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Use of Cucurbit [6] Uril as a Modifier in the Electrochemical determination of Antitumor Platinum (II) Complex: <i>Trans</i>-[PtCl<sub>2</sub>(Dimethylamine) (Isopropylamine)]. Application to Biological Samples

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American Journal of analytical Chemistry 2013年第6期4卷 314-322页

作者： Carmen S. H. Domínguez Pedro Hernández departamento de química analítica y análisis instrumental Facultad de Ciencias Universidad Autónoma de Madrid Cantoblanco Madrid Spain

A square wave voltammetry (DPV) method for trans-Pt[Cl2(Dimethylamine)(isopropylamine)] determination is developed. To this end, all the chemical and instrumental variables affecting the determination of trans-Pt[Cl2(Dimethylamine) (isopropylamine)] are optimized. From studies of the mechanisms governing the electrochemical response of trans-Pt[Cl2(Dimethylamine)(isopropylamine)], it was concluded that it was an electrochemically reversible system with an adsorptive oxidation phenomenon. Under optimal conditions, the variation of analytical signal (Ip) with trans-Pt[Cl2(Dimethylamine)(isopropylamine)] concentration was linear in the 0.05 μg·mL-1 to 10 μg·mL-1 range, with a LOD 91 μg·mL-1 of and a LOQ of 303 μg·mL-1, a RSD 1.10% and Er 0.72%. The optimized method was applied to the determination of trans-Pt[Cl2(Dimethylamine)(isopropylamine)] in biological fluids, in human urine and synthetic urine.

关键词： Trans-[PtCl2(Dimethylamine)(Isopropylamine)] Differential Pulse Voltammetry (DPV) Square Wave Voltammetry (SWV) Biological Fluids Human Urine

NHC-catalysed[3+2]-asymmetric annulation between pyrazolin-4,5-diones and enals:synthesis of novel spirocyclic pyrazolone γ-butyrolactones and computational study of mechanism and stereoselectivity

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Organic Chemistry Frontiers 2022年第2期9卷 420-427页

作者： Marta Gil-Ordonez Alicia Maestro Pablo Ortega Pablo G.Jambrina Jose M.Andres GIR-SintACat-Instituto Universitario CINquIMA y departamento de química Orgánica Facultad de CienciasUniversidad de ValladolidPaseo Belén 747011 ValladolidSpain departamento de química Física University of Salamanca37008 SalamancaSpain

Chiral pyrazolones with a spirocyclic centre at the C4-position are widely found in a large family of medically relevant *** recent years,organocatalysis,particularly that performed with quiral N-heterocyclic carbenes(NHCs),has allowed the enantioselective synthesis of these spirocyclic compounds despite its inherent *** this work,we describe the fully diastereo-and highly enantioselective synthesis of novel spirocyclic pyrazolone γ-butyrolactones via NHC-catalysed[3+2]annulation reaction of enals and 1H-pyrazol-4,*** understand the catalytic mechanism and origin of stereoselectivity,electronic structure calculations were carried *** considering various pathways,we concluded that the stereoselectivity-determining step is the formation of the lactone that proceeds after addition of the NHC derived homoenolate to the electrophilic carbonyl group of pyrazolin-4,*** calculations predict that the free energy barrier is lower for the(RS)product,which is also the main product experimentally obtained.

关键词： synthesis spiro mechanism

Use of Graphene and Cucurbit[7]uril Electrodes for the determination of Amantadine in Biological Fluids

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American Journal of analytical Chemistry 2015年第7期6卷 623-630页

作者： C. S. H. Domínguez P. Hernández Facultad de Ciencias de la Salud Universidad Estatal de Milagro Milagro Ecuador departamento de química analítica y análisis instrumental Facultad de Ciencias Universidad Autónoma de Madrid Cantoblanco Madrid Spain

A differential pulse voltammetry (DPV) method for amantadine (AT) determination is developed. To this end, all the chemical and instrumental variables affecting the determination of amantadine are optimized. These studies have used three types of glassy-carbon electrode, first electrode which has not undergone surface modification or coating, to then modify the working electrode surface with two kinds of suspensions: graphene and graphene-cucurbit[7]uril (CB[7]). From studies of the mechanisms governing the electrochemical response of amantadine, it was concluded that it is an electrochemically system with a diffusive reduction phenomenon. Under optimal conditions and with the appropriate electrode modification, we proceed to study the relation between the peak intensity with the analyte concentration. Thus, we find that when the electrode surface is covered with graphene-CB[7], two linear sections are obtained, the first one in the concentration range of between 0.05 μg·mL﹣1 and 0.75 μg·mL﹣1;and the second one between 1.00 μg·mL﹣1 and 6.00 μg·mL﹣1, with Er (%) = 87 and R.S.D. = 0.94% (n = 10 at 0.5 μg·mL﹣1 level). The minimum detectable amount was 15 ng·mL﹣1 while a concentration of 44 ng·mL﹣1 was calculated as determination limit. The optimized method was applied to the determination of amantadine in biological fluids.

