Chemistry and Materials Science

Abstract: Inspired by the newly discovered sandwich D_5d [Os(η⁵-B₅H₁₀)₂] as a carbon-free analog of ferrocene [Fe(η⁵-C₅H₅)₂] (Science 392, (2026): 411) and based on extensive global searches and first-principles theory calculations, we present herein the viable possibility of a staggered sandwich bis(η⁶-cycloborane)chromium D_6d [Cr(η⁶-(BH)₆H₆)₂] (1) with two equivalent η⁶- (BH)₆H₆ ligands isovalent with benzene as the boron analog of the eclipsed bis(η6-benzene)chromium D_6h [Cr(η⁶-C₆H₆)₂] (2). Detailed coordination bonding pattern, energy decomposition, and magnetically induced ring current analyses indicate that D_6d 1 matches the 18-electron rule (1S²1P⁶1D¹⁰) and exhibits similar aromaticity with D_6h 2, rendering high stability to the system. The metal-ring coordination bonding in D_6d 1 is dominated by effective Cr → (η⁶-(BH)₆H₆)₂ δ-back-donations which appear to be significantly stronger than the corresponding Cr → (η⁶-C₆H₆)₂ δ-back-donations in D_6h 2, leading to an unusually short ring-ring distance of 2.70 Å and large HOMO-LUMO gap of 7.06 eV in 1. D_6d 1 and D_6h 2 can also be used as building blocks to form their sandwich tetramers D_2h [Cr₄(BH)₄₈H₂₈] (3) and D_2h [Cr₄C₄₈H₂₈] (4) and sandwich two-dimensional nanosheets [Cr(η⁶-(BH)₆)₂] (5) and [Cr(η⁶-C₆)₂] (6) via partial or complete dehydrogenations, respectively.

Abstract: The development of lanthanide-based molecular magnetic materials incorporating organic radicals requires a fundamental understanding of how ligand modification influences magnetic exchange interactions while preserving the coordination environment around the metal center. In this predictive computational study, the electronic structures and magnetic properties of two hypothetical gadolinium(III) complexes with donor–acceptor semiquinone–nitronylnitroxide biradicals, Tp₂Gd(SQNN) (1) and Tp₂Gd(SQPhNN) (2), were investigated using SA-CASSCF/NEVPT2 calculations and compared with the previously characterized monoradical complex Tp₂Gd(SQ). The inclusion of dynamic correlation at the NEVPT2 level was essential for correctly predicting the antiferromagnetic nature of the Gd³⁺–biradical interaction, whereas SA-CASSCF alone yielded a ferromagnetic ground state. The computed exchange interaction between Gd³⁺ and the biradical in complexes 1 and 2 (J ≈ –2.6 cm⁻¹) is approximately two times weaker than that in Tp₂Gd(SQ) (J = –5.4 cm⁻¹). The intraligand exchange parameters JSQ–NN = 679.1 cm⁻¹ and JSQ–PhNN = 71.0 cm⁻¹ reflect strong ferromagnetic coupling within the biradical moieties. Application of the valence bond configuration interaction model yielded electronic coupling matrix elements HDA of 15283 cm⁻¹ and 6546 cm⁻¹ for the yttrium analogues of 1 and 2, respectively. The calculated magnetic susceptibility data for complexes 1 and 2 closely resemble the behavior of Tp₂Gd(SQ), although the characteristic temperatures differ due to the unequal exchange coupling strengths. This study demonstrates that modern computational methods enable reliable prediction of the key magnetic characteristics of heterospin systems based on their possible molecular structures.

