A. Brillante - Academia.edu (original) (raw)
Papers by A. Brillante
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Physical Chemistry Chemical Physics, 2018
This work presents a Raman based approach for the rapid identification of the molecular conformat... more This work presents a Raman based approach for the rapid identification of the molecular conformation in a series of new 2,3-thienoimide capped quaterthiophenes.
Dyes and Pigments, 2019
Supporting information 1. Crystal data and details of measurements for α-and β-thioindigo Pag. S2
Crystal Growth & Design, 2018
We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracya... more We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracyanoquinodimethane (TCNQ) grown by physical vapour transport (PVT) in argon atmosphere. One of the polymorphs, named , has stoichiometry 1:1 and adds to the three known structures with stoichiometry 1:1 (), 2:1 and 3:1. Interestingly, below (280 ± 10) K the structure undergoes a phase transition to what we refer to as the γ polymorph, with halving of the unit cell and reduction of symmetry from monoclinic to triclinic. Both new crystal structures present two alternating stacks with different intermolecular and intramolecular geometries. In stack S-I the perylene molecules show substantial deviations from planarity, with the angle between the naphthalene intramolecular moieties of 6.69º, and with the perylene and TCNQ molecular centroids shifted by 1.95 Å. In the second stack, S-II, the perylene is planar and the centroids almost coincident. Structural investigations on bond length complemented by vibrational IR spectroscopy indicate that in the new polymorphs the degree of charge transfer, can be 0 or 0.12. The higher value of ionicity to be due to donoracceptor pairs in the S-II, while molecules in S-I are closer to neutrality. Thus the ionicity of the donor-acceptor pair depends on the stack and is comparable to that one of the polymorph which we redetermined as = ± .
CrystEngComm, 2014
The solid state behaviour of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), a well-known blue luminesce... more The solid state behaviour of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), a well-known blue luminescent molecule, is presented. The crystal structures of four polymorphs and one solvate form are discussed and the experimental occurrence of the four polymorphs is rationalized.
Molecular Crystals and Liquid Crystals, 1979
ABSTRACT The polarized reflection spectra of single crystals of three weak charge transfer comple... more ABSTRACT The polarized reflection spectra of single crystals of three weak charge transfer complexes have been measured at 2 K. The Kramers-Kronig transformation was used to calculate the complex frequency dependent dielectric functions from the reflection data. The oscillator strengths and the positions of the charge transfer exciton levels have been determined.
Physical Review B, 2002
We calculate the lattice phonons and the electron-phonon coupling of the organic superconductor κ... more We calculate the lattice phonons and the electron-phonon coupling of the organic superconductor κ-(BEDT-TTF)2I3, reproducing all available experimental data connected to phonon dynamics. Low frequency intra-molecular vibrations are strongly mixed to lattice phonons. Both acoustic and optical phonons are appreciably coupled to electrons through the modulation of the hopping integrals (e-LP coupling). By comparing the results relevant to superconducting κ-and β *-(BEDT-TTF)2I3, we show that electron-phonon coupling is fundamental to the pairing mechanism. Both e-LP and electron-molecular vibration (e-MV) couplings are essential to reproduce the critical temperatures. The e-LP coupling is stronger, but e-MV is instrumental to increase the average phonon frequency.
New Developments in …, 2003
The Journal of Physical Chemistry C, 2010
... Francesca Costanzo*, Elisabetta Venuti, Raffaele Guido Della Valle, and Aldo Brillante,. Dipa... more ... Francesca Costanzo*, Elisabetta Venuti, Raffaele Guido Della Valle, and Aldo Brillante,. Dipartimento di Chimica Fisica ed Inorganica and INSTM-UdR Bologna, Università di Bologna, viale Risorgimento 4, I-40137 Bologna, Italy. ...
