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Fernández Galván, IgnacioORCID iD iconorcid.org/0000-0002-0684-7689
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Publications (10 of 22) Show all publications
Farahani, P., Oliveira, M. A., Fernández Galván, I. & Baader, W. J. (2017). A combined theoretical and experimental study on the mechanism of spiro-adamantyl-1,2-dioxetanone decomposition. RSC Advances, 7(28), 17462-17472.
Open this publication in new window or tab >>A combined theoretical and experimental study on the mechanism of spiro-adamantyl-1,2-dioxetanone decomposition
2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 28, p. 17462-17472Article in journal (Refereed) Published
Abstract [en]

1, 2-Dioxetanones have been considered as model compounds for bioluminescence processes. The unimolecular decomposition of these prototypes leads mainly to the formation of triplet excited states whereas in the catalysed decomposition of these peroxides singlet states are formed preferentially. Notwithstanding, these cyclic peroxides are important models to understand the general principles of chemiexcitation as they can be synthesised, purified and characterised. We report here results of experimental and theoretical approaches to investigating the decomposition mechanism of spiro-adamantyl- 1,2-dioxetanone. The activation parameters in the unimolecular decomposition of this derivative have been determined by isothermal kinetic measurements (30-70 degrees C) and the chemiluminescence activation energy calculated from the correlation of emission intensities. The activation energy for peroxide decomposition proved to be considerably lower than the chemiluminescence activation energy indicating the existence of different reaction pathways for ground and excited state formation. These experimental results are compared with the calculations at the complete active space second-order perturbation theory (CASPT2), which reveal a two-step biradical mechanism starting by weak peroxide bond breakage followed by carbon-carbon elongation. The theoretical findings also indicate different transition state energies on the excited and ground state surfaces during the C-C bond cleavage in agreement with the experimental activation parameters.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-322001 (URN)10.1039/c6ra26575h (DOI)000398802000063 ()
Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2017-12-18
Vacher, M., Brakestad, A., Karlsson, H. O., Fernández Galván, I. & Lindh, R. (2017). Dynamical Insights into the Decomposition of 1,2-Dioxetane. Journal of Chemical Theory and Computation, 13(6), 2448-2457.
Open this publication in new window or tab >>Dynamical Insights into the Decomposition of 1,2-Dioxetane
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2017 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 13, no 6, p. 2448-2457Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence in 1,2-dioxetane occurs through a thermally activated decomposition reaction into two formaldehyde molecules. Both ground-state and nonadiabatic dynamics (including singlet excited states) of the decomposition reaction have been simulated, starting from the first O–O bond-breaking transition structure. The ground-state dissociation occurs between t = 30 fs and t = 140 fs. The so-called entropic trap leads to frustrated dissociations, postponing the decomposition reaction. Specific geometrical conditions are necessary for the trajectories to escape from the entropic trap and for dissociation to be possible. The singlet excited states participate as well in the trapping of the molecule: dissociation including the nonadiabatic transitions to singlet excited states now occurs from t = 30 fs to t = 250 fs and later. Specific regions of the seam of the So/S1 conical intersections that would "retain" the molecule for longer on the excited state have been identified.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-329717 (URN)10.1021/acs.jctc.7b00198 (DOI)000403530100009 ()28437611 (PubMedID)
Funder
Swedish Research Council, 2012-3910
Available from: 2017-10-02 Created: 2017-10-02 Last updated: 2017-10-02Bibliographically approved
Vacher, M., Farahani, P., Valentini, A., Frutos, L. M., Karlsson, H. O., Fernández Galván, I. & Lindh, R. (2017). How Do Methyl Groups Enhance the Triplet Chemiexcitation Yield of Dioxetane?. Journal of Physical Chemistry Letters, 8(16), 3790-3794.
Open this publication in new window or tab >>How Do Methyl Groups Enhance the Triplet Chemiexcitation Yield of Dioxetane?
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2017 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 16, p. 3790-3794Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence is the emission of light as a result of a nonadiabatic chemical reaction. The present work is concerned with understanding the yield of chemiluminescence, in particular how it dramatically increases upon methylation of 1,2-dioxetane. Both ground-state and nonadiabatic dynamics (including singlet excited states) of the decomposition reaction of various methyl-substituted dioxetanes have been simulated. Methyl-substitution leads to a significant increase in the dissociation time scale. The rotation around the O-C-C-O dihedral angle is slowed; thus, the molecular system stays longer in the "entropic trap" region. A simple kinetic model is proposed to explain how this leads to a higher chemiluminescence yield. These results have important implications for the design of efficient chemiluminescent systems in medical, environmental, and industrial applications.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-334304 (URN)10.1021/acs.jpclett.7b01668 (DOI)000408187400012 ()28749694 (PubMedID)
Funder
Swedish Research Council, 2016-03398
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-11-23Bibliographically approved
Aquilante, F., Delcey, M. G., Pedersen, T. B., Fernández Galván, I. & Lindh, R. (2017). Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry. Molecular Physics, 115(17-18), 2052-2064.
Open this publication in new window or tab >>Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry
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2017 (English)In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 115, no 17-18, p. 2052-2064Article in journal (Refereed) Published
Abstract [en]

