Search results for "bond"

Microfabrication of hybrid fluid membrane for microengines

2015

International audience; This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dyna…

Studio delle prestazioni di giunzioni incollate ibride

2011

Le giunzioni ibride sono giunzioni in cui coesistono due differenti tipologie di giunzione, di cui una è l’incollaggio. L’articolo mostra i risultati di una campagna sperimentale volta a caratterizzare le prestazioni di giunti incollati ibridi in confronto ad alcune tipologie di giunzioni tradizionali. Si sono prese in considerazioni come tecnologie di giunzione tradizionali la saldatura a resistenza, la rivettatura a strappo, la clinciatura e la rivettatura auto perforante. In particolare si sono studiate le prestazioni di giunti a semplice sovrapposizione per differenti condizioni geometriche del giunto (spessore aderendi, passo tra i punti di fissaggio meccanico) e condizioni ambientali …

Mechanical behaviour of SPR/co-cured composite to aluminium joints

2012

Molecular and crystal structure of Nα-(9-fluorenyl)-methoxycarbonyl-L-ornithine hydrochloride diethyl ether solvate

2002

The solid-state conformation of the first N-protected ornithine derivative has been established by X-ray analysis. The hydrochloride of Nα-(9-fluorenyl)methoxycarbonyl-l-ornithine crystallises as diethyl ether solvate. The backbone (ω0 ϕ, ψ χ1) torsion angles are (174.9°,–84.0°, 145.9°,–171.0°). The conformation of the urethane amide bonds istrans. The ornithine aliphatic side chain adopts preferred fully extended conformation which is stabilised by the hydrogen bonding of the-NH3+ group to the diethyl ether molecule, carboxyl group and Cl− anions.

Dual Hydrogen Bond - Enamine Catalysis Enables a Direct Enantioselective Three-Component Domino Reaction

2011

A dual system, composed of an enantioselective enamine catalyst and a multiple-hydrogen-bond catalyst achieves the three-component enantioselective aldehyde—nitroalkene—aldehyde domino reaction using either two similar or two different aldehydes.

Hydrogen Bonding Donor–Acceptor Carbon Nanostructure

2012

The natural process of photosynthesis is paradigmatic in converting sunlight into energy. This complicated process requires a cascade of energy- and electron-transfer events in a highly organised matrix of electron–donor, electron–acceptor and antennae units and has prompted researchers to emulate it. In fact, energy- and electron-transfer processes play a pivotal role in molecular-scale optoelectronics. In this chapter we compile a number of remarkable examples of noncovalent aggregates formed by the combination of carbon-based electroactive species (fullerenes and carbon nanotubes) hydrogen bonded with a variety of moieties. We will show that: (a) the connection of complementary electroac…

Monitoring the hydrogen bond net configuration and the dimensionality of aniline and phenyloxamate by adding 1 H -pyrazole and isoxazole as substitue…

2019

This work describes the synthesis and characterization of a new class of oxamic acid derivatives containing pyrazole and isoxazole as substituents to investigate their ability to form hydrogen bonds aiming at applying them in crystal engineering and molecular self-recognition. In this respect, we report a new synthesis of 2-(4-nitrophenyl)-1,3-propanedial (1) in high yield using SOCl2 as a chlorinating agent. The new oxamic esters 4-(1H-pyrazol-4-yl)phenylene-N-(ethyloxamate) (2d) and 4-(1,2-oxazol-4-yl)phenylene-N-(ethyloxamate) (3d) were prepared from 1. The synthetic route consists of the cyclisation of 1 either with hydrazine to afford 4-(-aminophenyl)-1H-pyrazole (2a) or with hydroxyla…

4-[5-(4-Fluorophenyl)-3-isopropylisoxazol-4-yl]pyridin-2(1H)-one

2007

The crystal structure of the title compound, C17H15FN2O2, was determined as part of a study of the biological activity of pyridine-substituted isoxazole derivatives as mitogen-activated protein kinase (MAPK) inhibitors. In the crystal structure of the title compound, the compound exists in the lactam and not in the tautomeric pyridin-2-ol form. As the aromatic pyridine nitrogen is considered to be important for accepting a hydrogen bond from p38MAPK, the structure of the lactam unit is correlated with the loss of biological activity of the title compound in the p38MAPK assay. In the crystal structure, the lactam is involved in hydrogen bonds, forming chains along the b axis.

Combined study of anion recognition by a carbazole-based neutral tripodal receptor in a competitive environment

2012

Anion recognition studies have been carried out on a series of neutral synthetic receptors in which carbazole-2-carboxamide has been used as building block. Different ligands which include one to three carbazole units in their structure have been prepared. Binding experiments have been performed under competitive conditions in DMSO and DMSO-water solutions. The tripodal receptor offered a better host-guest association due to the synergistic effect of a well arranged set of hydrogen bonds. A selective response towards the biologically important pyrophosphate anion has been achieved. This selectivity is enhanced when studies are carried out with an increasing water content, which gets as high…

NMR crystallography of 2-Acylamino-6-[1H]pyridones: solid state NMR, GIPAW computational, and single crystal X-ray diffraction studies

2011

Abstract 2-Acylamino-6-[1H]-pyridones [acyl = RCO, where R = methyl (1), ethyl (2), iso-propyl (3), tert-butyl (4), and 1-adamantyl (5)] have been synthesized and characterized by NMR spectroscopy. From three congeners, 2, 3 and 5, also single crystal X-ray structures have been solved. For these derivatives GIPAW calculations acts as a “bridge” between solid-state NMR data and calculated chemical shifts based on X-ray determined geometry. In crystals all three compounds exist as pyridone tautomers possessing similar six-membered ring structure stabilized by intramolecular C O⋯HN hydrogen bond. Theoretical GIPAW calculated and experimental 13C and 15N CPMAS NMR shifts are in excellent agreem…