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Quantum Monte Carlo Algebraic Diagrammatic Construction (QMCADC) has been proposed as a reformulation of the second-order ADC scheme for the polarization propagator within the projection quantum Monte Carlo formalism. Dense-sparse partitioning and importance ranking filtering strategies are now exploited to accelerate its convergence and to alleviate the sign problem inherent in such calculations. By splitting the configuration space into dense and sparse subsets, the corresponding projection operator is decomposed into four distinct blocks. Deterministic calculations handle the dense-to-dense and sparse-to-dense blocks, while the remaining blocks, dense-to-sparse and sparse-to-sparse, are stochastically evaluated. The dense set is efficiently stored in a fixed-size array, and the sparse set is represented through conventional floating random Monte Carlo walks. The stochastic projection is further refined through importance ranking criteria, enabling a reduction in the required number of walkers with a controllable bias. Our results demonstrate the integration of dense-sparse partitioning with importance ranking filtering to significantly enhance the efficiency of QMCADC, enabling large-scale molecular excited-state calculations. Furthermore, this novel approach maximizes the utilization of the sparsity of ADC(2), transforming QMCADC into a tailored framework for ADC calculations. [ABSTRACT FROM AUTHOR]

Molecular photoswitches are widely used in material sciences, physics, chemistry, and biology. As needs grow more complex, materials have to react more than one‐dimensionally. The use of multiple photoswitches at once opens manifold opportunities for further improved and more complicated systems. However, this requires independent addressability, i.e., orthogonality, and reversible processes. Herein, the first study on ultrafast excited state dynamics of two orthogonal photoswitches, a push‐pull azobenzene and a donor‐acceptor Stenhouse adduct is reported. In order to gain detailed insight in their interactions and mutual influences on their photoswitching behavior, they are addressed individually and simultaneously via transient absorption spectroscopy supported by quantum chemical calculations. They show reversible photoswitchability and in addition, can be used in 4D printing to provide easy access to a plethora of functional devices. Furthermore, environmental influences on the excited state dynamics are examined using different solvents and thin films. Both compounds photoisomerize independently when addressed individually or simultaneously and only little impacts on the excited state dynamics are found. Especially the vibrational relaxation is affected by different surroundings changing the energy dissipation while hardly affecting the electronic states involved. The orthogonal and simultaneous addressability is thereby crucial for their usage in 4D printed microactuators. [ABSTRACT FROM AUTHOR]

Compounds with multiple photoswitching units are appealing for complex photochemical control of molecular materials and nanostructures. Herein, we synthesized novel meta‐ and para‐ connected (related to the nitrogen of the indoline) azobenzene‐spiropyran dyads, in which the central benzene unit is shared by both switches. We investigated their photochemistry using static and time‐resolved transient absorption spectroscopy as well as quantum chemical calculations. In the meta‐compound, the individual components are photochemically decoupled due to the meta‐pattern. In the para‐compound the spiro‐connectivity leads to a bifunctional photoswitchable system with a red‐shifted absorption. The azobenzene and the spiropyran can thus be addressed and switched independently by light of appropriate wavelength. Through the different connectivity patterns two different orthogonally photoswitchable systems have been obtained which are promising candidates for complex applications of light control. [ABSTRACT FROM AUTHOR]

Compounds with multiple photoswitching units are appealing for complex photochemical control of molecular materials and nanostructures. Herein, we synthesized novel meta‐ and para‐ connected (related to the nitrogen of the indoline) azobenzene‐spiropyran dyads, in which the central benzene unit is shared by both switches. We investigated their photochemistry using static and time‐resolved transient absorption spectroscopy as well as quantum chemical calculations. In the meta‐compound, the individual components are photochemically decoupled due to the meta‐pattern. In the para‐compound the spiro‐connectivity leads to a bifunctional photoswitchable system with a red‐shifted absorption. The azobenzene and the spiropyran can thus be addressed and switched independently by light of appropriate wavelength. Through the different connectivity patterns two different orthogonally photoswitchable systems have been obtained which are promising candidates for complex applications of light control. [ABSTRACT FROM AUTHOR]

A π‐expanded X‐type double [5]helicene comprising dihydropyracylene moieties was synthesized from commercially available acenaphthene. X‐ray crystallographic analysis revealed the unique highly twisted structure of the compound resulting in the occurrence of two enantiomers which were separated by chiral HPLC, owing to their high conformational stability. The compound shows strongly bathochromically shifted UV/vis absorption and emission bands with small Stokes shift and considerable photoluminescence quantum yield and circular polarized luminescence response. The electrochemical studies revealed five facilitated reversible redox events, including three reductions and two oxidations, thus qualifying the compound as chiral multistage redox amphoter. The experimental findings are in line with the computational studies based on density functional theory pointing towards increased spatial extension of the frontier molecular orbitals over the polycyclic framework and a considerably narrowed HOMO–LUMO gap. [ABSTRACT FROM AUTHOR]

Photochemistry. In their Research Article (e202314112), Andreas Dreuw, Josef Wachtveitl, Hermann A. Wegner et al. report two novel photoswitch azobenzene‐spiropyran dyads. The study provides the basis for the development of new multichromic switches for information and energy storage or other applications...By Torben Saßmannshausen; Anne Kunz; Nils Oberhof; Friederike Schneider; Chavdar Slavov; Andreas Dreuw; Josef Wachtveitl and Hermann A. WegnerReported by Author; Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

Photochemistry. In their Research Article (e202314112), Andreas Dreuw, Josef Wachtveitl, Hermann A. Wegner et al. report two novel photoswitch azobenzene‐spiropyran dyads. The study provides the basis for the development of new multichromic switches for information and energy storage or other applications...By Torben Saßmannshausen; Anne Kunz; Nils Oberhof; Friederike Schneider; Chavdar Slavov; Andreas Dreuw; Josef Wachtveitl and Hermann A. WegnerReported by Author; Author; Author; Author; Author; Author; Author; Author [Extracted from the article]