Dual fluorescence of 4-(dialkylamino)pyrimidines. Twisted intramolecular charge transfer state formation favored by hydrogen bond or by coordination to the metal ion

Herbich, Jerzy; Grabowski, Zbigniew R.; Wojtowicz, H.; Golankiewicz, K.

doi:10.1021/j100346a015

Cited by 59 publications

(49 citation statements)

References 7 publications

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“…Examples are known in the literature of TICT state formation favored by ground state hydrogen bonding formation on 4-(dialkylamino) pyrimidines (32)(33)(34). Both a and b fluorescence appeared and was influenced by the proton-donating ability of the n-alcohols.…”

Section: B Monocationmentioning

confidence: 99%

Photophysics of some substituted 3H-indole probe molecules and their charged species

Belletête¹,

Sarpal²,

Durocher³

1994

Can. J. Chem.

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The spectroscopic and photophysical parameters of neutral and cationic species of the following molecules have been discussed: 2-phenyl-3,3-dimethyl-3H-indole (1). 2-[@-amino)phenyl]-3.3-dimethyl-3H-indole (2), 2-[QI-dimethylamino)phenyl]-3,3-dimethyl-3H-indole (3), 2-[@-amino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (4). 2-[@-methylamino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (5),2-[@-dimethylamino)phenyl]-3,3-dimethyl-5-carb0eth0xy-3H-ind0le (6). Solvatochromic shifts have been interpreted in terms of the nature of the substituent groups and the state of solute-solvent interactions and complexation. The theoretical radiative decay rate constant (kt;) along with the bandwidth of the absorption profile of the different species involved have been used to discuss the geometrical changes from one species to the other in the ground state. The mirror-image relationship between absorption and fluorescence spectra has proven to be a good tool to discuss any geometrical changes occuning in the excited state. A radiationless torsional mechanism takes place in the excited state relaxation of the various species. The protonation of the ring nitrogen atom generates a highly planar cationic species which retains its conformation in the relaxed excited state. The very effective quenching of the monocation fluorescence is interpreted by the formation of a non-emissive TICT state.MICHEL BELLE~TE, RANIIT S. SARPAL et GILLES DUROCHER'. Can. J. Chem. 72,2239Chem. 72, (1994. On discute des paramktres spectroscopiques et photophysiques des espkces neutres et cationiques suivantes: 2-phCnyl-3,3-dimtthyl-3H-indole (I), 2-[@-amino)phCnyl]-3,3-dimCthyl-3H-indole (2), 2-[(p-dimtthylamino)phtnyl]-3,3-dimtthyl-3H-indole (3), 2-[@-amino)phtnyl]-3,3-dimtthyl-5-carboCthoxy-3H-indole (4), 2-[@-mCthylamino)phCnyl]-3,3-dimethyl-5-carbotthoxy-3H-indole (5) et 2-[@-dimtthylamino)phCnyl]-3,3-dimCthyl-3H-indole (6).On interprkte les dCplacements solvatochromiques en fonction de la nature des substituants et de 1'Ctat des interactions et de la complexation solut6solvant. On a utilisC les constantes thCoriques de vitesse de la dCgCnCrescence radiative (kt;) de concert avec la largeur de bande du profile d'absorption des difftrentes espkces impliqutes pour discuter des changements de gtomCtrie se produisant d'une espkce B l'autre dans l'ttat fondamental. On a prouvC que la relation d'image dans un miroir entre les spectres d'absorption et de fluorescence est un bon outil pour discuter de tout changement gComCtrique se produisant dans 1'Ctat excitt. Un mecanisme de torsion sans radiation se produit dans la relaxation de 1'Ctat excitC des diverses espkces. La protonation de l'atome d'azote dy cycle gtnkre une espkce cationique trks plane qui retient sa conformation dans I'Ctat excitC relaxt. On interprkte la dtsactivation trks efficace de la fluorescence du monocation par la formation d'un Ctat TICT qui ne donne pas d'Cmission.[Traduit par la rCdaction]

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Section: B Monocationmentioning

confidence: 99%

Photophysics of some substituted 3H-indole probe molecules and their charged species

Belletête¹,

Sarpal²,

Durocher³

1994

Can. J. Chem.

