Silver coordination polymers with tri- and hexacyanoethyl-functionalized macrocyclic ligands

Tri-and hexa-cyanoethyl functionalized 17-(L-1) and 42-membered (L-2) macrocyclic compounds were obtained by [1 + 1] (for L-1) or [2 + 2] (for L-2) cyclocondensation of the corresponding dialdehyde and diethylenetriamine, followed by hydrogenation by KBH4 and subsequent cyano-functionalization with acrylonitrile. They react with silver nitrate, leading to the formation of [AgL1](NO3) (1) and of the metalorganic coordination polymers [Ag-2(NO3)(2)L-1](n) (2) and {[Ag2L2](NO3)(2)}(n) (3). The complexes were characterized by elemental analysis, H-1 NMR, C-13 NMR, IR spectroscopies, and ESI-MS; moreover, L-2, 1, 2 and 3 were also characterized by single crystal X-ray diffraction. The metal cation in 1 is pentacoordinated with a N3O2 coordination environment; in 2, the metal cations display N4O2 octahedral and N2O3 square-pyramid coordination and in 3 they are in square-planar N-4 sites. In 1, the ligand acts as a pentadentate chelator, and in the other two cases, the ligands behave as octadentate chelators in a 1 kappa N-3:kappa O-2,2 kappa N,3 kappa N,4 kappa N (in 2) or 1 kappa N-3,2 kappa N-3,3 kappa N,4 kappa N fashion (in 3). The cyanoethyl strands of the ligands are directly involved in the formation of the 2D frameworks of 2 and 3, which in the former polymer can be viewed as a net composed of hexametallic 36-membered macrocyclic rings and in the latter generates extra hexametallic 58-membered cyclic sets that form zig-zag layers. The thermal analytical and electrochemical properties of these silver complexes were also studied.

Y Trinuclear Cu-II structural isomers coordination, magnetism, electrochemistry and catalytic activity towards the oxidation of alkanes

The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) with copper(II) nitrate, acetate or metaborate has led to the isomeric complexes [Cu-3(L)(2)(MeOH)(4)] (1), [Cu-3(L)(2)(MeOH)(2)]2MeOH (2) and [Cu-3(L)(2)(MeOH)(4)] (3), respectively, in which the ligand L exhibits dianionic (HL2-, in 1) or trianionic (L3-, in 2 and 3) pentadentate 1O,O,N:2N,O chelation modes. Complexes 1-3 were characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography, electrochemical methods and variable-temperature magnetic susceptibility measurements, which indicated that the intratrimer antiferromagnetic coupling is strong in the three complexes and that there exists very weak ferromagnetic intermolecular interactions in 1 but weak antiferromagnetic intermolecular interactions in both 2 and 3. Electrochemical experiments showed that in complexes 1-3 the Cu-II ions can be reduced, in distinct steps, to Cu-I and Cu-0. All the complexes act as efficient catalyst precursors under mild conditions for the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, leading to overall yields (based on the alkane) of up to 31% (TON = 1.55x10(3)) after 6 h in the presence of pyrazinecarboxylic acid.

Arylhydrazones of barbituric acid: synthesis, coordination ability and catalytic activity of their CoII, CoII/IIIand CuIIcomplexes toward peroxidative oxidation of alkanes

