Concepcio Rovira - Academia.edu (original) (raw)
Papers by Concepcio Rovira
J. Chem. Soc., Chem. Commun., 1995
ABSTRACT Cited By (since 1996): 31, Export Date: 24 April 2012, Source: Scopus
Synthetic Metals, 2003
The structural and magnetic characteristics of quantum spin-ladders are summarised and the possib... more The structural and magnetic characteristics of quantum spin-ladders are summarised and the possibilities of using TTF derivatives as molecular building blocks for developing such fascinating materials are discussed.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
The magnetic study of a purely organic biradical anion presenting electron transfer and ferromagn... more The magnetic study of a purely organic biradical anion presenting electron transfer and ferromagnetic coupling between two radical centers simultaneously is discussed. The mixed-valence molecule was first generated electrochemically and the electron transfer was detected by optical spectroscopy. ESR measurements not only made the determination of the ground state possible, but also gave further evidence of transient site-localisation of the
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
Page 1. ,4401. Crysr. Liq. Crysr., 1995, Vol. 271, pp. 1-12 Reprints available directly from the ... more Page 1. ,4401. Crysr. Liq. Crysr., 1995, Vol. 271, pp. 1-12 Reprints available directly from the publisher Photocopying permitted by license only 0 1995 OPA (Overseas Publishers Association) Amsterdam BV Published under ...
The Journal of Physical Chemistry Letters, 2013
The electron donor−acceptor dyad 1, based on a polychlorotriphenylmethyl radical subunit linked t... more The electron donor−acceptor dyad 1, based on a polychlorotriphenylmethyl radical subunit linked to a tetrathiafulvalene moiety, shows in DMF solution a reversible temperature-induced switching between diamagnetic dimers, observed at room temperature, and paramagnetic monomers at high temperature. Different optical and magnetic properties are observed for the two states of this supramolecular switch, related to the subtle interplay between intramolecular electron-transfer and intermolecular charge-transfer processes. SECTION: Physical Processes in Nanomaterials and Nanostructures
Journal of Materials Chemistry, 1997
J. Mater. Chem., 2010
... Commun., 2009, 316 RSC Article . 11, (a) U. Maitra, PV Kumar, N. Chandra, LJ D'Souza, MD... more ... Commun., 2009, 316 RSC Article . 11, (a) U. Maitra, PV Kumar, N. Chandra, LJ D'Souza, MD Prasanna and AR Raju, Chem. Commun., 1999, 595 RSC Article ; (b) BG Bag, GC Maity and SK Dinda, Org. Lett., 2006, 8, 5457 Article ChemPort ; (c) JR Moffat and DK Smith, Chem. ...
Journal of Low Temperature Physics, 2007
The charge transfer salts (DT-TTF)2[Ni(dcdmp)2], (DT-TTF)3[Cu(dcdmp)2]2 and (DT-TTF)3[Au(dcdmp)2]... more The charge transfer salts (DT-TTF)2[Ni(dcdmp)2], (DT-TTF)3[Cu(dcdmp)2]2 and (DT-TTF)3[Au(dcdmp)2]2, (dcdmp=2,3-dicyano5,6-dimercaptopyrazine) were obtained by electrocrystallisation and characterized. The Ni compound presents a structure consisting of stacks of fully oxidized donor pairs alternating with dianionic complexes. In the two other compounds the complex is monoanionic, the Au salt presenting a structure with stacks of donors triads alternating with pairs of complexes. All compounds display a semiconductor behavior with the highest electrical conductivity of 6.8 S/cm at room temperature being observed for the Cu salt.
Inorganica Chimica Acta, 2007
Journal of the American Chemical Society, Jan 20, 2011
Radical anions 1(-•)-5(-•), showing different lengths and incorporating up to five p-phenylenevin... more Radical anions 1(-•)-5(-•), showing different lengths and incorporating up to five p-phenylenevinylene (PPV) bridges between two polychlorinated triphenylmethyl units, have been prepared by chemical or electrochemical reductions from the corresponding diradicals 1-5 which were prepared using Wittig-Horner-type chemistry. Such radical anions enabled us to study, by means of UV-vis-NIR and variable-temperature electron spin resonance spectroscopies, the long-range intramolecular electron transfer (IET) phenomena in their ground states, probing the influence of increasing the lengths of the bridges without the need of using an external bias to promote IET. The temperature dependence of the IET rate constants of mixed-valence species 1(-•)-5(-•) revealed the presence of two different regimes at low and high temperatures in which the mechanisms of electron tunneling via superexchange and thermally activated hopping are competing. Both mechanisms occur to different extents, depending on t...
