Copper(I) Photocatalyzed Bromonitroalkylation of Olefins: Evidence for Highly Efficient Inner-Sphere Pathways.

We report the visible light-mediated copper-catalyzed vicinal difunctionalization of olefins utilizing bromonitroalkanes as ATRA reagents. This protocol is characterized by high yields and fast reaction times under environmentally benign reaction conditions with exceptional scope, allowing the rapid functionalization of both activated and unactivated olefins. Moreover, late-stage functionnalization of biologically active molecules and upscaling to gram quantities is demonstrated, which offers manifold possibilities for further transformations, e.g. access to nitro- and aminocyclopropanes. Besides the synthetic utility of the title transformation, this study undergirds the exclusive role of copper in photoredox catalysis showing its ability to stabilize and interact with radical intermediates in its coordination sphere. EPR studies suggest that such interactions can even outperform a highly favorable cyclization of transient to persistent radicals contrasting iridium-based photocatalysts.

Determining the number of integrals of motion by an adapted correlation dimension method.

An adapted correlation dimension algorithm is used to numerically determine the number of integrals of motion in a variety of conservative classical systems. The method is demonstrated on three sample systems that display various degrees of integrable and chaotic behavior: the Hénon-Heiles Hamiltonian, an asymmetric top molecule in an electric field, and the planetary system HD128311. Two additional applications of the method emerge: using the adapted correlation dimension algorithm (a) to study partial barriers and turnstiles in phase space and (b) to predict the long-time stability of planetary systems using short-time data.

Coherent Control of Penning and Associative Ionization: Insights from Symmetries.

Coherent control of reactive atomic and molecular collision processes remains elusive experimentally due to quantum interference-based requirements. Here, with insights from symmetry conditions, a viable method for controlling Penning and associative ionization in atomic collisions is proposed. Computational applications to He^{*}(^{3}S)-Li(^{2}S) and Ne^{*}(^{3}P_{2})-Ar(^{1}S_{0}) show extensive control over the ionization processes under experimentally feasible conditions.

Laser-induced molecular alignment in the presence of chaotic rotational dynamics.

Coherent control of chaotic molecular systems, using laser-assisted alignment of sulphur dioxide (SO2) molecules in the presence of a static electric field as an example, is considered. Conditions for which the classical version of this system is chaotic are established, and the quantum and classical analogs are shown to be in very good correspondence. It is found that the chaos present in the classical system does not impede the alignment, neither in the classical nor in the quantum system. Using the results of numerical calculations, we suggest that laser-assisted alignment is stable against rotational chaos for all asymmetric top molecules.

Exciting Molecules Close to the Rotational Quantum Resonance: Anderson Wall and Rotational Bloch Oscillations.

We describe a universal behavior of linear molecules excited by a periodic train of short laser pulses under conditions close to the quantum resonance. The quantum resonance effect causes an unlimited ballistic growth of the angular momentum. We show that a disturbance of the quantum resonance, either by the centrifugal distortion of the rotating molecules or a controlled detuning of the pulse train period from the so-called rotational revival time, eventually halts the growth by causing Anderson localization beyond a critical value of the angular momentum, the Anderson wall. Below the wall, the rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. We suggest optical experiments capable of observing the rotational Anderson wall and Bloch oscillations at near-ambient conditions with the help of existing laser technology.

Observation of Bloch Oscillations in Molecular Rotation.

We report the observation of rotational Bloch oscillations in a gas of nitrogen molecules kicked by a periodic train of femtosecond laser pulses. A controllable detuning from the quantum resonance creates an effective accelerating potential in angular momentum space, inducing Bloch-like oscillations of the rotational excitation. These oscillations are measured via the temporal modulation of the refractive index of the gas. Our results introduce room-temperature laser-kicked molecules as a new laboratory for studies of localization phenomena in quantum transport.

Edge states of periodically kicked quantum rotors.

We present a quantum localization phenomenon that exists in periodically kicked three-dimensional rotors, but is absent in the commonly studied two-dimensional ones: edge localization. We show that under the condition of a fractional quantum resonance there are states of the kicked rotor that are strongly localized near the edge of the angular momentum space at J=0. These states are analogs of surface states in crystalline solids, and they significantly affect resonant excitation of molecular rotation by laser pulse trains.

Anderson wall and BLOCH oscillations in molecular rotation.

We describe a universal behavior of linear molecules excited by a periodic train of short laser pulses under quantum resonance conditions. In a rigid rotor, the resonance causes an unlimited ballistic growth of the angular momentum. We show that the centrifugal distortion of rotating molecules eventually halts the growth, by causing Anderson localization beyond a critical value of the angular momentum--the Anderson wall. Its position solely depends on the molecular rotational constants and lies in the range of a few tens of ℏ. Below the wall, rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. We suggest optical experiments capable of observing the rotational Anderson wall and Bloch oscillations at near-ambient conditions with the help of existing laser technology.

Accurate quantum-chemical description of gold complexes with pyridine and its derivatives.

Interaction of gold with pyridine and its derivatives was studied by means of different wavefunction-based correlation methods and standar DFT functionals as well as accounting for dispersion correction. Comparison of the calculated binding energies with benchmark CCSD(T)results allows us to find an appropriate computational method, when considering the two structures reflecting the interaction of gold with the lone pair at nitrogen, on the one hand, and with the π-system of pyridine, on the other hand. Additional binding sites were evaluated, when performing potential energy surface calculations and structure optimizations. The enhancement of the interaction energy due to donor substituents in the 4-position of the pyridine molecule has been investigated.