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“…This difference in the formation of the TICT state in protic and aprotic solvents undoubtedly suggests that the specific interaction, namely the H-bonding interaction, favours the formation of the TICT state from the planar ICT state. The fact that intermolecular H-bonding between solute and solvent often favours TICT state formation is also indicated in other fluorophores [69][70][71][72]. Thus, if the solvent has H-bonding ability, the TICT state can be formed even at a solvent polarity much lower than would have been the case in aprotic solvents.…”

Section: Effect On the Ict To Tict Conversionmentioning

confidence: 89%

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

Nath

Kumbhakar

Pal

2010

Hydrogen Bonding and Transfer in the Excited State

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The Lippert-Mataga [1, 2] expression is the most generalized equation used to describe the solvent-dependent spectral shifts of many chromophoric molecules. The Lippert-Mataga equation considers mainly two characteristic factors of the solvents, namely the refractive index (n) and the static dielectric constant («). According to the Lippert-Mataga representation, a chromophore should show bathochromic shifts in the absorption and emission spectra and a linear increase in the Stokes shift with increasing solvent polarity parameter, Df (Df ¼ [(« À 1)/(2« þ 1) À (n 2 À 1)/(2n 2 þ 1)]). This general solvent effect predicted by the Lippert-Mataga equation is expected to be independent of the chemical properties of the chromophore and the solvent used.Besides its extensive use, the Lippert-Mataga equation fails to predict the spectral properties of several chromophores in different solvent environments [3][4][5][6][7][8]. This failure is mainly due to the presence of specific interactions of the chromophores with their surrounding solvent molecules. These specific interactions can arise owing to different mechanisms such as preferential solvation [9-11], charge transfer interaction [12], hydrogen bonding interaction [13][14][15], etc. The changes in spectral characteristics experienced by a chromophore owing to its specific interaction with the surrounding solvent can sometimes be much more prominent than those expected from the general solvent effect as predicted by the Lippert-Mataga equation. For example, N-phenyl-2-aminonaphthalene shows a structured emission spectrum in a non-polar solvent such as cyclohexane. However, the structures in the emission spectrum disappear, and the emission maxima undergo a large shift on the addition of just $0.2% of ethanol in the cyclohexane solution of the dye [16]. Further, it is seen that the spectrum of N-phenyl-2-aminonaphthalene in 3% ethanolic solution is only marginally different from that observed in the neat ethanol solution. Such a small amount of ethanol in

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“…The deviations from coplanarity (non-zero initial twist angle) should priinarily influence the kinetics of the process. Now, it seems rather that the reported irreversible electrocheinical oxidation potential of NEt3 may be wrong, specially as the vertical ionization potential decreases at the substitution of methyls by ethyl groups [26,27].…”

Section: Inversional Mode?mentioning

confidence: 97%

“…The effect can also be due to steric interactions of higher alkyls with the aromatic ring, resulting in non-planarity in the ground state. The effect of replacement of Me by Et was observed and discussed in the context of the TICT states of dialkylainino-pyrimidines [26]. The deviations from coplanarity (non-zero initial twist angle) should priinarily influence the kinetics of the process.…”

Section: Inversional Mode?mentioning

confidence: 99%

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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Dual fluorescence of 4-(dialkylamino)pyrimidines. Twisted intramolecular charge transfer state formation favored by hydrogen bond or by coordination to the metal ion

Cited by 59 publications

References 7 publications

Photophysics of some substituted 3H-indole probe molecules and their charged species

Photophysics of some substituted 3H-indole probe molecules and their charged species

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

Picosecond Transient Absorption Spectra and the Twisted Intramolecular Charge Transfer Phenomenon

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