Heteroleptic Ruthenium(II) Complexes with 2,2'-Bipyridines Having Carbonitriles as Anchoring Groups for ZnO Surfaces: Syntheses, Physicochemical Properties, and Applications in Organic Solar Cells.

Heteroleptic ruthenium (II) complexes were used for sensitizing ZnO surfaces in organic solar cells (OSCs) as mediators with photoactive layers. The complexes [Ru(4,4'-X2-bpy)(Mebpy-CN)2]2+ (with X = -CH3, -OCH3 and -N(CH3)2; bpy = 2,2'-bipyridine; Mebpy-CN = 4-methyl-2,2'-bipyridine-4'-carbonitrile) were synthesized and studied by analytical and spectroscopical techniques. Spectroscopic, photophysical, and electrochemical properties were tuned by changing the electron-donating ability of the -X substituents at the 4,4'-positions of the bpy ring and rationalized by quantum mechanical calculations. These complexes were attached through nitrile groups to ZnO as interfacial layer in an OSC device with a PBDB-T:ITIC photoactive layer. This modified inorganic electron transport layer generates enhancement in photoconversion of the solar cells, reaching up to a 23% increase with respect to the unsensitized OSCs. The introduction of these dyes suppresses some degradative reactions of the nonfullerene acceptor due to the photocatalytic activity of zinc oxide, which was maintained stable for about 11 months. Improving OSC efficiencies and stabilities can thus be achieved by a judicious combination of new inorganic and organic materials.

Síndrome DRESS / DRESS syndrome

Resumen: El síndrome DRESS es un reacción de hipersensibilidad a fármacos severa e idiosincrásica, caracterizada por exantema, fiebre, adenopatías, alteraciones hematológicas y afectación de varios órganos. La heterogeneidad de la manifestación clínica representa un desafío diagnóstico para el médico clínico, se requiere alto índice de sospecha y descartar un amplio espectro de diagnósticos diferenciales. Las reacciones cutáneas asociadas con fármacos pueden ser cuadros potencialmente mortales, el diagnóstico oportuno puede modificar el pronóstico del paciente. Describimos el cuadro clínico y tratamiento de un paciente de 15 años con insuficiencia renal crónica que fue hospitalizado por lesiones morbiliformes generalizadas concomitantes con fiebre, linfadenopatías, esplenomegalia y eosinofilia. Descartar procesos infecciosos, autoinmunitarios y neoplásicos fue posible con estudios complementarios; el antecedente de ingestión reciente de alopurinol y los datos clínicos y de laboratorio permitieron establecer el diagnóstico definitivo de síndrome DRESS. El paciente recibió corticoesteroides tópicos y sistémicos, las manifestaciones clínicas revirtieron a partir de la segunda semana de hospitalización. Se insiste en la importancia de la identificación de factores de riesgo asociados con la aparición de este síndrome.

Abstract: Dress syndrome is a severe and idiosyncratic reaction of hypersensitivity to drugs, characterized by rash, fever, lymphadenopathy, hematological alterations and systemic compromise, the heterogeneity of the clinical presentation represents a diagnostic challenge for the clinician, a high clinical suspicion is required and the need to rule out a wide spectrum of differential diagnoses. Cutaneous reactions associated with drugs can be potentially fatal, early diagnosis can modify the patient's prognosis. We describe the clinical case and treatment of a 15-year-old male patient with chronic renal failure who was hospitalized for generalized morbilliform lesions associated with fever, lymphadenopathy, splenomegaly and eosinophilia. Complementary studies ruled out infectious, autoimmune and neoplastic processes; the antecedent of recent intake of allopurinol together with clinical and laboratory data allowed to establish a definitive diagnosis of DRESS syndrome. Patient received topical and systemic corticosteroids, clinical manifestations reverted from the second week of hospitalization. We emphasize the importance of identifying risk factors associated with the development of this syndrome.

Improving the photosensitizing properties of ruthenium polypyridyl complexes using 4-methyl-2,2'-bipyridine-4'-carbonitrile as an auxiliary ligand.

