Excited-state dipole moments of dual fluorescent 4-(dialkylamino)benzonitriles: influence of alkyl chain length and effective solvent polarity

Schuddeboom, Wouter; Jonker, Stephan A.; Warman, John M.; Leinhos, Uwe; Kuehnle, W.; Zachariasse, Klaas A.

doi:10.1021/j100205a041

Cited by 358 publications

(551 citation statements)

References 3 publications

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“…We conclude that the dipole moments of the pure 3 ππ* states of PNA and its N-alkyl substituted derivatives are probably closer to 11 D than to the lower limit of 9 D. The former value is similar to the value of 12 D recently estimated for the dipole moment of the triplet state of (dimethylamino)benzonitrile using the present technique. 22 The large TRMC transients observed for the symmetrical compounds 2-PNA and 3-PNA indicate that the excitation energy must remain localized on a single nitro-anilino moiety for a time at least comparable with and possibly considerably longer than the ca. 15 ps reciprocal radian frequency of the microwaves.…”

Section: Resultsmentioning

confidence: 99%

Dipolar Triplet States ofp-Nitroaniline andN-Alkyl Derivatives with One-, Two-, and Three-Fold Symmetry

Schuddeboom¹,

Warman²,

Biemans³

et al. 1996

J. Phys. Chem.

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Photoexcitation of p-nitroaniline (PNA) and its N-alkyl derivatives results in the formation of triplet states with dipole moments considerably larger than that of the ground state, as monitored by time-resolved microwave conductivity (TRMC). The triplet state lifetime, τ T , is only 54 ns for PNA in benzene but increases to 1400 ns on N,N-dimethyl substitution and to 275 ns in the more polar solvent p-dioxane. This sensitivity of τ T is attributed to the close proximity of all of the lowest lying singlet and triplet nπ* and ππ* states of PNA, which results in substantial S 1 T T 1 mixing. The dipole moment of the "pure" 3 ππ* state is estimated to be 11 D. Methylene-bridged arrays of PNA moieties with two-and three-fold D n symmetry, 2-PNA and 3-PNA, are also found to have highly dipolar triplet states, indicating that symmetry breaking and exciton localization occur in T 1 . Flip-flop interchange between the resonant dipolar structures is estimated to take place on a time scale of tens of picoseconds. Collective interactions between the PNA moieties in the multichromphoric arrays results in a marked blue shift in the first absorption maximum from 384 nm for 1-PNA to 375 nm for 2-PNA and to 354 nm for 3-PNA.

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Section: Resultsmentioning

confidence: 99%

Dipolar Triplet States ofp-Nitroaniline andN-Alkyl Derivatives with One-, Two-, and Three-Fold Symmetry

Schuddeboom¹,

Warman²,

Biemans³

et al. 1996

J. Phys. Chem.

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“…The molecular geometry of the emitting charge transfer state is still controversial [3][4][5] and different structures have been proposed. Among them, we mention the twisted (T)-ICT by Grabowski and coworkers 6 (perhaps the most commonly accepted possibility), the planar (P)-ICT and wagging (W)-ICT by Zachariasse,[7][8] as well as the rehybridized (R)-ICT geometry [9][10][11] (a detailed account of the different mechanisms proposed in the literature as well as previous theoretical and experimental work on DMABN can be found in previous work 2 ). The "twisting" refers to torsion of the dimethylamino (DMA) group.…”

