Alessandra Degli Esposti | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)
Papers by Alessandra Degli Esposti
Journal of the Chemical Society, 1982
The mcd spectrum of the 9, 9′-spirobifluorene molecule is presented and discussed and the lowest ... more The mcd spectrum of the 9, 9′-spirobifluorene molecule is presented and discussed and the lowest excited state is shown to be doubly degenerate. CI wavefunctions are computed by the Pariser–Parr–Pople method with the inclusion of the σ–π interactions at the spiro ...
Physical Chemistry Chemical Physics, 2004
Two new compounds with four tertiary arylamine moieties connected in a fully para-conjugated syst... more Two new compounds with four tertiary arylamine moieties connected in a fully para-conjugated system have been synthesised in order to obtain new molecules having low ionisation potentials, as required for hole transporting materials in Organic Light Emitting Diodes (OLEDs). Their electrochemical properties have been measured and compared to seven different commercial triarylamines tested in the same experimental conditions. Using the AM1 geometries and the statistical average *
Helvetica Chimica Acta, Sep 1, 2004
The circular dichroism (CD) spectra of the powerful antimalarian active principle artemisinin (AR... more The circular dichroism (CD) spectra of the powerful antimalarian active principle artemisinin (ART; 1) from Artemisia annua, and of epiartemisinin (EPI, 2), its C(7) epimer, were studied in solution in the presence and absence of β‐cyclodextrin (β‐cd). A significant inversion of sign in the region of the second electronic transition was detected. The rotational strengths were successfully calculated within the time‐dependent density functional theory (DFT), which enabled us to establish a correlation between the molecular recognition and the biological acitivities of the two isomers.
Physical Chemistry Chemical Physics, 2005
A series of triphenylamine (TPA) based compounds is investigated by means of density functional t... more A series of triphenylamine (TPA) based compounds is investigated by means of density functional theory and cyclic voltammetry. Using the Nicholson's formalism, the measured ∆E p are correlated with B3LYP/6-31G* calculated reorganisation energies (λ), elucidating the trend followed by the electron transfer rate of these compounds. Besides the direct dependency upon the dimension of the cationic fragment contributing to the hole stabilisation, the λs are tuned by the symmetry local to the TPA units, as evidenced by the structural relaxation of the cations. MDTAB shows the interesting combination of low ionisation potential (IP) and low λ. This can make this compound interesting for practical applications in organic light emitting diodes (OLEDs) devices, due to the direct correlation of the IP and λ with the hole transfer efficiency to the anode, along with the hole mobility.
Journal of Chemical Physics, Jul 15, 1988
The harmonic and the cubic force fields of CH2F2 have been evaluated ab initio from the SCF energ... more The harmonic and the cubic force fields of CH2F2 have been evaluated ab initio from the SCF energy expression by analytic derivative methods. The computed cubic force constants were used as starting values in a least squares analysis of the experimental vibration–rotation constants of CH2F2 and CD2F2. A simple scaling procedure of the ab initio cubic force constants provides a complete cubic force field for the molecule and the best fit with the experimental data.
Journal of Chemical Physics, Jan 8, 2002
A new approach to the analysis of the internal phonons of tris(quinolin-8-olato) aluminum(III) is... more A new approach to the analysis of the internal phonons of tris(quinolin-8-olato) aluminum(III) is presented, which enlightens the role played by the ligands in determining the vibrational properties of the organometallic compound and evidences the importance of the contributions arising from the coupling terms among the three quinolinato fragments. An accurate exam of the normal modes of the meridianal isomer evidences the role of the interactions among the fragments in the vibrational dynamics of the ground state. Due to the special attention paid to the quinolinato fragments, a preliminary investigation on the vibrational properties of 8-hydroxyquinoline, taken as a model fragment, was also performed. The vibrational properties of the polymorph species β of the organometallic molecule were obtained refining the calculated frequencies, the dipole moment derivative matrix, and the polarizability derivative tensor derived by the hybrid density functional B3LYP/6-31G* comparing with the frequencies and intensities recorded by the infrared and the Raman spectroscopies performed on a polycrystalline sample. One thus obtains the most accurate intramolecular force constants up to date for the meridianal isomer in a crystalline phase.
