The interaction of CO2 with Cu, Co, and Y oxide clusters of different size, composition, and charge is investigated via infrared multiple-photon dissociation (IR-MPD) spectroscopy. The IR-MPD spectra of MxOy(CO2)+/- (M = Cu, Co, Y) complexes reveal the non-activated binding of CO2 to all cationic clusters. In contrast, CO2 is activated by all anions via formation of carbonate-like CO3 units. Density functional theory(DFT) calculations on M2O2 +/- model systems suggest that for CO2 activation in general, the energy difference between the cluster highest occupied molecular orbital (HOMO) and the CO2 lowest unoccupied molecular orbital (LUMO) is crucial. The binding motif of the activated CO2 molecule, however, depends on a fine interplay between the nature of the orbitals close to the HOMO and the oxidation state of the metal atoms. CO3 formation is favored when the cluster HOMO or any energetically close lying molecular orbital (MO) is at least partially localized on one of the cluster oxygen atoms. In contrast, if such MOs are energetically less favorable, η2-(C,O) and η2-(O,O) binding to one of the metal atoms can be favored, provided the already positively charged metal atom can transfer electron density, i.e., adopt an even higher oxidation state.
Reliable determination of ionization energies (IE) and electron affinities (EA) is essential for understanding energy-level alignment in solar cells. Here, we benchmark cyclic voltammetry (CV) and electrochemical voltage spectroscopy (EVS) for IE and EA determination against ultraviolet photoelectron spectroscopy (UPS) for IE and the combination of UPS and photothermal deflection spectroscopy (PDS) for EA. The investigated materials are FA 0.8 Cs 0.2 Pb ( I 1 - y Br y ) 3 perovskite thin films with varying bromide fraction y = 0-1. Onset potentials and energies were reproducibly extracted using tangent-based scripts, avoiding data smoothing and minimizing user bias. The optical band gap scales linearly with bromide fraction. The IE remains approximately constant up to y = 0.4 (EVS) and y = 0.6 (CV), increasing upon further substitution. All investigated methods consistently reveal a decrease in EA with increasing bromide content. Finally, we highlight practical considerations relevant to the application of EC methods and UPS.
We demonstrate that an efficient computational protocol for accurate quantum mechanical (QM) modeling of IR and Raman spectra of condensed-phase systems is applicable to aqueous zwitterions of L-alanine and L-valine. The approach is based on generating energetically low-lying cluster structures consisting of the solute surrounded by an explicit solvation shell, optimized at the DFT level. Such cluster models are shown to reliably reproduce experimental vibrational frequencies and relative IR and Raman intensities of both amino acids at the B3LYP-D3/def2-TZVP level, provided that 25 water molecules are included. The accuracy of the simulations is sufficient to resolve all three conformers of valine and to identify their spectroscopic signatures. Relative conformer populations are estimated from the experimental intensities of the corresponding conformational marker bands, and conformationally averaged optical rotations (OR) of valine are computed using several QM protocols for [α]D. A comparative analysis of the full set of computed OR values for both amino acids yields an intrinsic margin of error in TDDFT calculations of [α]D of approximately 50° cm3/(g dm).
Ammonia (NH3) decomposition is critical for a zero-carbon hydrogen economy. While gas-phase transition metal cations have been extensively studied as ideal model systems, the reactivity of anions remains largely unexplored. Herein, we report that the heteronuclear metal anion MoCoC- exhibits exceptional reactivity, sequentially activating four NH3 molecules and releasing five H2 molecules. The first two NH3 molecules are completely decomposed, releasing all six hydrogen atoms as three H2 to form MoCoCN2 -. The third and fourth NH3 molecules each release one additional H2, yielding the final product MoCoCN2(NH)2 -. Density functional theory calculations were employed to elucidate the decomposition mechanisms of the first two NH3 molecules. In the first step, which generates H2 and MoCoCNH-, bond state switching between Mo and Co facilitates the activation of H atoms in NH3, while the C atom in the cluster provides additional electron density. In the subsequent reaction with the second NH3 molecule, two H2 molecules are released, leading to MoCoCN2 -. In this step, Mo and Co act as hydrogen shuttles and electron donors for N─H bond activation. This study on MoCo-based anions for NH3 decomposition provides a theoretical foundation for elucidating the mechanism of condensed-phase MoCo catalysts in NH3 decomposition.
