20 research outputs found
Sequential double second-order nonlinear optical switch by an acido-triggered photochromic cyclometallated platinum(ii) complex.
International audienceAn unprecedented DTE-based Pt(II) complex, 2(o), which stands as the first example of a sequential double nonlinear optical switch, induced first by protonation and next upon irradiation with UV light is presented
Electric multipole moments of substituted acetylenic chains Η-(C≡C)n-H, X-(C≡C)n-H and Χ-(C≡C)n-X, electric (hyper)polarizability of acetylenic chains Η-(C≡C)n-H and their interaction induced electric properties with helium atoms H-(C≡C)n-H…He
The purpose of the present doctoral dissertation is the calculation of the electric multipole moments (dipole up to hexadecapole) of acetylenic chains under the general formulas H-(C≡C)n-H, Χ-(C≡C)n-H and Χ-(C≡C)n-X, n=1–7, X=F, Cl, Br, I, CN, NC, the systematic study of the (hyper)polarizabilities of the non substituted acetylenic chains Η-(C≡C)n-H, n=3–7 and finally the calculation of interaction induced electric properties of systems of the general formula Η-(C≡C)n-H…Ηe, n=1– 7. In all cases considered the ab initio SCF and MP2 methods have been used along with the very popular DFT methods B3LYP, B3PW91 and mPW1PW91. For the electric multipole moment calculations the cc-pVDZ basis set has been used in all cases and special attention has been paid in the way the properties of interest change by changing the substituent at the ends of the acetylenic chains. For the electric (hyper)polarizability calculations on the non substituted acetylenic chains H-(C≡C)n- H minimally polarized basis sets have been used and comparison was made with the results obtained by using larger basis sets. In order to calculate the above mentioned properties the finite field method was applied. Finally, calculations were performed in order to calculate the interaction induced electric properties of the systems Η-(C≡C)n- H…Ηe for two particular configurations while in order to avoid the basis set superposition error the Boys-Bernardi counterpoise method has been applied.Αντικείμενο της παρούσης διδακτορικής διατριβής αποτελεί ο υπολογισμός των ηλεκτρικών πολυπολικών ροπών (διπολική έως και δεκαεξαπολική) ακετυλενικών αλυσίδων οι οποίες υπάγονται στους γενικούς τύπους H-(C≡C)n-H, Χ-(C≡C)n-H και Χ-(C≡C)n-X, n=1–7, X=F, Cl, Br, I, CN, NC, η συστηματική μελέτη των (υπερ)πολωσιμοτήτων των μη υποκατεστημένων ακετυλενικών αλυσίδων Η-(C≡C)n- H, n=3–7 και τέλος ο υπολογισμός των ηλεκτρικών ιδιοτήτων αλληλεπίδρασης συστημάτων του τύπου Η-(C≡C)n-H…Ηe, n=1–7. Σε όλες τις περιπτώσεις χρησιμοποιήθηκαν οι ab initio μέθοδοι SCF και MP2 καθώς και οι ευρέως χρησιμοποιούμενες DFT μέθοδοι B3LYP, B3PW91 και mPW1PW91. Στους υπολογισμούς των ηλεκτρικών πολυπολικών ροπών χρησιμοποιήθηκε η βάση ccpVDZ σε όλες τις περιπτώσεις και ιδιαίτερη έμφαση δόθηκε στον τρόπο μεταβολής των υπό μελέτη ιδιοτήτων με την μεταβολή του υποκαταστάτη στα άκρα της αλυσίδας. Στους υπολογισμούς των ηλεκτρικών (υπερ)πολωσιμοτήτων των μη υποκατεστημένων ακετυλενικών αλυσίδων Η-(C≡C)n-H χρησιμοποιήθηκαν ελάχιστα πολωμένα σύνολα βάσης και πραγματοποιήθηκε σύγκριση με τα αποτελέσματα που προέκυψαν από την χρήση μεγαλύτερων συνόλων βάσης. Για τον υπολογισμό των εν λόγω ιδιοτήτων χρησιμοποιήθηκε η μέθοδος του πεπερασμένου πεδίου. Τέλος πραγματοποιήθηκαν υπολογισμοί των ηλεκτρικών ιδιοτήτων αλληλεπίδρασης συστημάτων Η-(C≡C)n-H…Ηe για δυο συγκεκριμένες διαμορφώσεις ενώ για την αποφυγή του σφάλματος υπέρθεσης συνόλου βάσης χρησιμοποιήθηκε η υπερμοριακή προσέγγιση των Boys-Bernardi
Improved Treatment of Surrounding Effects: UV/vis Absorption Properties of a Solvated Ru(II) Complex
International audienc
Optical Properties of Diarylethenes with TD-DFT: 0-0 Energies, Fluorescence, Stokes Shifts, and Vibronic Shapes
This contribution is an investigation of both the structures and optical properties of a set of 14 diverse, recently synthesized diarylethenes using Time-Dependent Density Functional Theory (TD-DFT) at the omega B97X-D/6-31G(d) level of theory. The linear response (LR) and state-specific (SS) versions of the Polarizable Continuum Model (PCM) have been adopted to account for the bulk solvation effects and their relative performances were critically accessed. It is shown, for the first time in the case of nontrivial diarylethenes, that TD-DFT provides good agreement between the experimental absorption-fluorescence crossing points (AFCPs) and their theoretical counterparts when a robust model accounting for both geometrical relaxation and vibrational corrections is used instead of the vertical approximation. On the other hand, the theoretical estimates for the Stokes shifts based on the vertical transition energies were found to be in disagreement with respect to experiment, prompting us to simulate the absorption/emission vibronic band shapes. It is proved that difficulties associated with the breakdown of the harmonic approximation in Cartesian coordinates exist for the investigated system, and we show how they can be at least partially overcome by means of a vertical approach including Duschinsky effects. Our results provide a valuable basis to rationalize the experimental vibronic structure of both emission and absorption bands and are expected to be a significant asset to the understanding of the optical properties of diarylethene derivatives
Theoretical evidence of photo-induced charge transfer from DNA to intercalated ruthenium (II) organometallic complexes
International audienc
Benzothiophene or Benzofuran Bridges in Diaryl Ethenes: Two-Step Access by Pd-Catalyzed C-H Activation and Theoretical/Experimental Studies on Their Photoreactivity
International audienc
Solvatomagnetic Comparison Method: A Proper Quantification ofSolvent Hydrogen-Bond Basicity
International audienc
Is the Tamm-Dancoff Approximation Reliable for the Calculation of Absorption and Fluorescence Band Shapes?
