A descriptive monitoring study of a non-anesthetist sedation quality program.

INTRODUCTION: sedation substantially improves the quality of digestive endoscopy procedures but may result in severe complications. METHODS: a joint commission-based multidisciplinary protocol was used to define a protocol for sedation by non-anesthesiologists. ASA 4 patients were excluded, as well as patients with a difficult airway, complex procedures and deep sedation. Quality based on the analysis of 9 indicators were monitored. Incomplete procedures were also monitored in order to assess efficacy. RESULTS: patient safety was established based on a very low incidence of complications and a rate of respiratory events of 1.07. Furthermore, a low rate of hypotension and bradycardia was found, as well as a low rate of pain, either during or after endoscopy and an incidence of unexpected admissions lower than 0.5%. The quality indicators measured reflect the evolution of the results of the program. CONCLUSIONS: ongoing sedation program monitoring in endoscopy allows the control of different quality dimensions and the implementation of steps for process improvement.

Grafting of porphyrin oligomers on single-walled carbon nanotubes by Hay coupling.

The fabrication of nanotube-based functional materials is still limited by the difficulty in incorporating highly engineered molecules onto the nanotube surface. To overcome this difficulty, the development of procedures involving two subsequent reaction steps on the nanotubes appeared particularly promising. It was previously demonstrated that "click chemistry" (CuAAC) permits efficiently functionalising nanotubes with a wide variety of materials (from inorganic to biological). In this work, we present an original strategy based on Hay coupling (i.e. the oxidative coupling between triple bonds) to fabricate nanotube-porphyrin conjugates. Porphyrins containing ethynyl functional groups were attached on single-walled carbon nanotubes (SWNTs) bearing phenylacetylene groups and the resulting materials were fully characterised.

Iron-Strapped Porphyrins with Carboxylic Acid Groups Hanging over the Coordination Site: Synthesis, X-ray Characterization, and Dioxygen Binding.

A series of myoglobin active site analogues were synthesized and characterized to investigate the dioxygen binding effects of a flexible distal strap over the coordination site. These four synthetic models differ mostly by the shape and polarity of their cavities and also possibly by motion of the distal strap attached to two of the meso carbon atoms. Each of the four models has an intramolecular nitrogen base that axially binds the iron(II) cation inside the porphyrin, but they differ either by the nature of the distal strap or by its mobility. The overhanging distal group is either a generally apolar ethyl malonate group or a polar malonic acid group which is also a strong H-bond donor. It is shown that, in the ferrous complex 2b bearing such an overhung malonic acid group in close proximity to the iron atom, the equilibrium rate for dioxygen binding is significantly enhanced in comparison to that of its ester precursor. In the case of the analogous complex 1b bearing a more mobile distal strap, one of the carboxylic acid groups binds the iron(II) cation, leading to a six-coordinate ferrous complex. Unexpectedly, this complex proved to be high-spin (S = 2) as shown by solid-state magnetic measurements. Whereas this unprecedented complex still binds dioxygen, the formation of the intramolecular six-coordinate complex precluded the measurement of its dioxygen affinity through direct quantitative gas titration monitored by UV-vis spectroscopy. However, in this case, the determination of the kinetic rate constants for dioxygen binding and dissociation by laser flash photolysis allowed the evaluation of the equilibrium rate. Together with three previous X-ray structures of iron complexes in the ααßß conformation, the structure of the cavity and the shape of the relaxed distal strap are also discussed with the consideration of the resolution of X-ray structures of two different free-base ligands in the ααßß conformation, with one bearing the ethyl malonate group and the second one bearing the malonic acid group. A third X-ray structure of the analogous ligand with the overhanging ethyl malonate group in the αßαß series allows a direct comparison of the distal strap in both geometries. This work reveals that the compound with the overhanging carboxylic acid group which cannot directly interact with the ferrous heme exhibits an increased dioxygen affinity by 2 orders of magnitude versus its ester precursor.

Trapping Nanostructures on Surfaces through Weak Interactions.

The assembly of imidazole-functionalized phenanthroline-strapped zinc porphyrins (ZnPorphen) with alkyl or polyethylene glycol (PEG) side chains was studied in solution and by AFM after casting on highly oriented pyrolytic graphite (HOPG) or mica. The nature of the solvent and its evaporation time influenced the morphology of the objects observed. On HOPG, short rods of about 100 nm were observed after fast evaporation of solutions of the alkyl derivatives in CHCl3 , THF, or pyridine, whereas islands of aligned rows of longer wires were obtained from methylcyclohexane (MCH). Slow evaporation of MCH led to a three-dimensional assembly. The PEG porphyrin assembled into short wires on HOPG or fibers on mica after slow evaporation of solutions in THF. This study shows the role of surface-molecule interactions in the interfacial assembly of ZnPorphen derivatives and contributes to understanding the parameters that control their noncovalent assembly into molecular wires on a surface.