Photoswitchable biomimetic membranes can be controlled by light and offer the possibility to study the role of membrane dynamics for the interaction with antimicrobial peptides. The α-helical peptide LAH4, a well-studied model system, interacts with membranes in a pH-dependent manner. It binds to the membrane surface at acidic pH and inserts into the membrane at basic pH conditions. Polarized attenuated total reflection (ATR) Fourier-transform infrared (FTIR) spectroscopy was employed to probe peptide orientation and structural changes, with particular emphasis on the pH-dependent response of LAH4 to light-induced membrane perturbations. Photoswitchable azoPC lipids were incorporated in large unilamellar vesicles (LUVs) as well as in DIBMA-stabilized nanodiscs, and the light-induced cis-to-trans isomerization of the azobenzene was monitored by characteristic vibrational modes showing a reversible transition between two membrane states for both membrane systems. The measurements reveal that photoswitching between the membrane states induces the reorientation of the surface-bound peptide toward a membrane-inserted state. The findings underline the potential of photoswitchable membranes for the study of lipid-peptide interactions as well as the importance of membrane dynamics for antimicrobial activity.
Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to evaluate the potential of coumarin-based dyes, 7-diethylamino-4-methylcoumarin (DAMC), Coumarin 102 (C102), Coumarin 153 (C153), Coumarin 343 (C343), Coumarin 6 (C6), Coumarin 7 (C7), and Coumarin 30 (C30), as sensitizers for dye-sensitized solar cells (DSSCs). Complementary experimental studies were performed to assess their photovoltaic performance. UV-vis absorption spectroscopy revealed the optical behavior of both isolated dyes and dye-sensitized TiO2 films, highlighting variations in light-harvesting capabilities and adsorption strengths. C343 exhibited the most favorable photovoltaic response among the investigated dyes, enabling mechanistic correlations between molecular structure, light-harvesting, charge-transfer dynamics, and device performance. C343 displayed short-circuit current density (JSC) of 1.12 mA cm-2, an open-circuit voltage (VOC) of 259 mV, and a fill factor (FF) of 40.
The Kemp elimination reaction can be catalyzed by computationally designed enzymes. After undergoing directed evolution, changes to the positioning of active site residues in Kemp eliminases can alter electric fields (EFs) and improve catalytic efficiency. However, optimizing EFs during the enzyme design process remains a challenge. Here we investigate how implicit solvation and external EFs reposition bond and ring critical points (CPs) in the reactant state of a truncated Kemp eliminase system using density functional theory and the quantum theory of atoms in molecules. We find that a linear correlation exists between the bond-ring CP distances integral to the Kemp elimination ring-opening reaction and activation barriers. The N─O stretching mode of the benzisoxazole ring that coincides with the reaction coordinate is also found to move ring CPs to varying degrees for each EF strength tested. EFs that move the ring CPs the largest magnitude and in the proper orientation toward the N─O bond CP correlate with the smallest activation barriers. Since reactant state QTAIM calculations are significantly less expensive than directly calculating activation barriers, this may provide an avenue for screening computationally designed enzymes that catalyze ring-opening reactions.
In this study, Co-Fe-B catalysts were synthesized separately in ethanol and aqueous media under ambient conditions using a chemical reduction-precipitation method for rapid and efficient hydrogen generation from sodium borohydride (NaBH4) hydrolysis. The structural and morphological properties of the synthesized catalysts were characterized by SEM-EDX and XRD analyses. The results demonstrated that the synthesis medium had a significant influence on the catalytic performance. At 30 °C, the hydrogen generation rate of the Co-Fe-B catalyst synthesized in ethanol reached 13,021.6 mL gcat-1 min-1, whereas the catalyst synthesized in water exhibited a hydrogen generation rate of 4005 mL gcat-1 min-1 under the same conditions. The hydrogen generation rate increased with increasing temperature, catalyst amount, and NaBH4 concentration. The reaction order was determined to be approximately 0.9, and the activation energy of the highly active catalyst was calculated as 37.72 kJ mol-1 using the Arrhenius equation. The enhanced catalytic activity of the catalyst synthesized in ethanol was attributed to the formation of a larger active surface area and electron transfer from boron to the active Co and Fe sites. These findings reveal that the synthesis medium plays a critical role in determining the structural properties and hydrogen generation performance of Co-Fe-B catalysts.
