Perhalogenmethylmercapto-heterocyclen,IX (perchlormethylmercapto)- und (perfluormethylmercapto)pyridine

Methods of substituting pyridine by perhalogenomethylmercapto groups are discussed. The side chain chlorination of 2-(methylmercapto)pyridine leads gradually to 2-(trichloromethylmercapto)pyridine hydrochloride ($\text{1a}$) and 2-(trichloromethylmercapto)pyridine ($\text{1b}$). Neither a direct reaction of pyridine with CF₃SCl nor the way over a Grignard reaction or a sulfenylcarboxylate lead to CF₃S-substituted products. Reactions of pyridine and bromopyridines with Hg(SCF₃)₂ yield 1:1-adducts ($\text{2a-d}$) only. Lithium tetrakis(1,2-dihydro-1-pyridyl)aluminate (LDPA) reacts with CF₃SCl to give 3-(trifluoromethylmercapto)pyridine ($\text{3}$); in addition a disubstituted product can be identified massspectroscopically. ¹H- and ¹⁹F-NMR-spectra are reported.     

Hyperfine Shifts of the 13C-NMR. in Protoporphyrin IX Iron (III) Dicyanide and Deuteroporphyrin IX Iron (III) Dicyanide

The ¹³C-NMR. in Zn(II) (Protoporphyrin IX), Fe(III) (Protoporphrin IX) (CN)₂, Zn(II) (Deuteroporphyrin IX dimethylester), and Fe(III) (Deuteroporphyrin IX) (CN)₂ have been identified, and the ¹³C hyperfine shifts in the iron complexes evaluated. In a partial analysis of these data the parameters Q^H, Q_CCH^H, and Q_C′CH^C, which characterize the isotropic coupling through hyperconjugation between the ¹H and ¹³C nuclei of the porphyrin side chains and the unpaired electron spin density on the aromatic ring carbon atoms, have been re-examined. This paper is part of an investigation of the electronic states in low spin ferric hemes and hemoproteins, and the relations between the electronic structures and the biological roles of these molecules.     

NO orientation and tilting in (nitrosyl)iron(II) deuteroporphyrin IX

To investigate issues concerning the coordination of the nitrosyl ligand in naturally occurring hemes, we report the spectroscopy and X-ray structure of five-coordinate [Fe(Deut)(NO)]. Bonding parameters are comparable with those observed for previously characterized synthetic porphyrin complexes of this type. The asymmetric pattern of the peripheral substitution of the porphyrin core allows us to examine aspects associated with ligand binding and orientation previously unobserved in the symmetrical synthetic porphyrins. The nitrosyl is found to be oriented in the direction of the less basic pyrrole rings. This observed orientation of the NO is considered in reference to those orientations reported in a series of related protein structures. Off-axis tilting, a property associated with ordered (nitrosyl)iron(II) porphyrinates, is also investigated.     

Coordination Studies of Iron(II) Protoporphyrin IX and Iron(II) Hematoporphyrin IX with 4,4′-Dipyridyl and other Nitrogenous Bases

Abstract

The results of spectral studies of iron(II) protopor-phyrin IX and iron(II) hematoporphyrin IX with several substituted pyridines are reported. The existence in solution of an iron(II) porphyrin complex coordinated to a water molecule and to a substituted pyridine was shown by isolation of the complex from solution. The complex isolated was dimeric inono-4,4′-dipyridyl diaquo iron(II) hematoporphyrin. Addition of ethanol to the aqueous solvent inhibits coordination of iron(II) porphyrins with substituted pyridines. The protoporphyrin ring enhances coordination relative to the hematoporphyrin ring.     

Compound I of naked heme (iron protoporphyrin IX)

Gaseous iron protoporphyrin IX (heme) ions, Fe(PP-IX)+, obtained by electrospray ionization of a methanol solution of hemin chloride, are allowed to react with ozone, forming a species that is tentatively assigned the structure of an oxo complex, namely, an oxo iron(IV) protoporphyrin IX radical-cation species, (PP-IX).+FeIV=O. This species, representing the naked core of the putative active oxidant (compound I) of heme enzymes, is characterized by its reactivity behavior in Fourier transform ion cyclotron resonance mass spectrometry, performing as an active O-atom donor. A quite distinct reactivity is displayed by an isomeric species, holding the additional oxygen on the porphyrin frame, Fe(PP-IX(O))+. This isomer undergoes a ligand addition process, as was previously observed for Fe(PP-IX)+.     

