RESUMO
BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most frequent cancer in childhood. Although intensive chemotherapy has improved survival in those patients, important side effects, including hyperbilirubinemia, are frequent. Gilbert syndrome (GS) is a frequent condition that causes a reduction in glucuronidation and intermittent hyperbilirubinemia episodes. This could provoke a greater exposure to some cytotoxic agents used in ALL, increasing the risk of toxicity. On the other hand, unexplained hyperbilirubinemia could lead to unnecessary modifications or even treatment withdrawals, which could increase the risk of relapse, but data regarding this in ALL pediatric population are scarce. METHODS: Retrospective study to analyze toxicity, outcome and treatment modifications related to GS in children diagnosed with ALL. RESULTS: A total of 23 of 159 patients were diagnosed with GS. They had statistically higher hyperbilirubinemias during all treatment phases (P < 0.0001) and a slower methotrexate clearance when it was administered during a 24-hr infusion at high doses (patients with GS: 74 hr ± 19 vs. patients without GS: 64 hr ± 8; P < .002). However, no relevant toxicity or delays in treatment were found in them. Finally, changes in treatment due to hyperbilirubinemia were only done in 5 patients with GS. CONCLUSIONS: Differences in outcome were not found in patients with GS. Universal screening for GS appears to be not necessary in pediatric patients with ALL. However, when hyperbilirubinemia is observed, it must be rule out in order to avoid unnecessary changes in treatment.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Análise Mutacional de DNA/estatística & dados numéricos , Doença de Gilbert/tratamento farmacológico , Glucuronosiltransferase/genética , Hiperbilirrubinemia/diagnóstico , Mutação/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Adolescente , Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Criança , Pré-Escolar , Feminino , Seguimentos , Doença de Gilbert/genética , Doença de Gilbert/mortalidade , Humanos , Hiperbilirrubinemia/induzido quimicamente , Hiperbilirrubinemia/genética , Lactente , Recém-Nascido , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida , Distribuição TecidualRESUMO
The coronavirus disease 2019 (COVID-19) outbreak has had a major impact on medical and surgical activities. A decline in facial trauma incidence was noticed during the lockdown period. The aim of this study was to evaluate the decline in maxillofacial trauma in France during this particular period. A retrospective multicentre comparative study was initiated in 13 major French public hospital centres. The incidence of facial trauma requiring surgery during the first month of lockdown was compared to that during equivalent periods in 2018 and 2019. Differences in the types of trauma were also analysed. Thirteen maxillofacial departments participated in the study. A significant decline in maxillofacial trauma volumes was observed when compared to equivalent periods in 2018 and 2019 (106 patients compared to 318 and 296 patients, respectively), with an average reduction of 65.5% (P=0.00087). The proportion of trauma due to sports and leisure was reduced when compared to reports in the literature. As a consequence, in the context of a pandemic, the material and human resources related to this activity could be reallocated to the management of other pathologies that cannot be postponed.
Assuntos
COVID-19 , Traumatismos Maxilofaciais , Controle de Doenças Transmissíveis , França/epidemiologia , Humanos , Traumatismos Maxilofaciais/epidemiologia , Estudos Retrospectivos , SARS-CoV-2RESUMO
Over 1,500 cystic fibrosis transmembrane conductance regulator (CFTR) gene sequence variations have been identified in patients with cystic fibrosis (CF) and related disorders involving an impaired function of the CFTR chloride channel. However, detailed structure-function analyses have only been established for a few of them. This study aimed evaluating the impact of eight N-terminus CFTR natural missense changes on channel behavior. By site-directed mutagenesis, we generated four CFTR variants in the N-terminal cytoplasmic tail (p.P5L, p.S50P, p.E60K, and p.R75Q) and four in the first transmembrane segment of membrane-spanning domain 1 (p.G85E/V, p.Y89C, and p.E92K). Immunoblot analysis revealed that p.S50P, p.E60K, p.G85E/V, and p.E92K produced only core-glycosylated proteins. Immunofluorescence and whole cell patch-clamp confirmed intracellular retention, thus reflecting a defect of CFTR folding and/or trafficking. In contrast, both p.R75Q and p.Y89C had a glycosylation pattern and a subcellular distribution comparable to the wild-type CFTR, while the percentage of mature p.P5L was considerably reduced, suggesting a major biogenesis flaw on this channel. Nevertheless, whole-cell chloride currents were recorded for all three variants. Single-channel patch-clamp analyses revealed that the channel activity of p.R75Q appeared similar to that of the wild-type CFTR, while both p.P5L and p.Y89C channels displayed abnormal gating. Overall, our results predict a major impact of the CFTR missense variants analyzed, except p.R75Q, on the CF phenotype and highlight the importance of the CFTR N-terminus on channel physiology.
Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/fisiologia , Mutação de Sentido Incorreto , Sequência de Aminoácidos , Animais , Linhagem Celular , Regulador de Condutância Transmembrana em Fibrose Cística/química , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Imunofluorescência , Glicosilação , Humanos , Dados de Sequência Molecular , Técnicas de Patch-Clamp , Dobramento de Proteína , Homologia de Sequência de Aminoácidos , Frações Subcelulares/metabolismoRESUMO
INTRODUCTION: The omental free flap is an effective tool for craniofacial reconstruction. However it is generally under-utilised by a large number of practitioners. This paper's goal is to increase awareness of this free flap's accessibility and to demonstrate that it can be an attractive option for reconstructive surgery. CLINICAL REPORT: This article outlines the details of a 57-year-old patient who required coverage of a fronto-parietal wound with dura mater exposure. After previous failed conventional free flap attempts, a procedure using the omental free flap was finally performed on this severe wound. The omentum was harvested via a 8cm laparotomy and anastomosed to the temporal vessels. The final result was successful, with a favorable aesthetic result. DISCUSSION: The omental free flap has many advantages: the pedicle length is long, it allows coverage of a large wound, it can be applied to a wound bed previously irradiated and infected, it has a low morbidity rate to the donor site, the surgical technique of harvesting is easy, the aesthetic result is satisfactory. However, the absence of skin slice is a disadvantage of the omental free flap because it makes monitoring difficult and it requires a skin graft in a second procedure. Laparoscopic harvest of omentum free flaps is a safe and effective tool in the reconstructive armamentarium. Every maxillofacial and plastic surgeon should aim to master and use this method as a legitimate option in some infrequent but appropriated cases.
Assuntos
Retalhos de Tecido Biológico , Laparoscopia , Estética Dentária , Humanos , Pessoa de Meia-Idade , Omento , Transplante de PeleRESUMO
INTRODUCTION: New generation osmotic gradient ektacytometry has become a powerful procedure for measuring red blood cell deformability and therefore for the diagnosis of red blood cell membrane disorders. In this study, we aim to provide further support to the usefulness of osmotic gradient ektacytometry for the differential diagnosis of hereditary spherocytosis by measuring the optimal cutoff values of the parameters provided by this technique. METHODS: A total of 65 cases of hereditary spherocytosis, 7 hereditary elliptocytosis, 3 hereditary xerocytosis, and 171 normal controls were analyzed with osmotic gradient ektacytometry in addition to the routine red blood cell laboratory techniques. The most robust osmoscan parameters for hereditary spherocytosis diagnosis were determined using receiver operating characteristic curve analysis. RESULTS: The best diagnostic criteria for hereditary spherocytosis were the combination of decreased minimal elongation index up to 3% and increased minimal osmolality point up to 5.2% when compared to the mean of controls. Using this established criterion, osmotic gradient ektacytometry reported a sensitivity of 93.85% and a specificity of 98.38% for the diagnosis of hereditary spherocytosis. CONCLUSION: Osmotic gradient ektacytometry is an effective diagnostic test for hereditary spherocytosis and enables its differential diagnosis with other red blood cell membrane diseases based on specific pathology profiles.
Assuntos
Deformação Eritrocítica , Membrana Eritrocítica/metabolismo , Citometria de Fluxo/instrumentação , Citometria de Fluxo/métodos , Esferocitose Hereditária/sangue , Esferocitose Hereditária/diagnóstico , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Doença Crônica , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , OsmoseRESUMO
PURPOSE: To study the presence of inwardly rectifying K(+) (Kir) channels in cultured bovine (BTM) and human (HTM) trabecular meshwork cells. METHODS: Cultures of BTM and HTM cells were obtained by an extracellular matrix digestion technique. Whole-cell patch-clamp recordings of BTM cells were performed with the appropriate solutions to detect K(+) currents. Also, Western blot analysis of Kir2.1 protein expression was performed on both cultured BTM and HTM cells. RESULTS: A strong inwardly rectifying current at negative potentials to the equilibrium potential for K(+) (E(K+)) and highly selective for K(+) was detected in 60% of cultured BTM cells. The slope conductance of the inward rectification was more pronounced when the extracellular [K(+)] was increased and was proportional to [K(+)](0.45). The current was blocked by Ba(2+) and Cs(+) in a voltage- and concentration-dependent manner, with K(d) at 0 mV, of 74.7 microM and 45.6 mM, respectively. Current amplitude was reduced by increasing extracellular [Ca(2+)]. The current was insensitive to 10 microM glibenclamide and 10 nM tertiapin. The application of 100 microM 8-Br-cAMP reduced the current by 50%. Kir2.1 channel expression was detected in confluent monolayers of BTM and HTM cells by Western blot analysis. CONCLUSIONS: A population of cultured BTM cells expressed an inwardly rectifying K(+) current that illustrates the biophysical and pharmacologic characteristics of the detected Kir2.1 channel protein. Kir2.1 channels are also thought to be present in HTM cells. Kir2.1 channels could be related to TM physiology, because they are involved in contractile and cell volume regulatory responses, two mechanisms that modify TM permeability.