Supramolecular hydrogels based on peptides have emerged as versatile soft materials owing to their biocompatibility, modularity, and tunable mechanical properties. To overcome the limitations of natural peptide sequences, nucleobase-peptide hybrids (nucleopeptides) have been developed, enabling coassembly and enhanced gel properties. However, their practical use requires a precise description of gelation kinetics, which remains difficult to model and predict. Herein, we apply a new rheological methodology to monitor the gelation of a specific type of supramolecular hydrogel, formulated from peptide/DNA nucleobase hybrids termed nucleopeptides. Thus, we developed an open-access program (available at https://doi.org/10.5281/zenodo.21317179) that successfully predicts the elastic moduli obtained experimentally for the four considered nucleopeptide-based hydrogels, as well as for multicomponent hydrogels formulated from nucleopeptide mixtures.
In this study, we used flexible and inexpensive diatomite/AgNPs strips and Layer-by-Layer (LbL) assembly to develop sandwich assays for the detection of cancer biomarkers of interest via Surface-enhanced Raman scattering (SERS). The modified SERS active strips were used to capture antigens of interest, incubate Raman probes, and generate SERS maps based on specific Raman peaks of the Raman probes. Simultaneous detection and quantification of multiple biomarkers, including HER2, CA15-3, CA27-29, PSA, and MUC4, were demonstrated by the immobilization of specific antibodies and the use of uniquely labeled Raman probes. Spatially resolved and co-immobilized multiplexing strategies were developed and successfully validated, showing high specificity and sensitivity with negligible background interference from serum components. The flexible and cost-effective nature of the diatomite/AgNPs substrate, combined with its strong SERS enhancement, offers significant advantages over traditional immunoassay techniques.
Ion migration within electrochemical cells fundamentally governs interfacial reaction kinetics, charge transport, and the formation of electric double layers, thereby critically determining the overall performance of electrochemical devices. However, conventional regulation strategies often suffer from limited controllability, high energy consumption, and undesirable side reactions. Magnetic fields have recently emerged as a green, noncontact external stimulus that can precisely manipulate ion migration through magnetohydrodynamic convection and magnetic gradient forces, at both microscopic (ion transport) and macroscopic (electrolyte flow) scales. This review briefly summarizes the core mechanisms of magnetic field‑modulated ion migration and three regulation strategies: external static magnetic field, external dynamic magnetic field, and in situ internal magnetic field constructed by magnetic materials. Recent advances and practical achievements of magnetic field modulated are reviewed across four key areas: electrochemical energy storage, electrochemical synthesis, electrocatalytic conversion, and precise ion separation. Finally, existing challenges and prospective development directions in this field are discussed. This review aims to consolidate the theoretical foundation of magnetic field-assisted electrochemical regulation and promote the theoretical improvement and large-scale practical application of this emerging regulation technology.
NASICON‐structured Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) solid electrolyte (SE) exhibits satisfactory ionic conductivity and robust mechanical strength, but it suffers from interfacial instability against lithium metal anodes due to Ti 4+ reduction, which limits its application in solid‐state lithium metal batteries (SSLMBs). Herein, we developed a sulfone‐based crystalline organic interlayer (COI) composed of dimethyl sulfone and lithium bis(trifluoromethanesulfonyl)imide at an optimized molar ratio of 8:2, and applied it to LATP pellet surfaces via a melt‐casting process. The standalone COI exhibits a room‐temperature ionic conductivity of 0.67 mS cm −1 . The resulting LATP@COI composite shows an ionic conductivity of 0.78 mS cm −1 and a critical current density of 1.5 mA cm −2 . Li|LATP@COI|Li symmetric cells deliver stable cycling for over 700 h at 0.1 mA cm −2 . Full cells using LiFePO 4 and LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode with the lithium metal anode retain 93.1% and 92.3% of their initial capacities after 200 cycles, respectively, while maintaining excellent rate capability up to 2 C and operable discharge down to −40 °C. This COI provides a practical interfacial‐engineering strategy to overcome the intrinsic limitations of LATP SEs for SSLMBs.
