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The bonding and spectroscopic properties of LaX and AcX (X = O and F) diatomic molecules were studied by high-level ab initio CCSD(T) and SO-CASPT2 electronic structure calculations. Bond dissociation energies (BDEs) were calculated at the Feller-Peterson-Dixon (FPD) level. Potential energy curves and spectroscopic constants for the lowest-lying spin-orbit Ω states were obtained at the SO-CASPT2/aQ-DK level. A dense manifold of excited states was described for the monofluorides with the ground states well separated from the excited states. The spectroscopic parameters were in good agreement with those reported experimentally for LaO and LaF. For the diatomic molecules containing actinides, no experimental data of these parameters was found, but the results were consistent with other high-level calculations. The BDEs calculated at the FPD level were 791.3 (LaO), 705.2 (AcO), 650.0 (LaF), and 678.6 (AcF) kJ/mol. The NBO analysis showed that the monofluorides are essentially ionic, which explains why the BDE(AcF) is higher than BDE(LaF); for the monoxides, covalent contributions involving the d orbitals of the metal and the p orbitals of the oxygen are stronger for LaO than AcO, which explains the higher BDE for LaO. The bond orders are predicted to be 2 for LaF and AcF, 3 for AcO, and higher than 3 for LaO.

Understanding and controlling molecular motions is of pivotal importance for designing molecular machinery and functional molecular systems, capable of performing complex tasks. Herein, we report a comprehensive theoretical study to elucidate the dynamic behavior of a bis(benzoxazole)-based overcrowded alkene displaying several coupled and uncoupled molecular motions. The benzoxazole moieties give rise to 4 different stable conformers that interconvert through single-bond rotations. By performing excited- and ground-state molecular dynamics simulations, DFT calculations, and NMR studies, we found that the photochemical E-Z isomerization of the central double bond of each stable conformer is directional and leads to a mixture of metastable isomers. This transformation is analogous to the classical Feringa-type molecular motors, with the notable difference that, during the photochemical isomerization and the subsequent thermal helix inversion (THI) steps, multiple possible pathways take place that involve single-bond rotations that can be both coupled and uncoupled to the rotation of the naphthyl half of the molecule.

High resolution infrared spectra of water-CO₂ dimers are further studied using tunable infrared sources to probe a pulsed slit jet supersonic expansion. The relatively weak transition of D₂O-CO₂ in the D₂O ν₁ fundamental region (≈2760 cm^-1) is observed for the first time, as are various spectra of D₂O-¹³CO₂. Combination bands involving the intermolecular in plane geared bend (disrotatory) mode are observed for H₂O-CO₂ (≈1642, 2397 cm^-1) in the H₂O ν₂ and CO₂ ν₃ regions, for HDO-CO₂ (≈2761 cm^-1) in the HDO ν₃ region, and for D₂O-CO₂ (≈2386, 2705 and 2821 cm^-1) in the CO₂ ν₃, D₂O ν₁, and D₂O ν₃ regions. A combination band involving the intermolecular in plane antigeared bend (conrotatory) mode is observed for D₂O-¹³CO₂ (≈2425 cm^-1) in the CO₂ ν₃ region. And finally, a combination band involving the intermolecular twist (internal rotation) mode is observed for D₂O-CO₂ (≈2874 cm^-1) in the D₂O ν₃ region. But this twist transition actually appears as two bands of similar intensity, separated by 2 cm^-1, suggesting an "accidental" near-coincidence of the "real" combination state with a "dark" background state of the same symmetry. Intermolecular mode frequencies determined from the combination bands are in very good agreement with a recent theoretical calculation based on a high-level ab initio potential surface.

Aerosols containing biological material (i.e., bioaerosols) impact public health by transporting toxins, allergens, and diseases and impact the climate by nucleating ice crystals and cloud droplets. Single particle characterization of primary biological aerosol particles (PBAPs) is essential, as individual particle physicochemical properties determine their impacts. Vibrational spectroscopies, such as infrared (IR) or Raman spectroscopy, provide detailed information about the biological components within atmospheric aerosols but these techniques have traditionally been limited due to the diffraction limit of IR radiation (particles >10 μm) and fluorescence of bioaerosol components overwhelming the Raman signal. Herein, we use photothermal infrared spectroscopy (PTIR) to overcome these limitations and characterize individual PBAPs down to 0.18 μm. Both optical-PTIR (O-PTIR) and atomic force microscopy-PTIR (AFM-PTIR) were used to characterize bioaerosol particles generated from a cyanobacterial harmful algal bloom (cHAB) dominated by Planktothrix agardhii. PTIR spectra contained modes consistent with traditional Fourier transform infrared (FTIR) spectra for biological species, including amide I (1630-1700 cm^-1) and amide II (1530-1560 cm^-1). The fractions of particles containing biological materials were greater in supermicron particles (1.8-3.2 μm) than in submicron particles (0.18-0.32 and 0.56-1.0 μm) for aerosolized cHAB water. These results demonstrate the potential of both O-PTIR and AFM-PTIR for studying a range of bioaerosols with vibrational spectroscopy.