Synthetic Metals, Mar 1, 2002
Computer simulation is a powerful tool for the analysis of the infrared (IR) and Raman spectra wh... more Computer simulation is a powerful tool for the analysis of the infrared (IR) and Raman spectra when supported by accurate calculations of the molecular vibrational properties. In fact, it allows the assignment of the vibrational features to the internal phonons and a complete characterization of the spectra. An accurate investigation of the normal modes of an organometallic molecule can also elucidate how the fragments participate in each vibration and which interaction forces contribute to the whole vibrational dynamics of complex systems. The case of tris(8-hydroxyquinoline)aluminium(III) in crystalline b-phase is considered to point out the relevant effects of the interactions among the fragments.
Berichte der Bunsengesellschaft für physikalische Chemie, Nov 1, 1990
Some recent theoretical studies of collision-induced energy transfer in electronically~xcite1 s~a... more Some recent theoretical studies of collision-induced energy transfer in electronically~xcite1 s~ates are reviewed. U~ing~cclurate ':!;ein~:ẽ lectronic wavefunctions potential energy surfaces have been computed for OH(X IT, AL) + He and .Ar, LI2 (A L u) +, ' _ (X'I +, A'IT u) + He, and CN (X'L + , A'IT) + He and used in quantum scattering calc~latlOn~of cross sections .and rate coe~clents for rotational, vibrational, and electronic energy transfer processes. In cases where c.OII~panson with accurate expenmental data IS possible, the theoretical and experimental data agree within 20-30 percent.
Applied Physics Letters, Jul 30, 2012
The bulk transport properties of an anthracene-containing poly(p-phenylene-ethynylene)-alt-poly (... more The bulk transport properties of an anthracene-containing poly(p-phenylene-ethynylene)-alt-poly (p-phenylene-vinylene) (AnE-PVstat) were investigated by small-signal time-of-flight. AnE-PVstat exhibited a very good ambipolar behaviour, consistent with the high delocalization of both frontier molecular orbitals. The transport of negative carriers was found to be even faster than that of positive carriers, with an electron drift mobility of about six times higher than that evaluated for holes, suggesting that conjugated polymers with carbon-carbon triple bonds could represent a promising platform toward high performance ambipolar materials for plastic electronics.
ChemInform, Jun 5, 1990
ChemInform Abstract (inversion splitting in the first excited state).
Journal of the Chemical Society, 1987
Page 1. J. Chem. SOC., Faraday Trans. 2, 1987, 83(12), 2235-2246 Large-amplitude Vibrations and M... more Page 1. J. Chem. SOC., Faraday Trans. 2, 1987, 83(12), 2235-2246 Large-amplitude Vibrations and Microwave Band Spectra Part 2.-1 -Adamantarnine Giorgio Corbelli, Alessandra Degli Esposti, Laura Favero and David G. Lister ...
Journal of Chemical Physics, Dec 1, 1987
RefDoc Bienvenue - Welcome. Refdoc est un service / is powered by. ...
Journal of Physical Chemistry A, Sep 1, 1997
The accuracy of two density functional derived modelsBLYP/6-31G* and B3LYP/6-31G*is tested to cal... more The accuracy of two density functional derived modelsBLYP/6-31G* and B3LYP/6-31G*is tested to calculate the molecular response to slow neutrons and infrared photons in a series of oligomers of thiophene. In the first type of experiment, the response is a function of the vibrational frequencies and the shapes of the normal modes; in the second, knowledge of the dipole moment surface is also necessary. The combination of the two simulations allows one to conclude that both models give fairly accurate vibrational frequencies and normal modes but may overestimate the infrared response in large systems. For this spectroscopy, BLYP/6-31G* and B3LYP/6-31G* find all the modes present in the experiment to be active. A few modes with modest activity are also calculated to appear strongly in the spectrum. Scaling of the force fields shows the complementary roles of the two methods. BLYP/6-31G* is very accuratescaling factor of 1.00in the calculation of the Cα−Cβ, Cα−Cα, and HCC force constants, and B3LYP/6-31G* does...