Carbon nanotube-templated synthesis of covalent porphyrin network for oxygen reduction reaction.

The development of innovative techniques for the functionalization of carbon nanotubes that preserve their exceptional quality, while robustly enriching their properties, is a central issue for their integration in applications. In this work, we describe the formation of a covalent network of porphyrins around MWNT surfaces. The approach is based on the adsorption of cobalt(II) meso-tetraethynylporphyrins on the nanotube sidewalls followed by the dimerization of the triple bonds via Hay-coupling; during the reaction, the nanotube acts as a template for the formation of the polymeric layer. The material shows an increased stability resulting from the cooperative effect of the multiple π-stacking interactions between the porphyrins and the nanotube and by the covalent links between the porphyrins. The nanotube hybrids were fully characterized and tested as the supported catalyst for the oxygen reduction reaction (ORR) in a series of electrochemical measurements under acidic conditions. Compared to similar systems in which monomeric porphyrins are simply physisorbed, MWNT-CoP hybrids showed a higher ORR activity associated with a number of exchanged electrons close to four, corresponding to the complete reduction of oxygen into water.

A pentanuclear lead(II) complex based on a strapped porphyrin with three different coordination modes.

We have previously described Pb(II) and Bi(III) bimetallic complexes with overhanging carboxylic acid strapped porphyrins in which one metal ion is bound to the N-core ("out-of-plane", OOP), whereas the second one is bound to the strap ("hanging-atop", HAT). In such complexes, the hemidirected coordination sphere of a HAT Pb(II) cation provides sufficient space for an additional binding of a neutral ligand (e.g., DMSO). Interestingly, investigations of the HAT metal coordination mode in a single strap porphyrin show that a HAT Pb(II) can also interact via intermolecular coordination bonds, allowing the self-assembly of two bimetallic complexes. In the pentanuclear Pb(II) complex we are describing in this Article, three different coordination modes were found. The OOP Pb(II) remains inert toward the supramolecular assembling process, whereas the HAT Pb(II) cation, in addition to its intramolecular carboxylate and regular exogenous acetate groups, coordinates an additional exogenous acetate. These two acetates are shared with a third lead(II) cation featuring a holo-directed coordination sphere, from which a centro-symmetric complex is assembled. Density functional theory calculations show some electron-density pockets in the vicinity of the hemidirected HAT Pb(II) atoms, which are associated with the presence of a stereochemically active lone pair of electrons. On the basis of the comparison with other HAT Pb(II) and Bi(III) systems, the "volume" of this lone pair correlates well with the bond distance distributions and the number of the proximal oxygen atoms tethered to the post-transition metal cation. It thus follows the order 6-coordinate Bi(III) > 6-coordinate Pb(II) > 5-coordinate Pb(II).

Host-guest complexation of [60]fullerenes and porphyrins enabled by "click chemistry".

Herein the synthesis, characterization, and organization of a first-generation dendritic fulleropyrrolidine bearing two pending porphyrins are reported. Both the dendron and the fullerene derivatives were synthesized by Cu(I) -catalyzed alkyne-azide cycloaddition (CuAAC). The electron-donor-acceptor conjugate possesses a shape that allows the formation of supramolecular complexes by encapsulation of C60 within the jaws of the two porphyrins of another molecule. The interactions between the two photoactive units (i.e., C60 and Zn-porphyrin) were confirmed by cyclic voltammetry as well as by steady-state and time-resolved spectroscopy. For example, a shift of about 85 mV was found for the first reduction of C60 in the electron-donor-acceptor conjugate compared with the parent molecules, which indicates that C60 is included in the jaws of the porphyrin. The fulleropyrrolidine compound exhibits a rich polymorphism, which was corroborated by AFM and SEM. In particular, it was found to form supramolecular fibrils when deposited on substrates. The morphology of the fibrils suggests that they are formed by several rows of fullerene-porphyrin complexes.

Characterization of a six-coordinate ferrous high-spin heme with both intramolecular axial carboxylic acid and pyridine.

