10(-8) M for all four of the analytes with detection limits (3sigma) of 1.04 x 10(-8), 2.31 x 10(-8), 1.54 x 10(-8), and 0.86 x 10(-8) M for Phe, Res, HQ, and Cat, respectively. The lifetime of the biomimetic sensor was 200 days at room temperature (at least 750 determinations). The catalytic properties of 1-CPE were characterized by chronoamperometry and were found to be in good agreement with Michaelis-Menten kinetics.

Chalcogen-Bridged Metal-Carbonyl Complexes

Publisher Summary The chemistry of transition metal–chalcogenide clusters has been widely explored. In some clusters, the behavior of selenium can be different from that of both sulfur and tellurium. Diversity in structure and reactivity features of chalcogen-bridged metal complexes has generated interest in the synthesis of new chalcogen-bridged complexes and study of their reactions toward inorganic and organic moieties. The advantages of using Se and Te in systematic syntheses of clusters are that the heavier congeners of S behave in a similar fashion in their ability to bridge and stabilize metal frameworks and the metal selenides and tellurides would have a high level of toxicity and unpleasant odor that can be associated with organoselenides and organotellurides. The chapter discusses the several approaches that are used for the synthesis of metal carbonyl polychalcogenide cationic, anionic, and neutral clusters.

Vapor-Diffusion-Mediated Single Crystal-to-Single Crystal Transformation of a Discrete Dimeric Copper(II) Complex to a Discrete Tetrameric Copper(II) Complex

The symmetric dimeric complex [Cu(mu(2)-hep)(TFA)(H(2)O)](2) (1) has been synthesized from 2-(2-hydroxyethyl)pyridine (hep-H), trifluoroacetic acid (TFA-H), and copper acetate in a 95:5 (v/v) MeOH-H(2)O mixture at 298 K. Each Cu(II) ion in 1 is linked with two mu(2)-alcoholic oxygen atoms and one pyridine nitrogen atom of hep, and the other two coordination sites are occupied by the oxygen donors of TFA and H(2)O. At room temperature, the blue single crystals of 1 transform to the green single crystals of a tetrameric complex, [Cu(4)(mu(3)-hep)(2)(mu(2)-hep)(2)(mu(2)-TFA)(2)(TFA)(2)] (2), in presence of alcoholic vapor. The facile single crystal-to-single crystal (SCSC) transformation of 1 to 2 is accompanied by the removal of coordinated H(2)O molecules in 1 and concomitant formation of four new covalent bonds, two Cu-O(mu(3)-hep) and two Cu-O(mu(2)-TFA). The SCSC transformation of 1 to 2 is selective to the alcoholic vapor; the exposure of single crystals of 1 to heat or light or in vacuum has resulted in an immediate loss in crystallinity.

Mixed chalcogen carbonyl compounds: IV.Reactivity of Fe2(CO)6(μ-STe) and Fe3(CO)9(μ3-S) (μ3-Te) towards coordinatively unsaturated species☆

Abstract Using Fe 2 (CO) 6 (μ-STe) and Fe 3 (CO) 9 (μ 3 -S)(μ 3 -Te) for the addition of coordinatively unsaturated species, the following new mixed metal, mixed chalcogen compounds have been obtained: Fe 2 (CO) 6 (μ 3 -S)(μ 3 -Te)M(PPh 3 ) 2 (M = Pt, Pd), Fe 2 Ru(CO) 9 (μ 3 -S)(μ 3 -Te) and Fe 4- x Ru x (CO) 11 (μ 4 -S)(μ 4 -Te) ( x = 0–2). The formation of the triphenylphosphine derivatives, Fe 3 (CO) 9 − x (PPh 3 ) x (μ 3 -S)(μ 3 -Te) ( x = 1,2) and Fe 3 (CO) 9 (PPh 3 )(μ 3 -S)(μ 3 -Te) are also reported.