Assuntos
Canais de Potássio Corretores do Fluxo de Internalização , Canais de Potássio/metabolismo , Malha Trabecular/metabolismo , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Animais , Bário/farmacologia , Western Blotting , Cálcio/farmacologia , Bovinos , Células Cultivadas , Césio/farmacologia , Relação Dose-Resposta a Droga , Humanos , Técnicas de Patch-Clamp , Potássio/metabolismo , Bloqueadores dos Canais de Potássio , Malha Trabecular/citologia , Malha Trabecular/efeitos dos fármacosRESUMO
PURPOSE: To analyze the influence of time of storage, the presence of albumin at physiological concentrations, and the perfusion with anisosmotic media on the aqueous humor outflow facility (C) of isolated bovine anterior segments (AS). METHODS: Anterior segments dissected from cow eyes were perfused at a constant pressure of 10 mm Hg with Dulbecco's modified Eagle's medium (DMEM; osmolality 300 mOsm/kg), with hyposmotic media (150, 210, and 270 mOsm/kg), or with hyperosmotic media (360, 420, and 480 mOsm/kg). Outflow facility was calculated every 5 seconds as the ratio between average inflow from the reservoir (in microliters per minute) and the perfusion pressure (in millimeters of mercury). Three groups were studied: a 0-hour group, with AS perfused with DMEM 1 to 3 hours after enucleation; a 0-hour alb-group, with AS perfused with DMEM plus 0.1 mg/ml albumin 1 to 3 hours after enucleation; and a 24-hour group, with AS perfused after storage for 24 hours in DMEM. In the 0-hour groups, perfusion with increasingly hyposmotic or hyperosmotic media was also made in 30-minute steps, followed by a return to isosmotic medium for 90 minutes. RESULTS: Perfusion of AS with DMEM for 9 hours caused a progressive increase in C that was statistically significant at 225 minutes in the 0-hour group perfused with DMEM and at 195 minutes in the 24-hour group perfused with DMEM. The 0-hour alb-group perfused with DMEM did not show changes in C throughout the 9-hour perfusion period. Perfusion with increasingly hyposmotic media induced a progressive decrease in C that did not recover on return to isotonic medium. Hyperosmotic media caused a progressive increase in C that returned to control values when isotonic medium was again perfused. CONCLUSIONS: Preservation of tissue for C measurements is best achieved with short storage time (1 to 3 hours). Physiological concentrations of albumin (0.1 mg/ml) prevent development of washout, suggesting that albumin or an albumin-bound factor in aqueous humor may play a role in the maintenance of outflow resistance. Outflow facility also may be influenced by volume changes in the trabecular meshwork.
