Anchoring of Rare-Earth-Based Single-Molecule Magnets on Single-Walled Carbon Nanotubes (original) (raw)
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Carbon Nanotube Nanoelectromechanical Systems as Magnetometers for Single-Molecule Magnets
ACS Nano, 2013
Due to outstanding mechanical and electronic properties, carbon nanotube nanoelectromechanical systems (NEMS) were recently proposed as ultrasensitive magnetometers for single-molecule magnets (SMM). In this article, we describe a noninvasive grafting of a SMM on a carbon nanotube NEMS, which conserves both the mechanical properties of the carbon nanotube NEMS and the magnetic properties of the SMM. We will demonstrate that the nonlinearity of a carbon nanotube's mechanical motion can be used to probe the reversal of a molecular spin, associated with a bis(phthalocyaninato)terbium(III) single-molecule magnet, providing an experimental evidence for the detection of a single spin by a mechanical degree of freedom on a molecular level.
Journal of the American Chemical Society, 2018
Herein we report the synthesis and characterization of a dinuclear Tb single-molecule magnet (SMM) with two [TbPc] units connected via a fused-phthalocyaninato ligand. The stable and robust complex [(obPc)Tb(Fused-Pc)Tb(obPc)] (1) was characterized by using synchrotron radiation measurements and other spectroscopic techniques (ESI-MS, FT-IR, UV). The magnetic couplings between the Tb ions and the two π radicals present in 1 were explored by means of density functional theory (DFT). Direct and alternating current magnetic susceptibility measurements were conducted on magnetically diluted and nondiluted samples of 1, indicating this compound to be an SMM with improved properties compared to those of the well-known [TbPc] and the axially symmetric dinuclear Tb phthalocyaninato triple-decker complex (Tb(obPc)). Assuming that the probability of quantum tunneling of the magnetization (QTM) occurring in one TbPc unit is P, the probability of QTM simultaneously occurring in 1 is P, meaning ...
Nano Letters, 2008
The electronic structure of isolated bis(phthalocyaninato) terbium(III) molecules, a novel single-molecular-magnet (SMM), supported on the Cu(111) surface has been characterized by density functional theory and scanning tunneling spectroscopy. These studies reveal that the interaction with the metal surface preserves both the molecular structure and the large spin magnetic moment of the metal center. The 4f electron states are not perturbed by the adsorption while a strong molecular/metal interaction can induce the suppression of the minor spin contribution delocalized over the molecular ligands. The calculations show that the inherent spin magnetic moment of the molecule is only weakly affected by the interaction with the surface and suggest that the SMM character might be preserved.
International Journal of Molecular Sciences, 2011
We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc 2 (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T B ~ 1 K) of isolated TbPc 2 SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined.
Magnetic behaviour of TbPc2 single-molecule magnets chemically grafted on silicon surface
Nature Communications, 2014
Single-molecule magnets (SMMs) are among the most promising molecular systems for the development of novel molecular electronics based on the spin transport. Going beyond the investigations focused on physisorbed SMMs, in this work the robust grafting of Terbium(III) bis(phthalocyaninato) complexes to silicon surface from a diluted solution is achieved by rational chemical design yielding the formation of a partially oriented monolayer on the conducting substrate. Here, by exploiting the surface sensitivity of X-ray circular magnetic dichroism we evidence an enhancement of the magnetic bistability of this single-molecule magnet, in contrast to the dramatic reduction of the magnetic hysteresis that characterises monolayer deposits evaporated on noble and ferromagnetic metals. Photoelectron spectroscopy investigations and density functional theory analysis suggest a non-innocent role played by the silicon substrate, evidencing the potentiality of this approach for robust integration of bistable magnetic molecules in electronic devices. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
A Diferrous Single-Molecule Magnet
European Journal of Inorganic Chemistry, 2007
The diferrous complex [Fe 2 (acpypentO)(NCO) 3 ] (1), (acpypentO -= the anion of 1,5-bis[2-pyridyl(1-ethylimino)]pentane-3-ol) was studied by spectroscopic (dual-mode Xband EPR and 57 Fe-Mössbauer) and magnetic (AC magnetic susceptibility) techniques. Complex 1 (A. K. Boudalis et al., Inorg. Chem. 2004, 43, 1574 was previously shown to exhibit an intramolecular ferromagnetic coupling with important single-ion anisotropies with marked differences in the singleion electronic parameters of the two iron sites. In this contribution, additional studies are carried out to probe its dynamic magnetic properties. Mössbauer spectra recorded at liquid helium temperatures indicate slow paramagnetic relaxation and a ground state of the system characterized by a non-Kramers doublet with an Ising-type anisotropy, a condition which favours single-molecule magnet (SMM) behaviour. A www.eurjic.org
