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Kichisuke Nishimoto - One of the best experts on this subject based on the ideXlab platform.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones part 2 evaluation of the spectrochemical softness based on the absolute hardness
Dyes and Pigments, 2001Co-Authors: Kimihiro Hiruta, Sumio Tokita, Tatsuya Tachikawa, Kichisuke NishimotoAbstract:Abstract The first Absorption Maxima of linear para acenoquinones (LPAs) were calculated by the Pariser–Parr–Pople molecular orbital (PPP MO) method using a novel, two-centre electron repulsion integral new-γ. The spectrochemical softness parameter k in the new-γ was evaluated from the absolute hardness, η PPP and η HMO , which were obtained by the PPP MO and the HMO level approximations, respectively. The first Absorption Maxima calculated using the new-γ with k obtained from η PPP are greatly improved to reproduce the observed values better than using the conventional Nishimoto·Mataga-γ function.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones
Dyes and Pigments, 1998Co-Authors: Kimihiro Hiruta, Sumio Tokita, Kichisuke NishimotoAbstract:Abstract In order to calculate the excitation energies of linear para acenoquinones (LPAs) more accurately by Pariser-Parr-Pople molecular orbital (PPP MO) method, the spectrochemical softness parameter k of a novel two centre electron repulsion integral new-γ are evaluated based on spectroactive portion (SP) in a molecular framework. SP is defined as the longest acene portion, including a quinonoid ring of LPAs. The calculated results using the new-γ are greatly improved compared with those using the conventional Nishimoto·Mataga γ function.
Kimihiro Hiruta - One of the best experts on this subject based on the ideXlab platform.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones part 2 evaluation of the spectrochemical softness based on the absolute hardness
Dyes and Pigments, 2001Co-Authors: Kimihiro Hiruta, Sumio Tokita, Tatsuya Tachikawa, Kichisuke NishimotoAbstract:Abstract The first Absorption Maxima of linear para acenoquinones (LPAs) were calculated by the Pariser–Parr–Pople molecular orbital (PPP MO) method using a novel, two-centre electron repulsion integral new-γ. The spectrochemical softness parameter k in the new-γ was evaluated from the absolute hardness, η PPP and η HMO , which were obtained by the PPP MO and the HMO level approximations, respectively. The first Absorption Maxima calculated using the new-γ with k obtained from η PPP are greatly improved to reproduce the observed values better than using the conventional Nishimoto·Mataga-γ function.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones
Dyes and Pigments, 1998Co-Authors: Kimihiro Hiruta, Sumio Tokita, Kichisuke NishimotoAbstract:Abstract In order to calculate the excitation energies of linear para acenoquinones (LPAs) more accurately by Pariser-Parr-Pople molecular orbital (PPP MO) method, the spectrochemical softness parameter k of a novel two centre electron repulsion integral new-γ are evaluated based on spectroactive portion (SP) in a molecular framework. SP is defined as the longest acene portion, including a quinonoid ring of LPAs. The calculated results using the new-γ are greatly improved compared with those using the conventional Nishimoto·Mataga γ function.
Minoru Sakurai - One of the best experts on this subject based on the ideXlab platform.
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theoretical study on the Absorption Maxima of real gfps
Chemical Physics Letters, 2010Co-Authors: Azuma Matsuura, Hiroyuki Sato, Tomohiko Hayashi, Atsuya Takahashi, Minoru SakuraiAbstract:Abstract The excited-state calculations for the real green fluorescent protein (GFP) and its mutants, including the wild-type GFP, Y66F, blue fluorescent protein, and cyan fluorescent protein, were carried out at the INDO/S-CIS//ONIOM (B3LYP/6-31G∗∗:AMBER) level. The numbers of singly excited configuration state functions at INDO/S-CIS were over 20 million. The calculated Absorption Maxima were in good agreement with the experimental data with a computational error of ⩽15 nm. For the wild-type GFP, INDO/S-CIS yielded a bathochromic shift of 38 nm with respect to its model chromophore in vacuo, which was also in good agreement with the extrapolated experimental shift of 45 nm.