Electrolyte-supported membrane electrode assemblies (MEAs) were fabricated using Cs3H2[BOB(PO4)3] (affectionately dubbed CsBOB) as the electrolyte and membrane separator and tested for proton conduction and power generation at temperatures up to 250 °C. The devices reached steady state ionic conductivities of 0.8-1.8 × 10-5 S cm-1 and produced commensurate power at nominal steady-state power densities of 0.6-1.2 × 10-2 mW cm-2 over the course of 160-h tests, thereby experimentally demonstrating that the CsBOB electrolyte does, in fact, conduct protons and is chemically stable under fuel cell operating conditions on the order of days. Machine-learned interatomic potentials (MLIP) trained on density functional theory calculations were used for molecular dynamics (MD) simulations, providing computational evidence confirming proton motion through bulk CsBOB. Importantly, the MLIP MD, bolstered by solid-state nuclear magnetic resonance (SS-NMR), also revealed that interstitial water plays a significant role in the CsBOB proton conduction mechanism under the operating conditions that were tested, helping provide high proton mobility. However, at these conductivities, electrochemistry is electrolyte limited; a 2-3 order-of-magnitude increase in proton conductivity is necessary for MEAs utilizing CsBOB electrolyte to achieve sufficiently high power densities for use in commercially competitive fuel cells. Future work will focus on improving CsBOB proton conductivity by increasing carrier density.
Here we develop an elasticity-based theory of crystallization in glasses that incorporates structural heterogeneity, fictive temperature, and polymorph-mediated pathways. In a glass, structural degrees of freedom are effectively frozen, so that the fictive temperature Tf remains higher than the ambient temperature T, rendering the system intrinsically out of equilibrium. A central result is that the crystal-glass interfacial penalty is renormalized in fragile systems by soft, liquid-like regions, leading to a subquadratic mismatch energy scaling as ΣR3/2 rather than the classical R2 form. Applying this framework to ethanol, we show that nucleation proceeds preferentially via a two-step route through a plastic crystalline polymorph. The associated barriers are dramatically reduced: the glass-to-plastic step exhibits barriers of only ∼5 kBT, compared to ∼102 kBT for the direct glass-to-crystal transition. This large separation explains the dominance of the Ostwald pathway and the emergence of a pronounced time-temperature-transformation (TTT) nose. In contrast, silica retains the classical R2 scaling due to its rigid network, leading to very large barriers and suppressed bulk nucleation.
Density functional theory-based molecular dynamics simulations with explicit solvent representation were employed to investigate the mechanism of electrochemical reduction of CO2-to-CO (CO2RR), catalyzed by a cobalt porphyrin complex (CoTPP) in aqueous solution. Our study focuses on the role of solvent molecules and a solvated potassium cation. The simulations reveal that solvent molecules play an active role in key reaction steps, significantly lowering the reaction barrier compared to previous results, primarily due to H-bond stabilization of the transition state. Additionally, the calculations indicate that the presence of water molecules disfavors the competing hydrogen evolution reaction. These findings underscore the importance of incorporating an explicit molecular description of the solvent to accurately estimate reaction energies, providing a realistic model that highlights the high selectivity of the CoTPP catalyst.
Beryllium dinitrogen and carbonyl cation complexes, Be(N2)n + and Be(CO)n + (n = 3-4), were produced in the gas phase by a laser vaporization-supersonic expansion ion source and investigated by infrared photodissociation spectroscopy in conjunction with quantum chemical calculations. Be(N2)3 + is assigned to a planar D3h-symmetric structure with three equivalent end-on coordinated molecular N2 ligands, whereas Be(N2)4 + is characterized as a weakly bound N2 adduct of Be(N2)3 +. The corresponding carbonyl complexes exhibit analogous structural motifs. Bonding analyses reveal that the L → Be (L = NN/CO) interactions in these end-on complexes are governed by L → Be σ donation, accompanied by weaker L ← Be π back-donation. In contrast to our previous study on Be(N2)3 (Angew. Chem. Int. Ed. 2020, 59, 10603), where both end-on and side-on coordination motifs coexist, only end-on structures are observed for the cationic species. The absence of side-on coordination is attributed to the positive charge, which significantly weakens π back-donation while only modestly enhancing σ donation, thereby destabilizing side-on binding motifs.
