Intramolecular Charge Transfer in 4-Aminobenzonitrile Does Not Need the Twist and May Not Need the Bend

Perveaux, Aurelie; Castro, Pedro J.; Lauvergnat, David; Reguero, Mar; Lasorne, Benjamin

doi:10.1021/acs.jpclett.5b00162

Cited by 32 publications

(30 citation statements)

References 21 publications

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“…In fact, it has been shown in a recent work 25 that the LE and ICT are degenerated also at planar geometries very near to the FC zone. This planar ICT/LE pathway could be faster than the pathway that evolves via ring piramidalization, a slower motion.…”

Section: Pathways Of Population Of the Excited State Minimamentioning

confidence: 94%

Intramolecular charge transfer in aminobenzonitriles and tetrafluoro counterparts: fluorescence explained by competition between low-lying excited states and radiationless deactivation. Part I: A mechanistic overview of the parent system ABN

Segado

Gómez

Reguero

2016

Phys. Chem. Chem. Phys.

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Recent theoretical and experimental studies on the Intramolecular Charge Transfer (ICT) reaction of some members of the aminobezonitrile family (ABN) suggest the involvement of a (π-σ*) excited state (called ICT(CN) in this work) in the ICT process and the existence of a partially twisted ICT species that could be responsible for the anomalous fluorescence observed. These suggestions made us to revise our previous study on the photophysics of ABN and dimethyl-ABN (DMABN), based on the analysis of the potential energy surfaces of the low-lying excited states by means of ab initio calculations, using the CASSCF/CASPT2 protocol. We have first focused our attention to ABN. We have found that the (π-σ*) excited state can be in fact an intermediary state in the path to populate the ICT bright state, although its involvement in the process is not very probable. Our results suggest that the ICT most stable species is the twisted ICT(TICT) and that the partially twisted ICT minimum found in previous studies could be an artefact of the computational method. We have also found that radiationless deactivation is a competitive reaction that must be taken into account to explain the fluorescence patterns of these systems. To confirm our theories, we have also studied other systems with a similar architecture but with a very different luminescence behaviour: dimethyl-ABN, and the 2,3,4,5-tetrafluoro derivatives of ABN and DMABN (ABN-4F and DMABN-4F). The extension of the work and the different approaches in the study of the parent system and of the derivatives make the division of the work in two parts advisable. Part I collects the characterization of the minima and reaction paths connecting the critical points of the potential energy surfaces of the states involved in the ICT reaction of ABN. We have obtained, for the first time, the pathways of radiationless deactivation for this compound. We have also computed transition energies from the excited minima, to interpret the excited state absorption (ESA) spectra obtained experimentally. This information helps in the elucidation of the mechanism of ICT. In Part II we show an analoguous study for DMABN and ABN-4F and DMABN-4F and analyse and compare these results and those of Part I to explain different luminescence behaviours of the four systems studied.

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Section: Pathways Of Population Of the Excited State Minimamentioning

confidence: 94%

Intramolecular charge transfer in aminobenzonitriles and tetrafluoro counterparts: fluorescence explained by competition between low-lying excited states and radiationless deactivation. Part I: A mechanistic overview of the parent system ABN

Segado

Gómez

Reguero

2016

Phys. Chem. Chem. Phys.

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“…The results of the computations allowed the authors to interpret the distinct experimental observations for the two molecules. Regarding ABN, Reguero, Lasorne and co-workers 146 found a new relaxation path connecting the LE and CT states based on a planar CIX rather than the twisted CIX supported by other groups. Segarra-Martí and Coto 147 studied the 4-(dimethylamino)benzoethyne (DMABE) molecule, which is isoelectronic with DMABN, but does not show dual fluorescence.…”

Section: Ring-opening and Ring-closurementioning

confidence: 67%

Advances in computational photochemistry and chemiluminescence of biological and nanotechnological molecules