Mixed chalcogen carbonyl compounds: synthesis and characterisation of (CO)6Fe2(μ3-Se)(μ3-Te)Pt(PPh3)2 Fe3(CO)7(PPh3)2(μ3-Se)(μ3-Te)

Abstract An improved method for isolation of pure Fe3(CO)9(μ3-Se)(μ3-Te) and Fe2(CO)6(μ-SeTe) has been developed. The mixed chalcogenide complex (CO)6Fe2(μ3-Se)(μ3-Te)Pt(PPh3)2 is formed exclusively on treatment of Fe2(CO)6(μ3-Se)(μ3-Te) with Pt(C2H4)(PPh3)2, or along with Fe3(PPh3)2(μ3-Se)(μ3-Te) when Fe3(CO)9(μ3-Se)(μ3-Te) is treated with Pt(PPh3)4. With PPh3, Fe3(CO)9(μ3-Se)(μ3-Te) forms an adduct, (CO)6Fe2(μ3-Se)(μ3-Te)Fe(CO)3(PPh3).

The contrasting roles of the various chalcogens in the synthesis of mixed metal complexes (CO)6Fe2(μ3-E)2M(PPh3)2 (E = Te, Se, S; M = Ni, Pd, Pt))

Abstract Reactions of Fe3E2(CO)9 (E = S, Se) with M(PPh3)4 (M = Ni, Pd, Pt), at room temperature, show a marked contrast with the analogous reaction of Fe3Te2(CO)9. Different mechanisms are suggested for the formation of the mixed-metal complexes, Fe2E2(CO)6M(PPh3)2 (E = S, Se, Te; M = Pd, Pt, and E = Te; M = Ni), depending on the chalcogen atom involved. The size of the chalcogen and that of the heterometal atom play crucial roles in the outcome of the reaction.

A new route to Fe2Te2M(CO)6(PPh3)2 (M = Ni, Pd, Pt) from Fe3Te2(CO)9 and M(PPh3)4

Abstract The synthesis, characterization and mechanism of formation of the mixed metal complexes, Fe 2 Te 2 M(CO) 6 (PPh 3 ) 2 (M = Ni, Pd, Pt), from Fe 3 Te 2 (CO) 9 and M(PPh 3 ) 4 are described.

TRINUCLEAR AND TETRANUCLEAR IRON RUTHENIUM CARBONYL CLUSTERS STABILIZED BY BRIDGING SELENIUM LIGANDS

Abstract At room temperature, Fe 2 (CO) 6 (μ-Se 2 ) reacts with Ru 3 (CO) 12 to form Fe 2 Ru 3 (CO) 17 (μ 4 -Se)(μ 3 -Se), and with Ru(CO) 4 (C 2 H 2 ) to form Fe 2 Ru(CO) 9 (μ 3 -Se) 2 . The latter reacts with Fe(CO) 5 under visible light irradiation to give Fe 3 Ru(CO) 11 (μ 4 -Se) 2 , and with Ru(CO) 4 (C 2 H 4 ) to form Fe 2 Ru 2 (CO) 11 (μ 4 -Se) 2 . Visible light irradiation of a solution containing Fe 3 (CO) 9 (μ 3 -Se) 2 and Fe(CO) 5 yields Fe 4 (CO) 11 (μ 4 -Se) 2 . A solution containing Fe 3 (CO) 9 (μ 3 -Se) 2 and Ru(CO) 4 (C 2 H 4 ) at room temperature with stirring yielded Fe 3 Ru(CO) 11 (μ 4 -Se) 2 .

Addition of organic and inorganic moieties to Fe2(CO)6(?-EE?) and Fe3(CO)9(?3-E)(?3-E?) [E=Se, Te;E?=S, Se, Te]

Reaction of the iron chalcogen carbonyl clusters Fe2(CO)6(μ-EE′) and Fe3(CO)9(μ3-E)(μ3-E′), [E=Se, Te;E′=S, Se, Te] with various inorganic and organic moieties produce a number of higher nuclearity clusters. The reactivity pattern of these iron chalcogen carbonyl compounds and the structure of the products formed are discussed.