Molybdenum(IV) dimeric complexes with N-alkylphenothiazines and their interactions with L-cysteine, L-histidine, 1,10-phenanthroline and 2,2′-bipyridyl

Abstract: A new series of lanthanide(III) nitrate complexes of 10-(2-dimethylaminopropyl)phenothiazine (promethazine or PM) with the general formula [Ln(PM)2(NO3)2]NO3, where Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, have been prepared and characterized based on elemental analysis, molar conductivity, magnetic susceptibility, spectroscopic data, and thermal studies Conductance study indicates a 1:1 ionic ratio for the complexes in solution The infrared spectra show that promethazine acts as a bidentate ligand using the heterocyclic nitrogen atom and tertiary nitrogen atom of the side chain as the sites of coordination Only two of the nitrate ions are coordinated bidentately to the central metal ion while another nitrate ion remains outside the coordination sphere A tentative structure has been proposed for the complexes

Abstract: The synthesis and reactivity of new lanthanocene complexes incorporating phenothiazine ligand are described. The reaction of phenothiazine (HPtz) with nBuLi in THF and subsequently with 1 equiv. of (C5H5)2LnCl(THF) gave the original complexes (C5H5)2LnPtz(THF) (Ln = Yb(1), Er(2), Dy(3), Y(4)). Treatment of complexes 1–4 with N,N′-diisopropylcarbodiimide results in mono-insertion of carbodiimide into the Ln–N(Ptz)-bond to yield the corresponding guanidinates (C5H5)2Ln[(iPrN)2C(Ptz)] (Ln = Yb (5), Er (6), Dy (7), Y(8)). Further investigations indicate that phenyl isothiocyanate react with complexes 1 and 4, giving the correspondent insertion products (C5H5)2Ln[SC(Ptz)NPh](THF) (Ln = Yb(9), Y(10)). All these complexes were characterized by elemental analysis and spectroscopic properties. The structures of complexes 2, 5 and 9 were also determined by the X-ray single crystal diffraction analysis. All these reactions provide a new strategy for introducing a functional substituent at the nitrogen atom of phenothiazine via forming a new C–N(ring) bond.

Abstract: FT-IR and FT-Raman spectra of 1H-2,2-dimethyl-3H-phenothiazin-4[10H]-one were recorded and analyzed. The vibrational wavenumbers were computed using HF/6-31G(d) and B3LYP/6-31G(d) basis. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectroscopies of the studied molecule. The first hyperpolarizability, infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The geometrical parameters of the title compound are in agreement with XRD crystal structure data. The red shift of the N H stretching wavenumber in the infrared spectrum from the computed wavenumber indicates the weakening of the N H bond.

Abstract: FT-IR and FT-Raman spectra of 1-(5,5-dioxido-10H-phenothiazin-10-yl)ethanone were recorded and analyzed. The vibrational wavenumbers were computed using B3LYP/6-31G∗ and SDD basis. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using NBO analysis. Molecular electrostatic potential was performed by the DFT method and infrared intensities and Raman activities are also reported. MEP shows that the negative potential sites are on oxygen atoms and the positive potential sites are around the nitrogen atoms. The geometrical parameters of the title compound (SDD) are in agreement with XRD crystal structure data. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of nonlinear optics.

Abstract: Polynuclear complexes of RHII and RHIII with fiveN-alkylphenothiazines as principal ligands have been prepared. The complexes were characterized by their elemental analyses, molar conductivities, and spectral data. The molecular formulae of the new complexes are as follows: [Rh3(PTZ)2(OH2)2Cl8]Cl, where PTZ=chlorpromazine or promethazine; [Rh3(EP)2(OH2)2Cl8][Rh(OH2)2Cl4], where EP=ethopropazine; [Rh4(TF)2(OH2)5Cl9]Cl·H2O, where TF=trifluoperazine; and [Rh2(TC)3(OH2)Cl6]. H2O, where TC=2-chlorophenothiazine. A tentative structure for each of the complexes is proposed.