The Journal of Physical Chemistry A, 2006
We have systematically sampled the potential energy surface of crystalline tetracene to identify ... more We have systematically sampled the potential energy surface of crystalline tetracene to identify its local minima. These minima represent all possible stable configurations and constitute the "inherent structures" of the system. The crystal is described in terms of rigid molecules with Coulombic and atom-atom interactions. Hundreds of distinct minima are identified, mostly belonging to the space groups P (triclinic) and P2(1)/c (monoclinic), with a variety of structural arrangements. The deepest minimum corresponds to the high temperature-low pressure polymorph. This is the only polymorph with a completely described X-ray structure, which is satisfactorily described by the calculations. The next deep minimum is likely to correspond to the low temperature-high pressure polymorph, which has been experimentally identified but not yet fully described.
Synthetic Metals, 1987
ABSTRACT The optical studies on the pressure induced phase transition of TTF-CA are briefly summa... more ABSTRACT The optical studies on the pressure induced phase transition of TTF-CA are briefly summarized. The high-pressure (up to about 3 GPa) infrared spectra of TTF-2,5Cl2BQ and of DBTTF-TCNQ charge-transfer crystals are presented and interpreted. We show that whereas TTF-CA undergoes a phase transition to an ionic and dimerized stack phase, TTF-2,5Cl2BQ remains nominally neutral (degree of ionicity, ϱ, ≈0.4) and with a substantially regular stack structure. DBTTF-TCNQ, on the other hand, undergoes a phase transition from a regular to a dimerized stack phase, accompanied by only a small increase of ϱ (from ≈0.2 to ≈0.4).
Physical Chemistry Chemical Physics, 2001
Molecular Crystals and Liquid Crystals, 2004
The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattic... more The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattice Dynamics (QHLD) method, based on atom-atom potential. We show that two crystalline phases of pentacene exist, rather similar in thermodynamic stability and in molecular density. The two phases can be easily distinguished by Raman spectroscopy in the 10-100 cm-1 spectral region. We have not found any temperature induced phase transition, whereas a sluggish phase change to the denser phase is induced by pressure. The bandwidths of the two phases are slightly different. The charge carrier coupling to low-frequency phonons is calculated.
Materials Science and Engineering: A, 2008
The understanding of the oxidation mechanism of 50 wt% SiC-50 wt% AlN composites obtained by mean... more The understanding of the oxidation mechanism of 50 wt% SiC-50 wt% AlN composites obtained by means of pressureless sintering without the protective powder bed and with Y 2 O 3 as sintering-aid were significantly improved by means of Raman spectroscopy. These analyses put in evidence that "amorphous carbon" started to be formed at 1300 • C as main effect of active oxidation of SiC. At higher temperature the crystallization process began and it was completed at 1500 • C when only graphite could be recognized. On the basis of these new evidences, oxidation effects on the mechanical properties of SiC-AlN-Y 2 O 3 composites were defined. First of all, heat treatment in air was able to induce a compressive surface stress due to the volume gain associated to the oxidation of the intergranular phase. As a consequence apparent fracture toughness showed a value of 6.6 MPa m 1/2 after a heat treatment at 1300 • C, while at higher temperature effects of active oxidation caused a decreasing up to 4.7 MPa m 1/2. This toughening mechanism was also used to improve the resistance to thermal shock, which was evaluated by performing quenching tests. Furthermore, passive oxidation induced the healing of superficial flaws by means of the formation of ␣-cristobalite. This phenomenon was assumed to be responsible for the increasing of the flexural strength.
Journal of Molecular Structure, 1982
Plasmon surface polariton (PSP) spectroscopy has been applied to dye monolayer assemblies on silv... more Plasmon surface polariton (PSP) spectroscopy has been applied to dye monolayer assemblies on silver films to study exciton-surface plasmon interactions. Depending on the orientation of the dye transition dipole moment the interaction leads to characteristic changes in the dispersion curve of PSP's in agreement with theoretical results.