New ortho-substituted arylhydrazones of barbituric acid, 5-(2-(2-hydroxyphenyl)hydrazono) pyrimidine-2,4,6(1H,3H,5H)-trione (H4L1) and the sodium salt of 2-(2-(2,4,6-trioxotetra-hydropyrimidin-5(2H)-ylidene)hydrazinyl) benzenesulfonic acid (H4L2), [Na(H3L2)(mu-H2O)(H2O)(2)](2) (1), were used in the synthesis of Cu-II, Co-II and Co-II/III complexes, [Cu(H2L1)(H2O)(im)]center dot 3H(2)O (im = imidazole) (2), [Co(H2O)(6)] [Co(H2L1)(2)](2)center dot 8H(2)O (3), [Co(H2L2)(im)(3)] (4), [Cu(H2L2)(im)(2)]center dot H2O (5) and [Co(H2O)(6)][H3L2](2)center dot 8H(2)O (6). The complexes are water soluble and the mono-or di-deprotonated ligands display different coordination modes, depending on the synthetic conditions. The electrochemical behaviour of all the compounds was investigated by cyclic voltammetry and controlled potential electrolysis, revealing that the ligands are also redox active. All the compounds were evaluated as catalysts for the peroxidative (with H2O2) oxidation of cyclohexane at room temperature. The compounds 2 and 3 are the most active ones (yields up to 21% and TON up to 213 are achieved, in the presence of 3).

Novel coordination polymers with (Pyrazolato)-based tectons: catalytic activity in the peroxidative oxidation of alcohols and cyclohexane

Coupling five rigid or flexible bis(pyrazolato)based tectons with late transition metal ions allowed us to isolate 18 coordination polymers (CPs). As assessed by thermal analysis, all of them possess a remarkable thermal stability, their decomposition temperatures lying in the range of 340-500 degrees C. As demonstrated by N-2 adsorption measurements at 77 K, their Langmuir specific surface areas span the rather vast range of 135-1758 m(2)/g, in agreement with the porous or dense polymeric architectures retrieved by powder X-ray diffraction structure solution methods. Two representative families of CPs, built up with either rigid or flexible spacers, were tested as catalysts in (0 the microwave-assisted solvent-free peroxidative oxidation of alcohols by t-BuOOH, and (ii) the peroxidative oxidation of cydohexane to cydohexanol and cydohexanone by H2O2 in acetonitrile. Those CPs bearing the rigid spacer, concurrently possessing higher specific surface areas, are more active than the corresponding ones with the flexible spacer. Moreover, the two copper(I)-containing CPs investigated exhibit the highest efficiency in both reactions, leading selectively to a maximum product yield of 92% (and TON up to 1.5 x 10(3)) in the oxidation of 1-phenylethanol and of 11% in the oxidation of cydohexane, the latter value being higher than that granted by the current industrial process.

Cyclopentadienyl-functionalised N-heterocyclic carbenes: synthesis, coordination to Mo, Ru, Rh

Dissertation presented to obtain the Ph.D degree in Chemistry

Design of the ISePorto robocup Middle-Size League Robotic Soccer Team: Control, Localisation and Coordination

Proceedings of the 10th Mediterranean Conference on Control and Automation - MED2002 Lisbon, Portugal, July 9-12, 2002

Interlimb Coordination During Step-to-Step Transition and Gait Performance

Most energy spent in walking is due to step-to-step transitions. During this phase, the interlimb coordination assumes a crucial role to meet the demands of postural and movement control. The authors review studies that have been carried out regarding the interlimb coordination during gait, as well as the basic biomechanical and neurophysiological principles of interlimb coordination. The knowledge gathered from these studies is useful for understanding step-to-step transition during gait from a motor control perspective and for interpreting walking impairments and inefficiency related to pathologies, such as stroke. This review shows that unimpaired walking is characterized by a consistent and reciprocal interlimb influence that is supported by biomechanical models, and spinal and supraspinal mechanisms. This interlimb coordination is perturbed in subjects with stroke.