Electrochemical properties of protoporphyrin IX zinc(II) films

The electrochemical properties of protoporphyrin IX zinc(II) (ZnPP) films on indium-tin oxide (ITO) substrate have been studied for three types of films with different arrangements, which were an adsorbed film of ZnPP and LB films of ZnPP and its hybrid with hexadecyltrimethylammonium bromide. Cyclic voltammetry (CV) measurement showed that, as the adsorbed amount of ZnPP increases, an irreversible oxidation peak of ZnPP film is intensified. This reveals that electrochemical properties depend on the adsorbed amount rather than the orientation of porphyrin molecules. It was also supported from CV measurement and ultraviolet-visible absorption spectroscopy that porphyrins adsorbed on ITO substrate were desorbed after the single scan of potential. Additionally, photoresponse of these ZnPP films was investigated by photocurrent measurement. The photocurrent generation is due to carboxylic acid moieties but not ZnPP macrocycles.     

Molecular Imprinted Polymers Prepared by Electropolymerization of Ni-(Protoporphyrin IX)

Abstract

The features of combining a chemically modified electrode (CME) with an artificial receptor system, prepared by imprinting electropolymerized [Ni

(Protoporphyrin IX) dimethyl ester] [Ni-(PPIX)] in the presence of nitrobenzene, were studied. The responses of the modified glassy carbon electrode towards template molecules were analyzed by cycling over the nitrobenzene reduction wave. The specific signal was much higher than the non-specific one which demonstrates the selectivity of such a system.

This approach has potential for preparation of selective polymeric films on the surface of different transducers.

     

Studies on the photophysical characteristics of poly(carboxylic acid)s bound protoporphyrin IX and metal complexes of protoporphyrin IX

The copolymers of methacrylic acid with protoporphyrin IX (PPIX) and the metal complexes, zinc protoporphyrin IX and magnesium protoporphyrin IX were synthesised and characterised. Corresponding acrylic acid copolymers were also synthesised. The steady state absorption and fluorescence spectral properties of the macromolecular bound fluorophores PPIX, Zn-PPIX and Mg-PPIX were investigated. Poly(methacrylic acid) bound protoporphyrin IX, zinc protoporphyrin IX and magnesium protoporphyrin IX show an increase in the fluorescence intensity and lifetime with increase in the pH in the range 2-8 with a marked transition around pH 6.0-7.0. The fluorophore concentration in the dilute solution of the copolymers is micromolar and the fluorophore to the carboxylic acid monomer ratios in the copolymer is around 10⁻³. The molecular weight of the copolymers is 100 ± 10 kD. The fluorescence decay curves of all the fluorophore bound polymers follow biexponential decay fit independent of pH. Poly(MAA-co-PPIX) and poly(MAA-co-MgPPIX) undergo well marked pH induced structural transitions in the pH range of 6.0-7.0 whereas poly(MAA-co-ZnPPIX) undergoes pH induced structural transitions in the pH range of 4.0. In the case of polyacrylic acid copolymers the changes observed in the steady state and time resolved fluorescence studies are less marked. The distinct hydrophobic and hydrophilic environments experienced by the fluorophore bound to PMMA are attributed to the dynamics of the macromolecules in dilute aqueous solutions manifested by the α-methyl group present in the copolymer. The studies carried out using the fluorophores in the time windows from 2 ns to 12 ns indicate evolving trends in the dynamic coiling and reverse coiling of poly methacrylic acid chain.     

Spectroscopic study of protoporphyrin IX zinc(II) encapsulated in sol-gel glass

Previous studies indicated that the organization of native porphyrins and their intentionally designated derivatives in solid substrates is of current interest because of the biological and practical importance of these compounds. In this paper, we report herein for the first time the incorporation of a functionalized diacid, protoporphyrin IX Zn(II) (Zn-pp-IX), successfully in a silica based transparent organic-inorganic hybrid material by choosing proper alkoxy silane containing amino-group via the sol-gel method. The entrapped guest was diagnosed using UV-vis sectrophotometry, emission spectroscopy, and infrared spectrometry; the properties of the encapsulated porphyrin were compared to those of the compound in solution. The results indicate that Zn-pp-IX is well distributed and homogeneously in the glass.     

