1,721,143 research outputs found
Formation of TbPc2 Single-Molecule Magnets’ Covalent 1D Structures via Acyclic Diene Metathesis
No full textWe present here a reaction scheme to connect TbPc2 single-molecule magnets into 1D architectures using acyclic diene metathesis. To investigate the impact of the bonding through aliphatic chains on the magnetic properties of TbPc2, we isolate and characterize the dimeric species obtained as one of the products of the reaction. Remarkably, the
magnetic properties are only slightly modified after the formation of the bond between molecules, enlightening the great potential of this reaction scheme
Erratic magnetic hysteresis of TbPc2 molecular nanomagnets
No full textTerbium(iii) bis-phthalocyaninato neutral complex, a robust and evaporable Single Molecule Magnet (SMM) with a record height of the anisotropy barrier, has recently attracted a great interest as an active unit in single molecule electronics, but at the same time its magnetic hysteresis has been found to be strongly affected when the environment is different from the crystalline phase. Here we present a systematic investigation of the magnetization dynamics in different environments, obtained by magnetic dilution, thermal treatment and sublimation of the molecules, to shed some light on the origin of the evanescence of the hysteretic behavior of this unique SMM. © 2013 The Royal Society of Chemistry
Urea vs. carbamate groups: a comparative study in a chiral C2 symmetric organogelator
No full textThe effect of the replacement of molecular moieties (carbamates vs. urea) that drive self-assembly for two organogelators with an identical C-2 symmetric molecular structure is described. The main properties of the gels obtained from the urea-based organogelators are also discussed. The proposed organogelators are chiral molecules and are able to express chirality also at the supramolecular level, thus allowing the employment of electronic circular dichroism to gain insight into the molecular-scale structure of fibrillar aggregates. With the same technique, the behavior of enantiomeric mixtures of the urea-based organogelators was investigated, revealing the occurrence of different self-sorting phenomena at the molecular and supramolecular scale. The urea-based organogelators demonstrated to be more efficient gelators with respect to the carbamate-based analogues, showing a high gel-to-sol transition temperature (up to 66 degrees C) and a very low minimum gelling concentration (0.85 mg mL(-1)). This study is a starting point for a deeper investigation of structure/property relationships and, taking into account the peculiar behavior detected for the enantiomeric mixtures, also of self-sorting and molecular recognition phenomena
Aqueous phase stability of multinary thiostannates
No full textThis research proposes a comprehensive study of the thermodynamic stability of the structurally similar Cu–Fe–Zn–Sn–S multinary sulfides, critical materials that are pivotal in advancing semiconductor technologies. In light of the scarcity of thermodynamic data in the extant literature concerning a relevant number of mineral phases, the missing data were estimated using a method based on the sum of molecular fragments. Consequently, a novel numerical extrapolation method derived from experimental thermochemical stability constants is integrated with the simulation capabilities of the PHREEQC software. This integration facilitates the meticulous charting (using the formalism of Pourbaix diagrams) of the stability domains of Cu–Fe–Zn–Sn–S multinary sulfides in aqueous environments. The present analysis addresses a critical knowledge gap regarding the aqueous stability of multinary sulfides, while introducing a robust theoretical framework for predicting their environmental and technological viability. This objective is accomplished by delineating the relative stability and precipitation boundaries of the studied phases, thereby providing invaluable insights for the development of these sustainable semiconducting materials. Consequently, this research makes two significant contributions. Firstly, it contributes to the theoretical understanding of multinary sulfide systems. Secondly, it establishes the foundation for their practical application in green technologies
Iodinated Bis(phthalocyaninato)terbium(III) Complexes: Versatile Platforms for Functionalization of Single-Molecule Magnets through Sonogashira Reaction
No full textNovel homoleptic octaiodinated bis(phthalocyaninato)terbium(III) complex Tb(PcI4)2 (1) and its heteroleptic counterpart tetraiodinated TbPc(PcI4) have been synthesized in their neutral forms and fully characterized. Their magnetic properties have been evaluated by standard magnetometry, and the results confirm the single-molecule magnet behavior of these two complexes. The eight aryl iodine moieties in the homo-leptic derivative 1 have been exploited to test the Sonogashira reaction with 4-pentyn-1-ol as alkynyl substrate at room temperature under standard conditions. The application of this new synthetic protocol for TbPc2 functionalization to different substrates will allow the introduction of a wide range of functionalities on LnPc2, which is a necessary prerequisite
for the development of SMM-based technologies
Molecular Magnetic Materials on Solid Surfaces
No full textThis PhD thesis summarises a study of the nanostructuration of single molecule magnets and organic radicals on metallic surfaces, carried out by the author in collaboration with a number of research groups in Italy, France, Germany and Israel. A tailored approach was followed to graft individual molecules to the surface, to characterise the morphology of the functionalised surfaces with standard scanning probe microscopy and to investigate their magnetic properties using X-Ray circular dichroism. The aim of this project was to develop the initial basis for the organisation and addressing of magnetic molecules with a view to the development of single molecule devices for data storage and molecular-spintronic applications
Molecular Magnetic Materials on Solid Surfaces
Full text linkThis PhD thesis summarises a study of the nanostructuration of single molecule magnets and organic radicals on metallic surfaces, carried out by the author in collaboration with a number of research groups in Italy, France, Germany and Israel. A tailored approach was followed to graft individual molecules to the surface, to characterise the morphology of the functionalised surfaces with standard scanning probe microscopy and to investigate their magnetic properties using X-Ray circular dichroism. The aim of this project was to develop the initial basis for the organisation and addressing of magnetic molecules with a view to the development of single molecule devices for data storage and molecular-spintronic applications
Propeller-Shaped Fe4 and Fe3M Molecular Nanomagnets: A Journey from Crystals to Addressable Single Molecules
No full textThis Microreview covers the preparation and investigation of Fe4 and Fe3M complexes with a propeller-like structure, most of which function as single-molecule magnets (SMMs). The magnetic characterization of these highly symmetric and chemically versatile complexes has enabled the establishment of important magneto-structural correlations regarding magnetic anisotropy and magnetic relaxation mechanisms in SMM materials. Their chemical stability and easy functionalization have been further exploited to process them into thin films, down to monolayers and submonolayers, using solution or vapor-phase methods. The proof so obtained that surface-supported molecules can largely retain the rich magnetic behavior of bulk phases has been a turning point in SMM research, which has the integration of SMMs into spintronic devices among its most ambitious goals
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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