Optically detected magnetic resonance study of the phosphorescent states of thiouracils

Taherian, M. R.; Maki, August H.

doi:10.1016/0301-0104(81)85087-2

Cited by 30 publications

(31 citation statements)

References 39 publications

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“…Copyright (2004) American Chemical Society the TD-B3LYP/6-311++G(d,p)//B3LYP/6-311++G(d,p) level [180]. It is evident from the Figure 14-3 that for uracil and thiouracils the lowest 3 * state has the lower energy than the 3 n * state both in the gas phase and in water solution and thus supporting the findings of Taherian and Maki [185] and Milder and Kliger [186] that the lowest triplet state of thiouracils is of the * type.…”

Section: Electronic Excited States Of Thiouracilssupporting

confidence: 76%

“…The n * state as the first triplet state of 4TUrd has been suggested by Salet et al [184]. However, optically detected magnetic resonance (ODMR) investigation of 1-methyl-2-thiouracil, 1-methyl-4-thiouracil and 1-methyl-2,4-dithiouracil [185] and laser photolysis study of uracil, 4TUrd and 1,3-dimethyl-4-thiouracil in different solvents along with INDO/S calculations [186] have suggested the first triplet state of thiouracils as the * type. The MCQDPT2/MCSCF level of calculations on 4TU have also indicated that the * state is the lowest triplet state in the molecule [181].…”

Section: Electronic Excited States Of Thiouracilsmentioning

confidence: 97%

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Computational Study of UV-Induced Excitations of DNA Fragments

Shukla

Leszczyński

2008

Challenges and Advances in Computational Chemistry and Physics

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The recent experimental and theoretical results in elucidating the structures and properties of ultraviolet (UV)-induced electronic excitations of DNA fragments and related analogs are discussed. Although, the electronic absorption maxima of nucleic acid bases are in the UV region of the energy spectrum, these genetic molecules are highly photostable. The observed photostability is the outcome of the extremely short excited state life-times. This fundamental characteristic of nucleic acid bases on the other hand is attained by the ultrafast nonradiative decay through internal conversion. Recent theoretical investigations unambiguously show that excited state geometries are generally nonplanar, though the amount of nonplanarity depends on the level of theory used in the calculation. It is also evident that conical intersections involving ground and excited state potential energy surfaces are instrumental for such nonradiative deactivation. Though, theory and experiments are complementary to each other, but the experimental progress in studying excited state properties are far ahead compared to the theoretical methods. For example, it is still very challenging for an extensive investigation of excited state properties of systems like nucleic acid bases at multi-configurational theoretical levels and with large basis sets augmented with diffuse functions. The theoretical and computational bottleneck impedes the investigation of effect of stacking interaction, which is of the fundamental importance for DNA, at the reliable theoretical level. However, we hope that with the theoretical and computational advances such investigations will be possible in near future

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Section: Electronic Excited States Of Thiouracilssupporting

confidence: 76%

Section: Electronic Excited States Of Thiouracilsmentioning

confidence: 97%

Computational Study of UV-Induced Excitations of DNA Fragments

Shukla

Leszczyński

2008

Challenges and Advances in Computational Chemistry and Physics

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“…from previous work (15). Figure 7 shows plots of Dn max vs here appear to be particularly well suited for obtaining these collected for each spectrum using 100 mW of applied microwave power quantities.…”

Section: Figmentioning

confidence: 95%

“…The band of lysozyme; the sweep rate is 100 Mhz/s. The upper points are experimenobserved is n 1 , the lowest frequency ODMR transition of tal with calculated response from best-fit values of parameters (Table 1, the three exhibited by this sample (15,17). In this case, all second row) superimposed.…”

Section: Figmentioning

confidence: 96%

“…These compounds were synthesized and purified as described there are five unknown parameters to be determined. These are the band center (n 0 ) and half-width at half-height previously (15). Mixed crystals were grown in the dark by slow evaporation of an ethanol solution of 1-Me-U con-(n 1/2 ) of the (assumed) Gaussian band shape, the decay constants of the sublevels undergoing magnetic resonance taining 0.75 mol% 1-Me-s 2 U in a desiccator over P 2 O 5 .…”

Section: Introductionmentioning

confidence: 99%

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