Section: Scheme 1 4-(nn-dimethylamino)-benzonitrile (Dmabn)mentioning

confidence: 99%

Ab Initio Multiple Spawning Photochemical Dynamics of DMABN Using GPUs

2017

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe ultrafast decay dynamics of 4-(N,N-dimethylamino)benzonitrile (DMABN) following photoexcitation was studied with the ab initio multiple spawning (AIMS) method, combined with GPU-accelerated linear-response time-dependent density functional theory (LR-TDDFT). We validate the LR-TDDFT method for this case and then present a detailed analysis of the first ≈200 fs of DMABN excited-state dynamics. Almost complete nonadiabatic population transfer from S 2 (the initially populated bright state) to S 1 takes place in less than 50 fs, without significant torsion of the dimethylamino (DMA) group.Significant torsion of the DMA group is only observed after the nuclear wavepacket reaches S 1 and acquires locally-excited electronic character. Our results show that torsion of the DMA group is not prerequisite for nonadiabatic transitions in DMABN, although such motion is indeed relevant on the lowest excited state (S 1 ).Curchod, et al. -DMABN -Page 2

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“…As to the effect of the long-chain alkyls in the amino group (in fact, the main effect appears between the Me 2 N-and Et 2 N-substituted compounds), the comparison of photophysics of DMAA and DOAA, as well as of DMABN and its long-chain homologues [6], can be stressed in the following. ‡Τhe difference between the spectra of DOHA and DMAA -absence of the triplet absorption in the older spectrum [10] -is due in part to different solvents, but mainly to the loss of sensitivity of the one-tiine photodiodes in the short-wave range, λ < 470 nin.…”

Section: Long-chain Effectsmentioning

confidence: 99%

“…Now, the most generally accepted hypothesis [2] is the one of the "twisted" intramolecular charge transfer state (TICT) according to which the D and Α moieties, limited in their stuctural degrees of flexibility, twist to orthogonality of their π-electronic systems [3,4]. Among the recently supported principally opposing hypotheses there are those assigning the dual fluorescence of DMABN and structurally related compounds either to the formation of exciplexes with the solvent [5], or to the pseudo Jahn-Teller distortion [6,7]. Marginally: both these views mutually oppose.…”

Section: Introductionmentioning

confidence: 99%

“…The inspiration was borrowed initially from the apparatus built in Bordeaux by Rulliére and his students [14], then modified and completed in many respects. Zachariasse et al [6] reported that the dialkylaminobenzonitriles with the methyl groups replaced by longer alkyls emit the long-wave Fa band with much higher relative yield than DMABN. For the internal rotation one could expect the contrary: large, voluminous groups should slow down the internal rotation.…”

Section: Introductionmentioning

confidence: 99%

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Picosecond Transient Absorption Spectra and the Twisted Intramolecular Charge Transfer Phenomenon

et al. 1995

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An improved model of a ckputer-controlled picosecond absorption spectrometer was designed and constructed. Its operatioii is described, and applied to the measurement of transient spectra of p-N, N-dioctylamino--acetophenone. The spectroscopy and photophysics of this ckpound are ckpared to the other ckpounds exhibiting the dual fluorescence, assigned usually to the adiabatic formation of the "twisted" intramolecular charge transfer excited state. The data are discussed in relatioii to alternative suggestion of an inversioii of the pyramidal amino nitrogen atk. The whole evidence supports the decoupling of the π-electronic systems of D+ and A-in the D+-A -polar excited state, in full accord with the "twisted" intramolecular charge transfer model. The peculiar behaviour of the long alkyl -NR2 derivatives (favouring the "twisted" intramolecular charge transfer state emission) seems to be primarily due to the decreasing oxidation potential of such electron donor groups.

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Excited-state dipole moments of dual fluorescent 4-(dialkylamino)benzonitriles: influence of alkyl chain length and effective solvent polarity

Cited by 358 publications

References 3 publications

Dipolar Triplet States ofp-Nitroaniline andN-Alkyl Derivatives with One-, Two-, and Three-Fold Symmetry

Dipolar Triplet States ofp-Nitroaniline andN-Alkyl Derivatives with One-, Two-, and Three-Fold Symmetry

Ab Initio Multiple Spawning Photochemical Dynamics of DMABN Using GPUs

Picosecond Transient Absorption Spectra and the Twisted Intramolecular Charge Transfer Phenomenon

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