Abstract: Alleviation of schizophrenic symptoms by phenothiazines and butyrophenones is associated with blockade of dopamine receptors, while exacerbation of symptoms by amphetamines appears to result from enhanced synaptic activity of dopamine and/or norepinephrine. The author suggests that biochemical labeling of the dopamine receptor with 3H-dopamine and 3H-haloperidol may clarify mechanisms of drug effects on the dopamine receptor.

Abstract: One of two general classes of molybdoenzymes contains mono— nuclear catalytic sites and effects oxidation or reduction of substrate x/x0 by oxygen atom transfer: X + (0)XO. The reaction LMoO2 + X —3LMo0 + X0 is well established in synthetic systems, and is frequently accompanied by dimerization of Mo(VI,IV) complexes to [LMo(V)0320. A general kinetic analysis allowing determination of oxotransfer rate constants in systems with p—oxo dimer formation is out— lined. EXAFS results for several enzymes indicate the minimal coordi— nation spheres Mo(VI)02(SR)2 and Mo(IV)0(SR)3 for oxidized and fully reduced forms, respecti'vely. In a synthetic approach to these sites, the ligand pyridine—2,6—bis(1 , 1—diphenylethanethiol) (L-N(SH)2) was prepared. Reaction with MoO 2(acac)2 afforded the 5-coordinate trigonal bipyramidal complex Mo02(L-NS2), which was converted to MoO(L-NS 2 (DMF) with Ph3 P in DMF • In this and other oxo-transfer reactions of these complexes, the gem—diphenyl groups sterically suppress dimerization to a OMo(V)-0-Mo(V)0 complex. This reaction is blocked in enzymes by protein structural constraints. MoO(L—NS2)(DMF) and Me2SO react to produce Mo02(L-NS2) and Me25. Substrate saturation kinetics are observed at sufficient Me2SO concentrations. The two reactions were coupled to generate a catalytic sulfoxide reduction/phosphine oxidation cycle. In a related reaction, d—biotin—d—sulfoxide is reduced by MoO(L-NS2)(DMF) to d-biotin. Inasmuch as d-biotin-d-sulfoxide reductase is a Mo cofactor—dependent enzyme, this reaction provides a meaningful model for an enzymatic oxo—transfer reaction • Kinetic data for various oxo—transfer reactions are presented and their relevance to enzymatic processes is discussed. INTRODUCTION Molybdenum—containing enzymes are of two types: nitrogenases (1—6), which catalyze the reduction of dinitrogen to ammonia, and oxo—transfer enzymes (2,3,7,8), which catalyze what is in effect the transfer of oxygen atoms from or to the substrates X/XO. The latter transformations may be written most simply as reaction [1] or, to emphasize the two—electron nature of the overall processes, as the half—reaction [2]. Representative molybdoenzymes of X+(O) xO [1] X+H20 ± XO+2H++2e [2] the oxo-transfer type are listed in Table 1 • For sulfite oxidase and xanthine oxidase/ dehydrogenase in particular, abundant evidence has demonstrated that a mononuclear Mo coordination unit is the catalytic site. In addition to this site, every enzyme that has been at least partially characterized contains one or more prosthetic groups (heme, flavin, Fe—S cluster) capable of electron storage and transfer. Both nitrogenase and oxo-transfer molybdoenzymes contain dissociable cofactors that are obligatory for catalytic activity but which, except for containing all the molybdenum in a given enzyme, are chemically unrelated. The cofactor of nitrogenase is a Mo—Fe—S cluster of incompletely defined composition and structure (9, 10). The cofactor (Mo—co) of oxo—transfer enzymes (11) is not yet well characterized but has been shown to contain a pterin nucleus carrying a potentially coordinating side chain. Certain leading results of the Duke group (12-14) bearing on the structure of Mo-co from several enzymes are schematically illustrated in Fig. 1. Denaturation of sulfite oxidase and xanthine dehydrogenase from chicken liver and Chlorella nitrate reductase with 6 M guanidine HC1 in the presence of KI and 12 led to dissociation of the same fluorescent species (form A). When denaturation was performed in boiling pH 2.5 solution, a different fluorescent species (form B) was released. The permanganate