Assuntos
Segmento Anterior do Olho/fisiologia , Humor Aquoso/metabolismo , Preservação de Órgãos , Soroalbumina Bovina/administração & dosagem , Animais , Bovinos , Soluções Hipertônicas/administração & dosagem , Soluções Hipotônicas/administração & dosagem , Concentração Osmolar , Perfusão , Fatores de Tempo , Malha Trabecular/fisiologiaRESUMO
PURPOSE: To investigate the effects of bradykinin (BK) on the outflow facility (C) of human and bovine perfused anterior segments, the [Ca2+]i of cultured bovine trabecular meshwork (BTM) cells, and the area and major axis of BTM cells. METHODS: Cellular studies were performed using first- through third-passage cultures of BTM cells. For [Ca2+]i and shape change assessment, BTM cells were loaded with fura-2 acetoxymethyl ester, and individual fluorescence images were analyzed after the different experimental manipulations. C studies were performed in vitro using human and bovine anterior segments perfused at constant pressure. RESULTS: Bradykinin at 10(-6) M elicited a [Ca2+]i increase of 8 to 10 times the basal levels in 90% of the studied cells. From the responder cells, 60% elicited a 15%+/-1% reduction of the initial cell area, and 37% showed a 13%+/-2% reduction of their major axis. Bradykinin failed to induce any effect in the presence of the BK-B2 receptor antagonist HOE-140. Zero [Ca2+]o the depletion of intracellular stores with thapsigargin, or the presence of the calmodulin antagonist W13, decreased the BK response significantly (P < 0.001; P < 0.001; and P < 0.05). A second application of BK elicited a significantly lower (P < 0.001) response than the previous one. Perfusion with 10(-6) M BK decreased CD, calculated as the area under the curve, by 13%+/-4% (P < 0.05) in human anterior segments and 12%+/-4% (P < 0.05) in bovine anterior segments. The presence of 10(-6) M HOE-140, a BK-B2 receptor antagonist, completely blocked the decrease in C after perfusion with BK. CONCLUSIONS: The C of human and bovine trabecular meshwork (perfused anterior segments) is decreased by BK, acting through BK-B2 receptors. Primary cultured BTM cells respond to BK stimulation by increasing their [Ca2+]i by mobilization of extracellular and intracellular Ca2+. Moreover, these cells are reduced in area and their major axis shortened after the [Ca2+]i peak elicited by BK through BK-B2 receptors. The [Ca2+]i mobilization and shape changes are calmodulin dependent. Taking into account the [Ca2+]i mobilization, the BTM shape changes, the decrease of C, and the temporal sequence of these parameters, a contraction of trabecular meshwork cells related to the functional role of trabecular meshwork is discussed.
Assuntos
Humor Aquoso/metabolismo , Bradicinina/farmacologia , Malha Trabecular/efeitos dos fármacos , Idoso , Idoso de 80 Anos ou mais , Animais , Bradicinina/análogos & derivados , Antagonistas dos Receptores da Bradicinina , Cálcio/metabolismo , Calmodulina/antagonistas & inibidores , Bovinos , Tamanho Celular/efeitos dos fármacos , Células Cultivadas , Fura-2/metabolismo , Humanos , Perfusão , Sulfonamidas/farmacologia , Malha Trabecular/citologia , Malha Trabecular/metabolismoRESUMO
Empirical potential structure refinement (EPSR) simulations are performed on total neutron scattering data from powder samples of polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE), both at 300 K. Starting from single strands of polymer consisting of between 30 and 60 monomers of tetrafluoroethylene and chlorotrifluoroethylene in each case, hexagonal simulation cells are constructed consisting of an array 25 (5×5) such strands placed on a hexagonal lattice. Allowed simulation moves are polymer translation moves along all three Cartesian axes, whole polymer rotations about the polymer axis, and individual atom moves within each polymer. For PTFE a number of Bragg peaks are visible in the scattering data and these are found to be consistent with a lattice spacing a(=b) = 5.69(1) Å with a dihedral angle along the (helical) chain of 166° which gives a repeat distance along the chain (c-axis) of ~19.6 Å. The positions of the Bragg peaks are well reproduced by this model, although there is a mismatch in the amplitudes of some of the higher order reflections between simulation and data. For PCTFE there is only one visible Bragg peak (100) which is well reproduced by a hexagonal lattice of atactic parallel polymers with a spacing of a(=b) = 6.37(1) Å. In this case the absence of distinct reflections along the polymer c-axis makes characterization of the internal dihedral angle difficult, but a model with a dihedral angle of 166° was less successful at fitting the diffuse scattering than a model where this angle was set to 180°, giving a nearly straight trans (zig-zag) structure. For PCTFE little change in structure could be discerned when the material was heated to 550 K, apart from a slight increase in lattice spacing. In both cases there is substantial diffuse scattering between the Bragg peaks, and this is correctly replicated by the EPSR simulations.
RESUMO
The effect of oxygen content on magnetic properties in the multiferroic YMn(2)O(5+δ) system was investigated with samples prepared under different oxygen pressures. Our results show that, with increasing oxygen content, the magnetic response changes from being dominated by the anomaly at â¼45 K to the one around 20 K. However, specific heat measurements and neutron powder diffraction studies indicate that the presence of the magnetic transition at â¼45 K is independent of oxygen content. The results suggest that oxygen nonstoichiometry can be one important degree of freedom in manipulating the multiferroic properties.
