Magnetic Properties, Spin-Vibration Couplings, and Temperature Effects in Phenalenyl and Triangulene.

We introduce a computational methodology for evaluating and analyzing spin-vibration couplings in molecular systems, enabling insights into the interplay between electronic spins and molecular vibrations. By mapping ab initio electronic structure calculations onto molecular spin Hamiltonians, our approach captures those vibrational interactions potentially driving spin relaxation process. Spin-vibration couplings, derived from Holstein and Peierls terms, highlight the pivotal role of vibrational mode symmetry in spin decoherence and efficient energy dissipation.

Twisting nanoporous graphene on graphene: electronic decoupling and chiral currents.

Nanoporous graphene (NPG), laterally bonded carbon nanoribbons, is a promising platform for controlling coherent electron propagation in the nanoscale. However, for its successful device integration NPG should ideally be on a substrate that preserves or enhances its anisotropic transport properties. Here, using an atomistic tight-binding model combined with nonequilibrium Green's functions, we study NPG on graphene and show that their electronic coupling is modulated as a function of the interlayer twist angle.

Real-Space Visualization of Canalized Ray Polaritons in a Single Van der Waals Thin Slab.

Polaritons are central to the development of nanophotonics, as they provide mechanisms for manipulating light at the nanoscale. A key advancement has been the demonstration of polariton canalization in which the energy flow is directed along a single direction. An intriguing case is the canalization of ray polaritons, characterized by an enhanced density of optical states.

Phase transitions, Dirac and Weyl semimetal states in MnGeBiTe.

Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological insulator (TI) [Formula: see text] have been carried out with gradual replacement of magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10% to 75%. It was shown that when Ge concentration increases, the bulk band gap decreases and reaches zero plateau in the concentration range of 45-60% while trivial surface states (TrSS) are present and exhibit an energy splitting of 100 and 70 meV in different types of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentration of about 40%.

Modeling and Elucidating the Behavior of a Thermoresponsive LCST Ionic Liquid.

Desalination of seawater by forward osmosis is a technology potentially able to address the global water scarcity problem. The major challenge limiting its widespread practical application is the design of a draw solute that can be separated from water by an energetically efficient process and then reused for the next cycle. Recent experiments demonstrate that a promising draw solute for forward-osmosis desalination is tetrabutylphosphonium 2,4,6-trimethylbenzenesulfonate ([P][TMBS]).

Giant Purcell Broadening and Lamb Shift for DNA-Assembled Near-Infrared Quantum Emitters.

Controlling the light emitted by individual molecules is instrumental to a number of advanced nanotechnologies ranging from super-resolution bioimaging and molecular sensing to quantum nanophotonics. Molecular emission can be tailored by modifying the local photonic environment, for example, by precisely placing a single molecule inside a plasmonic nanocavity with the help of DNA origami. Here, using this scalable approach, we show that commercial fluorophores may experience giant Purcell factors and Lamb shifts, reaching values on par with those recently reported in scanning tip experiments.

Folded-twisted mechanisms control dynamic redox properties, photophysics and electron transfer of anthanthrene-quinodimethanes.

The synthesis, electrochemical, spectroelectrochemical, photophysical and light induced electron transfer reactions in two new anthanthrene quinodimethanes have been studied and analyzed in the context of dynamic electrochemistry. Their properties are dependent on the interconversion between folded and twisted forms, which are separated by a relatively small energy range, thus allowing to explore their interconversion by variable temperature measurements. The photophysics of these molecules is mediated by a diradical excited state with a twisted structure that habilitates rapid intersystem crossing.

Polarisation-dependent Raman enhancement in hexagonal boron nitride membranes.

Raman spectroscopy is a powerful analytical method widely used in many fields of science and applications. However, one of the inherent issues of this method is a low signal-to-noise ratio for ultrathin and two-dimensional (2D) materials. To overcome this problem, techniques like surface-enhanced Raman spectroscopy (SERS) that rely on nanometer scale metallic particles are commonly employed.

Schottky Defects Suppress Nonradiative Recombination in CHNHPbI through Charge Localization.

Hybrid lead halide perovskites are promising materials for photovoltaic applications due to their exceptional optoelectronic properties. Here, we investigate the impact of Schottky defects─specifically PbI(V) and CHNHI (V) vacancies─on nonradiative recombination in CHNHPbI using time-dependent density functional theory and nonadiabatic (NA) molecular dynamics. Our results reveal that Schottky defects do not alter the fundamental bandgap or introduce trap states but instead distort the surrounding lattice, localizing the hole distribution.

Planar tetracoordinate beryllium in σ-aromatic Li4Be and Na4Be clusters: A missing member in first-octal row planar tetracoordinate family.

While planar tetracoordinate (pt) centers have been extensively explored from carbon to other octal-row elements or their heavier analogs, their counterparts involving alkali (A) and alkaline-earth metals (Ae) remain elusive due to the large atomic radius and absence of p orbitals. In this work, we found six hitherto unknown anionic ptA (A4A-) and neutral ptAe (A4Ae) centers through an extensive exploration of potential energy surfaces. The D4h-symmetry ptBe structures in Li4Be and Na4Be emerge as the lowest-energy configurations, and all the other ptA/ptAe structures are higher in energy or saddle points.

Methylammonium Lead Iodide across Physical Space: Phase Boundaries and Structural Collapse.

