Paramagnetic ruthenium(III) ortho-metallatedcomplexes. Synthesis, spectroscopic and redoxproperties

The reaction of (CS)Cl(PPh3)2RuII (μ-Cl)2 RuII (PPh3)2Cl(CS), A with the phenolic Schiff base ligands o-(OH)C6H4C(H)⊗N-C6H4(R), (R=p-OMe, Me, H, Cl, NO2; H2L1-H2L5) in methanol under aerobic conditions afforded the complexes RuIII(HL)2(PPh3) Cl, 1 and RuIII(L)(PPh3)(CH3OH)Cl, 2. In complexes 1 both the ligands (HL-) are bound to the metal center at the deprotonated phenolic oxygen and azomethine nitrogen and in the complexes 2 the L2- is in tridentate C,N,O mode where cyclometallation takes place from the ortho carbon atom of the amine fragment of H2L. During the reaction the metal ion is oxidized from the starting RuII in A to RuIII in the products 1 and 2. The complexes (1 and 2) are nonconducting and behave as one-electron paramagnets. Complexes display rhombic EPR spectra that have been analyzed to furnish values of axial (ν ) and rhombic (V) distortion parameters as well as energies of the two expected ligand field transitions (ν 1 and ν 2) within the t2 shell. One of the transitions (ν 2) has been observed in the predicted region. The complexes exhibit moderately strong ligand-to-metal charge-transfer transition in the visible region and intraligand transitions in the UV region. The complexes are electroactive and show ruthenium (IV)-ruthenium(III) (E½ , 0.75-0.88 V vs. Ag/AgCl) and ruthenium(III)-ruthenium(II) (E½ , -0.42 to -0.59 V) couples. The E½ values vary linearly with the Hammett constant of the substituents R. The role of coordination of phenolato function in stabilizing the unusual paramagnetic ruthenium(III) oxidation state in the complexes 2 is noted

Dinuclear ruthenium(II) bipyridine complexes having non-symmetric α,α′-diimine based neutral bridging ligands. Synthesis, spectroscopic and electrochemical properties

A group of three dinuclear ruthenium(II) complexes of the type [(bpy)2RuII(L)RuII(bpy)2](ClO4)4·2H2O, 1a–1c [bpy=2,2′-bipyridine, L=bridging ligand, NpC5H4CH=Ni–(R)–Ni=CHC5H4Np; R=none, 1a; R=–C6H4–, 1b; R=–CH2–C6H4–CH2–, 1c] have been synthesized and characterized. The complexes are essentially diamagnetic and behave as 1:4 electrolytes in acetonitrile solution. The mass of the molecular ion for the complex 1a and the geometry of the complexes 1 in solution have been assessed by fast atom bombardment (FAB) mass spectrometry and 1H/13C NMR spectroscopy, respectively. Complexes 1 display three metal-to-ligand charge-transfer (MLCT) transitions in the visible region, where the lowest energy MLCT transition is considered to be a dπ(RuII)→π*(L) transition. The other two higher energy MLCT transitions are believed to be dπ(RuII)→π*(bpy) transitions. Highly intense ligand-based π→π* transitions are observed in the UV region. In acetonitrile solvent, complexes 1 show one quasi-reversible two-electron oxidation process near 1.5 V vs. Ag/AgCl, due to simultaneous one-electron oxidations [ruthenium (III)⇌ruthenium(II)] of both of the ruthenium centers in 1 and multiple reductions in the range −0.5–−2.7 V vs. Ag/AgCl, due to successive reductions of the coordinated bridging ligand, L, as well as bipyridine. The chemically and electrochemically generated oxidized trivalent congeners of 1 are unstable at room temperature.© Elsevie

Ruthenium(II/III) bipyridine complexes incorporating thiol-based imine functions: synthesis, spectroscopic and redox properties