RESUMO
Oxygen-stoichiometric La(9.33) square(0.67)(Si(6)O(24))O2 and oxygen-excess La(8.65)Sr(1.35)(Ge(6)O(24))O(2.32) and La(8.65)Sr(1.35)(Si(6)O(24))O(2.32) oxy-apatites have been structurally characterized at low temperatures by the Rietveld method. Oxygen-interstitial distribution has been studied at 15 K for La(9.33) square(0.67)(Si(6)O(24))O2 and La(8.65)Sr(1.35)(Ge(6)O(24))O(2.32) by time-of-flight neutron powder diffraction and at 4 K for La(8.65)Sr(1.35)(Si(6)O(24))O(2.32) by constant-wavelength neutron powder diffraction. The low temperature structural study was undertaken in order to distinguish between the effects of static disorder, originated mainly from the presence of interstitial oxygens, and the anisotropic thermal vibrations. At such low temperatures, the influence of the anisotropic thermal vibrations is minimised. This structural study has firmly established the existence of interstitial oxygens in these materials, which may be useful as electrolytes for solid oxide fuel cells.
RESUMO
The effect of the average R-site ionic radius IR and variance on the orbital and magnetic order in R3+-doped YVO3 was studied in Y1-xLaxVO3 and Y1-x(La0.2337Lu0.7663)xVO3 with fixed IR. The orbital flipping temperature T{CG} increases nonlinearly with increasing R-site variance, indicating that the V-O-V bond angle is not the primary driving force stabilizing the C-type orbitally ordered phase. The suppressed thermal conductivity in the G-type orbitally ordered phase signals some remaining orbital randomness that is enhanced by t{2} and et hybridization in {3}T{1g} site symmetry.
RESUMO
The heavy fermion system exhibits properties that range from an incommensurate antiferromagnet for small to an exotic superconductor on the Ir-rich end of the phase diagram. At intermediate where antiferromagnetism coexists with superconductivity, two types of magnetic order are observed: the incommensurate one of and a new, commensurate antiferromagnetism that orders separately. The coexistence of -electron superconductivity with two distinct -electron magnetic orders is unique among unconventional superconductors, adding a new variety to the usual coexistence found in magnetic superconductors.
RESUMO
Several iron complexes [FeII(bpy)2(2+), FeII(OPPh3)4(2+), and FeII(PA)2] in combination with hydrogen peroxide (HOOH) catalytically hydroxylate aromatic substrates (ArH). The base-induced nucleophilic addition of HOOH to the electrophilic iron center yields the reactive intermediate of Fenton reagents [FeIILx2+ + HOOH<-->Lx+FeIIOOH(BH+)(1)]. The latter includes a 'stabilized' hydroxyl radical that is able to replace an aromatic hydrogen (H) with a hydroxyl group (HO) via an initial addition reaction. With PhCH3 and PhCH2CH3 as substrates free HO. (from the radiolysis of H2O) reacts via aryl addition (97 and 85%, respectively) to give Ar-Ar as the predominant product, whereas 1 favors H-atom abstraction from the alkyl group (50 and 80%, respectively) and the only detectable products from aryl addition are the respective substituted phenols (o:p-ArOH). Other substituted benzenes (PhX) undergo addition by free HO at the ortho and para aryl carbons (o:p ratio, 2), followed by dimerization and elimination of two H2O molecules to yield substituted biphenyls. In contrast, 1 reacts with PhX to yield substituted phenol (ArOH; o:p ratio, 0.5-1.1). With phenol (PhOH) as the substrate, reaction with 1 yields mainly catechol (o-Ar(OH)2; o:p ratio, 20). In a solvent matrix of MeCN:H2O (3:1 mol:mol ratio) the reaction efficiencies with FeII(bpy)2(2+) and FeII(OPPh3)4(2+) for the hydroxylation of benzene to phenol are 36 and 42%, respectively (product per HOOH).
Assuntos
Hidrocarbonetos/química , Peróxido de Hidrogênio/química , Ferro/química , Benzeno/química , Radical Hidroxila , Hidroxilação , Indicadores e Reagentes , Cinética , SolventesRESUMO
Authors present a new and complete from of EEC syndrome (ectrodactyly, ectodermal dysplasia and cleft lip-palate), analysing its' clinical, genetic and therapeutic aspects. Syndrome malformations involving mainly mesenchymal tissue and with diverse clinical expression suggest a heterogenetic heredity. Participation of environmental and unknown factors is not excluded.