The density-fitting technique for approximating electron-repulsion integrals relies on the quality of auxiliary basis sets. These are commonly obtained through data fitting, an approach that presents some shortcomings. On the other hand, it is possible to derive auxiliary basis sets by removing elements from the product space of both contracted and primitive orbitals by means of a particular form of inner projection technique that has come to be known as Cholesky decomposition (CD). This procedure allows for on-the-fly construction of auxiliary basis sets that may be used in conjunction with any quantum chemical method, i.e. unbiased auxiliary basis sets. One key feature of these sets is that they represent the electron-repulsion integral matrix in atomic orbital basis with an accuracy that can be systematically improved. Another key feature is represented by the fact that locality of fitting coefficients is obtained even with the long-ranged Coulomb metric, as result of integral accuracy. Here we report on recent advances in the development of the CD-based density fitting technology. In particular, the implementation of analytical gradients algorithms is reviewed and the present status of local formulations - potentially linear scaling - is analysed in detail.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keyword
Quantum chemistry, Lowdin's inner projections, Cholesky decomposition, density fitting, linear scaling
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-334507 (URN)10.1080/00268976.2017.1284354 (DOI)000408727700008 ()
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2017-12-14Bibliographically approved
Augusto, F. A., Francés-Monerris, A., Fdez. Galván, I., Roca-Sanjuán, D., Bastos, E. L., Baader, W. J. & Lindh, R. (2017). Mechanism of activated chemiluminescence of cyclic peroxides: 1,2-dioxetanes and 1,2-dioxetanones. Physical Chemistry, Chemical Physics - PCCP, 19(5), 3955-3962.
Open this publication in new window or tab >>Mechanism of activated chemiluminescence of cyclic peroxides: 1,2-dioxetanes and 1,2-dioxetanones
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 5, p. 3955-3962Article in journal (Refereed) Published
Abstract [en]

Almost all chemiluminescent and bioluminescent reactions involve cyclic peroxides. The structure of the peroxide and reaction conditions determine the quantum efficiency of light emission. Oxidizable fluorophores, the so-called activators, react with 1,2-dioxetanones promoting the former to their first singlet excited state. This transformation is inefficient and does not occur with 1,2-dioxetanes; however, they have been used as models for the efficient firefly bioluminescence. In this work, we use the SA-CASSCF/CASPT2 method to investigate the activated chemiexcitation of the parent 1,2-dioxetane and 1,2-dioxetanone. Our findings suggest that ground state decomposition of the peroxide competes efficiently with the chemiexcitation pathway, in agreement with the available experimental data. The formation of non-emissive triplet excited species is proposed to explain the low emission efficiency of the activated decomposition of 1,2-dioxetanone. Chemiexcitation is rationalized considering a peroxide/activator supermolecule undergoing an electron-transfer reaction followed by internal conversion.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:uu:diva-320470 (URN)10.1039/c6cp08154a (DOI)000395328100057 ()28106183 (PubMedID)
Available from: 2017-04-20 Created: 2017-04-20 Last updated: 2017-12-18
Valentini, A., Rivero, D., Zapata, F., García-Iriepa, C., Marazzi, M., Palmeiro, R., . . . Frutos, L. M. (2017). Optomechanical Control of Quantum Yield in Trans-Cis Ultrafast Photoisomerization of a Retinal Chromophore Model. Angewandte Chemie International Edition, 56(14), 3842-3846.
Open this publication in new window or tab >>Optomechanical Control of Quantum Yield in Trans-Cis Ultrafast Photoisomerization of a Retinal Chromophore Model
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2017 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 14, p. 3842-3846Article in journal (Refereed) Published
Abstract [en]