Abstract: Theоretical methоds are indispensable in studying phоtоcatalytic reactiоn pathways, the energy barriers оf each elementary reactiоn step and in elucidating the active sites in catalysis. Transitiоn metal sulfides оf the 3d elements, M = Fe, Cо, Ni, Cu, mimic natural reductase and carbоn mоnоxide dehydrоgenase enzymes. The exact envirоnment оf enzyme centers, which includes a prоtein surrоunding the active site and cооrdinated ligands, cannоt be achieved by synthesis. Careful mоdeling оf ligands cооrdinated tо the active site can predict whether phоtоactivatiоn оccurs and the ways tо enhance visible light absоrptiоn. Fоr heavier transitiоn metals, such as the f-blоck elements, the phоtоphysical prоperties becоme mоre prоnоunced. Frоm the cоmputatiоnal results, suppоrted by experiments, sulfur emerges as a key element in prоmоting phоtоchemical and phоtоphysical activity. Bridging sulfur in the clusters and cоmplexes оf the 3d elements (M2-S2) acts as an electrоn-dоnоr similar tо cооrdinated carbоnyl оr nitrоsyl ligands. Lanthanides alsо take advantage оf the cооrdinatiоn оf sulfur-cоntaining ligands tо fine-tune light absоrptiоn and light-emissiоn, prоducing lanthanide sulfide phоtоcatalysts оr high-intensity luminescent cоmplexes. The excited-state energy transfer mechanism and factоrs respоnsible fоr the specific lanthanide emissiоn are successfully predicted by cоmbined DFT/TDDFT, multireference and semiempirical calculatiоns in clоse cоrrelatiоn with experiment.

Abstract: In the Heikal Universal Theory of Selective Interfaces and Spatial Resonance natural boundaries, called Selective Interfacial Manifolds (Barzakh), mediate interactions in macroscopic, biological, chemical, nuclear, and quantum systems. Conventional scientific and cosmological systems, are largely dependent on just mechanical measuring instruments, along with seeming dimensions, to narrate the behaviors of matter and energy. This dependency places basic methodological limitations, which cannot consider into complex systems, and interfacial phenomena. To overcome this limitation, we present here The Heikal Theory of Topological Selective Interfacial Manifolds a universal theoretical/mathematical model that dictates all reactive endeavors, be they chemical, physical, geological or the like – rethinking interaction, scattering and -equilibrium on cosmological, microscopic and quantum scales of -orders – including those of double orders. This is based on a sound mathematical structure with well-defined topological metric tensors (G_μν -Barzakh), scattering S_matrix, geometric resistance coefficients (Λ_T), diagnostic resonance criteria (R_lock), and indices of topological transformation efficiency ηHeikal. This paradigm-level manifestation shows that all the manifestations of formation of objects, flow of matter and energy, and spatial regularity of the universe are controlled not by simple volumetry but by nano- and cosmic-scale Selective Interfacial Manifolds which serve as topological bridges and states of topological tension connecting different domains of any category of interaction. By treating astrodynamics, interfacial interactions, scattering amplitudes, and structural transitions under different boundary conditions the theory provides a unified mathematical treatment of the most ultra-efficient topological confinement states, as well as structural collapse mechanisms under oxidative stress. Therefore, this approach establishes the basis for a universal scientific model beyond classical disciplinary boundaries which might gain insights into a geometric unification of the cosmos from minute particles to gaping the vastness of outer space as shown in Figure 1.

Abstract: The electrocatalytic reduction of CO₂ (CO2RR) into value-added chemicals represents a promising strategy for achieving carbon-neutral energy conversion. However, it is fundamentally limited by sluggish reaction kinetics, insufficient product selectivity, and the competitive hydrogen evolution reaction (HER). Herein, density functional theory (DFT) calculations were employed to systematically investigate transition-metal single-atom catalysts anchored on boron and nitrogen co-doped graphene (TM@BNG), with the aim of elucidating the role of heteroatom-induced coordination engineering in modulating catalytic performance. The results demonstrate that B, N co-doping effectively tailors the electronic structure of the metal active sites, thereby optimizing the adsorption energetics of key intermediates and dictating the reaction pathways. Among the 27 candidates examined, Pd@BNG, Ag@BNG, Sc@BNG, Cu@BNG, Co@BNG, Cd@BNG, and Y@BNG exhibit superior catalytic activity and selectivity toward CO or HCOOH production, featuring low limiting potentials down to −0.06 V while simultaneously suppressing HER. Mechanistic analysis reveals that product selectivity is governed by the relative stabilization of *COOH and *HCOO intermediates during the initial proton-coupled electron transfer step. Furthermore, a physically interpretable descriptor (φ), constructed via machine-learning approaches based on intrinsic electronic properties, establishes a volcano-type correlation with the limiting potential, thereby enabling quantitative prediction of catalytic activity. Collectively, these findings elucidate the electronic-structure modulation of single-atom catalysts and establish a generalizable framework for the rational design of high-performance CO₂RR electrocatalysts.