Enzymatic activity mastered by altering metal coordination spheres

J Biol Inorg Chem (2008) 13:1185���1195 DOI 10.1007/s00775-008-0414-3

Sarcoplasmic reticulum calcium ATPase is inhibited by organic vanadium coordination compounds: pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an amavadine analogue

Inorg Chem. 2008 Jul 7;47(13):5677-84. doi: 10.1021/ic702405d

Periplasmic nitrate reductase revisited: a sulfur atom completes the sixth coordination of the catalytic molybdenum

J Biol Inorg Chem. 2008 Jun;13(5):737-53. doi: 10.1007/s00775-008-0359-6

Towards an engine for coordination-based architectural reconfigurations

Software recon���gurability became increasingly relevant to the architectural process due to the crescent dependency of modern societies on reliable and adaptable systems. Such systems are supposed to adapt themselves to surrounding environmental changes with minimal service disruption, if any. This paper introduces an engine that statically applies recon���gurations to (formal) models of software architectures. Recon���gurations are speci���ed using a domain speci���c language��� ReCooPLa���which targets the manipulation of software coordinationstructures,typicallyusedinservice-orientedarchitectures(soa).Theengine is responsible for the compilation of ReCooPLa instances and their application to the relevant coordination structures. The resulting con���gurations are amenable to formal analysis of qualitative and quantitative (probabilistic) properties.

Importancia del Ca2+ en la fisiolog��a esperm��tica: modulaci��n de su actividad por progesterona y prote��nas del plasma seminal. Importance of calcium in sperm physiology: its regulation by progesterone and proteins from the seminal plasma.

El objetivo general del proyecto es estudiar el efecto de la progesterona y de algunas prote��nas del plasma seminal sobre la actividad del Ca2+ en diferentes procesos fisiol��gicos que ocurren en el espermatozoide, los cuales est��n estrechamente relacionados con la capacidad fertilizante de esta c��lula. La progesterona, principal esteroide secretado por las c��lulas del cumulus oophorus, ejerce su efecto a trav��s de un receptor no-gen��mico provocando aumento en el calcio intracelular de los espermatozoides y, consecuentemente, promoviendo la capacitaci��n, la respuesta quimiot��ctica y la exocitosis acrosomal. Pese a estas observaciones, los mecanismos a trav��s de los cuales la progesterona estimula fen��menos tan diversos en el espermatozoide son a��n desconocidos. Tampoco se conoce con exactitud el papel funcional y los mecanismos de acci��n de algunas prote��nas del plasma seminal que interaccionan y se unen a los espermatozoides, con alta especificidad, durante la eyaculaci��n. Por lo tanto, resulta altamente interesante profundizar los estudios sobre las propiedades funcionales de las prote��nas caltrin (calcium transport inhibitor) y ��-microseminoprotein (MSP) del plasma seminal de mam��feros, las cuales responden a las caracter��sticas mencionadas. Los estudios hasta ahora realizados han dado cuenta de que caltrin inhibe la incorporaci��n de Ca2+ extracelular, previene la exocitosis acrosomal espont��nea y promueve la uni��n espermatozoide-zona pel��cida. Tambi��n hay datos preliminares que sugieren un efecto inhibitorio sobre la movilidad hiperactivada de los espermatozoides. Respecto a MSP, s��lo se sabe que inhibe la exocitosis acrosomal espont��nea y que su contenido, en el plasma seminal, guarda una relaci��n inversa con la fertilidad. Por todo lo expuesto, se propone estudiar los mecanismos de acci��n de la progesterona y las prote��nas caltrin y MSP sobre los procesos fisiol��gicos antes indicados. Para ello, se estudiar��n las variaciones de Ca2+ intracelular en espermatozoides individuales sometidos a diferentes tratamientos (gradientes de progesterona, capacitaci��n en presencia y ausencia de caltrin y/o MSP, etc.), usando video microscop��a de fluorescencia y an��lisis computarizado de im��genes. Tambi��n se examinar�� la influencia de estas mol��culas sobre la interacci��n de gametas y la fertilizaci��n.

Coordinaci��n socio-pol��tica. Redes de influencia y estructuras de poder en C��rdobaSocio-political coordination. Influence Networks and power structures in C��rdoba.

