Spectroscopy and photophysics of mono methyl-substituted alloxazines

Sikorska, Ewa; Khmelinskii, Igor; Bourdelande, J. L.; Bednarek, Aneta; Williams, Siân L.; Patel, Manisha J.; Worrall, David R.; Koput, Jacek; Sikorski, Marek

doi:10.1016/j.chemphys.2004.03.005

Cited by 23 publications

(15 citation statements)

References 42 publications

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“…Based on our earlier calculations that used time‐dependent density functional theory (TD‐DFT), all the tested derivatives of alloxazine have two pairs of closely located n , π * and π , π * transitions in the lowest energy part of the spectrum . Contrary to that, the transitions in the lowest energy part of the absorption spectrum of 5‐DAll and 1,3Me‐5‐DAll have pure π , π * character, as we predict and present in the Discussion section.…”

Section: Introductionmentioning

confidence: 59%

“…The increase in fluorescence quantum yields can also be observed for alloxazines in protic solvents . The fluorescence lifetimes of the 5‐deazaalloxazines are longer if compared to their “aza” analogs . Note that the N(1), N(3)‐substituted 1,3Me‐5‐DAll has shorter fluorescence lifetimes than its unsubstituted analog 5‐DAll.…”

Section: Resultsmentioning

confidence: 82%

“…The electronic structure and geometry of alloxazines was obtained by means of the quantum‐chemical ab initio and density functional theory (DFT) calculations. To allow direct comparison, the calculations were made in exactly the same way as in our earlier publication devoted to methyl‐substituted alloxazines . Namely, the calculations were performed using the B3LYP functional in conjunction with the modest 6‐31G+(d) split‐valence polarized basis set and with the correlation‐consistent basis sets of double‐zeta quality—aug‐cc‐pVDZ .…”

Section: Methodsmentioning

confidence: 99%

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Photophysics, Excited‐state Double‐Proton Transfer and Hydrogen‐bonding Properties of 5‐Deazaalloxazines

Prukała

Khmelinskii

Koput

et al. 2014

Photochem & Photobiology

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The photophysical properties of 5-deazaalloxazine and 1,3-dimethyl-5-deazaalloxazine were studied in different solvents. These compounds have higher values of fluorescence quantum yields and longer fluorescence lifetimes, compared to those obtained for their alloxazine analogs. Electronic structure and S0 -Si transitions were investigated using the ab initio methods [MP2, CIS(D), EOM-CCSD] with the correlation-consistent basis sets. Also the time-dependent density functional theory (TD-DFT) has been employed. The lowest singlet excited states of 5-deazaalloxazine and 1,3-dimethyl-5-deazaalloxazine are predicted to have the π, π* character, whereas similar alloxazines have two close-lying π, π* and n, π* transitions. Experimental steady-state and time-resolved spectral studies indicate formation of an isoalloxazinic excited state via excited-state double-proton transfer (ESDPT) catalyzed by an acetic acid molecule that forms a hydrogen bond complex with the 5-deazaalloxazine molecule. Solvatochromism of both 5-deazaalloxazine and its 1,3-dimethyl substituted derivative was analyzed using the Kamlet-Taft scale and four-parameter Catalán solvent scale. The most significant result of our studies is that the both scales show a strong influence of solvent acidity (hydrogen bond donating ability) on the emission properties of these compounds, indicating the importance of intermolecular solute-solvent hydrogen-bonding interactions in their excited state.

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Section: Introductionmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

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Photophysics, Excited‐state Double‐Proton Transfer and Hydrogen‐bonding Properties of 5‐Deazaalloxazines

Prukała

Khmelinskii

Koput

et al. 2014

Photochem & Photobiology

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“…The experimental studies of the photophysical properties of substituted alloxazines ( Figure 4.8, compound c) in ACN, dichloroethane, MeOH and water show a different behaviour in the first two solvents as compared with the protic solvents [104]. In protic solvents, beside a red-shift of the fluorescence band, an enhancement of the emission was noticed, the larger value being obtained in water.…”

Section: Hydrogen-bond-assisted Fluorescence Enhancementmentioning

confidence: 99%

“…This is correlated with the greater stabilization of a strong H-bonded state versus a weak or non-H-bonded state. This state interchange was experimentally suggested for many compounds that possess non-bonding electron pairs and first excited singlets of n-p Ã character in non-polar solvents [30,104,107].…”

Section: H-bond-induced Changes In the Excited-state Propertiesmentioning

confidence: 99%

Solute–Solvent Hydrogen Bond Formation in the Excited State. Experimental and Theoretical Evidence

Matei

Ionescu

Hillebrand

2010

Hydrogen Bonding and Transfer in the Excited State

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Hydrogen bonds (H-bonds) are of great importance in biological systems, as they are responsible for the secondary structure of proteins and nucleic acids and are also involved in the mechanisms of enzyme catalysis. Supramolecular chemistry makes use of H-bonds in building up novel compounds of various architectures.The identification of these interactions and the analysis of their influence on the photophysical properties are also important in designing new fluorophores for different applications, the processes involved being rather complex in nature and often only partially understood.The main feature reflecting H-bond interaction in both the ground and excited states is the solvatochromic effect on the absorption and fluorescence spectra. This implies that changes in the solvent nature or composition produce shifts in the position, shape and intensity of the spectral bands. The source of solvatochromic shifts is the different solvation of the ground and excited states: depending on the relative stabilization of these states by solvents, bathochromic (positive)or hypsochromic (negative)shifts of the maximum of the band can be observed experimentally. Thus, such changes are indicative of the interactions occurring between the solute and the solvent in its immediate vicinity. The solute-solvent interactions are classified into:1. non-specific interactions caused by polarity/polarizability effects; 2. specific interactions, such as H-bonds.

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