ChemInform, Jun 5, 1990
ChemInform Abstract (inversion splitting in the first excited state).
Journal of Molecular Structure-theochem, May 1, 1985
Ab initio computations have been performed on aniline and N-methylaniline using standard STO-3G o... more Ab initio computations have been performed on aniline and N-methylaniline using standard STO-3G orbitals to analyze the inversion barrier and the degree of non planarity in the two molecules. Our analysis indicates that the lowering of the barrier in N-methylaniline with respect to aniline is due to hyperconjugation.
Chemistry: A European Journal, Jul 3, 2017
Chemical Physics Letters, Aug 1, 1983
, l/tile Risorgimmto 4. 40136 Bologtta. Ita& Kctciied 20 Stay 1981: in final form 23 May 1983 WC ... more , l/tile Risorgimmto 4. 40136 Bologtta. Ita& Kctciied 20 Stay 1981: in final form 23 May 1983 WC stress the advantages of soMng directly the equations of perturbation theory by CI expansion instead of usirg the SUIII-O\~~ states formulation of two-photon absorption. A formula to compute the mntri\ element entering the expression for the cross section taking into account the nuclear depces of freedom is derived from the Karplus-Kolker variational principle_ Numerical applications to Hz are presented.
Chemistry: A European Journal, Aug 18, 2000
The rotational spectra of four (GT, TT, TG, and GG) of the five possible conformers of 1-fluorobu... more The rotational spectra of four (GT, TT, TG, and GG) of the five possible conformers of 1-fluorobutane have been assigned by combining free jet and conventional microwave spectroscopy. The geometry optimization was performed at the MP2 (full) level of theory with the 6-31G (d) and 6-311G (d, p) basis sets and by using the B3LYP (3df, 3pd) density functional method. The relative stability of the five rotamers is calculated at the QCISD (T)/6-311G (d, p) level of theory. In spite of the fact that ab initio calculations indicated the unobserved GG' conformer to be more stable than at least one of the observed conformers it was not possible to detect its rotational spectrum. GT and TG are the most and the least stable species, respectively. The rotational spectra of several vibrational satellites of the four conformers have been studied by conventional microwave spectroscopy. The overall conformational equilibrium is governed by the two-dimensional potential energy surface of the skeletal torsions MeC-CC and FC-CC, which have been evaluated by a flexible model analysis, based on the experimental values of the relative conformational and vibrational energy spacings, and on the shifts of second moments of inertia upon conformational change and vibrational excitation. The relative energy of the fifth stable conformer (GG') was determined to be 333 cm(-1) from flexible model calculations, and to be 271 cm(-1) from the most accurate ab initio calculations.
Journal of the Chemical Society, Faraday Transactions, 1997
ABSTRACT Ab initio calculations proved to be very useful in the assignment of the microwave spect... more ABSTRACT Ab initio calculations proved to be very useful in the assignment of the microwave spectrum of a fourth conformer (GG) of jet cooled 1-chlorobutane. Its energy has been calculated to be 140(50) cm -1 above the most stable conformer, TT. The rotational spectra of several vibrational satellites of the four conformers have been studied by conventional microwave spectroscopy. Using the relative conformational and vibrational energy spacings, and the shifts of second moments of inertia upon conformational change and vibrational excitation, the two-dimensional potential-energy surface of the skeletal torsions has been evaluated by a two-dimensional flexible model analysis. The relative energy of the fifth stable conformer (GG′) was found to be 475 cm -1 from flexible model calculations, and 730 cm -1 from the most accurate ab initio calculations. The high value of the energy probably prevented the observation of the rotational spectrum of this conformer.