关键词： Glassy-Carbon Electrode Amantadine Differential Pulse Voltammetry Human Urine

Pyrenetetraone-based covalent organic framework as an effective electrocatalyst for oxygen reduction reaction

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Nano Research 2022年第5期15卷 3907-3912页

作者： Paloma Garcia-Arroyo Emiliano Martinez-Perinan Jorge J.Cabrera-Trujillo Elena Salagre Enrique G.Michel Jose I.Martinez Encarnacion Lorenzo Jose L.Segura departamento de quimica Organica I Facultad de CC.QuimicasUniversidad Complutense de Madrid28040 MadridSpain departamento de quimica analitica y Analisis instrumental Facultad de CienciasUniversidad Autónoma de Madrid28049 MadridSpain departamento de Fisica de la Materia Condensada Universidad Autónoma de Madrid28049 MadridSpain Condensed Matter Physics Center(IFIMAC) Universidad Autónoma de Madrid28049 MadridSpain departamento de Nanoestructuras SuperficiesRecubrimientos y Astrofisica MolecularInstituto de Ciencia de Materiales de Madrid(ICMMCSIC)28049 MadridSpain Instituto Madrileno de Estudios Avanzados en Nanociencia(IMdeA-Nanociencia) 28049 MadridSpain Institute for Advanced Research in Chemical Sciences(IAdChem) Universidad Autonoma de Madrid28049 MadridSpain

A novel porous and crystalline two-dimensional(2D)electrochemically active covalent organic framework(COF)based on ortho-quinone units has been prepared as an innovative approach towards the development of organic cathode materials with multiple redox sites as an efficient electrocatalyst for the oxygen reduction reaction(ORR).In contrast with most of the previously reported COFs as electrocatalysts for the ORR,the electrocatalytic application of this material towards ORR has been investigated without adding any metal or conductive supporting material and avoiding any additional carbonization ***,the electrochemical properties of the COF material have been compared with two analogue amorphous frameworks with similar chemical composition,which points out the important role of the enhanced crystallinity and porosity of the COF network in its superior performance as an electrocatalyst towards ORR.

关键词： electrocatalysis oxygen reduction reaction metal free pyrenetetraone covalent organic framework

Imaging resolution of biocatalytic activity using nanoscale scanning electrochemical microscopy

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Nano Research 2018年第8期11卷 4232-4244页

作者： Jase M .Abad Alvaro y. Tesio EmUiano Martinez-Perinan Felix Pariente Encamacion Lorenzo departamento de qufmica analftica y Andlisis instrumental Universidad Aut6noma de Madrid Cantoblanco 28049 Madrid Spain Centro de Investigaci6n y desarrollo en Materiales Avanzados y Almacenamiento de Energfa de Jujuy-CIDMEJu (CONICET-UniversidadNacional de Jujuy) Centro de Desarrollo Tecnol6gico General Savio Av. Martijena s/n 4612-Palpald Jujuy Argentina Instituto Madrileno de Estudios Avanzados en Nanociencia (IMdeA-Nanociencia) Campus UAM Cantoblanco 28049 Madrid Spain

Scanning electrochemical microscopy represents a powerful tool for electro（chemical） characterization of surfaces, but its applicability has been limited in most cases at microscale spatial resolution, and the greatest challenge has been the scaling down to the nanoscale for fabrication and the use of nanometer-sized tips. Here, Pt nanoelectrodes with nanometer electroactive area were fabricated and employed for imaging a distribution of gold nanoparticles （AuNPs） and bioelectrocatalytic activity of a redox-active enzyme immobilized on gold surfaces.

关键词： scanning electrochemicalmicroscopy gold nanoparticle redox enzyme nanoelectrode lactate oxidase

Strategy for a Fast and Simple Method for Trace determination of Senecionine and Senecionine N-Oxide in Honey Using LVI in HPLC-MS/MS

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American Journal of analytical Chemistry 2014年第10期5卷 681-687页

作者： Lizandra Czermainski Bretanha Marcel Piovezan Alysson Fernandez Vasques Sako Moacir Geraldo Pizzolatti Gustavo Amadeu Micke departamento de química Universidade Federal de Santa Catarina Florianópolis Brazil

The aims of this study were to develop an HPLC-MS/MS method for the trace determination of senecionine (SEN) and senecionine N-oxide (SENNOX) in honey samples with simple dilution and to optimize the strategy for large volume injection (LVI). In the method development, the quantity of sugar, injection volume and sample pH were optimized to increase the efficiency and the retention factor of the analytes. Figures of merit of the proposed method include: good linearity (R2 > 0.99), limits of detection of 57 and 59 ng·kg﹣1 for SEN and SENNOX, respectively, and recovery in the range of 83.4% - 123%. The values for the instrumental precision in relation to the retention time and peak area were 0.65% and 7.1%, respectively, and for the intra-day precision they were greater than 0.95% and 9.7% for SEN and SENNOX, respectively. The LVI-HPLC-MS/MS procedure developed was applied to honey samples prepared by simple dilution with deionized water (1:8 w/w) and the pH was adjusted to 9.5 with NH4OH. The sample volume injected was 100 μL;concentrations in natural and industrialized honey were ﹤LOQ - 1071.3 μg·kg﹣1 for SEN and ﹤LOD - 16.9 μg·kg﹣1 for SENNOX.