The Journal of Chemical Physics, 1978
The uv spectra of single crystals of thiophene have been recorded in the spectral region 38 000–5... more The uv spectra of single crystals of thiophene have been recorded in the spectral region 38 000–50 000 cm−1 for temperatures down to 12 K. In the crystal spectrum the ? and ? absorption systems observed in the vapor phase have different polarization ratios and the ? system is not observed. Wavefunctions and energies have been computed for the lowest excited states by a relatively large orbital expansion and configuration mixing. The two intense electronic transitions are assigned to π–π* states of A1 and B2 symmetry and the intermediate absorption in the vapor spectrum is attributed to a Rydberg state.
The Journal of Chemical Physics, 2003
Using a quasi-Monte Carlo scheme, we search the potential energy surface of crystalline pentacene... more Using a quasi-Monte Carlo scheme, we search the potential energy surface of crystalline pentacene to sample its local minima, which represent the “inherent” structures, i.e., the possible configurations of mechanical equilibrium. The system is described in terms of rigid molecules interacting through a standard atom–atom potential model. Several hundreds of distinct minima are encountered, with a surprising variety of structural arrangements. We find that deep minima are easily accessible because they exhibit a favorable energy distribution and their attraction basins tend to be wide. Thanks to these features of the potential surface, the localization the global minimum becomes entirely feasible, allowing reliable a priori predictions of the crystallographic structures. The results for pentacene are very satisfactory. In fact, the two deepest minima correspond to the structures of the two known experimental polymorphs, which are described correctly. Further polymorphs are also likel...
High Pressure Research, 2000
The 1,3-dipolar cycloaddition of 2-and 3-benzothiopheneazide with (trimethyl-sily1)acetylene to y... more The 1,3-dipolar cycloaddition of 2-and 3-benzothiopheneazide with (trimethyl-sily1)acetylene to yield 1,2,3-triazoles has been studied at pressures up to 1 GPa. The kinetics as a function of pressure was followed interfacing a diamond anvil cell to a FTIR spectrometer. Alike with aryl azides, the rate of reaction was found to increase logarithmically with pressure with a yield close to quantitative.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Physical Chemistry Chemical Physics, 2018
This work presents a Raman based approach for the rapid identification of the molecular conformat... more This work presents a Raman based approach for the rapid identification of the molecular conformation in a series of new 2,3-thienoimide capped quaterthiophenes.
Dyes and Pigments, 2019
Supporting information 1. Crystal data and details of measurements for α-and β-thioindigo Pag. S2
Crystal Growth & Design, 2018
We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracya... more We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracyanoquinodimethane (TCNQ) grown by physical vapour transport (PVT) in argon atmosphere. One of the polymorphs, named , has stoichiometry 1:1 and adds to the three known structures with stoichiometry 1:1 (), 2:1 and 3:1. Interestingly, below (280 ± 10) K the structure undergoes a phase transition to what we refer to as the γ polymorph, with halving of the unit cell and reduction of symmetry from monoclinic to triclinic. Both new crystal structures present two alternating stacks with different intermolecular and intramolecular geometries. In stack S-I the perylene molecules show substantial deviations from planarity, with the angle between the naphthalene intramolecular moieties of 6.69º, and with the perylene and TCNQ molecular centroids shifted by 1.95 Å. In the second stack, S-II, the perylene is planar and the centroids almost coincident. Structural investigations on bond length complemented by vibrational IR spectroscopy indicate that in the new polymorphs the degree of charge transfer, can be 0 or 0.12. The higher value of ionicity to be due to donoracceptor pairs in the S-II, while molecules in S-I are closer to neutrality. Thus the ionicity of the donor-acceptor pair depends on the stack and is comparable to that one of the polymorph which we redetermined as = ± .
CrystEngComm, 2014
The solid state behaviour of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), a well-known blue luminesce... more The solid state behaviour of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), a well-known blue luminescent molecule, is presented. The crystal structures of four polymorphs and one solvate form are discussed and the experimental occurrence of the four polymorphs is rationalized.