Journal of the Chemical Society, 1982
The mcd spectrum of the 9, 9′-spirobifluorene molecule is presented and discussed and the lowest ... more The mcd spectrum of the 9, 9′-spirobifluorene molecule is presented and discussed and the lowest excited state is shown to be doubly degenerate. CI wavefunctions are computed by the Pariser–Parr–Pople method with the inclusion of the σ–π interactions at the spiro ...
Physical Chemistry Chemical Physics, 2004
Two new compounds with four tertiary arylamine moieties connected in a fully para-conjugated syst... more Two new compounds with four tertiary arylamine moieties connected in a fully para-conjugated system have been synthesised in order to obtain new molecules having low ionisation potentials, as required for hole transporting materials in Organic Light Emitting Diodes (OLEDs). Their electrochemical properties have been measured and compared to seven different commercial triarylamines tested in the same experimental conditions. Using the AM1 geometries and the statistical average *
Helvetica Chimica Acta, Sep 1, 2004
The circular dichroism (CD) spectra of the powerful antimalarian active principle artemisinin (AR... more The circular dichroism (CD) spectra of the powerful antimalarian active principle artemisinin (ART; 1) from Artemisia annua, and of epiartemisinin (EPI, 2), its C(7) epimer, were studied in solution in the presence and absence of β‐cyclodextrin (β‐cd). A significant inversion of sign in the region of the second electronic transition was detected. The rotational strengths were successfully calculated within the time‐dependent density functional theory (DFT), which enabled us to establish a correlation between the molecular recognition and the biological acitivities of the two isomers.
Physical Chemistry Chemical Physics, 2005
A series of triphenylamine (TPA) based compounds is investigated by means of density functional t... more A series of triphenylamine (TPA) based compounds is investigated by means of density functional theory and cyclic voltammetry. Using the Nicholson's formalism, the measured ∆E p are correlated with B3LYP/6-31G* calculated reorganisation energies (λ), elucidating the trend followed by the electron transfer rate of these compounds. Besides the direct dependency upon the dimension of the cationic fragment contributing to the hole stabilisation, the λs are tuned by the symmetry local to the TPA units, as evidenced by the structural relaxation of the cations. MDTAB shows the interesting combination of low ionisation potential (IP) and low λ. This can make this compound interesting for practical applications in organic light emitting diodes (OLEDs) devices, due to the direct correlation of the IP and λ with the hole transfer efficiency to the anode, along with the hole mobility.
Journal of Chemical Physics, Jul 15, 1988
The harmonic and the cubic force fields of CH2F2 have been evaluated ab initio from the SCF energ... more The harmonic and the cubic force fields of CH2F2 have been evaluated ab initio from the SCF energy expression by analytic derivative methods. The computed cubic force constants were used as starting values in a least squares analysis of the experimental vibration–rotation constants of CH2F2 and CD2F2. A simple scaling procedure of the ab initio cubic force constants provides a complete cubic force field for the molecule and the best fit with the experimental data.
Journal of Chemical Physics, Jan 8, 2002
A new approach to the analysis of the internal phonons of tris(quinolin-8-olato) aluminum(III) is... more A new approach to the analysis of the internal phonons of tris(quinolin-8-olato) aluminum(III) is presented, which enlightens the role played by the ligands in determining the vibrational properties of the organometallic compound and evidences the importance of the contributions arising from the coupling terms among the three quinolinato fragments. An accurate exam of the normal modes of the meridianal isomer evidences the role of the interactions among the fragments in the vibrational dynamics of the ground state. Due to the special attention paid to the quinolinato fragments, a preliminary investigation on the vibrational properties of 8-hydroxyquinoline, taken as a model fragment, was also performed. The vibrational properties of the polymorph species β of the organometallic molecule were obtained refining the calculated frequencies, the dipole moment derivative matrix, and the polarizability derivative tensor derived by the hybrid density functional B3LYP/6-31G* comparing with the frequencies and intensities recorded by the infrared and the Raman spectroscopies performed on a polycrystalline sample. One thus obtains the most accurate intramolecular force constants up to date for the meridianal isomer in a crystalline phase.