A group of five new ruthenium(II) bipyridine heterochelates of the type [RuII(bpy)2L]+ 1a–1e have been synthesized (bpy=2,2′-bipyridine; L=anionic form of the thiol-based imine ligands, HS–C6H4N=C(H)C6H4(R) (R=OMe, Me, H, Cl, NO2). The complexes 1a−1e are 1:1 conducting and diamagnetic. The complexes 1a−1e exhibit strong MLCT transitions in the visible region and intra-ligand transitions in the UV region. In acetonitrile solvent complexes show a reversible ruthenium(III)–ruthenium(II) couple in the range 0.2–0.4 V and irreversible ruthenium(III)→ruthenium(IV) oxidation in the range 1.15–1.73 V vs. SCE. Two successive bipyridine reductions are observed in the ranges −1.43 to −1.57 and −1.67 to −1.78 V vs. SCE. The complexes are susceptible to undergo stereoretentive oxidations to the trivalent ruthenium(III) congeners. The isolated one-electron paramagnetic ruthenium(III) complex, 1c+ exhibits weak rhombic EPR spectrum at 77 K (g1=2.106, g2=2.093, g3=1.966) in 1:1 chloroform–toluene. The EPR spectrum of 1c+ has been analyzed to furnish values of distortion parameters (Δ=8988 cm−1; V=0.8833 cm−1) and energy of the expected ligand field transitions (ν1=1028 nm and ν2=1186 nm) within the t2 shell. One of the ligand field transitions has been experimentally observed at 1265 nm.© Elsevie

A new class of sulfur bridged ruthenium–molybdenum complexes, (L)2RuII(μ-S)2MoIV(OH)2 [L=NC5H4N=NC6H4(R), R=H, o-Me/Cl, m-Me/Cl]. Synthesis, spectroscopic and electron-transfer properties

The reaction of (NH4)2MoVIS4 with the complexes ctc-RuII(L)2Cl2 (1a–1e) [L=NC5H4N=NC6H4(R), R=H, o-Me/Cl, m-Me/Cl; ctc=cis–trans–cis with respect to chlorides, pyridine and azo nitrogens respectively] in MeOH–H2O (1:1) resulted in a group of stable sulfur bridged ruthenium–molybdenum complexes of the type (L)2RuII(μ-S)2MoIV(OH)2 (2a–2e). In complexes 2 the terminal Mo=S bonds of the MoVIS42− unit get hydroxylated and the molybdenum ion is reduced from the starting MoVI in MoS42− to MoIV in the final product 2. The cis–trans–cis (with respect to sulfurs, pyridine and azo nitrogens respectively) configuration of the RuL2S2 fragment in 2 has been established by the 1H NMR spectroscopy. In dichloromethane solution the complexes 2 exhibit a strong dπ(RuII)→Lπ* MLCT transition near 550 nm, a strong sulfur to molybdenum LMCT transition near 500 nm and intra ligand π–π* transition in the UV region. In dichloromethane solution the complexes display reversible RuII⇌RuIII oxidation couples in the range 1.15–1.39 V, irreversible MoIV→MoV oxidations in the range 1.68–1.71 V vs SCE. Four successive reversible ligand (–N=N–) reductions are observed for each complex in the ranges −0.37→−0.67 V (one-electron), −0.81→−1.02 V (one-electron) and −1.48→−1.76 V (simultaneous two-electron reduction) vs SCE respectively. The presence of trivalent ruthenium in the oxidized solutions 2+ is evidenced by the rhombic EPR spectra. The EPR spectra of the coulometrically oxidized species 2+ have been analyzed to furnish values of axial (Δ=4590–5132 cm−1) and rhombic (ν=1776–2498 cm−1) distortion parameters as well as energies of the two expected ligand field transitions (γ1=3798–4022 cm−1) and (γ2=5752–6614 cm−1) within the t2 shell. One of the ligand field transitions has been observed experimentally at 6173 cm−1 and 6289 cm−1 for the complexes 2b+ and 2d+ respectively by near-IR spectra which are close to the computed γ2 values.© Elsevie

Ruthenium(II/III)–bipyridine complexes with four-membered sulphur donor co-ligands: synthesis, metal valence preference, spectroscopic and electron-transfer properties

