1999
DOI: 10.1039/a902063b
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Intersystem crossing (ISC) in DMABN and DMABA: Laser induced optoacoustic spectroscopy and semi-empirical (AM1) calculations

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Cited by 23 publications
(18 citation statements)
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“…2-(3-methoxy-2hydroxyphenyl)benzimidazole [29] and 2-(2'-hydroxyphenyl)benzothiazole [47]. For the present work, we have used the same commercial package, hyperchem 5.01 as described previously [46]. The geometry of the molecules has been optimised in the ground state using the AM1 method.…”
Section: Quantum Chemical Calculationsmentioning
confidence: 99%
“…2-(3-methoxy-2hydroxyphenyl)benzimidazole [29] and 2-(2'-hydroxyphenyl)benzothiazole [47]. For the present work, we have used the same commercial package, hyperchem 5.01 as described previously [46]. The geometry of the molecules has been optimised in the ground state using the AM1 method.…”
Section: Quantum Chemical Calculationsmentioning
confidence: 99%
“…The methods provide acceptable approximations to give results which are quite close to the experimental Ðndings.49h52 Recently, we have established the reliability of the AM1-SCI method through our calculations of the energies of di †erent electronic states of two Ñuorophores and thus, realisation of the variation of the non-radiative deactivation of the Ñuorophores via internal conversion (IC) and intersystem crossing (ISC) in di †erent solvents. 52 For the present semi-empirical calculations, we have used the commercial package, HYPERCHEM 5.01.53 The geometries of the molecules have been optimised in the ground state using the AM1 method. For the excited states, we have adopted the AM1-SCI, whereby we have considered all the conÐgurations (around 70 conÐgurations) within an energy window of 12 eV from the ground state, for the single electronic transitions only.…”
Section: Quantum Chemical Calculationsmentioning
confidence: 99%
“…22 Extension of similar time-resolved spectroscopy experiments to several DMABN derivatives indicates the TICT model and the ICT state hydrogen-bonding effect are generally applicable to this class of dual fluorescence molecules. 23 The deactivation through non-radiative dynamics of the singlet excited states and the nature of the triplet state have also been extensively studied experimentally 12,[24][25][26][27][28][29] and theoretically 17,[30][31][32][33] for these compounds. ISC has been shown to be the principal deactivation channel for the singlet states, irrespective of the solvent polarity.…”
Section: Introductionmentioning
confidence: 99%
“…25,26 Most of these studies indicate that the lowest triplet state ( 3 T 1 ) of DMABN and its flexible derivatives generally have a planar pp* state nature and that, irrespective of solvent polarity, only this non-ICT triplet state is active in the excited singlet to triplet ISC and phosphorescence processes. [26][27][28][31][32][33] However, this view has been challenged by the observation of a solvent effect on the triplet absorption spectra 27 and especially the TRIR studies reported by Hamaguchi et al 12 as well as the recent triplet state lifetime measurement performed by Chattopadhyay et al 34 They identify a twisted triplet state ( 3 TICT) state and suggest coexistence of two distinct triplets of different structural and electronic properties, the planar pp* nature 3 LE and twisted ICT nature 3 TICT, in polar solvent but only the 3 LE in non-polar solvent. 12,34 To address this issue, we have performed TA and nanosecond TR 3 measurement for DMABN in non-polar hexane and polar methanol solvents.…”
Section: Introductionmentioning
confidence: 99%