Jaume Veciana - Academia.edu (original) (raw)
Papers by Jaume Veciana
Physical Chemistry Chemical Physics, 2010
Polychorinated trityl radicals bearing carboxilate substituents are water soluble persistent radi... more Polychorinated trityl radicals bearing carboxilate substituents are water soluble persistent radicals that can be used for Dynamic Nuclear Polarization. In contrast to other trityl radicals, the polarization mechanism differs from the classical solid effect. DFT calculations performed to rationalize this behaviour support the hypothesis that polarization is transferred from the unpaired electron to chlorine nuclei and from these to carbon by spin diffusion. The marked differences observed between neutral and anionic forms of the radical will be discussed.
Journal of the American Chemical Society, 2007
The functionalisation of surfaces with organic radicals, such as perchlorotriphenylmethyl (PTM) r... more The functionalisation of surfaces with organic radicals, such as perchlorotriphenylmethyl (PTM) radicals or tris(2,4,6-trichloro-phenyl)methyl (TTM) radicals, is appealing for the development of molecular spintronic devices. Conventionally, organic radicals are chemisorbed to metal substrates by using long alkyl or aromatic spacers resulting in a weak spin–electron coupling between the radical and the substrate. To circumvent this problem, here we have employed a new design strategy for the fabrication of radical self-assembled monolayers (r-SAMs). This newly designed radical–anchor (R–A) molecule, a TTM based radical disulfide (1), can be easily synthesized and it was here characterized by electron spin resonance (ESR), cyclic voltammetry (CV) and superconducting quantum interference device magnetometry (SQUID). We have succeeded in fabricating TTM based r-SAMs by using thiolate bonds (Au–S and Ag–S) where the TTM cores are only one-atom distance from the metal surface for the firs...
Chemistry – A European Journal
Herein we present a comprehensive study of the highly oxidized species of multiple-decker complex... more Herein we present a comprehensive study of the highly oxidized species of multiple-decker complexes composed of Tb(III) and Cd(II) ions and two to five phthalocyaninato ligands, which are stabilized by electron-donating n-butoxy chains. Paramagnetic 1H NMR measurements for the series of triple, quadruple and quintuple-decker complexes revealed that ligand oxidations lead to a decrease in magnetic anisotropy, as predicted from ab initio calculations. Unusual paramagnetic shifts were observed in +2e charged quadruple and quintuple-decker complexes, indicating that those two species are actually triplet biradicals. The X-ray structural analysis for the series of oxidized multiple-decker complexes revealed that all the species show an axial compression induced by the ligand oxidations, resulting in the bowl-shaped distortion of the ligands, in agreement with predictions from DFT calculations. Magnetic measurements revealed that the series of complexes show single-molecule magnet (SMM) p...
Angewandte Chemie International Edition
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 11, 2018
Single-component conductors based on neutral organic radicals have received a lot of attention du... more Single-component conductors based on neutral organic radicals have received a lot of attention due to the possibility that the unpaired electron can serve as a charge carrier without the need of a previous doping process. Although most of these systems are based on delocalized planar radicals, we present here a nonplanar and spin localized radical based on a tetrathiafulvalene (TTF) moiety, linked to a perchlorotriphenylmethyl (PTM) radical by a conjugated bridge, which exhibits a semiconducting behavior upon application of high pressure. The synthesis, electronic properties, and crystal structure of this neutral radical TTF-Ph-PTM derivative (1) are reported and implications of its crystalline structure on its electrical properties are discussed. On the other hand, the non-radical derivative (2), which is isostructural with the radical 1, shows an insulating behavior at all measured pressures. The different electronic structures of these two isostructural systems have a direct infl...
Small (Weinheim an der Bergstrasse, Germany), 2018
A new kind of fluorescent organic nanoparticles (FONs) is obtained using quatsomes (QSs), a famil... more A new kind of fluorescent organic nanoparticles (FONs) is obtained using quatsomes (QSs), a family of nanovesicles proposed as scaffolds for the nanostructuration of commercial lipophilic carbocyanines (1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI), 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indodicarbocyanine perchlorate (DiD), and 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indotricarbocyanine iodide (DiR)) in aqueous media. The obtained FONs, prepared by a CO -based technology, show excellent colloidal- and photostability, outperforming other nanoformulations of the dyes, and improve the optical properties of the fluorophores in water. Molecular dynamics simulations provide an atomistic picture of the disposition of the dyes within the membrane. The potential of QSs for biological imaging is demonstrated by performing superresolution microscopy of the DiI-loaded vesicles in vitro and in cells. Therefore, fluorescent QSs const...