A group of stable ruthenium(II) and (III) mixed-ligand tris-chelated complexes of the type [Run+(bpy)(L)2]z+ (1–8, n=2, Z=0; 9, n=3, Z=1) have been synthesized and characterized (bpy=2,2′-bipyridine; L=anionic form of the ligands, ROC(S)SK, (R=Me, Et, n Pr, i Pr, n Bu, i Bu, –CH2–Ph) or (EtO)2P(S)SNH4 or (Et)2NC(S)SNa). The complexes 1–8 are diamagnetic and electrically neutral and the complex 9 is one-electron paramagnetic and behaves as 1:1 electrolyte in acetonitrile solvent. The complexes 1–8 and 9 display two MLCT transitions near 530, 370 nm and 663, 438 nm respectively. Intra-ligand bipyridine based π–π* transition is observed near 300 nm. The complexes 1–8 exhibit room-temperature emission from the highest energy MLCT band (~370 nm). At room temperature the lifetime of the excited states for the complexes 2 and 8 are found to be 90 and 95 ns respectively. In acetonitrile solution the complexes 1–9 show a reversible ruthenium(III)–ruthenium(II) couple in the range −0.08 → 0.40 V and irreversible ruthenium(III)–ruthenium(IV) oxidation in the range 1.19–1.45 V vs Ag/AgCl. One reversible bipyridine reduction is observed for each complex in the range −1.70 → −1.85 V vs Ag/AgCl. The presence of trivalent ruthenium in the oxidized solution for one complex 1 is evidenced by the axial EPR spectrum at 77 K. The isolated trivalent complex 9 also exhibits an axial EPR spectrum at 77 K. The EPR spectra of the trivalent ruthenium complexes (1+ and 9) have been analyzed to furnish values of distortion parameters (Δ(cm−1)→1+, 3689; 9, 3699) and energies of the two expected ligand field transitions (ν1(cm−1)→1+, 3489; 9, 3497 and ν2(cm−1)→1+, 4339; 9, 4348) within the t2 shell. One of the ligand field transitions has been experimentally observed at 4673 cm−1 for complex 9 and which close to the computed ν2 value (4348 cm−1).© Elsevie

A case of hypersensitivity to soluble and isophane insulins but not to insulin glargine

Insulin is an important agent for the treatment of diabetes mellitus (DM). Allergic reactions to insulin therapy, although rare, have been evident since animal insulin became available for the treatment of DM in 1922. Hypersensitivity to insulin has considerably been reduced with the introduction of human insulin produced by recombinant deoxyribonucleic acid technology. Here, we present a case of Type 2 DM who demonstrated immediate (Type 1) hypersensitivity reaction on the sites of subcutaneous injection of soluble and isophane insulin but insulin glargine was tolerated well and provided good glycemic control

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Not AvailableThe present experiment was carried out to evaluate the breeding value of Satputia inbreds and to formulate suitable breeding strategies following 7 × 7 half-diallel mating design for genetic improvement of ridge gourd (Luffa acutangula Roxb.). Twenty-one F1 hybrids along with seven parental lines, including two hermaphrodite inbreds, were evaluated in randomized block design with three replications. The highly significant mean squares due to parents, hybrids and parents versus hybrids for all the eleven traits studied indicate the presence of sufficient amount of genetic variation. Prevalence of additive genetic variance indicates the usefulness of hybridization followed by selection approaches for plant stature and earliness parameters, while heterosis breeding would be suitable to improve yield potential as indicated by predominance of non-additive genetic variance. Plant stature and earliness are peculiar traits of hermaphrodite ridge gourd which is inherited in its progenies. The parents DRG-2, Satputia Long and Satputia Small were good combiners for a number of characters, including yield/plant. Ten crosses having hermaphrodite inbred as one of the parents, excelled for high per se performance along with desirable specific combining ability effects. The present findings reveal the breeding value and potentiality of hermaphrodite Satputia lines in the genetic improvement for ‘‘ideal plant type’’ in ridge gourd.Not Availabl

Not Available

Not AvailableThe present experiment was carried out to evaluate the breeding value of Satputia inbreds and to formulate suitable breeding strategies following 7 × 7 half-diallel mating design for genetic improvement of ridge gourd (Luffa acutangula Roxb.). Twenty-one F1 hybrids along with seven parental lines, including two hermaphrodite inbreds, were evaluated in randomized block design with three replications. The highly significant mean squares due to parents, hybrids and parents versus hybrids for all the eleven traits studied indicate the presence of sufficient amount of genetic variation. Prevalence of additive genetic variance indicates the usefulness of hybridization followed by selection approaches for plant stature and earliness parameters, while heterosis breeding would be suitable to improve yield potential as indicated by predominance of non-additive genetic variance. Plant stature and earliness are peculiar traits of hermaphrodite ridge gourd which is inherited in its progenies. The parents DRG-2, Satputia Long and Satputia Small were good combiners for a number of characters, including yield/plant. Ten crosses having hermaphrodite inbred as one of the parents, excelled for high per se performance along with desirable specific combining ability effects. The present findings reveal the breeding value and potentiality of hermaphrodite Satputia lines in the genetic improvement for ‘‘ideal plant type’’ in ridge gourd.Not Availabl