Los mecanismos de producci��n y reproducci��n de la influencia pol��tica es una importante ��rea de estudio de la ciencia pol��tica en las ��ltimas d��cadas. En la misma se han disputado diferentes teor��as, desde las que plantean la influencia predominante de grupos de poder y sectores corporativos tanto en las decisiones del estado como en las no decisiones, hasta los que plantean que existe la puja de diferentes intereses dentro del Estado pero que no existe ning��n grupo predominante. El an��lisis de redes (network analysis) permite estudiar este objeto mediante la observaci��n de la estructura de relaciones de los actores influyentes dentro de la pol��tica provincial. En esta area de estudio, este proyecto propone estudiar de qu�� manera se produce y reproduce la influencia pol��tica en la Provincia de C��rdoba.Las hip��tesis que plantea el proyecto son las siguientes: H1- La estructura del poder socio-pol��tico provincial adquiere una configuraci��n reticular en la que existe un n��cleo de actores que representan intereses tradicionales organizados y permite un escaso acceso de nuevas organizaciones que defienden intereses sociales difusos. H2- En el proceso de influencia sociopol��tica provincial operan mecanismos de influencia interpersonales directos e indirectos (Brokerage) que permiten a los actores acceder e influir en los decisores p��blicos. H3- En el proceso de influencia socio-pol��tica interviene una diversidad de recursos de poder que los actores utilizan para influir las pol��ticas p��blicas. Para esto se propone como objetivos del proyecto los siguientes: 1- Identificar y analizar la estructura de poder e influencia que subyace a la pol��tica provincial. 2- Analizar los intereses, actores y sectores incluidos y excluidos de la estructura de influencia pol��tica. 3- Analizar los mecanismos y recursos de producci��n y reproducci��n del poder y la influencia. 4- Analizar las ��reas de pol��tica del estado provincial que resultan lugar de influencia de los actores y sectores que configuran la estructura de poder socio-pol��tica. 5- Analizar el sistema de decisi��n colectiva (policy domain) en dos ��reas de pol��tica provincial. 6- Analizar los recursos que posibilitan a los actores ejercer poder e influencia en las ��reas de pol��ticas estudiadas. Para la verificaci��n emp��rica de las hip��tesis se realiza un dise��o de investigaci��n que incluye el mapeo y an��lisis de dos tipos de redes pol��ticas diferentes, la "red de influencia en la pol��tica provincial" y la red de influencia en un "��rea de pol��ticas p��blicas". La reconstrucci��n de las redes pol��ticas se realizar�� mediante entrevistas semi-estructuradas a actores sociales y pol��ticos en un muestreo no probabil��stico de tipo "bola de nieve". La investigaci��n pretende realizar un aporte a la comprensi��n de la coordinaci��n pol��tica y, en tal sentido, espera alcanzar una adecuada descripci��n y comprensi��n de los procesos de influencia y de estructuraci��n del poder en la Provincia de C��rdoba.

Mecanismo de interacci��n, calcio dependiente, entre Calcineurina y PERK, involucrado en el Estr��s de Ret��culo Endopl��smico. Ca2+ -dependent mechanism of interaction between Calcineurin and PERK involved in Endoplasmic Reticulum Stress.