Hybrid perovskites exhibit complex structures and phase behavior under different thermodynamic conditions and chemical environments, the understanding of which continues to be pivotally important for tailoring their properties toward improved operational stability. To this end, we present for the first time a comprehensive neutron and synchrotron diffraction investigation over the pressure-temperature phase diagram of the paradigmatic hybrid organic-inorganic perovskite methylammonium lead iodide (MAPbI). This ambitious experimental campaign down to cryogenic temperatures and tens of kilobars was supported by extensive molecular dynamics simulations validated by the experimental data, to track the structural evolution of MAPbI under external physical stimuli at the atomic and molecular levels.

Role of the Radical Character in Singlet Fission: An Ab Initio and Quantum Chemical Topology Analysis.

The radical character of molecules exhibiting singlet fission is related to the energy level matching relationships that facilitate this process. Using a linear H model molecule, we employ quantum chemical topology descriptors based on full configuration interaction calculations to rationalize singlet fission. In this context, the influence of the closed-shell to diradical and diradical to tetraradical character on the singlet fission energy matching conditions is analyzed.

Polarizability, plasmons and damping in pseudospin-1 gapped materials with a flat band.

The subject of our present investigation is the collective electronic properties of various types of pseudospin-1 Dirac-cone materials with a flat band and finite bandgaps in their low-energy spectra. Specifically, we have calculated the dynamical polarization, plasmon dispersions, as well as their decay rates due to Landau damping and presented the closed-form analytical expressions for the wave function overlaps for both the gapped dice lattice and the Lieb lattice. The gapped dice lattice is a special case of the more general-T3model such that its band structure is symmetric and the flat band remains dispersionless.

Field-Induced Antiferromagnetic Correlations in a Nanopatterned Van der Waals Ferromagnet: A Potential Artificial Spin Ice.

Nano-patterned magnetic materials have opened new venues for the investigation of strongly correlated phenomena including artificial spin-ice systems, geometric frustration, and magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin 2D van der Waals (vdW) magnets, a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter can be assessed. Here, it is shown that square islands of CrGeTe vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin-ice.

An overview on plasmon-enhanced photoluminescence via metallic nanoantennas.

In the realm of nanotechnology, the integration of quantum emitters with plasmonic nanostructures has emerged as an innovative pathway for applications in quantum technologies, sensing, and imaging. This research paper provides a comprehensive exploration of the photoluminescence enhancement induced by the interaction between quantum emitters and tailored nanostructure configurations. Four canonical nanoantennas (spheres, rods, disks, and crescents) are systematically investigated theoretically in three distinct configurations (single, gap, and nanoparticle-on-mirror nanoantennas), as a representative selection of the most fundamental and commonly studied structures and arrangements.

Correction: Perylene-derivative singlet exciton fission in water solution.

[This corrects the article DOI: 10.1039/D4SC04732J.].

Optically driven plasmons in graphene/hBN van der Waals heterostructures: simulating s-SNOM measurements.

Converting transverse photons into longitudinal two-dimensional plasmon--polaritons (2D-PP) and vice versa presents a significant challenge within the fields of photonics and plasmonics. Therefore, understanding the mechanism which increases the photon - 2D-PP conversion efficiency could significantly contribute to those efforts. In this study, we theoretically examine how efficiently incident radiation, when scattered by a silver spherical nanoparticle (Ag-NP), can be transformed into 2D-PP within van der Waals (vdW) heterostructures composed of hexagonal boron nitride and graphene (hBN/Gr composites).

Time-Resolved Chemical Bonding Structure Evolution by Direct-Dynamics Chemical Simulations.

Direct-dynamics simulations monitor atomic nuclei trajectories during chemical reactions, where chemical bonds are broken and new ones are formed. While they provide valuable information about the ongoing nuclear dynamics, the evolution of the chemical bonds is customarily overlooked, thus, hindering key information about the reaction mechanism. Here we examine the evolution of the chemical bonds for the three main mechanisms of the F + CHCHCl reaction using quasi-classical trajectories for the nuclei, and global natural orbitals for the electrons.

Scattering of CO from Vacant-MoSe with O Adsorbates: Is CO Formed?

Using ab initio molecular dynamics (AIMD) simulations, based on density functional theory that also accounts for van der Waals interactions, we study the oxidation of gas-phase CO on MoSe with a Se vacancy and oxygen coverage of 0.125 ML. In the equilibrium configuration, one of the O atoms is adsorbed on the vacancy and the other one atop one Se atom.

Coordination Compounds as Antivirals against Neglected Tropical Diseases.

Neglected tropical viral diseases are a burden to social and economic welfare being responsible for higher pathogen-related mortality rates and chronic debilitating patient conditions. Climatic changes have widened up the infectibility ratio of such diseases, with autochthonous transmission in formerly temperate-to-cold environments. The slow-paced development of potential vaccines followed by the inexistence of antiviral drugs for such diseases considerably worsens the situation.

Supramolecular chemistry in solution and solid-gas interfaces: synthesis and photophysical properties of monocolor and bicolor fluorescent sensors for barium tagging in neutrinoless double beta decay.

Translation of photophysical properties of fluorescent sensors from solution to solid-gas environments functionalized surfaces constitutes a challenge in chemistry. In this work, we report on the chemical synthesis, barium capture ability and photophysical properties of two families of monocolor and bicolor fluorescent sensors. These sensors were prepared to capture barium cations that can be produced in neutrinoless double beta decay of Xe-136.

Electron-Spin Relaxation in Boron-Doped Graphene Nanoribbons.

Boron-doped graphene nanoribbons are promising platforms for developing organic materials with magnetic properties. Boron dopants can be used to create localized magnetic states in nanoribbons with tunable interactions. Controlling the coherence times of these magnetic states is the very first step in designing materials for quantum computation or information storage.