Design, syntheses and biological activity of novel ALS inhibitors (IX)

Quantitative structure-activity relationships for herbicidal activity against rape of sulfonylurea and triazolopyrimidine-2-sulfonamide derivatives were examined three-dimensionally using comparative molecular field analysis (CoMFA). The CoMFA results show that the slopes in steric and electrostatic fields around the molecule were significant for both series in governing the potency variations in herbicidal activity. Based upon the successful superposition between the two series, the herbicidal activity was analyzable with a single equation for the combined set of compounds, which suggested that the two different series of compounds have a common region of the receptor site. Project supported by the National Natural Science Foundation of China (Grant No. 29832050), the Special Key Fund of Natural Science of Tianjin (Grant No. 983801011) and the Doctoral Fund of the Education Ministry of China.     

Zur Koordinationschemie des Rhenium(VII). IX. 8-Hydroxychinolin-Komplexe des Rhenium (VII)

Coordination Chemistry of Rhenium (VII). IX. 8-Hydroxyquinoline Complexes of Rhenium (VII) Perrhenylchloride gives with 8-hydroxyquinoline complexes of the composition ReO₃cl(HOx)₂ in small polar solvents and ReO₃Cl(HOx)· nHOx, (n ≈? 0.3 to 1) in the presence of alcohols. The conditions of preparation and the properties refer to an unidentate ligand HOx in ReO₃Cl(HOx)₂ and a bidentate ligand in ReO₃Cl(HOx) · nHOx. The quinolinato complex ReO₃Ox (DMF) is formed in DMF.     

Poly[Ni(II)Protoporphyrin IX] Modified Electrode for Amperometric Detection of Acetylcholine (Ach) and Choline (Ch)

Abstract

Poly[Ni(II)Protoporphyrin IX] (pNiPP) modified electrode can be used as an alternative method for direct amperometric detection of Acetylcholine (Ach) and Choline (Ch). This response is highly dependent on the electrode potential, that must be higher than +0.4 V versus Ag/AgCl with a maximum at +0.6 V.

Other amino derivatives such as ethanolamine and tetrabutyl ammonium hydroxide did not show amperometric response in the same experimental conditions. On the contrary, KCl shows an increasing amperometric signal in flow injection for a concentration range of 10^?3 to 1 M, indicating certain sensitivity of membrane to Cl^? ions. The lowest detection limit corresponds to the highest cationic volume. The response for acetylcholine is slightly higher than for choline and is almost completely non‐linear for both substrates. The proposed model for the response is Y=(A×X)/(B+X) according to AICc Akaike method.

Choline, in a complex solution, was analyzed by HPLC with the chemically modified electrode as detector.     

Diborane as a reducing agent IX: Reduction of aTris(trifluoroacetyl)enaminospiroindoline

Summary Reduction of the title compound (2) with diborane furnishes 1-trifluoroethyl-3-(2-(trifluoroethylamino)ethyl)-3-vinylindoline (4), 1-hydroxy-trifluoroethyl-3-(2-(trifluoroethylamino)ethyl)indole (5), and 1-methyl-2-trifluoroethyl-1,2,3,4-tetrahydro--carboline (6). However, treatment of2 with lithium aluminum hydride, H₂/Pd on charcoal, and sodium borohydride affords hydroxyspiroindolenine8, hydroxy-bis(trifluoroacetyl)enaminospiroindoline9, andN-ethyltryptamine7, respectively. The results are discussed and the mechanisms of the reactions leading to4–8 are presented.

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Diboran als Reduktionsmittel, 9. Mitt.: Reduktion einesTris(trifluoroacetyl)enaminospiroindolins

Zusammenfassung Reduktion der Titelverbindung (2) mit Diboran ergibt 1-Trifluoroethyl-3-(2-(trifluoroethylamino)ethyl)-3-vinylindolin (4), 1-Hydroxy-trifluoroethyl-3-(2-(trifluoroethylamino)ethyl)indol (5) und 1-Methyl-2-trifluoroethyl-1,2,3,4-tetrahydro--carbolin (6). Behandlung von2 mit Lithiumaluminiumhydrid, H₂/Pd auf Aktivkohle und Natriumborhydrid führt jedoch zu Hydroxyspiroindolenin8, Hydroxy-bis(trifluoroacetyl)enaminospiroindolin9 und N-Ethyltryptamin (7). Die Ergebnisse werden diskutiert und die Mechanismen der zu den Produkten4–8 führenden Reaktionen werden vorgestellt.