Synthetic Metals
Single crystals of the charge-transfer complex (BTDM-TI'F)-TCNQ, showing metallic character down ... more Single crystals of the charge-transfer complex (BTDM-TI'F)-TCNQ, showing metallic character down to 26K, have been obtained. The X-Ray structure reveals segregated stacks of donors and acceptors in a very similar packing with the related HMTSF-TCNQ complex. Electronic structure calculations using a tight-binding model indicate that (BTDM-TIT)-TCNQ is an almost pure 1D metal. The electronic and magnetic properties are in accordance with its electronic and structural characteristics. This complex shows the lowest transition temperature reported up to date for charge transfer complexes of TI'F derivatives.
Physical review letters, Jan 17, 2017
Superconductors containing magnetic impurities exhibit intriguing phenomena derived from the comp... more Superconductors containing magnetic impurities exhibit intriguing phenomena derived from the competition between Cooper pairing and Kondo screening. At the heart of this competition are the Yu-Shiba-Rusinov (Shiba) states which arise from the pair breaking effects a magnetic impurity has on a superconducting host. Hybrid superconductor-molecular junctions offer unique access to these states but the added complexity in fabricating such devices has kept their exploration to a minimum. Here, we report on the successful integration of a model spin 1/2 impurity, in the form of a neutral and stable all organic radical molecule, in proximity-induced superconducting break junctions. Our measurements reveal excitations which are characteristic of a spin-induced Shiba state due to the radical's unpaired spin strongly coupled to a superconductor. By virtue of a variable molecule-electrode coupling, we access both the singlet and doublet ground states of the hybrid system which give rise to...
Journal of the American Chemical Society, Mar 16, 2017
This Communication describes the mechanism of charge transport across self-assembled monolayers (... more This Communication describes the mechanism of charge transport across self-assembled monolayers (SAMs) of two donor-acceptor systems consisting of a polychlorotriphenylmethyl (PTM) electron-acceptor moiety linked to an electron-donor ferrocene (Fc) unit supported by ultraflat template-stripped Au and contacted by a eutectic alloy of gallium and indium top contacts. The electronic and supramolecular structures of these SAMs were well characterized. The PTM unit can be switched between the nonradical and radical forms, which influences the rectification behavior of the junction. Junctions with nonradical units rectify currents via the highest occupied molecular orbital (HOMO) with a rectification ratio R = 99, but junctions with radical units have a new accessible state, a single-unoccupied molecular orbital (SUMO), which turns rectification off and drops R to 6.
Organic Letters, Jul 5, 2013
Reviews of Chemical Intermediates, 1988
J Incl Phenom Macrocycl Chem, 1987
Http Www Libreriasaulamedica Com, 2001
Physical Chemistry Chemical Physics, 2010
Polychorinated trityl radicals bearing carboxilate substituents are water soluble persistent radi... more Polychorinated trityl radicals bearing carboxilate substituents are water soluble persistent radicals that can be used for Dynamic Nuclear Polarization. In contrast to other trityl radicals, the polarization mechanism differs from the classical solid effect. DFT calculations performed to rationalize this behaviour support the hypothesis that polarization is transferred from the unpaired electron to chlorine nuclei and from these to carbon by spin diffusion. The marked differences observed between neutral and anionic forms of the radical will be discussed.
Journal of the American Chemical Society, 2007
The functionalisation of surfaces with organic radicals, such as perchlorotriphenylmethyl (PTM) r... more The functionalisation of surfaces with organic radicals, such as perchlorotriphenylmethyl (PTM) radicals or tris(2,4,6-trichloro-phenyl)methyl (TTM) radicals, is appealing for the development of molecular spintronic devices. Conventionally, organic radicals are chemisorbed to metal substrates by using long alkyl or aromatic spacers resulting in a weak spin–electron coupling between the radical and the substrate. To circumvent this problem, here we have employed a new design strategy for the fabrication of radical self-assembled monolayers (r-SAMs). This newly designed radical–anchor (R–A) molecule, a TTM based radical disulfide (1), can be easily synthesized and it was here characterized by electron spin resonance (ESR), cyclic voltammetry (CV) and superconducting quantum interference device magnetometry (SQUID). We have succeeded in fabricating TTM based r-SAMs by using thiolate bonds (Au–S and Ag–S) where the TTM cores are only one-atom distance from the metal surface for the firs...
Chemistry – A European Journal
Herein we present a comprehensive study of the highly oxidized species of multiple-decker complex... more Herein we present a comprehensive study of the highly oxidized species of multiple-decker complexes composed of Tb(III) and Cd(II) ions and two to five phthalocyaninato ligands, which are stabilized by electron-donating n-butoxy chains. Paramagnetic 1H NMR measurements for the series of triple, quadruple and quintuple-decker complexes revealed that ligand oxidations lead to a decrease in magnetic anisotropy, as predicted from ab initio calculations. Unusual paramagnetic shifts were observed in +2e charged quadruple and quintuple-decker complexes, indicating that those two species are actually triplet biradicals. The X-ray structural analysis for the series of oxidized multiple-decker complexes revealed that all the species show an axial compression induced by the ligand oxidations, resulting in the bowl-shaped distortion of the ligands, in agreement with predictions from DFT calculations. Magnetic measurements revealed that the series of complexes show single-molecule magnet (SMM) p...