We report in this work the synthesis and spectroscopic, electrochemical, spectroelectrochemical, and photophysical characterization of a novel series of ruthenium polypyridyl complexes with 4-methyl-2,2'-bipyridine-4'-carbonitrile (Mebpy-CN) as an auxiliary ligand of general formula [Ru(bpy)3-x(Mebpy-CN)x](PF6)2 (x = 1-3) (with bpy = 2,2'-bipyridine). A significant increase in the lifetime and quantum yield of emission of the lowest (3)MLCT excited state is disclosed when going from x = 1 to x = 3, evidencing an improvement of the photosensitizing properties with respect to [Ru(bpy)3](PF6)2. Furthermore, quenching by molecular oxygen of (3)MLCT excited states of the three complexes produced singlet molecular oxygen ((1)O2) with quantum yield values higher than that of [Ru(bpy)3](2+) in CH3CN. The structure of the complex with x = 1 has been determined by X-ray diffraction. The photoconductivity of ZnO nanowires covered with this same complex is increased by an order of magnitude, pointing to its feasibility as a component of a DSSC. A new dinuclear complex with Mebpy-CN as a bridging ligand has also been prepared and characterized by physicochemical techniques. The derived mixed-valent species of formula [(bpy)2Ru(II)(Mebpy-CN)Ru(III)(NH3)5](5+) displays a considerable metal-metal electronic coupling due to the delocalization effect of a nitrile group in the 4' position of the bpy ring.

Dependence of the broad frequency dielectric spectra of colloidal polystyrene particle suspensions on the difference between the counterion and co-ion diffusion coefficients.

Dielectric properties of four suspensions of spherical polystyrene particles were measured at 25 degrees C over a broad frequency range extending from 100 Hz to 10 MHz, using a HP 4192 A Impedance Analyzer. The instrument was coupled to a cell with parallel platinum black electrodes and variable spacing, and the quadrupole calibration method was used. The aqueous electrolyte solutions were prepared using equal concentrations of NaCl, KCl, NaAc, or KAc, so that the calculated Debye screening length and Zeta potential remained constant, while the conductivity changed. The polystyrene particles used (Interfacial Dynamics Corp., surfactant-free white sulfate latex) have a diameter of 1 micron and a surface charge density that is independent of the pH. The dielectric spectra were described using the Nettelblad-Niklasson expression combined with a Debye type high-frequency term and analyzed using the Shilov-Dukhin theory and numerical results. The theoretical prediction that the low-frequency dispersion parameters are determined by the co-ion diffusion coefficient was experimentally confirmed. This also allowed to justify an alternative definition of the characteristic time of the low-frequency dispersion. On the contrary, the prediction that the high-frequency dispersion parameters are determined by the diffusion coefficient of counterions could not be confirmed, possibly due to experimental problems. However, the zeta-potential values deduced from high-frequency data were compatible with values deduced from electrophoretic mobility measurements.

Comparative analysis of hematocrit measurements by dielectric and impedance techniques.

In a previous paper, a new dielectric technique was used to estimate hematocrit (HTC) in extracorporeal blood circulation systems, independently of plasma conductivity or osmolarity. Although many impedance techniques have been formerly proposed in the literature, none has been evaluated against plasma conductivity and osmolarity. Herein, we estimate HTC based on permittivity changes and also with other four techniques found in the literature. Besides, the error incurred in each is also studied when plasma conductivity and osmolarity changed as much as 1 mS/cm and 50 mOsm/kg, respectively. The dielectric (permittivity) technique has an error close to 5.4%, while the others showed both tendencies, i.e., lower error (2.5%, two of them) and higher error (8.6% and 16.3%, the other two). The dielectric technique, even though did not produce the lowest error, provides a well-described physical model along with simple instrumentation.

Hematocrit measurement by dielectric spectroscopy.

Based on permittivity changes, a new method to measure hematocrit (HCT) in extracorporeal blood systems is presented. Human blood samples were tested at different HCT levels pairing the values of permittivity change, obtained by means of a commercial impedance analyzer, with traditional centrifugation measurements. Data were correlated using both linear and nonlinear regression. When using the lineal model, the comparison yielded a high correlation coefficient (r = 0.99). Theoretical simplifications suggest that the method is independent of changes in the conductivities of the intracellular and extracellular compartments. The influence of osmolarity and conductivity of the extracellular compartment was analyzed. It is shown that HCT can be predicted within an error lower than 5% when those parameters changed as much as 1 mS/cm and 50 mOsm/kg, respectively. Thus, the method appears as valid and viable showing good possibilities in applications such as renal dialysis.