2,1,3-Benzochalcogenadiazoles and their halogen derivatives (chalcogen = S, Se, Te; halogen = F, Cl, Br, I) are widely employed in organic optoelectronics as chromophoric/fluorophoric electron-acceptor building blocks. In this work they are specified as an advantageous small-molecule platform for multicentered (Se, Te; Cl, Br, I) spin-orbit coupling (SOC) affecting optical properties of π-organics. Electronic absorption and emission/photoluminescence spectra of 4,7-di- and 4,5,6,7-tetrahalogenated 2,1,3-benzochalcogenadiazoles E/X' and E/X, respectively (E = chalcogen, X = halogen), have been studied in solid-state and THF solutions experimentally and theoretically. It has been found that the nature of E is the key factor controlling the photophysical properties of E/X' and E/X, such as energy levels, Stokes shifts, and the photoluminescence quantum yields, while X serves for further fine tuning of the properties. Combined E and X variation allows target-oriented design of absorptive and emissive materials for metal-free SOC-controlled optoelectronics and emerging spin-orbitronics.
NASICON-structured Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte (SE) exhibits satisfactory ionic conductivity and robust mechanical strength, but it suffers from interfacial instability against lithium metal anodes due to Ti4+ reduction, which limits its application in solid-state lithium metal batteries (SSLMBs). Herein, we developed a sulfone-based crystalline organic interlayer (COI) composed of dimethyl sulfone and lithium bis(trifluoromethanesulfonyl)imide at an optimized molar ratio of 8:2, and applied it to LATP pellet surfaces via a melt-casting process. The standalone COI exhibits a room-temperature ionic conductivity of 0.67 mS cm-1. The resulting LATP@COI composite shows an ionic conductivity of 0.78 mS cm-1 and a critical current density of 1.5 mA cm-2. Li|LATP@COI|Li symmetric cells deliver stable cycling for over 700 h at 0.1 mA cm-2. Full cells using LiFePO4 and LiNi0.5Co0.2Mn0.3O2 cathode with the lithium metal anode retain 93.1% and 92.3% of their initial capacities after 200 cycles, respectively, while maintaining excellent rate capability up to 2 C and operable discharge down to -40 °C. This COI provides a practical interfacial-engineering strategy to overcome the intrinsic limitations of LATP SEs for SSLMBs.
Chalcone-based π-conjugated systems have attracted significant attention due to their tunable electronic properties and well-defined structure-property relationships. In this work, we have designed, synthesized, and characterized three D-π-D chalcone derivatives, IITR-9, IITR-10, and IITR-11, by incorporating different electron-donating groups, such as triphenylamine and carbazole, at the periphery of the chalcone backbone. The excited state dynamics of these molecules were investigated using femtosecond transient absorption spectroscopy (TAS). It was found that IITR-9, IITR-10, and IITR-11 exhibit an intramolecular charge-transfer (ICT) state, consistent with the solvatochromic behavior and theoretical calculations. TAS results demonstrate that the symmetric derivatives, IITR-9 and IITR-10, which have the same donor group on both sides of the chalcone framework, exhibit a long-lived excited-state absorption band that persists beyond the experimental time window of ~8 ns, suggesting triplet-state formation. However, the asymmetric derivative IITR-11, which consists of electron-donating groups of different strengths, exhibits radiative relaxation from the ICT state with a timescale of 3.0 ± 0.2 ns. These findings demonstrate that the nature of the electron-donating group critically governs the excited-state pathways in chalcone derivatives, including CT and triplet state formation, highlighting its potential for designing optoelectronic applications.
All-inorganic halide perovskites, especially CsPbBr3 microrods, are often considered to be optically stable and less defect-prone compared to their organometallic counterparts. Nevertheless, reports of photoluminescence (PL) blinking in bulk perovskite systems till date are restricted to organometallic halide perovskite nano-/microrods, leaving it an open question whether similar intermittency behavior can be observed in all-inorganic halide perovskites of comparable dimensions. Intriguingly, we witnessed multilevel PL fluctuations (flickering) in individual green-emitting CsPbBr3 microrods. Wide-field PL microscopy reveals that the intensity fluctuations are nearly identical along the microrod, owing to charge carrier migration and waveguide-assisted propagation. Our measurements on single microrod suggest that the flickering dynamics is strongly influenced by excitation power, excitation energy, and local environmental constituents. Under dry argon environment, a substantial reduction in the PL intensity is observed, indicating the formation of a large number of nonradiative (NR) traps, which quenches all the photogenerated carriers, suppressing overall emission intensity and PL flickering. The exposure of oxygen and moisture passivates these NR traps along with generation of a few photo-induced supertraps. Our findings establish that spatiotemporally correlated intermittency is not limited to organometallic perovskites but extends to all-inorganic perovskite bulk emitters as well, in presence of certain atmospheric constituents.