Faraday Discuss., 2006
To study molecules able to act as good &a... more To study molecules able to act as good "molecular wires", intramolecular electron transfer between two triphenylmethyl redox centers connected by bridges with different topologies and substituents have been studied in solution, both by UV-Vis-NIR and EPR spectroscopies. The synthetic methodology used allows a complete control of the geometry of polychlorotriphenylmethyl diradicals 1 and 2, which have para and meta topologies, respectively, as well as of their E/Z isomerism. This fact is used to show the influence of the different topologies in the ease of electron transfer, which is larger for the para than for the meta isomer where a small or negligible electronic coupling is observed. The related diradical 3 that have the same topology as the para isomer 1 but bearing two substituents on the central phenyl ring shows similar ease of electron transfer, that the para isomer 1.
The European Physical Journal B, 2002
: This article reports the investigation of a new low-dimensional organic salt, (TTDM-TTF)2 [Au... more : This article reports the investigation of a new low-dimensional organic salt, (TTDM-TTF)2 [Au(mnt)2], by single crystal X-ray diffraction, static magnetic susceptibility, EPR, thermopower, electrical resistivity measurements under pressure up to 25 kbar and band structure calculations. The crystal structure consists in a dimerized head to tail stacking of TTDM-TTF molecules separated by layers of orthogonal Au(mnt)2 anions. The absence of overlap between neighboring chains coming from this particular crystal structure leads to an extreme one-dimensionality (1-D) for which the carriers of the half-filled conduction band become strongly localized in a Mott-Hubbard insulating state. This material is the first 1-D conductor in which the Mott-Hubbard insulating character cannot be suppressed under pressure.
CrystEngComm, 2009
The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magne... more The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magnetic properties of the a-(BEDT-TTF) 2 [Mn 2 Cl 5 (H 2 O) 5 ] radical cation salt with a new type of magnetic polymeric complex anion, [Mn 2 Cl 5 (H 2 O) 5 ] À N , are reported. The crystal structure is characterized by radical cation layers alternating with layers of the polymeric 1-D chain anions constructed from MnCl 3 (H 2 O) 3 and MnCl 4 (H 2 O) 2 octahedra connected to each other via the apical Cl atoms. The calculated electronic band structure suggests that the salt should be a stable 2-D metal and the conductivity measurements show that it exhibits metallic behavior down to 0.4 K. Shubnikov-de Haas oscillations, observed at B > 10 T, are characterized by two fundamental frequencies, corresponding to cross-sections of the Fermi surface, in agreement with the electronic band structure calculations. Magnetic measurements reveal antiferromagnetic correlations in the anion network.
Chemistry - A European Journal, 2011
Chemistry, 2001
Intramolecular electrontransfer phenomena in the radical anions derived from the partial reductio... more Intramolecular electrontransfer phenomena in the radical anions derived from the partial reduction of diradicals (E,E)-p-divinylbenzene-b,b'-ylene bis(4-tetradecachlorotriphenylmethyl) diradical (1) and (E,E)m-divinylbenzene-b,b'-ylene bis(4-tetradecachlorotriphenylmethyl) diradical (2) have been studied by optical and ESR spectroscopy. The synthetic methodology used allows for complete control of the geometry of diradicals 1 and 2, which have para and meta topologies, respectively, as well as of their E/Z isomerism. This fact is used to show the influence of the different topologies on the ease of electron transfer, which is larger for the para than for the meta isomer, in which a small or negligible electronic coupling is observed. A related monoradical compound (E)-bis-(pentachlorophenyl)[4-(4-bromophenylb-styryl)-2,3,5,6-tetrachlorophenyl]methyl radical (3), which has only one such redox site, has also been obtained and studied for comparison purposes.
Chemistry of Materials, 1995
... Institut de CiBncia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Spa... more ... Institut de CiBncia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Spain Syaulan Yang, Haeseong Lee, and Dwaine 0. Cowan ... DuPont 4929 silver paste was mixed with 2-butoxyethyl acetate as a thinner for mounting contacts. ...
Chemical Physics Letters, 2012
We present a working example of phase recognition by lattice phonon Raman spectroscopy, a techniq... more We present a working example of phase recognition by lattice phonon Raman spectroscopy, a technique which has proved to be a powerful tool for identifying new polymorphs. The spectra show that a newly resolved triclinic structure of the organic semiconductor dibenzo ...
