191016-27-0Relevant academic research and scientific papers
Secondary alpha isotope effects on deuterium tunneling in triplet o-methylanthrones: Extraordinary sensitivity to barrier width
Campos, Luis M.,Warrier, Manoj V.,Peterfy, Krisztina,Houk,Garcia-Garibay, Miguel A.
, p. 10178 - 10179 (2007/10/03)
The rates of deuterium transfer in the photoenolization of triplet 1,4-dimethyl-10H-anthracen-9-one (1) with varying degrees of deuterium label in their methyl groups (1-d3, 1-d2, and 1-d) have been investigated as a function of temperature between 5 and 77 K. Measurable rate constants in the case of 1-d3 and 1-d2 were used to construct Arrhenius plots which illustrate the expected curvature and leveling off of rate constant versus temperature. The difference in tunneling rate constants of 1-d3 and 1-d2 yields a tunneling isotope effect, TIE = 2.4, which is attributed to the secondary alpha isotopic substitution. Density functional theory (DFT, B3LYP/6-31G*) calculations were carried out to obtain structural and energetic information for the H(D) transfer along the triplet state zero-point energy levels. The temperature dependence of the rate constants for each isotopologue was simulated with a model that considers the frequency of the C-D stretching mode and the quantum mechanical permeability determined from calculated energy parameters. The model suggests that a difference in barrier width of only 0.015 A between 1-d3 and 1-d2 leads to the observed 2-fold difference between tunneling rates. Copyright
Use of kinetic isotope effects to delineate the role of phenylalanine 87 in P450BM-3
Rock, Dan A.,Boitano, Anthony E.,Wahlstrom, Jan L.,Rock, Denise A.,Jones, Jeffrey P.
, p. 107 - 118 (2007/10/03)
The substrate oxidation rates of P450BM-3 are unparalleled in the cytochrome P450 (CYP) superfamily of enzymes. Furthermore, the bacterial enzyme, originating from Bacillus megaterium, has been used repeatedly as a model to study the metabolism
Chemical pressure effect by selective deuteration in the molecular-based conductor, 2,5-dimethyl-N,N'-dicyano-p-benzoquinone immine-copper salt, (DMe-DCNQI)2Cu
Aonuma, Shuji,Sawa, Hiroshi,Kato, Reizo
, p. 1541 - 1550 (2007/10/02)
The mixed-valence copper salt of DMe-DCNQI91, where DMe-DCNQI=2,5-dimethyl-N,N'-dicyano-p-benzoquinone diimine) is a molecular conductor whose electrical and magnetic properties are quite sensitive to pressure.We have performed selective deuteriation of the molecule 1.By control of the position and number of deuterium atoms, the low-pressure region (ca. 500 bar) in the pressure-temperature phase diagram of (1)2Cu was reproduced at ambient pressure.The equivalency of the deuteriation and pressure effects is explained from steric origins; 'contraction' aroused by the slightly shorter C-D bond (steric isotope effect) and 'constriction' by pressure.