Synthetic Metals, Mar 1, 2002
Computer simulation is a powerful tool for the analysis of the infrared (IR) and Raman spectra wh... more Computer simulation is a powerful tool for the analysis of the infrared (IR) and Raman spectra when supported by accurate calculations of the molecular vibrational properties. In fact, it allows the assignment of the vibrational features to the internal phonons and a complete characterization of the spectra. An accurate investigation of the normal modes of an organometallic molecule can also elucidate how the fragments participate in each vibration and which interaction forces contribute to the whole vibrational dynamics of complex systems. The case of tris(8-hydroxyquinoline)aluminium(III) in crystalline b-phase is considered to point out the relevant effects of the interactions among the fragments.
Berichte der Bunsengesellschaft für physikalische Chemie, Nov 1, 1990
Some recent theoretical studies of collision-induced energy transfer in electronically~xcite1 s~a... more Some recent theoretical studies of collision-induced energy transfer in electronically~xcite1 s~ates are reviewed. U~ing~cclurate ':!;ein~:ẽ lectronic wavefunctions potential energy surfaces have been computed for OH(X IT, AL) + He and .Ar, LI2 (A L u) +, ' _ (X'I +, A'IT u) + He, and CN (X'L + , A'IT) + He and used in quantum scattering calc~latlOn~of cross sections .and rate coe~clents for rotational, vibrational, and electronic energy transfer processes. In cases where c.OII~panson with accurate expenmental data IS possible, the theoretical and experimental data agree within 20-30 percent.
Applied Physics Letters, Jul 30, 2012
The bulk transport properties of an anthracene-containing poly(p-phenylene-ethynylene)-alt-poly (... more The bulk transport properties of an anthracene-containing poly(p-phenylene-ethynylene)-alt-poly (p-phenylene-vinylene) (AnE-PVstat) were investigated by small-signal time-of-flight. AnE-PVstat exhibited a very good ambipolar behaviour, consistent with the high delocalization of both frontier molecular orbitals. The transport of negative carriers was found to be even faster than that of positive carriers, with an electron drift mobility of about six times higher than that evaluated for holes, suggesting that conjugated polymers with carbon-carbon triple bonds could represent a promising platform toward high performance ambipolar materials for plastic electronics.
ChemInform, Jun 5, 1990
ChemInform Abstract (inversion splitting in the first excited state).
Journal of the Chemical Society, 1987
Page 1. J. Chem. SOC., Faraday Trans. 2, 1987, 83(12), 2235-2246 Large-amplitude Vibrations and M... more Page 1. J. Chem. SOC., Faraday Trans. 2, 1987, 83(12), 2235-2246 Large-amplitude Vibrations and Microwave Band Spectra Part 2.-1 -Adamantarnine Giorgio Corbelli, Alessandra Degli Esposti, Laura Favero and David G. Lister ...
Journal of Chemical Physics, Dec 1, 1987
RefDoc Bienvenue - Welcome. Refdoc est un service / is powered by. ...
Journal of Physical Chemistry A, Sep 1, 1997
The accuracy of two density functional derived modelsBLYP/6-31G* and B3LYP/6-31G*is tested to cal... more The accuracy of two density functional derived modelsBLYP/6-31G* and B3LYP/6-31G*is tested to calculate the molecular response to slow neutrons and infrared photons in a series of oligomers of thiophene. In the first type of experiment, the response is a function of the vibrational frequencies and the shapes of the normal modes; in the second, knowledge of the dipole moment surface is also necessary. The combination of the two simulations allows one to conclude that both models give fairly accurate vibrational frequencies and normal modes but may overestimate the infrared response in large systems. For this spectroscopy, BLYP/6-31G* and B3LYP/6-31G* find all the modes present in the experiment to be active. A few modes with modest activity are also calculated to appear strongly in the spectrum. Scaling of the force fields shows the complementary roles of the two methods. BLYP/6-31G* is very accuratescaling factor of 1.00in the calculation of the Cα−Cβ, Cα−Cα, and HCC force constants, and B3LYP/6-31G* does...