Roca‐Sanjuán¹,

Francés‐Monerris²,

Galván³

et al. 2016

Photochemistry

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Recent advances (2014-2015) in computational photochemistry and chemiluminescence derive from the development of theory and from the application of state-of-the-art and new methodology to challenging electronic-structure problems. Method developments have mainly focused, first, on the improvement of approximate and cheap methods to provide a better description of non-adiabatic processes, second, on the modification of accurate methods in order to decrease the computation time and, finally, on dynamics approaches able to provide information that can be directly compared with experimental data, such as yields and lifetimes. Applications of the ab initio quantum-chemistry methods have given rise to relevant findings in distinct fields of the excited-state chemistry. We briefly summarise, in this chapter, the achievements on photochemical mechanisms and chemically-induced excited-state phenomena of interest in biology and nanotechnology.

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“…Hence the major path ways for the formation of triplet state was from the local excited singlet state and PICT. 21 …”

Section: Resultsmentioning

confidence: 99%

“…However the dynamics of the charge transfer processes are significantly controlled by solvation dynamics and intramolecular relaxation [10][11] . A large number of experimental [12][13][14][15][16][17][18][19][20] and theoretical 6,[21][22][23][24][25][26] studies have been devoted to understand the underlying mechanism controlling the electronic pathways, geometrical structure and dynamics of the photoinduced intramolecular charge transfer (ICT) state in the excited state relaxation of the different electron donor-acceptor -conjugated systems upon photoexcitation [4][5] . Though the characteristics of the ICT state with dual fluorescence are described by different models including planar 27 , partially twisted or pre twisted 28 , twisted 29 , rehybridized 30 and multifaceted dynamics 31 , controversies on the mechanism of ICT are prevalent 21,26,[32][33] .…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Cascade of Photoinduced Ultrafast Intramolecular Charge Transfer Dynamics in Diphenyl Acetylene Derivatives: Via Solvation and Intramolecular Relaxation

Karunakaran

Das

2016

J. Phys. Chem. B

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Interaction of light with electron donor-acceptor π-conjugated systems leading to intramolecular charge transfer (ICT) plays an essential role in transformation of light energy. Here the cascade of photoinduced ICT processes is directly observed by investigating the excited state relaxation dynamics of cyano and mono/di methoxy substituted diphenyl acetylene derivatives using femtosecond pump-probe spectroscopy and nanosecond laser flash photolysis. The femtosecond transient absorption spectra of the chromophores upon ultrafast excitation reveal the dynamics of intermediates involved in transition from initially populated Frank-Condon state to local excited state (LE). It also provides the dynamic details of the transition from the LE to the charge transfer state yielding the formation of the radical ions. Finally, the charge transfer state decays to the triplet state by geminate charge recombination. The latter dynamics are observed in the nanosecond transient absorption spectra. It is found that excited state relaxation pathways are controlled by different stages of solvation and intramolecular relaxation depending on the solvent polarity. The twisted ICT state is more stabilized (978 ps) in acetonitrile than cyclohexane where major components of transient absorption originate from the S1 state.

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Intramolecular Charge Transfer in 4-Aminobenzonitrile Does Not Need the Twist and May Not Need the Bend

Cited by 32 publications

References 21 publications

Intramolecular charge transfer in aminobenzonitriles and tetrafluoro counterparts: fluorescence explained by competition between low-lying excited states and radiationless deactivation. Part I: A mechanistic overview of the parent system ABN

Intramolecular charge transfer in aminobenzonitriles and tetrafluoro counterparts: fluorescence explained by competition between low-lying excited states and radiationless deactivation. Part I: A mechanistic overview of the parent system ABN

Advances in computational photochemistry and chemiluminescence of biological and nanotechnological molecules

Direct Observation of Cascade of Photoinduced Ultrafast Intramolecular Charge Transfer Dynamics in Diphenyl Acetylene Derivatives: Via Solvation and Intramolecular Relaxation

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