Angewandte Chemie, 1995
sititen) wares nicht moglich, die absolute Struktur der Tieftemperaturform zu bestimnien. Ebenfal... more sititen) wares nicht moglich, die absolute Struktur der Tieftemperaturform zu bestimnien. Ebenfalls konnte nicht gekliirt werden, ob es zu einer bei diesem Phasenubergang zu erwartenden Bildung von Inversionszwillingen gekommen ist, da eine Zwiliings-Verfeinerung fast gleiche Parameter und R-Werte ergab.-Weitere Einzelheiten zu den Krisldllstrukturuntersuchungen konnen beim
Angewandte Chemie International Edition, 2012
J. Chem. Soc., Chem. Commun., 1995
ABSTRACT Cited By (since 1996): 31, Export Date: 24 April 2012, Source: Scopus
Synthetic Metals, 2003
The structural and magnetic characteristics of quantum spin-ladders are summarised and the possib... more The structural and magnetic characteristics of quantum spin-ladders are summarised and the possibilities of using TTF derivatives as molecular building blocks for developing such fascinating materials are discussed.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
The magnetic study of a purely organic biradical anion presenting electron transfer and ferromagn... more The magnetic study of a purely organic biradical anion presenting electron transfer and ferromagnetic coupling between two radical centers simultaneously is discussed. The mixed-valence molecule was first generated electrochemically and the electron transfer was detected by optical spectroscopy. ESR measurements not only made the determination of the ground state possible, but also gave further evidence of transient site-localisation of the
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
Page 1. ,4401. Crysr. Liq. Crysr., 1995, Vol. 271, pp. 1-12 Reprints available directly from the ... more Page 1. ,4401. Crysr. Liq. Crysr., 1995, Vol. 271, pp. 1-12 Reprints available directly from the publisher Photocopying permitted by license only 0 1995 OPA (Overseas Publishers Association) Amsterdam BV Published under ...
The Journal of Physical Chemistry Letters, 2013
The electron donor−acceptor dyad 1, based on a polychlorotriphenylmethyl radical subunit linked t... more The electron donor−acceptor dyad 1, based on a polychlorotriphenylmethyl radical subunit linked to a tetrathiafulvalene moiety, shows in DMF solution a reversible temperature-induced switching between diamagnetic dimers, observed at room temperature, and paramagnetic monomers at high temperature. Different optical and magnetic properties are observed for the two states of this supramolecular switch, related to the subtle interplay between intramolecular electron-transfer and intermolecular charge-transfer processes. SECTION: Physical Processes in Nanomaterials and Nanostructures
Journal of Materials Chemistry, 1997
J. Mater. Chem., 2010
... Commun., 2009, 316 RSC Article . 11, (a) U. Maitra, PV Kumar, N. Chandra, LJ D'Souza, MD... more ... Commun., 2009, 316 RSC Article . 11, (a) U. Maitra, PV Kumar, N. Chandra, LJ D'Souza, MD Prasanna and AR Raju, Chem. Commun., 1999, 595 RSC Article ; (b) BG Bag, GC Maity and SK Dinda, Org. Lett., 2006, 8, 5457 Article ChemPort ; (c) JR Moffat and DK Smith, Chem. ...
Journal of Low Temperature Physics, 2007
The charge transfer salts (DT-TTF)2[Ni(dcdmp)2], (DT-TTF)3[Cu(dcdmp)2]2 and (DT-TTF)3[Au(dcdmp)2]... more The charge transfer salts (DT-TTF)2[Ni(dcdmp)2], (DT-TTF)3[Cu(dcdmp)2]2 and (DT-TTF)3[Au(dcdmp)2]2, (dcdmp=2,3-dicyano5,6-dimercaptopyrazine) were obtained by electrocrystallisation and characterized. The Ni compound presents a structure consisting of stacks of fully oxidized donor pairs alternating with dianionic complexes. In the two other compounds the complex is monoanionic, the Au salt presenting a structure with stacks of donors triads alternating with pairs of complexes. All compounds display a semiconductor behavior with the highest electrical conductivity of 6.8 S/cm at room temperature being observed for the Cu salt.
Inorganica Chimica Acta, 2007
Journal of the American Chemical Society, Jan 20, 2011
Radical anions 1(-•)-5(-•), showing different lengths and incorporating up to five p-phenylenevin... more Radical anions 1(-•)-5(-•), showing different lengths and incorporating up to five p-phenylenevinylene (PPV) bridges between two polychlorinated triphenylmethyl units, have been prepared by chemical or electrochemical reductions from the corresponding diradicals 1-5 which were prepared using Wittig-Horner-type chemistry. Such radical anions enabled us to study, by means of UV-vis-NIR and variable-temperature electron spin resonance spectroscopies, the long-range intramolecular electron transfer (IET) phenomena in their ground states, probing the influence of increasing the lengths of the bridges without the need of using an external bias to promote IET. The temperature dependence of the IET rate constants of mixed-valence species 1(-•)-5(-•) revealed the presence of two different regimes at low and high temperatures in which the mechanisms of electron tunneling via superexchange and thermally activated hopping are competing. Both mechanisms occur to different extents, depending on t...