Angewandte Chemie International Edition
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 11, 2018
Single-component conductors based on neutral organic radicals have received a lot of attention du... more Single-component conductors based on neutral organic radicals have received a lot of attention due to the possibility that the unpaired electron can serve as a charge carrier without the need of a previous doping process. Although most of these systems are based on delocalized planar radicals, we present here a nonplanar and spin localized radical based on a tetrathiafulvalene (TTF) moiety, linked to a perchlorotriphenylmethyl (PTM) radical by a conjugated bridge, which exhibits a semiconducting behavior upon application of high pressure. The synthesis, electronic properties, and crystal structure of this neutral radical TTF-Ph-PTM derivative (1) are reported and implications of its crystalline structure on its electrical properties are discussed. On the other hand, the non-radical derivative (2), which is isostructural with the radical 1, shows an insulating behavior at all measured pressures. The different electronic structures of these two isostructural systems have a direct infl...
Small (Weinheim an der Bergstrasse, Germany), 2018
A new kind of fluorescent organic nanoparticles (FONs) is obtained using quatsomes (QSs), a famil... more A new kind of fluorescent organic nanoparticles (FONs) is obtained using quatsomes (QSs), a family of nanovesicles proposed as scaffolds for the nanostructuration of commercial lipophilic carbocyanines (1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI), 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indodicarbocyanine perchlorate (DiD), and 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indotricarbocyanine iodide (DiR)) in aqueous media. The obtained FONs, prepared by a CO -based technology, show excellent colloidal- and photostability, outperforming other nanoformulations of the dyes, and improve the optical properties of the fluorophores in water. Molecular dynamics simulations provide an atomistic picture of the disposition of the dyes within the membrane. The potential of QSs for biological imaging is demonstrated by performing superresolution microscopy of the DiI-loaded vesicles in vitro and in cells. Therefore, fluorescent QSs const...
Synthetic Metals
Single crystals of the charge-transfer complex (BTDM-TI'F)-TCNQ, showing metallic character down ... more Single crystals of the charge-transfer complex (BTDM-TI'F)-TCNQ, showing metallic character down to 26K, have been obtained. The X-Ray structure reveals segregated stacks of donors and acceptors in a very similar packing with the related HMTSF-TCNQ complex. Electronic structure calculations using a tight-binding model indicate that (BTDM-TIT)-TCNQ is an almost pure 1D metal. The electronic and magnetic properties are in accordance with its electronic and structural characteristics. This complex shows the lowest transition temperature reported up to date for charge transfer complexes of TI'F derivatives.
Physical review letters, Jan 17, 2017
Superconductors containing magnetic impurities exhibit intriguing phenomena derived from the comp... more Superconductors containing magnetic impurities exhibit intriguing phenomena derived from the competition between Cooper pairing and Kondo screening. At the heart of this competition are the Yu-Shiba-Rusinov (Shiba) states which arise from the pair breaking effects a magnetic impurity has on a superconducting host. Hybrid superconductor-molecular junctions offer unique access to these states but the added complexity in fabricating such devices has kept their exploration to a minimum. Here, we report on the successful integration of a model spin 1/2 impurity, in the form of a neutral and stable all organic radical molecule, in proximity-induced superconducting break junctions. Our measurements reveal excitations which are characteristic of a spin-induced Shiba state due to the radical's unpaired spin strongly coupled to a superconductor. By virtue of a variable molecule-electrode coupling, we access both the singlet and doublet ground states of the hybrid system which give rise to...
Journal of the American Chemical Society, Mar 16, 2017
This Communication describes the mechanism of charge transport across self-assembled monolayers (... more This Communication describes the mechanism of charge transport across self-assembled monolayers (SAMs) of two donor-acceptor systems consisting of a polychlorotriphenylmethyl (PTM) electron-acceptor moiety linked to an electron-donor ferrocene (Fc) unit supported by ultraflat template-stripped Au and contacted by a eutectic alloy of gallium and indium top contacts. The electronic and supramolecular structures of these SAMs were well characterized. The PTM unit can be switched between the nonradical and radical forms, which influences the rectification behavior of the junction. Junctions with nonradical units rectify currents via the highest occupied molecular orbital (HOMO) with a rectification ratio R = 99, but junctions with radical units have a new accessible state, a single-unoccupied molecular orbital (SUMO), which turns rectification off and drops R to 6.
Organic Letters, Jul 5, 2013
Reviews of Chemical Intermediates, 1988
J Incl Phenom Macrocycl Chem, 1987
Http Www Libreriasaulamedica Com, 2001