Molecular Crystals and Liquid Crystals, 1979
ABSTRACT The polarized reflection spectra of single crystals of three weak charge transfer comple... more ABSTRACT The polarized reflection spectra of single crystals of three weak charge transfer complexes have been measured at 2 K. The Kramers-Kronig transformation was used to calculate the complex frequency dependent dielectric functions from the reflection data. The oscillator strengths and the positions of the charge transfer exciton levels have been determined.
Physical Review B, 2002
We calculate the lattice phonons and the electron-phonon coupling of the organic superconductor κ... more We calculate the lattice phonons and the electron-phonon coupling of the organic superconductor κ-(BEDT-TTF)2I3, reproducing all available experimental data connected to phonon dynamics. Low frequency intra-molecular vibrations are strongly mixed to lattice phonons. Both acoustic and optical phonons are appreciably coupled to electrons through the modulation of the hopping integrals (e-LP coupling). By comparing the results relevant to superconducting κ-and β *-(BEDT-TTF)2I3, we show that electron-phonon coupling is fundamental to the pairing mechanism. Both e-LP and electron-molecular vibration (e-MV) couplings are essential to reproduce the critical temperatures. The e-LP coupling is stronger, but e-MV is instrumental to increase the average phonon frequency.
New Developments in …, 2003
The Journal of Physical Chemistry C, 2010
... Francesca Costanzo*, Elisabetta Venuti, Raffaele Guido Della Valle, and Aldo Brillante,. Dipa... more ... Francesca Costanzo*, Elisabetta Venuti, Raffaele Guido Della Valle, and Aldo Brillante,. Dipartimento di Chimica Fisica ed Inorganica and INSTM-UdR Bologna, Università di Bologna, viale Risorgimento 4, I-40137 Bologna, Italy. ...
The Journal of Physical Chemistry A, 2006
We have systematically sampled the potential energy surface of crystalline tetracene to identify ... more We have systematically sampled the potential energy surface of crystalline tetracene to identify its local minima. These minima represent all possible stable configurations and constitute the "inherent structures" of the system. The crystal is described in terms of rigid molecules with Coulombic and atom-atom interactions. Hundreds of distinct minima are identified, mostly belonging to the space groups P (triclinic) and P2(1)/c (monoclinic), with a variety of structural arrangements. The deepest minimum corresponds to the high temperature-low pressure polymorph. This is the only polymorph with a completely described X-ray structure, which is satisfactorily described by the calculations. The next deep minimum is likely to correspond to the low temperature-high pressure polymorph, which has been experimentally identified but not yet fully described.
Synthetic Metals, 1987
ABSTRACT The optical studies on the pressure induced phase transition of TTF-CA are briefly summa... more ABSTRACT The optical studies on the pressure induced phase transition of TTF-CA are briefly summarized. The high-pressure (up to about 3 GPa) infrared spectra of TTF-2,5Cl2BQ and of DBTTF-TCNQ charge-transfer crystals are presented and interpreted. We show that whereas TTF-CA undergoes a phase transition to an ionic and dimerized stack phase, TTF-2,5Cl2BQ remains nominally neutral (degree of ionicity, ϱ, ≈0.4) and with a substantially regular stack structure. DBTTF-TCNQ, on the other hand, undergoes a phase transition from a regular to a dimerized stack phase, accompanied by only a small increase of ϱ (from ≈0.2 to ≈0.4).
Physical Chemistry Chemical Physics, 2001
Molecular Crystals and Liquid Crystals, 2004
The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattic... more The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattice Dynamics (QHLD) method, based on atom-atom potential. We show that two crystalline phases of pentacene exist, rather similar in thermodynamic stability and in molecular density. The two phases can be easily distinguished by Raman spectroscopy in the 10-100 cm-1 spectral region. We have not found any temperature induced phase transition, whereas a sluggish phase change to the denser phase is induced by pressure. The bandwidths of the two phases are slightly different. The charge carrier coupling to low-frequency phonons is calculated.
