Peroxidase activity of new mixed‐valence cobalt complexes with ligands derived from pyridoxal

New mixed‐valence cobalt complexes with ligands derived from pyridoxal were synthesized and characterized, and their application as mimetics of the peroxidase enzyme was investigated. Single‐crystal X‐ray diffraction was used to analyze all complex structures in the solid state and their electrochemical behavior was investigated. A reactivity pattern was observed in the complex synthesis regarding the cobalt compounds from which analogous zwitterionic derivatives were obtained. The importance of these compounds lies in understanding their behavior in an oxidizing environment and evaluating whether they can activate hydrogen peroxide to oxidize phenolic compounds. In nature, enzymes called peroxidases, which efficiently oxidize phenolic compounds, trigger many reactions involving the activation of hydrogen peroxide to oxidize organic substrates. However, these enzymes present several disadvantages, including denaturation and elevated costs. Therefore, these limitations can be overcome by expanding research into the study of synthetic catalysts for the oxidation of phenolic compounds using hydrogen peroxide, which is a highly relevant field of bioinorganic chemistry.     

Polymer solar cells based on quinoxaline and dialkylthienyl substituted benzodithiophene with enhanced open circuit voltage

A poly[benzodithiophene‐alt‐di‐2‐thienyl‐quinoxaline] series (PBDTDPQ‐EH, PBDTDPQ‐OD, and PBDTDPQ‐HDT) was synthesized via Stille coupling. Deep highest occupied molecular orbital (HOMO) levels were achieved by the introduction of 2‐decyl‐4‐hexyl‐thiophen‐yl (HDT) side chains. The introduction of the various side chains increased the molecular weight of the polymers, and the polymers dissolved well in common organic solvents at room temperature. The HOMO energy level (?5.20 to ?5.49 eV) decreased because of the 2D conjugated structure. X‐ray diffraction analysis showed that PBDTDPQ‐OD had a slightly edge‐on structure. In the case of PBDTDPQ‐HDT, however, the structure was amorphous due to the thiophene side chain, and the extent of π stacking increased. After fabricating bulk‐heterojunction‐type polymer solar cells, the OPV characteristics were evaluated. The values of open‐circuit voltage (V_oc), short‐circuit current (J_sc), fill factor, and power conversion efficiency (PCE) were 0.88 V, 7.9 mA cm^?2, 45.4%, and 3.2%, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1028–1036     

Ring-expansion of tertiary cyclic alpha-vinylamines by tandem conjugate addition to (p-toluenesulfonyl)ethyne and formal 3-aza-Cope rearrangement

A novel ring-expansion protocol is based on the conjugate additions of cyclic alpha-vinylamines to (p-toluenesulfonyl)ethyne, followed by aza-Cope rearrangements of the resulting zwitterions, to afford medium and large-ring cyclic amines under remarkably mild conditions.     

K isomers in 254No: probing single-particle energies and pairing strengths in the heaviest nuclei

We have identified two isomers in 254No, built on two- and four-quasiparticle excitations, with quantum numbers K pi = 8- and (14+), as well as a low-energy 2-quasiparticle Kpi = 3+ state. The occurrence of isomers establishes that K is a good quantum number and therefore that the nucleus has an axial prolate shape. The 2-quasiparticle states probe the energies of the proton levels that govern the stability of superheavy nuclei, test 2-quasiparticle energies from theory, and thereby check their predictions of magic gaps.     

Regiochemical switching in Diels-Alder cycloadditions by change in oxidation state of removable diene sulfur substituents. Synthesis of carbazoles by sequential heteroannulation and Diels-Alder cycloaddition

The palladium-catalyzed heteroannulation of N-carbobenzyloxy-o-iodoanilines with 1-phenylthio-1,3-butadiene afforded indolines 7, which were oxidized with DDQ to produce vinylogous 2-(phenylthio)indoles 8. The latter compounds underwent highly regioselective Diels-Alder cycloadditions with methyl propiolate in the presence of MeAlCl(2) or AlCl(3), with simultaneous elimination of benzenethiol, to afford methyl N-(carbobenzyloxy)carbazole-3-carboxylates 9 and, in some cases, the N-deprotected derivatives 11. This is the opposite regiochemistry of that observed previously with the corresponding sulfone analogues of 8. Thus, the regiochemistry of the cycloaddition can be effectively controlled by appropriate choice of oxidation state of the diene sulfur substituent.     

Titanocene-based group-11 metal ions; solid-state structure of {[(η-C5H4SiMe3)2Ti(CCPh)2]2Ag}NO3

The reaction of [Ti](CCR)₂ {[Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 1a, R = Fc, Fc = (η⁵-C₅H₄)Fe(η⁵-C₅H₅); 1b, R = Ph} with MX {2a, MX = [Cu(NCCH₃)₄]BF₄; M = Ag; 2b, X = ClO₄; 2c, X = NO₃} in a 2:1 molar ratio produces the trinuclear heterobimetallic (Ti₂M) or heptanuclear heterotrimetallic (Ti₂MFe₄) complexes [{[Ti](μ-σ,π-CCR)₂}₂M]X (R = Fc: 3a, M = Cu, X = BF₄; 3b, M = Ag, X = ClO₄. R = Ph: 3c, M = Cu, X = BF₄; 3d, M = Ag, X = ClO₄: 3e, M = Ag, X = NO₃) in high yield. Complexes 3c-3e are also accessible, when {[Ti](μ-σ,π-CCPh)₂}MX (M = Cu: 4a, X = FBF₃; M = Ag: 4b, X = OClO₃; 4c, X = ONO₂) is reacted with one equivalent of 1b. Transferring this reaction scheme to [Ti](CCSiMe₃)₂ (1c) only the formation of the heterobimetallic tweezer complex {[Ti](μ-σ,π-CCSiMe₃)₂}MX {4d, MX = [Cu(NCCH₃)]BF₄; 4e, MX = AgOClO₃} is observed which is attributed to the bulkiness of the acetylide-bound Me₃Si group. The solid-state structure of 3e is reported. In 3e, two [Ti](CCPh)₂ tweezer moieties are chelate-bound by their carbon-carbon triple bonds to a silver(I) ion, resulting in a pseudo-tetrahedral environment at the group-11 metal. is acting as counter-ion to cationic [{[Ti](CCPh)₂}₂Ag]⁺.Additionally, the result of cyclic voltammetric studies on [{[Ti](μ-σ,π-CCPh)₂}₂Cu]BF₄ (3c) is reported.     

Synthesis and structural characterization of cadmium(II) complexes with chelating keto-hydroxy compounds: The X-ray molecular structure of [Cd2(nq)4(H2O)4]·3H2O (nqH = 2-hydroxynaphthoquinone)

The reaction of cadmium(II) acetate dehydrate with the complexing agents tropolone (tropH), 2-hydroxynaphthoquinone (nqH), 1,2-dihydroxyanthraquinone (alizH₂), and 1,8-dihydroxyanthraquinone (chryzH₂), afforded the complexes [Cd(trop)₂] 1, [Cd₂(nq)₄(H₂O)₄]·3H₂O 2·3H₂O, [Cd(alizH)₂(H₂O)₃] 3, and [Cd(chryzH)₂(H₂O)₂] 4, respectively. The X-ray molecular structure of the dinuclear complex 2·3H₂O reveals that each cadmium(II) atom is seven-coordinated. The nature of water molecules (lattice or coordinated) was discerned by thermogravimetric studies. The ¹¹³Cd NMR spectra were discussed in light of the chemical exchange.