Nature Nanotechnology, 2013
Magnetic relaxation processes were first discussed for a crystal of paramagnetic transition ions 1 . It was suggested that mechanical vibrations of the crystal lattice (phonons) modulate the crystal electric field of the magnetic ion, thus inducing a 'direct' relaxation between two different spin states 1-3 . Direct relaxation has also been predicted for single-molecule magnets with a large spin and a high magnetic anisotropy and was first demonstrated in a Mn 12 acetate crystal 8 . The spin-lattice relaxation time for such a direct transition is limited by the phonon density of states at the spin resonance 1 . In a three-dimensional system, such as a single-molecule magnet crystal, the phonon energy spectrum is continuous, but in a one-dimensional system, like a suspended carbon nanotube, the spectrum is discrete and can be engineered to an extremely low density of states 9 . An individual single-molecule magnet, coupled to a suspended carbon nanotube, should therefore exhibit extremely long relaxation times 9 and the system's reduced size should result in a strong spin-phonon coupling 10,11 . Here, we provide the first experimental evidence for a strong spin-phonon coupling between a single molecule spin and a carbon nanotube resonator, ultimately enabling coherent spin manipulation and quantum entanglement 10,11 .
Beilstein journal of nanotechnology, 2014
Single-crystal angular-resolved magnetometry and wavefunction-based calculations have been used to reconsider the magnetic properties of a recently reported Dy(III)-based single-molecule magnet, namely [Dy(hfac)3(L(1))] with hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate and L(1) = 2-(4,5-bis(propylthio)-1,3-dithiol-2-ylidene)-6-(pyridin-2-yl)-5H-[1,3]dithiolo[4',5':4,5]benzo[1,2-d]imidazole. The magnetic susceptibility and magnetization at low temperature are found to be strongly influenced by supramolecular interactions. Moreover, taking into account the hydrogen-bond networks in the calculations allows to explain the orientation of the magnetic axes. This strongly suggests that hydrogen bonds play an important role in the modulation of the electrostatic environment around the Dy(III) center that governs the nature of its magnetic ground-state and the orientation of its anisotropy axes. We thus show here that SMM properties that rely on supramolecular organization may not...
A novel class of tetrairon(III) single-molecule magnets with graphene-binding groups
Polyhedron, 2009
Tripods of general formula R'-O-CH 2 C(CH 2 OH) 3 are excellent site-specific ligands for the preparation of functionalized Fe 4 single-molecule magnets. Herein, we describe the synthesis and characterization of two novel complexes designed to bind graphene surfaces, in which the R group consists of an alkyl spacer -(CH 2 ) n -(n = 6 and 10) and a terminal pyrenyl moiety. The site-specific ligand substitution on [Fe 4 (O-Me) 6 (dpm) 6 ] (Hdpm = dipivaloylmethane) with the new tripods has been studied with 2 H NMR on isotopically-enriched samples, revealing that, once formed, these clusters are stable in solution over long timescales. It was not possible to isolate the new compounds as crystalline solids, nevertheless they were chemically characterized by elemental analysis and 1 H NMR. The presence of the pyrenyl ending groups prompted us to investigate the effect of metal complexation on fluorescence, and a full pyrene-to-iron cluster excitation energy transfer was observed. The analysis of the magnetic behaviour revealed an S = 5 ground spin state with a negative zero-field splitting parameter D = À0.42 cm À1 .
Molecules
Molecular magnets attached to carbon nanotubes (CNT) are being studied as potential candidates for developing spintronic and quantum technologies. However, the functionalization routes used to develop these hybrid systems can drastically affect their respective physiochemical properties. Due to the complexity of this systems, little work has been directed at establishing the correlation between the degree of functionalization and the magnetic character. Here, we demonstrate the chemical functionalization degree associated with molecular magnet loading can be utilized for controlled tuning the magnetic properties of a CNT-lanthanide hybrid complex. CNT functionalization degree was evaluated by interpreting minor Raman phonon modes in relation to the controlled reaction conditions. These findings were exploited in attaching a rare-earth-based molecular magnet (Gd-DTPA) to the CNTs. Inductively coupled plasma mass spectrometry, time-of-flight secondary ion mass spectrometry and super c...