ChemInform, Jun 5, 1990
ChemInform Abstract (inversion splitting in the first excited state).
Journal of Molecular Structure-theochem, May 1, 1985
Ab initio computations have been performed on aniline and N-methylaniline using standard STO-3G o... more Ab initio computations have been performed on aniline and N-methylaniline using standard STO-3G orbitals to analyze the inversion barrier and the degree of non planarity in the two molecules. Our analysis indicates that the lowering of the barrier in N-methylaniline with respect to aniline is due to hyperconjugation.
Chemistry: A European Journal, Jul 3, 2017
Chemical Physics Letters, Aug 1, 1983
, l/tile Risorgimmto 4. 40136 Bologtta. Ita& Kctciied 20 Stay 1981: in final form 23 May 1983 WC ... more , l/tile Risorgimmto 4. 40136 Bologtta. Ita& Kctciied 20 Stay 1981: in final form 23 May 1983 WC stress the advantages of soMng directly the equations of perturbation theory by CI expansion instead of usirg the SUIII-O\~~ states formulation of two-photon absorption. A formula to compute the mntri\ element entering the expression for the cross section taking into account the nuclear depces of freedom is derived from the Karplus-Kolker variational principle_ Numerical applications to Hz are presented.
Chemistry: A European Journal, Aug 18, 2000
The rotational spectra of four (GT, TT, TG, and GG) of the five possible conformers of 1-fluorobu... more The rotational spectra of four (GT, TT, TG, and GG) of the five possible conformers of 1-fluorobutane have been assigned by combining free jet and conventional microwave spectroscopy. The geometry optimization was performed at the MP2 (full) level of theory with the 6-31G (d) and 6-311G (d, p) basis sets and by using the B3LYP (3df, 3pd) density functional method. The relative stability of the five rotamers is calculated at the QCISD (T)/6-311G (d, p) level of theory. In spite of the fact that ab initio calculations indicated the unobserved GG' conformer to be more stable than at least one of the observed conformers it was not possible to detect its rotational spectrum. GT and TG are the most and the least stable species, respectively. The rotational spectra of several vibrational satellites of the four conformers have been studied by conventional microwave spectroscopy. The overall conformational equilibrium is governed by the two-dimensional potential energy surface of the skeletal torsions MeC-CC and FC-CC, which have been evaluated by a flexible model analysis, based on the experimental values of the relative conformational and vibrational energy spacings, and on the shifts of second moments of inertia upon conformational change and vibrational excitation. The relative energy of the fifth stable conformer (GG') was determined to be 333 cm(-1) from flexible model calculations, and to be 271 cm(-1) from the most accurate ab initio calculations.
Journal of the Chemical Society, Faraday Transactions, 1997
ABSTRACT Ab initio calculations proved to be very useful in the assignment of the microwave spect... more ABSTRACT Ab initio calculations proved to be very useful in the assignment of the microwave spectrum of a fourth conformer (GG) of jet cooled 1-chlorobutane. Its energy has been calculated to be 140(50) cm -1 above the most stable conformer, TT. The rotational spectra of several vibrational satellites of the four conformers have been studied by conventional microwave spectroscopy. Using the relative conformational and vibrational energy spacings, and the shifts of second moments of inertia upon conformational change and vibrational excitation, the two-dimensional potential-energy surface of the skeletal torsions has been evaluated by a two-dimensional flexible model analysis. The relative energy of the fifth stable conformer (GG′) was found to be 475 cm -1 from flexible model calculations, and 730 cm -1 from the most accurate ab initio calculations. The high value of the energy probably prevented the observation of the rotational spectrum of this conformer.