Abstract: Counterion-deficient liquid states are formulated within a solvent-general framework for charge-selective forcing under rapid electrostatic relaxation. When the Maxwell relaxation time is short relative to the forcing or chemical timescale, persistent bulk space charge is not an admissible long-lived description: the liquid interior relaxes toward near electroneutrality, finite residual charge localizes predominantly at the interface, and the compensating opposite charge need not be stored as an ordinary dissolved counterion in the same phase. On that basis, two complementary forcing branches are developed. In the negative branch, low-entry-energy electron delivery reduces dissolved cations or plates neutral material by populating the lowest accessible acceptor manifold, leaving anion-rich dissolved states. In the positive branch, low-entry-energy noble-gas dications act as formally universal two-electron scavengers that remove electrons from the highest available occupied density, including solvated-electron populations, lone-pair-rich molecular donors, and halide anions. A solvent-general admissibility window is derived in terms of entry kinetic energy, Maxwell relaxation, interfacial field, Rayleigh stability, leakage time, and heat-removal capacity. From these constraints, explicit operatingcurrent bounds are obtained, and an illustrative aqueous benchmark shows how Rayleigh, dielectric, and thermal limits separate in practice. Water, electron-solvating media such as calcium in tetrahydrofuran, and halide-containing liquids such as LiCl in tetrahydrofuran serve as representative realizations. The framework therefore yields predictive bookkeeping relations, dimensionless admissibility parameters, a noble-gas dication energy ladder, operational current ceilings, and experimentally falsifiable signatures that distinguish counterion-deficient chemistry from ordinary dissolved countercharge compensation.

Abstract: This paper investigates the application of the Symbolic Difference Structure (SSD) method as an innovative tool for multidimensional analysis and classification of elements in the periodic system. By applying the SSD algorithm (\(k=3\)) to five key physicochemical properties—atomic mass, electronegativity, first ionization energy, number of unpaired electrons, and melting point—the study demonstrates that the periodic system exhibits a recognizable numerical geometry that can be systematically quantified. The results show that SSD classification does not alter established chemical periodicity but enables: (1) quantitative discrimination between genuine nuclear anomalies and metrological artifacts, (2) identification of characteristic “hotspots’’ where multiple properties change simultaneously, and (3) a heuristic framework for predicting properties of heavy and superheavy elements. The analysis is extended using monoisotopic masses and correlation studies, confirming the diagnostic value of the method and opening new pathways for comparative analysis in materials science and chemical education.

Abstract: We present D2BIA_discrete, a zero-cost computational framework for predicting local aromaticity in linear acenes without quantum chemical calculations. The model partitions π-electron density using a 61/39 localized/delocalized ratio derived from spin-coupled valence bond and QTAIM analyses, combined with Slater-type orbital decay to estimate ring-center electron density. Three progressive refinements introduce molecular topology weighting, tunable bond-sharing (α), and depth-dependent attenuation (γ) parameters. Leave-one-n-out cross-validation on benzene through undecacene yields optimal parameters α=1.00 and γ=0.05, achieving ring-by-ring predictions with R²=0.456 and RMSE=2.394×10⁻³ against fluorescence aromaticity index (FLU). Model 2 provides excellent molecular-averaged correlations (R²>0.93 for FLU, PDI, HOMA) and reliable ring-level predictions for terminal and first internal rings. Local LONOCV D2BIA_discrete has excellent metrics with six-center index (R² = 0.922, R = 0.960, RMSE = 0.219, MAE = 0.139, MRE = 4.83%), showing importance of zero-cost D2BIA_discrete to obtain local aromaticity of linear acenes in agreement with SCI gradients for the same group. This is our third work based on the so-called discrete geometry chemistry.