El Estr��s de Ret��culo Endopl��smico (RE) es inducido por la acumulaci��n de prote��nas sin plegar en el lumen de la organela. Esto se puede observar en diversas situaciones fisio-patol��gicas como durante una infecci��n viral o en proceso isqu��mico. Adem��s, contribuye a la base molecular de numerosas enfermedades ya sea ��ndole metab��lico (Fibrosis qu��stica o Diabetes Miellitus) o neurodegenerativas como mal de Alzheimer o Parkinson (Mutat Res, 2005, 569). Para restablecer la homeostasis en la organela se activa una se��al de transducci��n (UPR), cuya respuesta inmediata es la atenuaci��n de la s��ntesis de prote��na debido a la fosforilaci��n de subunidad alpha del factor eucari��tico de iniciaci��n de translaci��n (eIF2��) v��a PERK. Esta es una prote��na de membrana de RE que detecta estr��s. Bajo condiciones normales, PERK est�� inactiva debido a la asociaci��n de su dominio luminar con la chaperona BIP (Nat Cell Biol, 2000, 2: 326). Frente a una situaci��n de estr��s, la chaperona se disocia causando desinhibici��n. Recientemente, (Plos One 5: e11925) se observ��, bajo condiciones de estr��s, un aumento de Ca2+ citos��lico y un r��pido incremento de la expresi��n de calcineurina (CN), una fosfatasa citos��lica dependiente de calcio, heterodim��rica formada por una subunidad catal��tica (CN-A) y una regulatoria (CN-B). Adem��s, CN interacciona, sin intermediarios, con el dominio citos��lico de PERK favoreciendo su trans-autofosforilaci��n. Resultados preliminares indican que, astrocitos CNA��-/- exhibieron, en condiciones basales, un mayor n��mero de c��lulas muertas y de niveles de eIF2�� fosforilado que los astrocitos CNA��-/-. Hip��tesis: CNA��/B interacciona con PERK cuando el Ca2+ citos��lico esta incrementado luego de haberse inducido Estr��s de RE, lo cual promueve dimerizaci��n y auto-fosforilaci��n de la quinasa, acentu��ndose as�� la fosforilaci��n de eIF2�� e inhibici��n de la s��ntesis de prote��nas. Esta activaci��n citos��lica de PERK colaborar��a con la ya descrita, desinhibici��n luminal llevada cabo por BIP. Cuando el Ca2+ citos��lico retorna a los niveles basales, PERK fosforila a CN, reduciendo su afinidad de uni��n y disoci��ndose el complejo CN/PERK. Objetivo general: Definir las condiciones por las cuales CN interacciona con PERK y regula la fosforilaci��n de eIF2�� e inhibici��n de la s��ntesis de prote��na. Objetivos espec��ficos: I-Estudiar la diferencia de afinidades y dependencia de Ca2+, de las dos isoformas de CN (�� y ��) en su asociaci��n con PERK. Adem��s verificar la posible participaci��n de la subunidad B de CN en esta interacci��n. II-Determinar si la auto-fosforilaci��n de PERK es diferencialmente regulada por las dos isoformas de CN. III-Discernir la relaci��n del estado de fosforilaci��n de CN con su uni��n a PERK. IV-Determinar efectos fisiol��gicos de la interacci��n de CN-PERK durante la respuesta de Estr��s de RE. Para llevar a cabo este proyecto se realizar��n experimentos de biolog��a molecular, interacci��n prote��na-prote��na, ensayos de fosforilaci��n in vitro y un perfil de polisoma con astrocitos CNA��-/- , CNA���-/- y astrocitos controles. Se espera encontrar una mayor afinidad de uni��n a PERK de la isoforma �� de CN y en condiciones donde la concentraci��n de Ca2+ sea del orden micromolar e imite niveles del i��n durante un estr��s. Con respecto al estado de fosforilaci��n de CN, debido a los resultados preliminares, donde solo se la encontr�� fosforilada en condiciones basales, se piensa que CN podr��a interactuar con mayor afinidad con PERK cuando CN se encuentre desfosforilada. Por ��ltimo, se espera encontrar un aumento de eIF2�� fosforilado y una acentuaci��n de la atenuaci��n de la s��ntesis de prote��na como consecuencia de la mayor activaci��n de PERK por su asociaci��n con la isoforma �� de CN en astrocitos donde el Estr��s de RE se indujo por privaci��n de oxigeno y glucosa. Estos experimentos permitir��n avanzar en el estudio de una nueva funci��n citoprotectora de CN recientemente descrita por nuestro grupo de trabajo y sus implicancias en un modelo de isquemia. The accumulation of unfolded proteins into the Endoplasmic Reticulum (ER) activates a signal transduction cascade called Unfolding Protein Response (UPR), which attempts to restore homeostasis in the organelle. (PKR)-like-ER kinase (PERK) is an early stress response transmembrane protein that is generally inactive due to its association with the chaperone BIP. During ER stress, BIP is tritrated by the unfolded protein, leading PERK activation and phosphorylation of eukaryotic initiation factor-2 alpha (eIF2alpha), which attenuates protein s��ntesis. If ER damage is too great and homeostasis is not restored within a certain period of time, an apoptotic response is elicited. We recently demonstrated a cytosolic Ca2+ increase in Xenopus oocytes after induce ER stress. Moreover, calcineurin A/B, a an heterotrimeric Ca2+ dependent phosphatases (CN-A/B), associates with PERK increasing its auto-phosphorylation and significantly enhancing cell viability. Preliminary results suggest that, CN-A��-/- knockout astrocytes exhibit a significant higher eIF2�� phosphorylated level compared to CN-A��-/- astrocytes. Our working hypothesis establishes that: CN binds to PERK when cytosolic Ca2+ is initially increased by ER stress, promoting dimerization and autophosphorylation, which leads to phosphorylation of elF2�� and subsequently attenuation of protein translation. When cytosolic Ca2+ returns to resting levels, PERK phosphorylates CN, reducing its binding affinity so that the CN/PERK complex dissociates. The goal of this project is to determine the conditions by which CN binding to PERK attenuates protein translation during the ER stress response and subsequently, to determine how the interaction of CN with PERK is terminated when stress is removed. To perform this project is planed to do molecular biology experiments, pull down assays, in vitro phosphorylations and assess overall mRNA translation efficiency doing a polisome profile.

