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Abstract In this work we report the synthesis, structure, and electronic properties of carbon‐rich compounds dehydrobiphenyleno[12]annulenes (DBP[12]As) comprising antiaromatic four‐membered rings (4MR) and 12‐membered ring (12MR). Ultraviolet–visible absorption spectra and electrochemical behaviors of DBP[12]As confirmed their relatively narrow highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap values and high HOMO energy levels, which were supported by density functional theory simulations. Parent DBP[12]A adopts a slipped herringbone structure in a crystalline state, with the molecules forming 1D stacks via π–π interactions. The experimentally derived bond lengths, bonding analyses using the Wiberg bond indices, and localized orbital locator calculation support a stronger double bond character for the 12MR bonds than the 4MR bonds in the inner six‐membered ring. The chemical shifts of hydrogens in¹H NMR spectra, as well as magnetically induced ring current analyses using quantum chemical calculations, indicate that the 4MRs have stronger antiaromatic character than the 12MR. The present information is useful for a fundamental understanding of carbon‐rich compounds with different antiaromatic units as well as designing novel molecules with unique electronic properties. 

This article highlights recent computational research on heme-based carbene transfer reactions. Mechanistic insights reveal how cofactor components, coordination modes, substrates, and protein environments influence reactivity and selectivity. 

Abstract Variational quantum eigensolvers (VQEs) represent a promising approach to computing molecular ground states and energies on modern quantum computers. These approaches use a classical computer to optimize the parameters of a trial wave function, while the quantum computer simulates the energy by preparing and measuring a set of bitstring observations, referred to as shots, over which an expected value is computed. Although more shots improve the accuracy of the expected ground state, it also increases the simulation cost. Hence, we propose modifications to the standard Bayesian optimization algorithm to leverage few‐shot circuit observations to solve VQEs with fewer quantum resources. We demonstrate the effectiveness of our proposed approach, Bayesian optimization with priors on surface topology (BOPT), by comparing optimizers for molecular systems and demonstrate how current quantum hardware can aid in finding ground‐state energies. 

Lignin‐derived deep eutectic solvents (DESs) have been investigated as sustainable green media for biomass processing. However, the properties and processability of DESs have not been fully understood with the chemical structures of their constituents for biomass fractionation. In this article, the properties of the phenolic DESs are discussed with different numbers of functional groups, such as –OCH₃and –CHO in their hydrogen bond donor (HBD) structures. The formation of DES is significantly related to the hydrogen bond between its constituents, identified by nuclear magnetic resonance (NMR) analysis and density functional theory calculation (DFT). Lower viscosity and net basicity of DES are achieved with fewer –OCH₃on HBD structures, resulting in enhanced processability and fractionation efficiency. The thermal stability of the DES is also influenced by the –OCH₃and –CHO of HBD, as indicated by its onset temperature. The recyclability of the phenolic DES is confirmed by the fractionation performance of the recycled DES. Understanding the structural impacts of DES constituents on the properties and performance is crucial for designing solvents in biorefinery applications. 

Abstract Optically active point defects in wide‐bandgap semiconductors have been demonstrated to be attractive for a variety of quantum and nanoscale applications. In particular, color centers in hexagonal boron nitride (hBN) have recently gained substantial attention owing to their spectral tunability, brightness, stability, and room‐temperature operation. Despite all of the recent studies, precise detection of the defect‐induced mid‐gap electronic states (MESs) and their simultaneous correlations with the observed emission in hBN remain elusive. Directly probing these MESs provides a powerful approach toward atomic identification and optical control of the defect centers underlying the sub‐bandgap emission in hBN. Combining optical and electron spectroscopy, the existence of mid‐gap absorptive features is revealed at the emissive sites in hBN, along with an atom‐by‐atom identification of the underlying defect configuration. The atomically resolved defect structure, primarily constituted by vacancies and carbon/oxygen substitutions, is further studied via first‐principles calculations, which support the correlation with the observed MESs through the electronic density of states. This work provides a direct relationship between the observed visible emission in hBN, the underlying defect structure, and its absorptive MESs, opening venues for atomic‐scale and optical control in hBN for quantum technology. 

