Juan Manuel Manríquez

Selective oxidants for organometallic compounds containing a stabilising anion of highly reactive cations: (3,5(CF3)2C6H3)4B−)Cp2Fe+ and (3,5(CF3)2C6H3)4B−)Cp*2Fe+

A major interest in ferrocenium compounds arises from their usefulness as selective oxidants to prepare mixed-valence metallocenic stable compounds. In this paper, Cp 2 FeBAr′ 4 =((3,5(CF 3 ) 2 C 6 H 3 ) 4 B − )Cp 2 Fe + ) ( a ), and Cp* 2 FeBAr′ 4 =((3,5(CF 3 ) 2 C 6 H 3 ) 4 B − ) Cp* 2 Fe + ) ( b ) are reported. These compounds have wide applications in the obtention of new organometallic salts with improved stability. The selective oxidation capacity of compounds a and b was investigated by the reaction of [Cp*Co II (C 8 H 6 )Fe II (C 8 H 7 )] with stoichiometric quantities of Cp 2 FeBAr′ 4 or Cp* 2 FeBAr′ 4 where [Cp*Co III (C 8 H 6 )Fe II (C 8 H 7 )]BAr′ 4 was exclusively obtained. All salts that have BAr′ 4 − as counterion showed an enhanced solubility in low-polarity solvents, especially in diethyl ether. This fact allowed us to perform non-conventional measurements like cyclic voltammetry in diethyl ether as solvent with NaBAr′ 4 as supporting electrolyte. Single-crystal structural determination of a and b was also achieved.

Synthesis, characterization and computational studies of (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butylphenol

(E)-2-{((2-Aminopyridin-3-yl)imino)-methyl}-4,6-di-tert-butyl-phenol (3), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, 1H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer.

Experimental and theoretical studies of the ancillary ligand (E)-2-((3-amino-pyridin-4-ylimino)-methyl)-4,6-di-tert-butylphenol in the rhenium(I) core

The fac-[Re(CO)3(deeb)L]+ complex (C2) where L is the (E)-2-((3-amino-pyridin-4-ylimino)-methyl)-4,6-di-tert-butylphenol ancillary ligand, which presents an intramolecular hydrogen bond, has been synthesized and characterized using UV-vis, 1H-NMR, FT-IR, cyclic voltammetry and DFT calculations. The UV-vis absorption and emission properties have been studied at room temperature and the results were compared with TDDFT calculations including spin–orbit effects. We report an alternative synthesis route for the fac-Re(CO)3(deeb)Br (C1) complex where deeb = (4,4′-diethanoate)-2,2′-bpy. Besides, we have found that the C1 shows a red shift in the emission spectrum due to the nature of the ancillary electron donating ligand, while the C2 complex shows a blue shift in the emission spectrum suggesting that the ancillary ligand L has electron withdrawing ability and the importance of the intramolecular hydrogen bond. The calculations suggest that an experimental mixed absorption band at 361 nm could be assigned to MLCT and LLCT transitions. The electron withdrawing nature of the ancillary ligand in C2 explains the electrochemical behavior, which shows the oxidation of ReI at 1.83 V and the reduction of deeb at −0.77 V.

Theoretical and experimental characterization of a novel pyridine benzimidazole: suitability for fluorescence staining in cells and antimicrobial properties

Benzimidazoles presenting intramolecular hydrogen bonding interactions have been normally used to better understand the role of H-bonding in biological processes. Here, we present an experimental and theoretical study of a new compound [2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol]; (B2), a benzimidazole derivate, exhibiting an intramolecular hydrogen bond. B2 was synthesized and characterized by its 1H, HHCOSY, FT-IR and mass spectra (EI-MS 323 M+). The electronic and optical properties of B2 were studied with theoretical calculations using density functional theory (DFT) and time-dependent DFT (TDDFT). B2 showed luminescent emission at room temperature in different solvents, with a large Stokes shift (e.g.; λex = 335 nm; λem = 510 nm in acetonitrile). Also, the quantum yield (φ = 0.21) and theoretical band emission are reported. We found that B2 exhibited a fluorescence emission at around 500 nm in ethanol and in acetonitrile that could be quenched by aqueous solutions of Hg(NO3)2 in the range of micro molar concentrations. Cyclic voltammetry in acetonitrile showed a strong anodic response due to a quasireversible process, with reduction and oxidation waves at −1.28 and −0.47 V vs. SCE. Regarding the biological properties, we assessed the antimicrobial activity of B2 in Salmonella enterica (bacteria), Cryptococcus spp. (yeast), Candida albicans (yeast), Candida tropicalis (yeast) and Botrytis cinerea (mold). To this end, we determined the minimal inhibitory concentration (MIC) (for bacteria and yeasts), the growth inhibition halos (for yeasts), and the inhibition of mycelial growth (for the mold). We observed that B2 exerted an antifungal effect against Cryptococcus spp. and Botrytis cinerea. In addition, due to its fluorescence properties, B2 has proven to be a suitable marker to observe bacteria (Salmonella enterica and an Escherichia coli derivative), yeasts (Candida albicans), and even human cells (SKOV-3 and HEK-293) by confocal microscopy.

