Search results for "Magnetism"

The behavior of correlation functions in trans-polyacetylene: quantum Monte Carlo study

2002

We present results of a quantum Monte Carlo simulation of the one-dimensional half-filled Hubbard model to study different correlation functions in the trans-polyacetylene (t-PA) polymer. Magnetic structure of the model in t-PA is studied for a different range values of the Hubbard repulsion interactions, U and V ,w here U 4t , with V ∈[ U/2 ,U ] (t is the hopping matrix elements). In this work, we investigate the behavior of the magnetic correlation functions for different phases transitions between different ordering (antiferromagnetic and ferromagnetic) by varying the nearest-neighbor interactions U and V between different atomic sites. Our results indicate that there is a presence of a …

Synthesis and characterization of a new layered organic-inorganic hybrid nickel(II) 1,4 : 5,8-naphthalenediimide bis-phosphonate, exhibiting canted a…

2008

A new Ni(II) layered hybrid organic-inorganic compound of formula Ni{sub 2}[(NDI-BP)(H{sub 2}O){sub 2}].2H{sub 2}O has been prepared in very mild conditions from N,N'-bis(2-phosphonoethyl)napthalene-1,4:5,8-tetracarboximide (NDI-BP ligand) and NiCl{sub 2}. The X-ray powder structure characterization of the title compound suggests a pillared layered organic-inorganic hybrid structure. The distance between the organic and inorganic layers has been found to be 17.8 A. The inorganic layers consist of corner sharing [NiO{sub 5}(H{sub 2}O)] octahedra and they are pillared by the diphosphonate groups. DC and AC magnetic measurements as a function of temperature and field indicate the presence of 2…

Dinuclear alkoxo-bridged copper(II) coordination polymers: Syntheses, structural and magnetic properties

2010

Abstract The alkoxo-bridged dinuclear copper(II) complexes [Cu2(ap)2(NO2)2] (1), [Cu2(ap)2(C6H5COO)2] (2) and [Cu2(ap)2μ-1,3-C6H4(COO)2(dmso)2]·dmso (3) (ap = 3-aminopropanolato and dmso = dimethyl sulfoxide) have been synthesized via self-assembly from copper(II) perchlorate, 3-aminopropanol as main chelating ligand and nitrite and isophthalate anions as spacers and benzoate anion as auxiliary ligand. Complexes 1 and 3 crystallize as 2D and 1D coordination polymers, respectively, and their structures consist of dinuclear [Cu2(ap)2]2+ units connected with nitrite and isophthalate ligands. The adjacent dinuclear units of 2 and 1D polymers of 3 are further connected by hydrogen bonds resultin…

TTF charge transfer salts containing cyanometallate anions [M(phen)(CN)4]− (M=Cr or Fe; phen=1,10-phenanthroline)

2006

Abstract Two new charge transfer salts of TTF with the counter anions [M(phen)(CN) 4 ] − (phen = 1,10-phenanthroline, M = Cr ( I ) and Fe ( II )) are described. The structures consist of alternating stacks of dimerised TTF + cations and [M(phen)(CN) 4 ] − anions and they are linked together by many short S⋯S contacts and hydrogen bonds. Within the organic stack, two dimerised TTF + cations are arranged in a slipped face-to-face mode with short intra-dimer and long inter-dimer S⋯S distances. Strong antiferromagnetic exchange was found in the TTF + dimers. Conductivity measurements show that compound I is a semiconductor.

Reversible Supracolloidal Self-Assembly of Cobalt Nanoparticles to Hollow Capsids and Their Superstructures

2017

| openaire: EC/FP7/291364/EU//MIMEFUN The synthesis and spontaneous, reversible supracolloidal hydrogen bond-driven self-assembly of cobalt nanoparticles (CoNPs) into hollow shell-like capsids and their directed assembly to higher order superstructures is presented. CoNPs and capsids form in one step upon mixing dicobalt octacarbonyl (Co2CO8) and p-aminobenzoic acid (pABA) in 1,2-dichlorobenzene using heating-up synthesis without additional catalysts or stabilizers. This leads to pABA capped CoNPs (core ca. 5nm) with a narrow size distribution. They spontaneously assemble into tunable spherical capsids (d≈50-200nm) with a few-layered shells, as driven by inter-nanoparticle hydrogen bonds th…

Structure Determination from Powder X-Ray Diffraction Data of a Hydrogen-Bonded Molecular Solid with Competing Ferromagnetic and Antiferromagnetic In…

1995

Protonated malonate: the influence of the hydrogen bonds on the magnetic behaviour

2004

One hydrogen malonato-bridged complex of formula [Cu(Hmal)2] (1) and two polymorphous malonato-bridged complexes of formula [Cu(H2O)(H2mal)(mal)] (2 and 3), in which the three species of the malonate (H2mal, Hmal−, and mal2−) are present, were synthesised and characterized by X-ray diffraction [H2mal = malonic acid]. Their structures consist of corrugated malonate layers of [Cu(Hmal)2] (1) and [Cu(H2O)(H2mal)(mal)] (2 and 3) units bridged by carboxylate–malonate groups. The layers are linked through hydrogen bonds leading to a three-dimensional network. Variable-temperature (1.9–290 K) magnetic susceptibility measurements indicate the occurrence of weak ferromagnetic interactions between th…

Hypnosis, Animal Magnetism, and Monstrosity in late Nineteenth Century English Literature

2019

We will explore the literary image of animal magnetism and hypnosis through the analysis of two works of fiction: the novels Richard Marsh’s The Beetle: A Mystery (1897) and Bram Stoker’s Dracula (1897). During all the 19th century and mainly at its last, many authors used animal magnetism and hypnosis in their fictional creations in an environmental or plot way, so much that Arthur Quiller-Couch, an important literary critic of the nineteenth century, spoke about the emergence of a new literary subgenre that he called “hypnotic fiction”. Starting from the idea that in this mesmeric and hypnotic fiction literature you can clearly trace differentiated stereotypes of magnetizers and hypnotist…

Spin canting in Re(IV) complexes: magnetic properties of [ReX4(bpym)] ( X = Cl and Br; bpym = 2,2′-bipyrimidine)

2008

The mononuclear complexes [ReCl4(bpym)] (1) and [ReBr4(bpym)] (2) (bpym = 2,2′-bipyrimidine) are weak ferromagnets. Magnetic ordering occurs below 7.0 (1) and 20.0 K (2) and good hysteresis loops are observed for the two compounds at 2.0 K. A spin-canting phenomenon, i.e., a non-strict linearity of the individual spins aligned in an anti-parallel way by intermolecular antiferromagnetic coupling occurring in many Re(IV) complexes, accounts for these magnetic features which are unusual in molecular solids such as 1 and 2.

Factors that affect the permeability of commercial hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system

2013

A demonstration plant with two commercial HF ultrafiltration membrane modules (PURON (R), Koch Membrane Systems, PUR-PSH31) was operated with urban wastewater. The effect of the main operating variables on membrane performance at sub-critical and supracritical filtration conditions was tested. The physical operating variables that affected membrane performance most were gas sparging intensity and back-flush (BF) frequency. Indeed, low gas sparging intensities (around 0.23 Nm(3) h(-1) m(-2)) and low BF frequencies (30s back-flush for every 10 basic filtration relaxation cycles) were enough to enable membranes to be operated sub-critically even when levels of mixed liquor total solids were hi…