Absorption maxima study of chromophores of indigoid dyes

Chen, P. C.

doi:10.1002/(sici)1097-461x(1996)60:2<681::aid-qua6>3.0.co;2-t

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…Compared with known indigoide compounds, the molecular structure of chromophores and indigoide dyes is different because of the lack of five-memebered and phenyl rings in the chromphores. 45,46 In this way, the calcu-…”

Section: Geometry Optimizationmentioning

confidence: 99%

Characterization of indigo carmine with surface‐enhanced resonance Raman spectroscopy (SERRS) using silver colloids and island films, and theoretical calculations

Peica

Kiefer

2007

J Raman Spectroscopy

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The application of resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopies to the qualitative and semiquantitative analysis of the artificial dye indigo carmine has been examined using sodium-citrate-reduced silver colloid and island films with various roughnesses. Additional, the Raman spectrum of the solid state and density functional theory (DFT) calculations helped to a better understanding of the fully optimized geometry and of the vibrational wavenumbers of the dye. A strong chemical interaction of indigo carmine with the silver colloidal particles was observed mainly at very low concentration of 0.03 × 10 −9 M and with silver film surfaces at a concentration of 10 −4 M. The indigo carmine orientation possibilities while going to different metallic substrates are discussed.

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Section: Geometry Optimizationmentioning

confidence: 99%

Characterization of indigo carmine with surface‐enhanced resonance Raman spectroscopy (SERRS) using silver colloids and island films, and theoretical calculations

Peica

Kiefer

2007

J Raman Spectroscopy

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“…Semiempirical calculations performed in the 1960s to the 1980s led to the conclusion that the basic chromophore of the indigo dyes is the central C=C bond together with the adjacent C=O and N-H groups. [38][39][40][41][42][43] The excitation energies of singlet excited states of indigo have been extensively studied with ab initio methods 44,45 as well as, more recently, with time-dependent density functional theory (TDDFT) and with inclusion of solvation effects by a polarizable continuum model. [46][47][48][49] However, little attention has been paid to the photochemical reactions of indigo, such as ESIPT and trans → cis photoisomerization.…”

Section: Introductionmentioning

confidence: 99%

Molecular mechanisms of the photostability of indigo

Yamazaki

Sobolewski

Domcke

2011

Phys. Chem. Chem. Phys.

135

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The photophysics of indigo as well as of bispyrroleindigo, the basic chromophore of indigo, has been investigated with ab initio electronic-structure calculations. Vertical electronic excitation energies and excited-state potential-energy profiles have been calculated with the CASSCF, CASPT2 and CC2 methods. The calculations reveal that indigo and bispyrroleindigo undergo intramolecular single-proton transfer between adjacent N-H and C=O groups in the (1)ππ* excited state. The nearly barrierless proton transfer provides the pathway for a very efficient deactivation of the (1)ππ* state via a conical intersection with the ground state. While a low-lying S(1)-S(0) conical intersection exists also after double-proton transfer, the latter reaction path exhibits a much higher barrier. The reaction path for trans→cis photoisomerization via the twisting of the central C=C bond has been investigated for bispyrroleindigo. It has been found that the twisting of the central C=C bond is unlikely to play a role in the photochemistry of indigo, because of a large potential-energy barrier and a rather high energy of the S(1)-S(0) conical intersection of the twisted structure. These findings indicate that the exceptional photostability of indigo is the result of rapid internal conversion via intramolecular single-proton transfer, combined with the absence of a low-barrier reaction path for the generation of the cis isomer via trans→cis photoisomerization.

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“…20 Computationally, the early semiempirical studies on indigo 1,2,32,33 were complemented in recent years by ab initio and time-dependent density functional theory (TDDFT) calculations addressing the spectra of indigo and its derivatives. 23,[34][35][36] Theoretical studies on the photoinduced processes of indigo are still rare. We are aware of only one investigation with high-level electronic structure calculations: Yamazaki et al employed the complete active space self-consistent field (CASSCF) method, second-order perturbation theory based on the CASSCF reference (CASPT2), and approximate secondorder coupled-cluster singles-and-doubles (CC2) theory to calculate vertical excitation energies and to explore the excitedstate potential energy surfaces (PES) for proton transfer and trans-cis isomerization of indigo (1) and bispyrroleindigo (2).…”

Section: Introductionmentioning

confidence: 99%

Nonadiabatic dynamics of a truncated indigo model

Cui

Thiel

2012

Phys. Chem. Chem. Phys.

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Indigo (1) is stable when exposed to ultraviolet light. We employ electronic structure calculations and nonadiabatic trajectory surface-hopping dynamics simulations to study the photoinduced processes and the photoprotection mechanism of an indigo model, bispyrroleindigo (2). Consistent with recent static ab initio calculations on 1 and 2 (Phys. Chem. Chem. Phys., 2011, 13, 1618), we find an efficient deactivation process that proceeds as follows. After vertical photoexcitation, the S(1)(ππ*) state undergoes an essentially barrierless intramolecular single proton transfer and relaxes to the minimum of an S(1) tautomer, which is structurally and energetically close to a nearby conical intersection that acts as a funnel to the S(0) state; after this internal conversion, a reverse single hydrogen transfer leads back to the equilibrium structure of the most stable S(0) tautomer. This deactivation process is completely dominant in our semiempirical OM2/MRCI nonadiabatic dynamics simulations. The other two mechanisms considered previously, namely excited-state intramolecular double proton transfer and trans-cis double bond isomerization, are not seen in any of the 325 trajectories of the present surface-hopping simulations. On the basis of the computed time-dependent populations of the S(1) state, we estimate an S(1) lifetime of about 700 fs for 2 in the gas phase.

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Absorption maxima study of chromophores of indigoid dyes

Cited by 6 publications

References 17 publications

Characterization of indigo carmine with surface‐enhanced resonance Raman spectroscopy (SERRS) using silver colloids and island films, and theoretical calculations

Characterization of indigo carmine with surface‐enhanced resonance Raman spectroscopy (SERRS) using silver colloids and island films, and theoretical calculations

Molecular mechanisms of the photostability of indigo

Nonadiabatic dynamics of a truncated indigo model

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