Due to the increased expression of iron storage proteins in cancer cells, utilizing the endogenous iron-catalyzed Fenton reaction for cancer ferroptosis therapy has recently emerged as a prominent research focus. However, endogenous iron primarily exists within ferroxidase FTH1 in the Fe (III)-bound state, hindering the effective catalysis of the Fenton reaction. Herein, an endogenous iron(II) self-enriched Fenton nanocatalyst (BAI@cLANCs) is fabricated by encapsulating the FTH1 inhibitor baicalin (BAI) in cross-linked lipoic acid nanocarriers (cLANCs) to amplify endogenous ferroptosis. Once internalized, BAI@cLANCs are disrupted by glutathione (GSH) in tumor cells to release BAI, which inhibits FTH1 activity and hinders Fe²⁺ oxidation. Meanwhile, cLANCs degrade into dihydrolipoic acid (DHLA), which reduces Fe³⁺ to Fe²⁺, synergically enriching endogenous Fe²⁺. Simultaneously, both BAI and DHLA stimulate H₂O₂ production and facilitate the Fenton reaction to produce abundant ^·OH, thereby triggering lipid peroxidation and inducing tumor ferroptosis. Moreover, the reduction of Fe³⁺ to Fe²⁺ depletes GSH, facilitating ^·OH production and inactivating glutathione peroxidase-4, ultimately amplifying tumor ferroptosis. Overall, this work highlights the potential of an endogenous iron(II) self-enriched Fenton nanocatalyst for cancer ferroptosis therapy, providing a paradigm for amplifying endogenous ferroptosis by inhibiting FTH1 activity and reducing iron(III) to enrich endogenous iron(II).

The temperature dependence of concerted proton-electron transfer (CPET) reactions of two anthracene-phenol-pyridine (An-PhOH-py) triads is investigated in toluene. Light excitation forms an anthracene local excited state (^1*An), which undergoes CPET to form a charge separated state (CSS, An^•--PhO^•-pyH⁺), which in turn undergoes CPET charge recombination (CR). In toluene, compared with polar solvents, the CSS is energetically destabilized. First, this makes another reaction competitive with CPET, which we propose is proton-coupled energy transfer (PCEnT) from ^1*An to form the short-lived excited state keto tautomer of the phenol-pyridine subunit (*[PhO═pyH]). Second, it puts CR deep into the Marcus inverted region, and CSS lifetimes therefore reach several nanoseconds at room temperature. The slow kinetics makes CR to the anthracene triplet state (^3*An) competitive, as well as another reaction that is strongly activated and dominates CSS deactivation at T ≥ 240 K for one of the triads. The latter is proposed to be CR via initial formation of the same [*PhO═PyH] state as above by an unusual electron transfer (ET) from An^•- to pyH⁺, instead of CR with the juxtaposed PhO^•. The two different pathways to form *[PhO═pyH] lead to CSS yields and lifetimes that vary significantly with temperature, and in markedly different ways between the triads. This is rationalized by the differences in the energies of the states involved. The results broaden the scope and understanding of the still rare phenomena of inverted CPET and PCEnT and may aid toward their use in solar fuels and photoredox catalysis.

In many simple viruses and virus-like particles, the protein capsid self-assembles around a nucleic-acid genome. Although the assembly process has been studied in detail, relatively little is known about how the capsid disassembles, a potentially important step for infection (in viruses) or cargo delivery (in virus-like particles). We investigate capsid disassembly using a coarse-grained molecular dynamics model of a T = 1 dodecahedral capsid and an RNA-like polymer. We alter the interactions between the subunits of the capsid as well as the ionic strength of the solution to induce partial or complete disassembly of self-assembled particles. We find that disassembly follows nucleation-and-growth kinetics, where the nucleation barrier is related to the interaction strengths as well as to the conformation of the polymer. In particular, we find that polymer segments that interact with adjacent subunits reinforce the subunit-subunit contacts. These results have implications for the design of virus-like particles for applications such as drug delivery. A cargo designed with reinforcement in mind might be used to control the stability of such particles and mediate disassembly.

Physical vapor deposition is widely used in the fabrication of organic light-emitting diodes and has the potential to adjust the density and orientation through substrate temperature control, which may lead to enhanced electrical performance. However, it is unclear whether this enhanced property is because of the horizontal molecular orientation or the increased density. The effects of the density and orientation on the electrical properties of a potential electron transport material, (3-dibenzo[c,h]acridin-7-yl)phenyl)diphenylphosphine oxide (TPPO-dibenzacridine), were investigated. According to the gyration tensor analysis, TPPO-dibenzacridine resembled an oblate ellipsoid. Furthermore, these films exhibited the highest density when prepared at a substrate temperature of 87.5% of the glass transition temperature with an increase in density of approximately 1.5%. Variable angle spectroscopic ellipsometry measurements confirmed that the transition dipole moment direction of the dibenzacridine moiety, which is involved in the electrical properties, remained isotropic at this temperature. Although horizontal orientations are known to optimize their π-π overlap and improve the electrical properties, the lowest driving voltage was observed under these conditions, which led to the conclusion that the enhanced electrical properties of TPPO-dibenzacridine are greatly influenced by the increased density rather than by the molecular orientation.