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Enyne diesters derived from biaryls and related substrates undergo intramolecular [2+2]‐cycloaddition and concomitant cyclo‐reversion when treated with 10 mol% In(OTf)3 in 1,2‐dichloroethane. This enyne metathesis type cycloisomerization reaction enables the synthesis of phenanthrene, benzophenanthrene, benzotetraphene and other polycyclic (hetero)aromatic compounds bearing a synthetically useful diethyl β‐(hetero)arylidene malonate moiety in a step‐ and atom‐economic manner. In(OTf)3‐catalyzed two independent intramolecular cycloisomerization on substrates 5 a and 5 b provides direct access to benzotetraphenes 6 a and 6 b containing bis(diethyl β‐phenylmethylene malonate) moiety. Tetrasubstituted vinylidene malonate 4 a, substiututed by two different aromatic groups, is stereoselectively converted into E‐ and Z‐isomer of triaryl group containing all carbon tetrasubstituted olefins (8 a, 8 a′ and 8 b) via Pd‐catalyzed stereoselective decarboxylative arylation reaction. [ABSTRACT FROM AUTHOR]

The design of multiphase optical nanocomposites necessitates the understanding of coexisting phases' morphology and chemistry which have deterministic impacts on light–matter interaction. A prominent example is gradient refractive index (GRIN) materials proposed to realize an arbitrarily shaped, single optical component with minimal chromatic aberration. Ge‐As‐Pb‐Se materials are promising for GRIN due to their ability to exhibit spatially varying volume fraction of high‐index Pb‐rich phases in low index matrices. These materials are characterized to date, exclusively using transmission electron microscopy to reveal their phase separation and induced crystalline phase(s). It is found in the study that the intrinsic 2D perspective of the technique has hindered the identification of true morphology. To clarify this ambiguity, atom probe tomography (APT) is utilized to gain the first‐ever observation of the nanocomposites' microstructure and its evolution upon heat treatment in a 3D space. The APT‐quantified geometry and chemistry of coexisting phases are considered to predict the effective media's optical behaviors which closely match experimental data, enabling the establishment of the material's predictive and accurate process–structure–property relationship. Findings in the study demonstrate the robustness and advantage of the APT‐assisted characterization in the design and realization of GRIN materials. [ABSTRACT FROM AUTHOR]

The design of active optical devices integrating second‐order nonlinear (SONL) optical responses typically relies on the use of dielectric crystalline materials such as lithium niobate (LN) or semiconductors such as GaAs. Despite high SONL susceptibilities, these materials present important geometry constrains inherent to their crystalline nature limiting the complexity of the designed photonic systems. Conversely, amorphous materials are versatile optical media compatible with broad platform designs possessing a wide range of optical properties attributable to their composition flexibility. Demonstrated here for the first time in an amorphous inorganic material, a magnitude of SONL optical susceptibility (χ(2) = 29 pm V−1 at 1.06 µm) comparable to that of LN single crystal is reported. By using a thermo‐electrical imprinting process, fine control of the induced uniaxial anisotropy is demonstrated at the micrometer scale. This work paves the way for the future design of integrated nonlinear photonic circuits based on amorphous inorganic materials enabled by the spatially selective and high SONL optical susceptibility of these promising and novel optical materials. [ABSTRACT FROM AUTHOR]

Electrically tunable optical devices present diverse functionalities for manipulating electromagnetic waves by leveraging elements capable of reversibly switching between different optical states. This adaptability in adjusting their responses to electromagnetic waves after fabrication is crucial for developing more efficient and compact optical systems for a broad range of applications, including sensing, imaging, telecommunications, and data storage. Chalcogenide‐based phase‐change materials (PCMs) have shown great promise due to their stable, nonvolatile phase transition between amorphous and crystalline states. Nonetheless, optimizing the switching parameters of PCM devices and maintaining their stable operation over thousands of cycles with minimal variation can be challenging. Herein, the critical role of PCM pattern as well as electrical pulse form in achieving reliable and stable switching is reported on, extending the operational lifetime of the device beyond 13000 switching events. To achieve this, a computer‐aided algorithm that monitors optical changes in the device and adjusts the applied voltage in accordance with the phase transformation process is developed, thereby significantly enhancing the lifetime of these reconfigurable devices. The findings reveal that patterned PCM structures show significantly higher endurance compared to blanket PCM thin films. [ABSTRACT FROM AUTHOR]

The reaction allows an efficient access to amides. [ABSTRACT FROM AUTHOR]