The quantum yield of a photochemical reaction is one of the most fundamental quantities in photochemistry, as it measures the efficiency of the transduction of light energy into chemical energy. Nature has evolved photoreceptors in which the reactivity of a chromophore is enhanced by its molecular environment to achieve high quantum yields. The retinal chromophore sterically constrained inside rhodopsin proteins represents an outstanding example of such a control. In a more general framework, mechanical forces acting on a molecular system can strongly modify its reactivity. Herein, we show that the exertion of tensile forces on a simplified retinal chromophore model provokes a substantial and regular increase in the trans-to-cis photoisomerization quantum yield in a counter-intuitive way, as these extension forces facilitate the formation of the more compressed cis photoisomer. A rationale for the mechanochemical effect on this photoisomerization mechanism is also proposed.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keyword
mechanochemistry, photoisomerization, quantum yield control, retinal models, semiclassical dynamics
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-320042 (URN)10.1002/anie.201611265 (DOI)000397346200009 ()28251753 (PubMedID)
Available from: 2017-04-13 Created: 2017-04-13 Last updated: 2017-12-18
Garcia-Prieto, F. F., Muñoz-Losa, A., Fdez. Galvan, I., Sanchez, M. L., Aguilar, M. A. & Martin, M. E. (2017). QM/MM Study of Substituent and Solvent Effects on the Excited State Dynamics of the Photoactive Yellow Protein Chromophore. Journal of Chemical Theory and Computation, 13(2), 737-748.
Open this publication in new window or tab >>QM/MM Study of Substituent and Solvent Effects on the Excited State Dynamics of the Photoactive Yellow Protein Chromophore
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2017 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 13, no 2, p. 737-748Article in journal (Refereed) Published
Abstract [en]

Substituent and solvent effects on the excited state dynamics of the Photoactive Yellow Protein chromophore are studied using the average solvent electrostatic potential from molecular dynamics (ASEP/MD) method. Four molecular models were considered: the ester and thioester derivatives of the p-coumaric acid anion and their methylated derivatives. We found that the solvent produces dramatic modifications on the free energy profile of the S1 state: 1) Two twisted structures that are minima in the gas phase could not be located in aqueous solution. 2) Conical intersections (CIs) associated with the rotation of the single bond adjacent to the phenyl group are found for the four derivatives in water solution but only for thio derivatives in the gas phase. 3) The relative stability of minima and CIs is reverted with respect to the gas phase values, affecting the prevalent de-excitation paths. As a consequence of these changes, three competitive de-excitation channels are open in aqueous solution: the fluorescence emission from a planar minimum on S1, the transcis photoisomerization through a CI that involves the rotation of the vinyl double bond, and the nonradiative, nonreactive, de-excitation through the CI associated with the rotation of the single bond adjacent to the phenyl group. In the gas phase, the minima are the structures with the lower energy, while in solution these are the conical intersections. In solution, the de-excitation prevalent path seems to be the photoisomerization for oxo compounds, while thio compounds return to the initial trans ground state without emission.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-320767 (URN)10.1021/acs.jctc.6b01069 (DOI)000394924000031 ()28072537 (PubMedID)
Available from: 2017-04-25 Created: 2017-04-25 Last updated: 2017-12-18
Francés-Monerris, A., Fernández Galván, I., Lindh, R. & Roca-Sanjuan, D. (2017). Triplet versus singlet chemiexcitation mechanism in dioxetanone: a CASSCF/CASPT2 study. Theoretical Chemistry accounts, 136(6), Article ID 70.
Open this publication in new window or tab >>Triplet versus singlet chemiexcitation mechanism in dioxetanone: a CASSCF/CASPT2 study
2017 (English)In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 136, no 6, article id 70Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence is a fundamental process of chemistry consisting in the conversion of chemical energy stored in chemical bonds into light. It is used by nature and by man-made technology, being especially relevant in chemical analysis. The understanding of the phenomenon strongly relies in the study of peroxide models such as 1,2-dioxetanones. In the present contribution, the singlet S2 and the triplet T2 potential energy surfaces of the unimolecular decomposition of 1,2-dioxetanone have been mapped along the O-O and C-C bond coordinates on the grounds of the multiconfigurational CASPT2//CASSCF approach. Results confirm the energy degeneracy between T2, T1, S1, and S0 at the TS region, whereas S2 is unambiguously predicted at higher energies. Triplet-state population is also supported by the spin-orbit couplings between the singlet and triplet states partaking in the process. In particular, the first-principle calculations show that decomposition along the T2 state is a competitive process, having a small (similar to 3 kcal/mol) energy barrier from the ground-state TS structure. The present findings can explain the higher quantum yield of triplet-state population with respect to the excited singlet states recorded experimentally for the uni-molecular decomposition of 1,2-dioxetanone models.