Exerc��cio e restri����o alimentar aumentam o RNAm de prote��nas do tr��nsito de Ca2+ mioc��rdico em ratos

FUNDAMENTO: Treinamento f��sico (TF) aumenta a sensibilidade dos horm��nios tireoidianos (HT) e a express��o g��nica de estruturas moleculares envolvidas no movimento intracelular de c��lcio do mioc��rdio, enquanto a restri����o alimentar (RIA) promove efeitos contr��rios ao TF. OBJETIVO: Avaliar os efeitos da associa����o TF e RIA sobre os n��veis plasm��ticos dos HT e a produ����o de mRNA dos receptores HT e estruturas moleculares do movimento de c��lcio do mioc��rdio de ratos. M��TODOS: Utilizaram-se ratos Wistar Kyoto divididos em: controle (C, n = 7), RIA (R50, n = 7), exerc��cio f��sico (EX, n = 7) e exerc��cio f��sico + RIA (EX50, n = 7). A RIA foi de 50% e o TF foi nata����o (1 hora/dia, cinco sess��es/semana, 12 semanas consecutivas). Avaliaram-se as concentra����es s��ricas de triiodotironina (T3), tiroxina (T4) e horm��nio tireotr��fico (TSH). O mRNA da bomba de c��lcio do ret��culo sarcoplasm��tico (SERCA2a), fosfolamban (PLB), trocador Na+/Ca+2 (NCX), canal lento de c��lcio (canal-L), rianodina (RYR), calsequestrina (CQS) e receptor de HT (TRα1 e TRβ1) do mioc��rdio foram avaliados por rea����o em cadeia da polimerase (PCR) em tempo real. RESULTADOS: RIA reduziu o T4, TSH e mRNA do TRα1 e aumentou a express��o da PLB, NCX e canal-L. TF aumentou a express��o do TRβ1, canal-L e NCX. A associa����o TF e RIA reduziu T4 e TSH e aumentou o mRNA do TRβ1, SERCA2a, NCX, PLB e correla����o do TRβ1 com a CQS e NCX. CONCLUS��O: Associa����o TF e RIA aumentou o mRNA das estruturas moleculares c��lcio transiente, por��m o eixo HT-receptor n��o parece participar da transcri����o g��nica dessas estruturas.