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Asymmetric phase-transfer catalysis (PTC) has risen to prominence over the last decade as a straightforward synthetic methodology for the preparation of pharmacologically active compounds in enantiomerically pure form. However, the complex interplay of weak nonbonded interactions (between catalyst and substrate) that could account for the stereoselection in(More)
High level ab initio correlated (CASPT2) computations have been used to elucidate the details of the photoinduced molecular motion and decay mechanisms of a realistic phytochrome chromophore model in vacuo and to explore the reasons underneath its photophysical/photochemical properties. Competitive deactivation routes emerge that unveil the primary(More)
We have employed hybrid CASPT2//CASSCF/AMBER calculations to map the (1)L(a)(1pipi*) deactivation path of a single quantum mechanical adenine in a d(A)(10).d(T)(10) double strand in water that is treated at the molecular mechanics level. We find that (a) the L(a) relaxation route is flatter in DNA than in vacuo and (b) the L(a) relaxation energy in DNA is(More)
Neonicotinoid insecticides selectively target the invertebrate nicotinic acetylcholine receptor and disrupt excitatory cholinergic neurotransmission. First launched over 20 years ago, their broad pest spectrum, variety of application methods and relatively low risk to nontarget organisms have resulted in this class dominating the insecticide market with(More)
A QM/MM investigation, based on a DFT(B3LYP)//Amber-ff99 potential, has been carried out to elucidate the mechanism of diaminopimelate epimerase. This enzyme catalyzes the reversible stereoconversion of one of the two stereocenters of diaminopimelate and represents a promising target for rational drug design aimed to develop new selective antibacterial(More)
Hybrid QM(CASPT2//CASSCF/6-31G*)/MM(Amber) computations have been used to map the photoisomerization path of the retinal chromophore in Rhodopsin and explore the reasons behind the photoactivity efficiency and spectral control in the visual pigments. It is shown that while the electrostatic environment plays a central role in properly tuning the optical(More)
Ironing out the details: Proline and pyrrolidine derivatives (Hayashi- Jørgensen catalysts) are considered "work horses" in organocatalysis. This report describes a new effective ferrocenyl pyrrolidine catalyst that is able to perform well in benchmark organocatalytic reactions (see figure). The ferrocene moiety controls the conformational space and a(More)
The reduction potentials of the title compounds 4 have been measured by cyclic voltammetry. The effect of the substituents has been evaluated by using a linear free energy relationship treatment, thus evidencing that the present ortho-substituents affect the Epc values basically by electronic effects. A comparison with data previously collected on(More)
The enzyme proline racemase from the eukaryotic parasite Trypanosoma cruzi (responsible for endemic Chagas disease) catalyzes the reversible stereoinversion of chiral Calpha in proline. We employed a new combined quantum mechanical and molecular mechanical (QM/MM) potential to study the reaction mechanism of the enzyme. Three critical points were found: two(More)
The photochemical cis-trans isomerization of retinal in rhodopsin is investigated by structure sampling and excited state QM/MM trajectories with surface hopping. The calculations uncover the motions responsible for photoproduct formation and elucidate the reasons behind the efficient photoisomerization in the primary event of visual transduction.