The reliability of
the Tamm–Dancoff approximation (TDA)
for predicting vibrationally resolved absorption and emission spectra
of several prototypical conjugated molecules has been addressed by
performing a series of extensive theoretical calculations. To this
end, we have systematically compared the TDA results with the full
Time-Dependent Density Functional Theory (TDDFT), the Random Phase
Approximation (RPA), as well as the Configuration Interaction Singles
(CIS) methods that are routinely employed for the prediction of optical
spectra of large molecules. Comparisons have been made with experimental
results for both the band shapes and 0–0 energies. They revealed
that TDA is generally able to reproduce the experimental band shapes
along with the positions of the absorption and emission peaks. With
respect to TDDFT, TDA leads to an underestimation of the relative
intensities for most cases but does not alter any other feature of
the spectra. For the case of 0–0 energies, it leads to a better
agreement between theory and experiment compared to TDDFT for the
majority of the molecules studied, at least when combined with the
popular B3LYP functional
Optical Properties of Diarylethenes with TD-DFT: 0–0 Energies, Fluorescence, Stokes Shifts, and Vibronic Shapes
This contribution is an investigation
of both the structures and
optical properties of a set of 14 diverse, recently synthesized diarylethenes
using Time-Dependent Density Functional Theory (TD-DFT) at the ωB97X-D/6-31G(d)
level of theory. The linear response (LR) and state-specific (SS)
versions of the Polarizable Continuum Model (PCM) have been adopted
to account for the bulk solvation effects and their relative performances
were critically accessed. It is shown, for the first time in the case
of nontrivial diarylethenes, that TD-DFT provides good agreement between
the experimental absorption-fluorescence crossing points (AFCPs) and
their theoretical counterparts when a robust model accounting for
both geometrical relaxation and vibrational corrections is used instead
of the vertical approximation. On the other hand, the theoretical
estimates for the Stokes shifts based on the vertical transition energies
were found to be in disagreement with respect to experiment, prompting
us to simulate the absorption/emission vibronic band shapes. It is
proved that difficulties associated with the breakdown of the harmonic
approximation in Cartesian coordinates exist for the investigated
system, and we show how they can be at least partially overcome by
means of a vertical approach including Duschinsky effects. Our results
provide a valuable basis to rationalize the experimental vibronic
structure of both emission and absorption bands and are expected to
be a significant asset to the understanding of the optical properties
of diarylethene derivatives
A Database of Dispersion-Induction DI, Electrostatic ES, and Hydrogen Bonding α<sub>1</sub> and β<sub>1</sub> Solvent Parameters and Some Applications to the Multiparameter Correlation Analysis of Solvent Effects
For
about 300 solvents, we propose a database of new solvent parameters
describing empirically solute/solvent interactions: DI for dispersion and induction, ES for electrostatic interactions between
permanent multipoles, α<sub>1</sub> for solute Lewis base/solvent
Lewis acid interactions, and β<sub>1</sub> for solute hydrogen-bond
donor/solvent hydrogen-bond acceptor interactions. The main advantage
over previous parametrizations is the easiness of extension of this
database to newly designed solvents, since only three probes, the
betaine dye 30, 4-fluorophenol, and 4-fluoroanisole are required.
These parameters can be entered into the linear solvation energy relationship <i>A</i> = <i>A</i><sub>0</sub> + di(DI) + <i>e</i>ES + <i>a</i>α<sub>1</sub> + <i>b</i>β<sub>1</sub> to predict a large number of varied physicochemical properties <i>A</i> and to rationalize the multiple intermolecular forces
at the origin of solvent effects through a simple examination of the
sign and magnitude of regression coefficients di, <i>e</i>, <i>a</i>, and <i>b</i>. Such a rationalization
is illustrated for conformational and tautomeric equilibria and is
supported by quantum-mechanical calculations