Abstract Electron‐beam deposition stands as a versatile technique utilized for the accurate and controlled thin‐film deposition of a wide range of materials that readily undergo evaporation. However, silicon, a commonly used material, is prone to oxidation during the deposition process because of the presence of water vapors and oxygen in the chamber. To overcome this challenge, a tailored approach is developed that involves controlling the deposition conditions, including the base pressure in the chamber and the deposition rate. Silicon oxidation is successfully overcome, and this results in achieving refractive index values comparable to those obtained with alternative deposition methods for amorphous silicon. The research shows that the deposition conditions can be utilized effectively to tune the refractive index, providing flexibility in achieving the desired optical properties. It is demonstrated that Mie‐resonant metasurfaces exhibit strong collective resonances, driven by the coherent coupling of Mie modes within the periodic nanoantenna lattice, as evidenced by distinct spectral features in the scattering response. These resonances are observed to be highly tunable, with spectral shifts corresponding to controlled variations in the electron‐beam deposition parameters and silicon oxidation. The approach enables silicon deposition for metasurfaces, which presents exciting possibilities for tailoring and designing advanced nanostructures with unique optical characteristics. 

Abstract Diamond as a material has many unique properties. Its high optical dispersion, extraordinarily high mechanical strength, and unparalleled thermal conductivity have long made it a material of interest for applications such as high‐temperature electronics and as wear‐resistance coatings. More recently, diamond has emerged as a material with a wide range of applications in chemistry and biology. The high intrinsic stability of diamond, coupled with the ability to modify diamond surfaces with a wide range of inorganic, organic, and biological species via highly stable covalent linkages, provides a wealth of opportunity to couple diamond's chemical properties with its extraordinary physical properties. The practical utility of diamond has been greatly expanded in recent years through dramatic advances in the ability to produce diamond in bulk, thin film, and nanoparticle form, with controlled doping and purity at modest cost. These advances, together with diamond's highly stable and tunable surface chemistry with versatility of physical structure enable a wide range of emerging applications of interest to chemists, including quantum science, biomedicine, energy storage, and catalysis. Yet, to fully exploit the unique properties of diamond, some formidable chemical challenges lie ahead. We begin by reviewing some of the features of diamond that are of particular importance to the chemistry community. We aim to highlight some of the important applications where diamond chemistry plays a key role, identify some of the key observations, and outline some of the future directions and opportunities for diamond in the chemical world. 

The C‐terminal decarboxylation of peptides provides an important opportunity to synthesize modern peptide pharmaceuticals that contain C‐terminal amides. This transformation can be achieved by electrochemical oxidation; however, the standard implementation depends on oxidation potential for selectivity which may represent a challenge when amino acid residues containing electroactive side chains are present. To address this limitation, an alternative mechanistic paradigm has been introduced for selective decarboxylation of a C‐terminal carboxylate, one that relies on a chelation event. In a proof‐of‐principle experiment used to probe and define the viability of this mechanism, it is demonstrated that the combination of an iron mediator and a C‐terminal glutamate residue can be used to conduct the reaction in the presence of the more electron‐rich tyrosine residue frequently found in medicinally active peptides. Investigations into the reaction specifics and the scope/limitations provide key insights into the reaction mechanism and how such processes can be optimized. The success of the method highlighted here points to a more general binding‐based approach to drive C‐terminal decarboxylation that utilizes a functional group motif not possible at any other position in a peptide. 

Abstract Octalenobisterphenylene1(also known as terphenylene dimer) was synthesized from 3,3′,5,5′‐tetraaryl‐substituted biaryl bytert‐butyllithium‐mediated cyclization followed by oxidative coupling. This one‐pot two‐step protocol facilitated the successive formation of four four‐membered and two eight‐membered rings. Treatment of1with sodium metal, followed by crystallization from THF, yielded the remarkable diradical dianion [(1^•–)₂]²⁻, where the two molecular halves are connected by four σ bonds. The cyclodimerization is driven by the pronounced reactivity and strain of the central six‐membered ring within the [3]phenylene subunit. The structure and diradical nature of [(Na⁺)₂(1^•–)₂] were confirmed through X‐ray crystallography, DFT computations, and¹H NMR and ESR spectra. These investigations revealed that the two spins, one on each molecular half, exhibit minimal mutual interaction.