Faraday Discuss., 2006
To study molecules able to act as good &a... more To study molecules able to act as good "molecular wires", intramolecular electron transfer between two triphenylmethyl redox centers connected by bridges with different topologies and substituents have been studied in solution, both by UV-Vis-NIR and EPR spectroscopies. The synthetic methodology used allows a complete control of the geometry of polychlorotriphenylmethyl diradicals 1 and 2, which have para and meta topologies, respectively, as well as of their E/Z isomerism. This fact is used to show the influence of the different topologies in the ease of electron transfer, which is larger for the para than for the meta isomer where a small or negligible electronic coupling is observed. The related diradical 3 that have the same topology as the para isomer 1 but bearing two substituents on the central phenyl ring shows similar ease of electron transfer, that the para isomer 1.
The European Physical Journal B, 2002
: This article reports the investigation of a new low-dimensional organic salt, (TTDM-TTF)2 [Au... more : This article reports the investigation of a new low-dimensional organic salt, (TTDM-TTF)2 [Au(mnt)2], by single crystal X-ray diffraction, static magnetic susceptibility, EPR, thermopower, electrical resistivity measurements under pressure up to 25 kbar and band structure calculations. The crystal structure consists in a dimerized head to tail stacking of TTDM-TTF molecules separated by layers of orthogonal Au(mnt)2 anions. The absence of overlap between neighboring chains coming from this particular crystal structure leads to an extreme one-dimensionality (1-D) for which the carriers of the half-filled conduction band become strongly localized in a Mott-Hubbard insulating state. This material is the first 1-D conductor in which the Mott-Hubbard insulating character cannot be suppressed under pressure.
CrystEngComm, 2009
The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magne... more The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magnetic properties of the a-(BEDT-TTF) 2 [Mn 2 Cl 5 (H 2 O) 5 ] radical cation salt with a new type of magnetic polymeric complex anion, [Mn 2 Cl 5 (H 2 O) 5 ] À N , are reported. The crystal structure is characterized by radical cation layers alternating with layers of the polymeric 1-D chain anions constructed from MnCl 3 (H 2 O) 3 and MnCl 4 (H 2 O) 2 octahedra connected to each other via the apical Cl atoms. The calculated electronic band structure suggests that the salt should be a stable 2-D metal and the conductivity measurements show that it exhibits metallic behavior down to 0.4 K. Shubnikov-de Haas oscillations, observed at B > 10 T, are characterized by two fundamental frequencies, corresponding to cross-sections of the Fermi surface, in agreement with the electronic band structure calculations. Magnetic measurements reveal antiferromagnetic correlations in the anion network.
Chemistry - A European Journal, 2011
Chemistry, 2001
Intramolecular electrontransfer phenomena in the radical anions derived from the partial reductio... more Intramolecular electrontransfer phenomena in the radical anions derived from the partial reduction of diradicals (E,E)-p-divinylbenzene-b,b'-ylene bis(4-tetradecachlorotriphenylmethyl) diradical (1) and (E,E)m-divinylbenzene-b,b'-ylene bis(4-tetradecachlorotriphenylmethyl) diradical (2) have been studied by optical and ESR spectroscopy. The synthetic methodology used allows for complete control of the geometry of diradicals 1 and 2, which have para and meta topologies, respectively, as well as of their E/Z isomerism. This fact is used to show the influence of the different topologies on the ease of electron transfer, which is larger for the para than for the meta isomer, in which a small or negligible electronic coupling is observed. A related monoradical compound (E)-bis-(pentachlorophenyl)[4-(4-bromophenylb-styryl)-2,3,5,6-tetrachlorophenyl]methyl radical (3), which has only one such redox site, has also been obtained and studied for comparison purposes.
Chemistry of Materials, 1995
... Institut de CiBncia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Spa... more ... Institut de CiBncia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Spain Syaulan Yang, Haeseong Lee, and Dwaine 0. Cowan ... DuPont 4929 silver paste was mixed with 2-butoxyethyl acetate as a thinner for mounting contacts. ...
Chemical Physics Letters, 2012
We present a working example of phase recognition by lattice phonon Raman spectroscopy, a techniq... more We present a working example of phase recognition by lattice phonon Raman spectroscopy, a technique which has proved to be a powerful tool for identifying new polymorphs. The spectra show that a newly resolved triclinic structure of the organic semiconductor dibenzo ...
Angewandte Chemie, 1995
sititen) wares nicht moglich, die absolute Struktur der Tieftemperaturform zu bestimnien. Ebenfal... more sititen) wares nicht moglich, die absolute Struktur der Tieftemperaturform zu bestimnien. Ebenfalls konnte nicht gekliirt werden, ob es zu einer bei diesem Phasenubergang zu erwartenden Bildung von Inversionszwillingen gekommen ist, da eine Zwiliings-Verfeinerung fast gleiche Parameter und R-Werte ergab.-Weitere Einzelheiten zu den Krisldllstrukturuntersuchungen konnen beim
Angewandte Chemie International Edition, 2012