INDO study

Lloyd, R. V. Wood, D. E. Free-radicals in an adamantane matrix. 8. EPR and INDO study of benzyl, anilino, and phenoxy radicals and their fluorinated derivatives. J. Am. 

In the superexchange regime, the tunneling may be mediated by the DNA bases, by the backbone, or by the solvent. Theoretical (INDO) studies by Cave and coworkers predicted a /I of about 2.0 for water, and they estimated (using a limited set of water configurations) that the ab initio value would fall in the range of 1.5-1.8 [91]. The experiments of Gray and... 

Beveridge and Miller B1> in an INDO study, have calculated the vibronic effects in substituted methyl redicals and have satisfactorily reproduced the trends of isotope effects on isotropic coupling constants (Table 37). 

D. W. Clack, J. C. Evans, A. Y. Obaid, and C. C. Rowlands, An electron spin, ENDOR, and TRIPLE resonance and INDO study of fluorine-substituted 7V,7V -diphenyl-4,4 -bipyridynium radical cations, J. Chem. Soc., Perkin Trans. 2 1985, 1653 -1657. 

ENDOR and NMR studies in conjunction with theoretical AMI and/or INDO studies (in particular RHF-INDO/SP) have contributed greatly to the understanding of the carotenoid radical cation and the description of the charge delocalization along the polyene chain (Piekara-Sady et al., 1991 Hand et al., 1993 Piekara-Sady et al., 1993,1995). An improved crystal structure of j3-carotene reported by Senge et al. (1992) has been used and provided the basis for the success of some of the theoretical descriptions. ENDOR studies have also been successfully performed on /3-carotene and canthaxanthin radicals produced photochemically on Nafion films and silica gel (Piekara-Sady et al., 1991 Wu et al., 1991), and... 

Structure. The straiued configuration of ethylene oxide has been a subject for bonding and molecular orbital studies. Valence bond and early molecular orbital studies have been reviewed (28). Intermediate neglect of differential overlap (INDO) and localized molecular orbital (LMO) calculations have also been performed (29—31). The LMO bond density maps show that the bond density is strongly polarized toward the oxygen atom (30). Maximum bond density hes outside of the CCO triangle, as suggested by the bent bonds of valence—bond theory (32). The H-nmr spectmm of ethylene oxide is consistent with these calculations (33). 

Not much information has been added in recent years to the earlier studies of tautomeric equilibria of benzimidazoles based on basicity measurements [76AHC(S1), p. 292]. For 5(6)- and 4(7)-substituted benzimidazoles and 2-methyl-5(6)-substituted benzimidazoles values are very close to 1, which indicates near equivalence in the stability of N1(H) and N3(H) tautomers. The tautomeric equilibria of 2-substituted (H, NH2, OMe, CN) 5-nitrobenzimidazoles and 4-nitrobenzimidazoles were analyzed with the use of semiempirical MINDO/3 and INDO methods. It was predicted that electron-releasing groups in position 2 shifted the equilibria to the 6-NO2 and 4-NO2 tautomers, respectively. 

We note dial highly correlated calculations performed on isolated slilbene indicate that the first excited stale strongly optically coupled lo die ground stale is mil (he lowest in energy, in contrast to the INDO/SCI results [44 however, emission lakes place from the strongly coupled excited stale when relaxation effects are considered thus, the exact ordering of the lowest two excited stales in slilbene does not modify the main conclusions of our study. 

Previous studies indicate that osmotic gradients promote membrane fusion, while hyperosmotic conditions inhibit membrane fusion during exocytosis. Consistent with this idea is the observation that the release of lysosomal enzymes from rabbit neutrophils, induced by the chemotactic peptide J -formylmethionyl-leucyl-phenylalanine (FMLP), is inhibited almost 80% in a 700-mosmol/kg medium. Inhibition is immediate (within 10 s), increases with osmolality, and is independent of the osmoticant. Neutrophils loaded with the calcium indicator indo-1 exhibit an FMLP-induced calcium signal that is inhibited by hyperosmolality. Hyperosmolality (700 mosmol/kg) increases basal calcium levels and reduces the peak of the calcium signal elicited by FMLP at concentrations ranging from 10 ° to 10 M. 

In summary, all the experiments expressly selected to check the theoretical description provided fairly clear evidence in favour of both the basic electronic model proposed for the BMPC photoisomerization (involving a TICT-like state) and the essential characteristics of the intramolecular S and S, potential surfaces as derived from CS INDO Cl calculations. Now, combining the results of the present investigation with those of previous studies [24,25] we are in a position to fix the following points about the mechanism and dynamics of BMPC excited-state relaxation l)photoexcitation (So-Si)of the stable (trans) form results in the formation of the 3-4 cis planar isomer, as well as recovery of the trans one, through a perpendicular CT-like S] minimum of intramolecular origin, 2) a small intramolecular barrier (1.-1.2 kcal mol ) is interposed between the secondary trans and the absolute perp minima, 3) the thermal back 3-4 cis trans isomerization requires travelling over a substantial intramolecular barrier (=18 kcal moM) at the perp conformation, 4) solvent polarity effects come into play primarily around the perp conformation, due to localization of the... 

From the results obtained, it was found that compound 10a showed very high fluorescence intensity in the presence of the BSA and BSA/SDS mixture ( F 0.27) together with a noticeable emission enhancement. The presence of dimethyl indo-lenyl increased the affinity of the dyes to both native and denatured proteins. The authors proposed compound 10a for further studies as fluorescent probes for protein detection. 

Prasad and coworkers60 studied the ESR spectra of cation radicals of dienes, trienes, tetraenes and pentaenes formed in CFCI3 matrix by X-ray irradiation. The structures of the resulting cation radicals were deduced by comparing the experimental coupling constant to those derived from INDO calculation. The unpaired spin density decreases with increasing chain length. 

The geometry of nitronates has not been adequately studied by quantum-chemical calculations. For example, the bond lengths in nitronate Me2C=N(0)OMe were calculated by the INDO method for ideal geometry (248). 

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