Synthesis of a bis-strapped porphyrin with a pyridyl residue on one side and a malonic acid on the other side gives after iron(II) insertion a six-coordinate complex in which both apical groups are the two axial ligands of the iron atom. Unexpectedly, this six-coordinate iron(II) complex proves to be high-spin, likely due to some stabilization of the axial metal-ligand antibonding orbitals.

Coordination studies of bis-strapped-hanging-carboxylate porphyrins. X-ray characterization of a five-coordinate iron(II) complex with a built-in axial base.

The comparison of two series of preorganized strapped porphyrins, derived from both the alphabetaalphabeta and alphaalphabetabeta conformers of meso-tetrakis(aminophenyl)porphyrin, and the coordination studies of their affinity for O(2) are reported. Both series of ligands bear a proximal built-in axial base and a polar distal side defined by either a hanging malonyl ester or a hanging malonic acid residue. In the alphabetaalphabeta model, the carboxylic acid groups are maintained in an apical location at a fixed distance from the distal oxygen atom of iron-bound O(2). A particular emphasis is placed on the alphaalphabetabeta series, for which the crystal structure of the five-coordinate (S = 2) iron(II) ester complex was determined. In this series, the distal strap can adopt either a tilted conformation or a vertical position over the Fe(II) core, allowing changes in the distance between the carboxylic groups and the bound O(2).

Structural characterization of zinc and iron (II/III) complexes of a porphyrin bearing two built-in nitrogen bases. An example of high-spin diaqua-iron(III) bromo complex.

A bis-strapped porphyrin with two intramolecular nitrogen bases was synthesized, and its zinc(II), iron(II), and iron(III) complexes have been structurally characterized. Whereas the zinc(II) complex is square pyramidal five-coordinate and the iron(II) complex is six-coordinate despite a significant distortion of the macrocycle induced by the rigidity of the straps, the iron(III) complex exhibits a peculiar bis-aqua structure in which no intramolecular axial base is bound to the iron atom in the porphyrin. Furthermore, on one side, the bromide counteranion of the iron is bound inside the cycle formed by a strap and establishes a hydrogen bond with an axially bound water molecule. On the other side, a residual HBr molecule protonates one pyridine base leading to the formation of an intermolecular pyridinium-pyridine hydrogen bond. The large ionic radius of the high-spin iron(III) cation is accommodated in the macrocycle with no displacement of the metal out of the mean porphyrinic plane, with an average Fe-Np bond distance of 2.057 A, and the axial Fe-Ow(aqua) bond distance measured at 2.090 A. As a result, this high-spin iron(III) bis-aqua complex is only lightly distorted.

Estudio descriptivo de monitorización de un programa de calidad de sedación por no anestesiólogos / A descriptive monitoring study of a non-anesthetist sedation quality program

Introducción: la sedación mejora sensiblemente la calidad de la endoscopia digestiva, aunque puede tener complicaciones graves. Métodos: protocolo multidisciplinar en base a la joint comission que defina el protocolo de sedación por no anestesiólogos. Se excluyen pacientes ASA 4 o con vía aérea difícil, pruebas complejas y sedación profunda. Controlamos la calidad en base al análisis de 9 indicadores. También se monitorizan las pruebas incompletas para valorar eficacia. Resultados: la seguridad del paciente se establece en base a una incidencia de complicaciones muy baja, con una incidencia de eventos respiratorios de 1,07. Además, se encuentra una baja incidencia de hipotensión y bradicardia, al igual que del dolor durante y después de la endoscopia y una incidencia menor del 0,5% de ingresos no esperados. Los indicadores de calidad medidos nos indican la evolución de los resultados del programa. Conclusiones: la monitorización continuada de los programas de sedación en endoscopia permiten controlar las diferentes dimensiones de la calidad e implementar medidas que mejoren el proceso

Introduction: sedation substantially improves the quality of digestive endoscopy procedures but may result in severe complications. Methods: a joint commission-based multidisciplinary protocol was used to define a protocol for sedation by non-anesthesiologists. ASA 4 patients were excluded, as well as patients with a difficult airway, complex procedures and deep sedation. Quality based on the analysis of 9 indicators were monitored. Incomplete procedures were also monitored in order to assess efficacy. Results: patient safety was established based on a very low incidence of complications and a rate of respiratory events of 1.07. Furthermore, a low rate of hypotension and bradycardia was found, as well as a low rate of pain, either during or after endoscopy and an incidence of unexpected admissions lower than 0.5%. The quality indicators measured reflect the evolution of the results of the program. Conclusions: ongoing sedation program monitoring in endoscopy allows the control of different quality dimensions and the implementation of steps for process improvement