关键词： Large Volume Injection HPLC-MS/MS Honey Senecionine Senecionine N-Oxide

Electrochemically driven phenothiazine modification of carbon nanodots

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Nano Research 2018年第12期11卷 6405-6416页

作者： Monica Mediavilla Emiliano Martinez-Perinan Iria Bravo Tania Garcia-Mendiola Monica Revenga-Parra Felix Pariente Encarnacion Lorenzo departamento de qufmica analftica yAndlisis instrumental UniversidadAutonoma de MadridMadrid28049Spain Instituto Madrileno de Estudios Avanzados (IMdeA)Nanociencia Faraday9Campus UAMCantoblancoMadrid28049Spain Institute for Advanced Research in Chemical Sciences (IAdChem) UniversidadAutonoma de MadridMadrid 28049Spain

Carbon nanodots (CNDs) with enriched periphery carboxylic groups were synthesized using the low-cost starting material glucose. The obtained CNDs were assembled onto Au electrodes following one of two strategies: covalent bonding, using cystamine as a cross-linker, or by drop-casting. The immobilized CNDs were covalently modified with the phenothiazine Azure A via electron transfer chemistry; in particular via reactions with aryl diazonium salts. The reaction mechanism for the diazonium functionalization of CNDs was investigated. Spectroelectrochemistry experiments confirmed that electrografting, rather than adsorption, governs the functionalization of CNDs with Azure A. Finally, the application of these CNDs as electrocatalysts for the oxidation of hydrazine was demonstrated.

关键词： carbon nanodots Azure A electrografting phenothiazine

Physicochemical and Sensory Properties of Gummy Candies Enriched with Pineapple and Papaya Peel Powders

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Food and Nutrition Sciences 2019年第11期10卷 1300-1312页

作者： Karla Fabiola Romo-Zamarrón Laura Eugenia Pérez-Cabrera Alberto Tecante departamento de Tecnología de Alimentos Universidad Autónoma de Aguascalientes Aguascalientes México departamento de Alimentos y Biotecnología Facultad de Química Universidad Nacional Autónoma de México Mexico City México.

Currently, the production of minimally processed foods generates many by-products that are not optimally exploited. Pineapple and papaya peels dehydrated by circulating hot air and freeze drying, with different particle sizes, were used as powder ingredients to enrich gummy candies. Modifications in soluble solids (°Bx), pH, water activity (aw), color, instrumental texture, and sensory perception of the products were assessed regarding powder-free controls. The inclusion of 5 g/100g of each fruit peel powder resulted in candies with stable acidity, °Bx, aw, and pH. Freeze-dried peels with smaller particle size produced better physicochemical, sensory, instrumental texture, and color characteristics because the powders were easily and homogeneously distributed, reinforcing thus the structure of the gel, and producing better coloring.

关键词： Candy Gel Papaya Pineapple Powders

The first meteorological observations at a tropical high elevation site:Antisana,1846

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Journal of Mountain Science 2016年第6期13卷 1047-1055页

作者： Aria Ma M.FARRONA Fernando DOMINGUEZ-CASTRO Ma Cruz GALLEGO Jose M.VAquERO departamento de Fisica Facultad de CienciasUniversidad de ExtremaduraBadajoz 06071Spain Instituto de Fisica de Cantabria(UC-CSIC) Santander 39005Spain departamento de Ingenieria Civily Ambiental Escuela Politecnica NacionalQuito 170112Ecuador Instituto Nacional de Meteorologiae Hidrologia Quito 170135Ecuador instituto universitario de investigación del agua cambio climático y sostenibilidad (iacys) universidad de extremaduraBadajoz 06071，Spain departamento de física centro universitario de mérida universidad de extremaduraMerida 06800Spain

Antisana is a stratovolcano with an associated glacier located in the Ecuadorian Andes. Dr Aguirre made meteorological readings every day, at every hour from sunrise to sunset, from december 1845 to december 1846, at Antisana using a meteorological station at 4060 mamsl （meters above mean sea level）. Unfortunately, only the monthly average data have been preserved. These meteorological data are here studied and compared with the closest modern stations for monthly values of temperature, rainfall, and pressure. According to these comparisons, the year 1846 was rainy and cold in comparison with the current climate. Moreover, these observations have been useful to help resolve a debate about a possible E1Nifio event in 1846 with the high precipitation in Antisana and quito in 1846 discarding the occurrence of an E1 Nifio event. The probable occurrence of a La Nifia event is discussed. These data are the earliest known systematic instrumental meteorological observations taken at above 4000 mamsl.

关键词： Early instrumental records Glacier Pastclimate conditions