Keyword
Quantum chemistry, Excited states, CASSCF/CASPT2, Chemiluminescence, Dioxetanone decomposition, Triplet states
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-329733 (URN)10.1007/s00214-017-2095-x (DOI)000404250000001 ()
Funder
Swedish Research Council, 2012-3910eSSENCE - An eScience Collaboration
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-12-28Bibliographically approved
Jorner, K., Dreos, A., Emanuelsson, R., El Bakouri, O., Fernández Galván, I., Borjesson, K., . . . Ottosson, H. (2017). Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems. Journal of Materials Chemistry A, 5(24), 12369-12378.
Open this publication in new window or tab >>Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems
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2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 24, p. 12369-12378Article in journal (Refereed) Published
Abstract [en]

Developing norbornadiene-quadricyclane (NBD-QC) systems for molecular solar-thermal (MOST) energy storage is often a process of trial and error. By studying a series of norbornadienes (NBD-R-2) doubly substituted at the C7-position with R = H, Me, and iPr, we untangle the interrelated factors affecting MOST performance through a combination of experiment and theory. Increasing the steric bulk along the NBD-R-2 series gave higher quantum yields, slightly red-shifted absorptions, and longer thermal lifetimes of the energy-rich QC isomer. However, these advantages are counterbalanced by lower energy storage capacities, and overall R = Me appears most promising for short-term MOST applications. Computationally we find that it is the destabilization of the NBD isomer over the QC isomer with increasing steric bulk that is responsible for most of the observed trends and we can also predict the relative quantum yields by characterizing the S-1/S-0 conical intersections. The significantly increased thermal half-life of NBD-iPr(2) is caused by a higher activation entropy, highlighting a novel strategy to improve thermal half-lives of MOST compounds and other photo-switchable molecules without affecting their electronic properties. The potential of the NBD-R-2 compounds in devices is also explored, demonstrating a solar energy storage efficiency of up to 0.2%. Finally, we show how the insights gained in this study can be used to identify strategies to improve already existing NBD-QC systems.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Chemical Sciences Engineering and Technology Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-329636 (URN)10.1039/c7ta04259k (DOI)000403664800043 ()
Funder
Swedish Research Council, 2015-04538, 2011-04177, 2012-3910, 2016-03398Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research Ragnar Söderbergs stiftelse
Available from: 2017-09-21 Created: 2017-09-21 Last updated: 2017-12-08Bibliographically approved
Aquilante, F., Autschbach, J., Carlson, R. K., Chibotaru, L. F., Delcey, M. G., De Vico, L., . . . Lindh, R. (2016). Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table. Journal of Computational Chemistry, 37(5), 506-541.
Open this publication in new window or tab >>Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table
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2016 (English)In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 37, no 5, p. 506-541Article in journal (Refereed) Published
Abstract [en]

In this report, we summarize and describe the recent unique updates and additions to the Molcas quantum chemistry program suite as contained in release version 8. These updates include natural and spin orbitals for studies of magnetic properties, local and linear scaling methods for the Douglas-Kroll-Hess transformation, the generalized active space concept in MCSCF methods, a combination of multiconfigurational wave functions with density functional theory in the MC-PDFT method, additional methods for computation of magnetic properties, methods for diabatization, analytical gradients of state average complete active space SCF in association with density fitting, methods for constrained fragment optimization, large-scale parallel multireference configuration interaction including analytic gradients via the interface to the Columbus package, and approximations of the CASPT2 method to be used for computations of large systems. In addition, the report includes the description of a computational machinery for nonlinear optical spectroscopy through an interface to the QM/MM package Cobramm. Further, a module to run molecular dynamics simulations is added, two surface hopping algorithms are included to enable nonadiabatic calculations, and the DQ method for diabatization is added. Finally, we report on the subject of improvements with respects to alternative file options and parallelization.

Keyword
electron correlation, gradients, molecular dynamics, parallelization, relativistic
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-279555 (URN)10.1002/jcc.24221 (DOI)000369176900005 ()26561362 (PubMedID)
Funder
EU, European Research Council, 291198Swedish Research CouncileSSENCE - An eScience CollaborationSwedish National Infrastructure for Computing (SNIC)Swedish Research Council, 2012-3910
Available from: 2016-03-02 Created: 2016-03-02 Last updated: 2017-11-30Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0684-7689

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