Fundamental Study on Arsenic(III) Halides (AsX3; X = Br, I) toward the Construction of C3-Symmetrical Monodentate Arsenic Ligands.

Arsenic ligands have attracted considerable attention in coordination chemistry. Arsenic(III) halides are the most important starting materials in the preparation of monodentate arsenic ligands. In this work, we optimized the synthetic methodologies of arsenic(III) halides (AsX3; X = Br, I) and examined the difference of their physical properties such as solubility to organic solvent and reactivity to nucleophiles. In addition, a wide variety of monodentate arsenic ligands were prepared with the obtained AsX3. Finally, the obtained monodentate arsenic ligands were utilized for copper-free Sonogashira cross-coupling reaction in the reaction system with porphyrin. The results showed that monodentate arsenic ligands have higher catalytic activity compared with triphenylphosphine because of the difference of the electronic features of lone pairs between arsenic and phosphorus atoms.

Bis-Metal Complexes of Doubly N-Confused Dioxohexaphyrins as Potential Near-Infrared-II Photoacoustic Dyes.

We investigated the detailed photophysical properties of a series of bis-metal (Zn and Cu) dioxohexaphyrin complexes as potential second near-infrared (NIR-II)-light responsive dyes. A cisoid-configured 28π-electron-conjugated dioxohexaphyrin analogue (c-3a) containing two peculiar "confused pyrrole" moieties in the framework is identified as a reduced isomer derivative of a transoid 26π-dioxohexaphyrin (t-2a). The symmetry-altered structure of c-3a affords a heteroleptic inner environment within the NNNN/NNOO donor core, which imparts its highly flexible electronic features and nonplanar geometry. The macrocycle c-3a can be transformed into the corresponding 26π-electron congener (c-2a) having a coplanar rectangular structure by unique solvent-mediated redox reactivity. Furthermore, upon metal complexation, saddle-distorted bis-metal complexes (c-M2-2a) were formed as the 26π-conjugated structural isomer of the trans-dioxohexaphyrin species (i.e., t-M2-2a). These isoelectronic dioxohexaphyrins demonstrate precise geometry-dependent photophysical properties. Broad tailing NIR-II absorption, weak emissive character, and rapid-decay of the S1 state are observed for c-Zn2-2a. In contrast, the coplanar t-M2-2a exhibits efficient photoacoustic response upon laser excitation with NIR-II light (λ > 1000 nm). To the best of our knowledge, this is the first example of an expanded porphyrin-based photoacoustic contrast agent responsive to NIR-II light.

Application of Quantum Annealing to Nurse Scheduling Problem.

Quantum annealing is a promising heuristic method to solve combinatorial optimization problems, and efforts to quantify performance on real-world problems provide insights into how this approach may be best used in practice. We investigate the empirical performance of quantum annealing to solve the Nurse Scheduling Problem (NSP) with hard constraints using the D-Wave 2000Q quantum annealing device. NSP seeks the optimal assignment for a set of nurses to shifts under an accompanying set of constraints on schedule and personnel. After reducing NSP to a novel Ising-type Hamiltonian, we evaluate the solution quality obtained from the D-Wave 2000Q against the constraint requirements as well as the diversity of solutions. For the test problems explored here, our results indicate that quantum annealing recovers satisfying solutions for NSP and suggests the heuristic method is potentially achievable for practical use. Moreover, we observe that solution quality can be greatly improved through the use of reverse annealing, in which it is possible to refine returned results by using the annealing process a second time. We compare the performance of NSP using both forward and reverse annealing methods and describe how this approach might be used in practice.