Frenkel exciton photodynamics of self-assembled monolayers of azobiphenyls

Gil, Eduarda Sangiogo; Persico, Maurizio; Granucci, Giovanni

doi:10.1063/5.0122109

Cited by 10 publications

(36 citation statements)

References 20 publications

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“…Notably, after transition to the nπ * manifold, the exciton is strongly localized (F 22 = 1, F H = 1, IPR = 1; FTDM and IPR curves are less noisy than for the ππ * manifold) and it remains at a single fragment (X = 2 for the shown trajectory) without being transferred. This is in agreement with the recent conclusion of Sangiogo Gil et al 46 Importantly, the absence of the exciton transfer in the nπ * manifold is observed for almost all trajectories with an exception of two trajectories for tetramer 3.5 Å and two trajectories for SAM 3.5 Å. And for these exceptional trajectories, only a single transfer event takes place per trajectory.…”

Section: Lphivsupporting

confidence: 92%

“…In our present work, we also come to a similar conclusion, and in what follows we will compare our results to the results of Ref. 46 where applicable.…”

Section: Introductionsupporting

confidence: 86%

“…It is again in qualitative agreement with previous simulations. 29,33,46 It is interesting to compare the obtained lifetimes to those reported in the recent study employing exciton model / surface hopping approach, performed for 12 QM azobenzene chromophores. 46 After ππ * excitation, the following lifetimes were obtained: τ ππ * ≈ 0.27 ps and τ nπ * ≈ 3.41 ps.…”

Section: Resultsmentioning

confidence: 87%

“…29,33,46 It is interesting to compare the obtained lifetimes to those reported in the recent study employing exciton model / surface hopping approach, performed for 12 QM azobenzene chromophores. 46 After ππ * excitation, the following lifetimes were obtained: τ ππ * ≈ 0.27 ps and τ nπ * ≈ 3.41 ps. Whereas a direct comparison is not possible since the considered systems are different, we note that the ππ * lifetime of Ref.…”

Section: Resultsmentioning

confidence: 87%

“…45 This method has then been applied to an azobenzene-containing SAM model including twelve chromophores in the QM region. 46 The central result of Ref. 46 is the absense of exciton transfer between azobenzenes in the nπ * manifold and, thus, its unimportance for quenching isomerization.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Exciton localization and transfer in azobenzene aggregates: A surface hopping molecular dynamics study

Titov

2023

Preprint

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Molecular photoswitches are a promising class of molecules for development of new functional, light-controlled materials. In complex systems, composed of multiple photoswitchable units, photophysical and photochemical properties may be altered as compared to isolated chromophores. And phenomena such as excitation energy transfer may arise in the aggregated state. In the present work, using nonadiabatic molecular dynamics simulations in conjunction with transition density matrix analysis, we study exciton dynamics in H-type tetramers of azobenzene, a prototypical molecular switch. We consider “free” and “constrained” (embedded in an environment of additional azobenzene molecules) models with different intermolecular distances (3.5 and 5.5 Å). Our simulations reveal ultrafast exciton localization upon ππ* excitation, occurring on a sub-100 fs timescale, and proceeding faster for the longer separation distance than for the shorter one. We also find that exciton transfer takes place during excited state dynamics in the ππ* manifold but it is strongly inhibited in the nπ* manifold. Moreover, we find that the ππ* trans→cis isomerization quantum yields are lower by a factor of about three for free / not strongly constrained tetramers than for the monomer, and no switching is observed for the most tightly packed model.

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Section: Lphivsupporting

confidence: 92%

“…In our present work, we also come to a similar conclusion, and in what follows we will compare our results to the results of Ref. 46 where applicable.…”

Section: Introductionsupporting

confidence: 86%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Exciton localization and transfer in azobenzene aggregates: A surface hopping molecular dynamics study

Titov

2023

Preprint

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Exciton States of Azobenzene Aggregates: A First‐Principles Study

Titov

Beqiraj

2023

Advcd Theory and Sims

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Interaction between azobenzene-containing molecules in supramolecular structures or self-assembled monolayers (SAMs) results in the formation of molecular exciton states. These states determine photophysical and photochemical processes in such assemblies. Here, using first-principles quantum chemical calculations, optical spectra and exciton delocalization of the exciton states in model clusters of azobenzene molecules are studied. Specifically, 1D linear chains and 2D SAM-like arrangements are considered, and the exciton states are computed by means of time-dependent long-range corrected density functional theory (TD-lc-DFT) and ab initio configuration interaction singles (CIS), for clusters including up to 18 azobenzene molecules. The nature of the exciton states is analyzed using transition density matrix analysis. In addition, a connection to periodic systems is made applying the Bethe-Salpeter equation (BSE)/Green's function many-body perturbation theory (GW) approach to a selected system. It is found that the brightest excitons are dominated by local excitations. The energetic location of charge transfer states in the electronic spectra of aggregates depends to a large extent on a given method and distance between nearest neighbors. Furthermore, it is analized how an excitonic delocalization pattern changes with varying molecular orientation in the unit cell of SAMs.

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An algorithm for very high pressure molecular dynamics simulations

Tesi,

Cammi,

Granucci

et al. 2024

J Comput Chem

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We describe a method to run simulations of ground or excited state dynamics under extremely high pressures. The method is based on the introduction of a fictitious ideal gas that exerts the required pressure on a molecular sample and is therefore called XP‐GAS (eXtreme Pressure by Gas Atoms in a Sphere). The algorithm is most suitable for approximately spherical clusters of molecules described by quantum chemistry methods, Molecular Mechanics or mixed QM/MM approaches. We compare the results obtained by the algorithm here presented and by the XP‐PCM approach, based on a continuum description of the environment. As a test case, we study the conformational dynamics of 1,3‐butadiene either as an isolated molecule (“naked” butadiene) or embedded in a cluster of argon atoms, under pressures up to 15 GPa. Overall, our results show that the XP‐GAS QM/MM simulation method is in good agreement with the XP‐PCM QM/Continuum model (Cammi model) in describing the effect of the pressure on static properties as the equilibrium geometry of butadiene in the ground state. Furthermore, the comparison of XP‐GAS simulations with naked butadiene and butadiene in argon shows the importance, for XP‐GAS and related methods, of a realistic representation of the medium in modelling pressure effects.

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Frenkel exciton photodynamics of self-assembled monolayers of azobiphenyls

Cited by 10 publications

References 20 publications

Exciton localization and transfer in azobenzene aggregates: A surface hopping molecular dynamics study

Exciton localization and transfer in azobenzene aggregates: A surface hopping molecular dynamics study

Exciton States of Azobenzene Aggregates: A First‐Principles Study

An algorithm for very high pressure molecular dynamics simulations

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