Assuntos
Fissura Palatina/genética , Displasia Ectodérmica/genética , Sindactilia/genética , Fissura Palatina/complicações , Displasia Ectodérmica/complicações , Feminino , Pé/diagnóstico por imagem , Mãos/diagnóstico por imagem , Humanos , Lactente , Sindactilia/complicações , Sindactilia/diagnóstico por imagem , Síndrome , UrografiaRESUMO
The host-guest interactions between ortho- (Ph), pyro- (Pp), and tripolyphosphate (Tr) anions together with ATP (At), ADP (Ad), and AMP (Am) nucleotides and the two hexaazamacrocyclic ligands 1,15-dioxa-4,8,12,18,22,26-hexaazacyclooctacosane (Pn) and 1,13-dioxa-4,7,10,16,20,24-hexaazacyclohexacosane (Op) have been investigated by potentiometric equilibrium methods. Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic attraction between the host and the guest. Formation constants for all the species obtained are reported. The selectivity of the Pn and Op ligands with regard to the different phosphate and nucleotide substrates is discussed and illustrated with total species distribution diagrams. A comparison is also carried out, with the results obtained in this work and those obtained previously with three other closely related hexaazamacrocyclic ligands. This comparison manifests the importance of ligand basicity, rigidity, and pi-stacking capability in order to understand their binding and selectivity.
Assuntos
Compostos Aza/química , Nucleotídeos/química , Fosfatos/química , Éteres/química , Ligantes , Espectroscopia de Ressonância MagnéticaRESUMO
The host-guest interactions between ortho- (Ph), pyro- (Pp), and tripolyphosphate (Tr) anions together with ATP (At), ADP (Ad), and AMP (Am) nucleotides and the hexaazamacrocyclic ligand 3,7,11,19,23,27-hexaazatricyclo[27311(13,17)]triaconta- 1(32),13,15,17(34),29(33),30-hexaene (Bn) have been investigated by potentiometric equilibrium methods. Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic attraction between the host and the guest. Formation constants for all the species obtained are reported. The selectivity of the Bn ligand with regard to the phosphate and nucleotide substrates is discussed and illustrated with species distribution diagrams. A comparison of the present results with those obtained for the similar but smaller macrocyclic ligand 3,6,9,17,20,23- hexaazatricyclo[23311(11,15)]triaconta-1(29),11(30),12,14,25,27-hexaene (Bd) is also discussed. It is found that the competition of the Bd and Bn ligands for the formation of ternary species with a specific substrate is strongly dependent on the p[H]. The crystal structure of the compound [(H6Bn)(H2PO4)6]2H2O with empirical formula C28H68N6O26P6 has been solved by means of X-ray diffraction analysis. The compound belongs to the triclinic P1 space group with Z = 1, a = 8892(2) A, b = 9369(4) A, c = 16337(8) A, alpha = 7372(4) degrees, beta = 8301(4) degrees, and gamma = 6481(3) degrees. The phosphate counterions are found to bridge adjacent layers of macrocyclic molecules through an extensive hydrogen-bonding network
RESUMO
We have prepared a new family of ruthenium complexes containing the bpea ligand (where bpea stands for N,N-bis(2-pyridyl)ethylamine), with general formula [Ru(bpea)(bpy)(X)](n+) (2, X = Cl(-); 3, X = H(2)O; 4, X = OH(-)), and the trisaqua complex [Ru(bpea)(H2O)(3)](2+), 6. The complexes have been characterized through elemental analyses, UV-vis and (1)H NMR spectroscopy, and electrochemical studies. For complex 3, the X-ray diffraction structure has also been solved. The compound belongs to the monoclinic P2(1)/m space group, with Z = 2, a = 7.9298(6) A, b = 18.0226(19) A, c = 10.6911(8) A, and beta = 107.549(8) degrees. The Ru metal center has a distorted octahedral geometry, with the O atom of the aquo ligand placed in a trans position with regard to the aliphatic N atom of the bpea ligand so that the molecule possesses a symmetry plane. NMR spectra show that the complex maintains its structure in aqueous solution, and that the corresponding chloro complex also has a similar structural arrangement. The pH dependence of the redox potential for the complex [Ru(bpea)(bpy)(H2O)](PF(6))(2) is reported, as well as the ability of the corresponding oxo complex to catalyze the oxidation of benzylic alcohol to benzaldehyde in both chemical and electrochemical manners.