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am1 pm3 and pm5 calculations of the Absorption Maxima of basic organic dyes
Journal of Molecular Structure-theochem, 2008Co-Authors: Azuma Matsuura, Hiroyuki Sato, Atsuya Takahashi, Wataru Sotoyama, Minoru SakuraiAbstract:Abstract The Absorption Maxima, λ max , of various organic dyes such as indigo, azobenzene, phenylamine, hydrazone, anthraquinone, naphthoquinone, and malachite green were calculated using the AM1, PM3, and PM5 semiempirical molecular orbital theories with the configuration interaction singles (CIS) and random phase approximation (RPA) approaches. The calculated λ max were then compared with the values obtained by CNDO/S, INDO/S, ab initio CIS, and time-dependent density functional theory (TD-DFT). We found that the λ max values calculated by AM1, PM3, and PM5 were in good correlation with the observed λ max values. When B3LYP/cc-pVDZ optimized geometries were used, the square of the correlation coefficients between the calculated and observed λ max , r λ 2 , at the AM1-RPA, PM3-RPA, and PM5-RPA levels were 0.891, 0.897, and 0.927, respectively. In particular, r λ 2 at PM5-RPA//B3LYP/cc-pVDZ was the largest among those obtained from all the other calculations including TD/B3LYP/cc-pVDZ//B3LYP/cc-pVDZ ( r λ 2 = 0.827 ) . Accordingly, the standard deviation of the difference between observed and calculated λ max by the linear regression function at PM5-RPA//B3LYP/cc-pVDZ was the smallest. It was therefore concluded that this method was the most promising for the prediction of λ max of various dyes among the computational methods studied here. When AM1 optimized geometries were used, r λ 2 at the AM1-RPA, PM3-RPA, and PM5-RPA levels were 0.822, 0.841, and 0.901, respectively, and they were also comparable to that at TD/B3LYP/cc-pVDZ//B3LYP/cc-pVDZ. Therefore, although some calibration efforts may be needed for AM1 geometries, PM5-RPA(CIS)//AM1 may be a second candidate available for the prediction of the Absorption Maxima of dyes, especially in the case of emphasizing computational cost.
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accurate evaluation of the Absorption Maxima of retinal proteins based on a hybrid qm mm method
Journal of Computational Chemistry, 2006Co-Authors: Azuma Matsuura, Hiroyuki Sato, Hirohiko Houjou, Shino Saito, Tomohiko Hayashi, Minoru SakuraiAbstract:Here we improved our hybrid QM/MM methodology (Houjou et al. J Phys Chem B 2001, 105, 867) for evaluating the Absorption Maxima of photoreceptor proteins. The renewed method was applied to evaluation of the Absorption Maxima of several retinal proteins and photoactive yellow protein. The calculated Absorption Maxima were in good agreement with the corresponding experimental data with a computational error of <10 nm. In addition, our calculations reproduced the experimental gas-phase Absorption Maxima of model chromophores (protonated all-trans retinal Schiff base and deprotonated thiophenyl-p-coumarate) with the same accuracy. It is expected that our methodology allows for definitive interpretation of the spectral tuning mechanism of retinal proteins.
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theoretical evaluation of medium effects on Absorption Maxima of molecular solutes i formulation of a new method based on the self consistent reaction field theory
Journal of Chemical Physics, 1997Co-Authors: Hirohiko Houjou, Minoru Sakurai, Yoshio InoueAbstract:A new method is formulated for evaluating solvent effects on the Absorption Maxima of molecules. The method is based on a self-consistent reaction field polarizable continuum model (SCRF-PCM), coupled with the configuration interaction (CI) procedure. We propose a new scheme in which the polarization of solvent, induced by the excitation of a solute molecule, is partitioned into orientational and electronic contributions, and the exact expression of excitation energy is derived with nonspecific parameters of solvents, i.e., dielectric constant and refractive index. On the basis of this result, the expression of the diagonal element of the CI matrix is derived. In addition, we show that the expression of the off-diagonal element can be obtained without losing generality under the condition that the solute wave function is expressed by the Hartree product. The present method is implemented into a semiempirical molecular orbital calculation program. It is demonstrated that the test calculation for a merocyanine dye well reproduces the solvatochromic shifts observed over a variety of solvents with wide ranges of dielectric constant and refractive index.
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dielectric medium effects on Absorption Maxima of protonated retinylidene schiff bases as models of rhodopsin
Chemistry Letters, 1996Co-Authors: Hirohiko Houjou, Minoru Sakurai, Yoshio InoueAbstract:Dielectric medium effects on Absorption Maxima of protonated retinal Schiff bases (PSB) are studied using a reaction field theory incorporated into the INDO/S method. The calculation shows that a counterion, such as carboxylate, has no explicit role in regulating the Absorption maximum of PSB even in a low dielectric medium.
Sumio Tokita - One of the best experts on this subject based on the ideXlab platform.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones part 2 evaluation of the spectrochemical softness based on the absolute hardness
Dyes and Pigments, 2001Co-Authors: Kimihiro Hiruta, Sumio Tokita, Tatsuya Tachikawa, Kichisuke NishimotoAbstract:Abstract The first Absorption Maxima of linear para acenoquinones (LPAs) were calculated by the Pariser–Parr–Pople molecular orbital (PPP MO) method using a novel, two-centre electron repulsion integral new-γ. The spectrochemical softness parameter k in the new-γ was evaluated from the absolute hardness, η PPP and η HMO , which were obtained by the PPP MO and the HMO level approximations, respectively. The first Absorption Maxima calculated using the new-γ with k obtained from η PPP are greatly improved to reproduce the observed values better than using the conventional Nishimoto·Mataga-γ function.
