In this paper, the origins of enantioselectivity in asymmetric ketone hydrogenation catalyzed by RuH(2)(binap)(cydn) (cydn = trans-1,2-diaminocyclohexane) were discussed. Fifteen substrates involving aromatic, heteroaromatic, olefinic and dialkyl prochiral ketones were used to probe the catalytic mechanism and find an effective way to predict the chirality of the products. The calculated result...

The substituent effects on the ring-opening reaction of cyclobutene radical cations have been studied at the Becke3LYP/6-31G* level of theory. The effect on the reaction energies and activation energies of the concerted and stepwise pathways of electron-donating substituents such as methyl and methoxy as well as electron-withdrawing substituents such as nitrile and carboxaldehyde in the 3-posit...

One- and two-photon absorption cross-sections and spectra and the photophysical properties of eight perylenetetracarboxy-3,4:9,10-diimide (PDI) derivatives are reported and analyzed. The investigated compounds are characterized by direct binding of the phenyl rings of the substituents to the bay positions of the perylene core. They have been designed to test the effects of differences in the el...

H (Rydberg) atom photofragment translational spectroscopy and ab initio electronic structure calculations are used to explore ways in which ring substituents affect the photofragmentation dynamics of gas phase pyrroles. S1 ← S0 (σ* ← π) excitation in bare pyrrole is electric dipole forbidden but gains transition probability by vibronic mixing with higher electronic states. The S1 state is disso...

Hydrogen and dihydrogen bonding of the fluorinated alcohol (CF(3))(2)CHOH with the transition metal complex WH(CO)(2)(NO)(PMe(3))(2) has been explored by a set of four exemplary density functional theory methods that comprises the BP86, PBE, B3LYP and TPSS functionals. The hydride, nitrosyl and carbonyl ligands of the tungsten complex have been considered as sites of protonation. The main effec...

Absorption spectra for 2,3-diaryl-2,3-diazabicyclo[2.2.2]octane radical cations (2(X)(*+)) and for their monoaryl analogues 2-tert-butyl-3-aryl-2,3-diazabicyclo[2.2.2]octane radical cations (1(X)(*+)) having para chloro, bromo, iodo, cyano, phenyl, and nitro substituents are reported and compared with those for the previously reported 1- and 2(H)(*+) and 1- and 2(OMe)(*+). The calculated geomet...

The physical properties and function of hydrogels are shown to depend on the substituents present in three novel 1,3,5-tri-azaadamantane (TAA) cross-linkers. Gel stiffness and degradation rate at varied pHs could be predictably tuned with the cross-linker substituents used to form the gel. Subsequently, protein release from the hydrogel were controlled with chemical structure of the cross-linker.

A series of C4 substituted alpha-ketooxazoles were examined as inhibitors of the serine hydrolase fatty acid amide hydrolase in efforts that further define and generalize a fundamental substituent effect on enzyme inhibitory potency. Thus, a plot of the Hammett sigma(m) versus -logK(i) provided a linear correlation (R(2)=0.90) with a slope of 3.37 (rho=3.37), that is of a magnitude that indicat...

A series of 50 oxime esters bearing various substituents were designed and synthesized as photoinitiators (48 them never before only B1 B10 reported). Good light absorption properties in the visible range observed for these esters. Some structures exhibited better photoinitiation abilities than diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) upon exposure to a LED@405 nm. Interestingly, P...

Volatile trends are established for a series of M(b-diketonate)n complexes, where M = Cu (n = 2); Al, Sc, Cr, Fe, Co, Ga (n = 3); Zr (n = 4) and b-diketonate = acetylacetonate (acac), trifluoroacetylacetonate (tfac), hexafluoroacetylacetonate (hfac) and 2,2,6,6-tetramethyl-3,5-heptanedionate (tmhd). Sublimation enthalpies (DHsub) were calculated from thermogravimetric analysis (TGA) data, which...