Materials Science and Engineering: A, 2008
The understanding of the oxidation mechanism of 50 wt% SiC-50 wt% AlN composites obtained by mean... more The understanding of the oxidation mechanism of 50 wt% SiC-50 wt% AlN composites obtained by means of pressureless sintering without the protective powder bed and with Y 2 O 3 as sintering-aid were significantly improved by means of Raman spectroscopy. These analyses put in evidence that "amorphous carbon" started to be formed at 1300 • C as main effect of active oxidation of SiC. At higher temperature the crystallization process began and it was completed at 1500 • C when only graphite could be recognized. On the basis of these new evidences, oxidation effects on the mechanical properties of SiC-AlN-Y 2 O 3 composites were defined. First of all, heat treatment in air was able to induce a compressive surface stress due to the volume gain associated to the oxidation of the intergranular phase. As a consequence apparent fracture toughness showed a value of 6.6 MPa m 1/2 after a heat treatment at 1300 • C, while at higher temperature effects of active oxidation caused a decreasing up to 4.7 MPa m 1/2. This toughening mechanism was also used to improve the resistance to thermal shock, which was evaluated by performing quenching tests. Furthermore, passive oxidation induced the healing of superficial flaws by means of the formation of ␣-cristobalite. This phenomenon was assumed to be responsible for the increasing of the flexural strength.
Journal of Molecular Structure, 1982
Plasmon surface polariton (PSP) spectroscopy has been applied to dye monolayer assemblies on silv... more Plasmon surface polariton (PSP) spectroscopy has been applied to dye monolayer assemblies on silver films to study exciton-surface plasmon interactions. Depending on the orientation of the dye transition dipole moment the interaction leads to characteristic changes in the dispersion curve of PSP's in agreement with theoretical results.
The Journal of Chemical Physics, 1978
The uv spectra of single crystals of thiophene have been recorded in the spectral region 38 000–5... more The uv spectra of single crystals of thiophene have been recorded in the spectral region 38 000–50 000 cm−1 for temperatures down to 12 K. In the crystal spectrum the ? and ? absorption systems observed in the vapor phase have different polarization ratios and the ? system is not observed. Wavefunctions and energies have been computed for the lowest excited states by a relatively large orbital expansion and configuration mixing. The two intense electronic transitions are assigned to π–π* states of A1 and B2 symmetry and the intermediate absorption in the vapor spectrum is attributed to a Rydberg state.
The Journal of Chemical Physics, 2003
Using a quasi-Monte Carlo scheme, we search the potential energy surface of crystalline pentacene... more Using a quasi-Monte Carlo scheme, we search the potential energy surface of crystalline pentacene to sample its local minima, which represent the “inherent” structures, i.e., the possible configurations of mechanical equilibrium. The system is described in terms of rigid molecules interacting through a standard atom–atom potential model. Several hundreds of distinct minima are encountered, with a surprising variety of structural arrangements. We find that deep minima are easily accessible because they exhibit a favorable energy distribution and their attraction basins tend to be wide. Thanks to these features of the potential surface, the localization the global minimum becomes entirely feasible, allowing reliable a priori predictions of the crystallographic structures. The results for pentacene are very satisfactory. In fact, the two deepest minima correspond to the structures of the two known experimental polymorphs, which are described correctly. Further polymorphs are also likel...
High Pressure Research, 2000
The 1,3-dipolar cycloaddition of 2-and 3-benzothiopheneazide with (trimethyl-sily1)acetylene to y... more The 1,3-dipolar cycloaddition of 2-and 3-benzothiopheneazide with (trimethyl-sily1)acetylene to yield 1,2,3-triazoles has been studied at pressures up to 1 GPa. The kinetics as a function of pressure was followed interfacing a diamond anvil cell to a FTIR spectrometer. Alike with aryl azides, the rate of reaction was found to increase logarithmically with pressure with a yield close to quantitative.