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practical ppp molecular orbital calculations of Absorption Maxima of quinones
Dyes and Pigments, 1998Co-Authors: Kimihiro Hiruta, Sumio Tokita, Kichisuke NishimotoAbstract:Abstract In order to calculate the excitation energies of linear para acenoquinones (LPAs) more accurately by Pariser-Parr-Pople molecular orbital (PPP MO) method, the spectrochemical softness parameter k of a novel two centre electron repulsion integral new-γ are evaluated based on spectroactive portion (SP) in a molecular framework. SP is defined as the longest acene portion, including a quinonoid ring of LPAs. The calculated results using the new-γ are greatly improved compared with those using the conventional Nishimoto·Mataga γ function.
Indrek Renge - One of the best experts on this subject based on the ideXlab platform.
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solvent effects on the Absorption Maxima of fullerenes c60 and c70
The Journal of Physical Chemistry, 1995Co-Authors: Indrek RengeAbstract:Absorption spectra of fullerenes C{sub 60} and C{sub 70} have been recorded between 200 and 700 nm in liquid n-alkanes at room temperature. Solvent shifts (-p) of band Maxima vary from 900 cm{sup -1} (the 636 nm band in C{sub 70}) to 18000-19000 cm{sup -1} (the 209 nm band in C{sub 60} and the 210 nm band in C{sub 70}) per unit Lorentz-Lorenz function {phi}(n{sup 2}). The dispersive shift of the equally intense 256 nm band in C{sub 60} and 235 nm band in C{sub 70} yields {Delta}{alpha} values of 41 {+-} 2 and 79 {+-} 10 A{sup 3}, respectively. Allowed transitions between 300 and 400 nm possess a relatively small solvent shift and {Delta}{alpha}: -p = 2000-2500 cm{sup -1} and {Delta}{alpha} = 20-25 A{sup 3}. Published values of Absorption and fluorescence Maxima in cold jets, vapors, solid inert gases, solvent and polymer glasses, and doped and neat crystals have been plotted as a function of {phi}(n{sup 2}). A purely thermal bathochromic shift of 50-100 cm{sup -1} between low (4-77K) and ambient temperatures could be established for 620, 404 (C{sub 60}), and 636 nm (C{sub 70}) bands. The large bandwidth of allowed transitions(<400 nm) has been accounted for in termsmore » of a much stronger Franck-Condon coupling to higher harmonics of intramolecular vibrations than that in planar aromatic hydrocarbons. 61 refs., 8 figs., 8 tabs.« less
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solvent effects on the visible Absorption Maxima of tetrapyrrolic pigments
The Journal of Physical Chemistry, 1993Co-Authors: Indrek RengeAbstract:Visible Absorption spectra of several porphyrins, phthalocyanine, their metal complexes, chlorin, and bacteriochlorophyll a are recorded in nonpolar and aprotic polar solvents at room temperature. Excellent linear dependence of the Absorption band Maxima on the Lorentz-Lorenz function O(n 2 ) =(n 2 -1)/(n 2 +2) (n is the refractive index) is observed for most of the compounds in n-alkanes. Spectral bands are red-shifted on the increase of O(n 2 ) due to the dispersive stabilization of the excited state. Solvent shifts were rationalized in terms of the Liptay and the Bakshiev equations by using transition energies and dipole moments as well as the changes in polarizability (Δα) as molecular parameters, respectively
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solvent dependence of the visible Absorption Maxima of meso tetraphenylporphine
Chemical Physics Letters, 1991Co-Authors: Indrek RengeAbstract:Abstract Spectral Maxima of S 1 and S 2 bands, their vibronic satellites S 11 and S 21 as well as the Soret band have been measured for meso-tetraphenylporphine at room temperature. The increase in polarizability, evaluated from the solvent-induced band shifts in non-polar n -alkanes, is equal to about 5, 15 and 36 A 3 for S 1 , S 2 and the Soret transitions, respectively. The significance of the small and biophysical processes is pointed out. The S 1 and S 2 transition frequencies undergo opposite solvent shifts with increasing dielectric constant. It is proposed that as a result of dielectric screening, the central hydrogen ions move closer to each other. This leads to the reduction of the inequivalence of two NN symmetry axes and to the decrease of S 2 −S 1 splitting.