New linked di-germanocenes and di-stannocenes

Abstract New bridged di-germanocenes and di-stannocenes 2 have been synthesized from a reaction between (pentamethylcyclopentadienyl)metal chloride and the dilithium salts of the corresponding linked cyclopentadienyl ligands (spacer: phenylene, biphenylene, thiophene) in good yields. These di-metallocenes react easily with catechol giving preferentially the substitution reaction. With iodine or with metal 14 dichloride (M=Ge, Sn), the oxidative products are unstable and rapidly loose the linked cyclopentadienyl ligand. Starting from SnCl2, the ionic half-sandwich compound [Cp*Ge][SnCl3] 8, so obtained, was characterized by X-ray diffraction analysis which reveals a polymeric form in the solid state. The reaction of the di-germanocenes with o-quinone leads to the expected cycloadducts, stable in the case of permethylated compounds. An unusual single electron transfer reaction takes place with [Cp2Fe][BF4] and the transient cation radical rapidly gives [Cp*Ge][BF4]. Mass spectra measurements and electrochemistry study confirm the weak stability of this cationic species.

Synthesis and characterization of [Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*] and [Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*] BF4−

Abstract [Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*]n+ (Cp*=pentamethylciclopentadiene, n=0, 1), respectively named complexes V and VI, were synthesized and characterized. The X-ray structure has been solved and 1H-, 13C-NMR and elemental analysis were performed for the n=0 complex. Cyclic voltammetry showed a potential difference of 360 mV within the two redox peaks. An absorption band at 850 nm was assigned to an intervalence band. The Mossbauer investigations show a uniform Fe2+ environment for the neutral compound and two sites, assigned to Fe2+ and Fe3+ for the monoxidized compound. The information gathered by all the previously mentioned techniques indicates that the studied binuclear compound belongs to the mixed valence class II using Robin and Day classification.

Eosinophilic annular erythema: complete clinical response with dapsone

dominant pattern have also been reported, and such cases are difficult to differentiate from HBT. The bilateral clinical presentation, presence of telangiectasias, absence of previous trauma, and appearance of the lesions in both twins makes HBT a more likely diagnosis in our two patients. We have found only two reports in the literature of HBT in patients with no family history and none in monochorionic twins.

Effect of the homo- and heterobimetallic compounds derived from s-indacene on the thermal decomposition of ammonium perchlorate

This contribution describes an approaching about the catalytic activity of the homo- and heterobimetallic complexes derived from s-indacene on the thermal decomposition of ammonium perchlorate (abbreviate AP). The complexes, anti-[Cp*Fe-s-Ic′-FeCp*] (1), anti-[Cp*Fe-s-Ic′-CoCp*] (2), anti-[Cp*Fe-s-Ic′-NiCp*] (3) and anti-[Cp*Fe-s-Ic′-Mn(CO)3] (4) (with s-Ic′: 2,6-diethyl-4,8-dimethyl-s-indaceneiide), were compared with the catalytic activity of the catocene (cat) complex previously reported. Furthermore, in order to clarify the mechanism of the bimetallic compounds, it was tested ferrocene (Fc) compound as burning rate (BR) catalyst on the thermal decomposition of AP. These compounds shown a shift on the peak temperature to left and an increase released heats during thermal decomposition of AP. The burning rate catalytic activity of Fc, 1, 2, 3 and 4 on thermal decomposition of AP was examined by thermogravimetry and differential scanning calorimetry techniques.

Skin rash, dyspnea and bone pain: secondary syphilis

A 50-year-old healthy male was seen for a 6-week history of right leg pain, occasional dyspnea and extensive non-pruritic skin rash in trunk and extremities (Fig. 1A). Physical examination revealed tachypnea with normal breath sounds and a non-confluent maculo-papular rash in the trunk and extremities. No adenopathies, mucosal or palmo-plantar lesions were evident. A contrast-enhanced CT scan showed presence of multiple axillary, hilar, and mediastinal lymphadenopathy (Fig. 1B), and bilateral and diffusely distributed pulmonary nodules with ground-glass density (Fig. 1C). Bone scintigraphy showed increased uptake of isotope on the right tibia (Fig. 1D). The Rapid Plasma Reagin test (RPR) was positive in 128 dilutions, with a positive Treponema pallidum microhemagglutination assay. Human immunodeficiency virus and serology of other

Electronic structure and metal–metal communication in (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni) complexes: a DFT investigation

DFT calculations with full geometry optimization have been performed on the series (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni), as well as on the cations of the Fe, Co and Ni complexes. The compounds where M = Fe and Ni (as-indacene series) and M = Mn, Fe and Co (s-indacene series) were found to possess closed-shell ground states. In the mixed-valent cations as well as in the other open-shell species, the degree of metal–metal communication and the participation of the ligand into the spin density were evaluated. In general, the larger the total electron number, the larger the metal–metal communication and ligand participation to the frontier orbitals.