Abstract: The review presents the first attempt to build the virtual world of free-radical polymerization of vinyl monomers itself and in the presence of small additives of stable radicals in due course of extended virtual experiment. Chain-reaction essence of the chemical process; quantum-chemical concept of elementary reactions; spin theory of radicals; and digital-twin of their presentation lay the foundation of the world formed, which opens a new vision of the role of IT technologies for the virtualization of various chemical processes

Abstract: This review presents the covalent chemistry of carbon within the spin-radical concept of electron interaction. Using the language of valence bond trimodality, the regions of classical spinless covalence and its spin counterpart are defined. Carbon is the only element exhibiting spin covalent chemistry. Classical covalent chemistry of carbon concerns molecular substances whose valence bond structure includes segregate or chained single sp3C-C bonds. Substances with double sp2C=C and triple sp1C≡C bonds are the subject of spin covalent chemistry of carbon. The mathematical apparatus of spin covalence forms the basis of algorithms governing the chemical modification of carbon substances, polymerization processes, and catalysis involving them, making it possible to supplement the empirical spin covalent chemistry of carbon with its virtual analog.

Abstract:

This computational study investigates the thermal decomposition of 1,2,4-triazol-3(2H)-ones and their thione analogues using Density Functional Theory (DFT). The reaction proceeds via a concerted, six-membered cyclic transition state, primarily driven by the breaking of the N–N bond. A key finding is that the accuracy of the calculated activation energies (Ea) strongly depends on the choice of the DFT functional. For sulfur-containing systems (thiones), the hybrid functional APFD (with 25% Hartree-Fock exchange) provides the most reliable results, effectively describing their higher polarizability. In contrast, for oxygen-containing systems (triazolones), the dispersion-corrected functional B97D-GD3BJ (with 0% Hartree-Fock exchange) delivers superior accuracy by better modeling electrostatic and dispersion interactions. The -CH₂CH₂CN group at the N-2 position acts not only as a protecting group, but also stabilizes the transition state through non-covalent interactions. Electron-withdrawing substituents slightly increase the Ea, while electron-donating groups decrease it. Sulfur analogues consistently show significantly lower activation energies (by ~40 kJ/mol) than their oxygen counterparts, explaining their experimentally observed faster decomposition. This work establishes a dual-methodology computational framework for accurately predicting the kinetics of these reactions, providing valuable insights for the regioselective synthesis of biologically relevant triazole derivatives via controlled pyrolysis.

Abstract:

Tuberculosis, caused by Mycobacterium tuberculosis (M. tb), remains a leading global threat, escalated now by the rise of multidrug-resistant (MDR-TB) and extensively drug-resistant (XDR-TB) strains. In search of a novel anti-tubercular agent with a distinct mechanism of action, this study explores deep-sea marine metabolites as potential inhibitors of the F₄₂₀-dependent oxidoreductase Rv1155, a redox enzyme essential for M. tb survival. A total of 2,773 marine-derived compounds curated from the CMNPD, Reaxys, and MarinLit databases were screened using an integrated CADD workflow combining molecular docking, in-silico ADMET profiling, and molecular dynamics (MD) simulations. Docking results revealed several metabolites with high affinity for the Rv1155 binding pocket, and three compounds: Upenamide (CMNPD_22964), Aspyronol (Compound_1749), and Fiscpropionate F (Compound_1796) as hit candidates. Among these, Upenamide displayed the strongest binding and stable protein-ligand dynamics, while Aspyronol demonstrated a promising ADMET profile comparable to that of the native cofactor F₄₂₀₂. These findings highlight the potential of deep-sea marine metabolites as a valuable source of anti-tubercular scaffolds and establish a computationally driven, cost-effective framework for discovering inhibitors targeting F₄₂₀-dependent enzymes. This approach provides a foundation for future experimental validation and expansion to additional F₄₂₀-related drug targets in M. tb.

Abstract:

The reactions of formaldehyde oxide (CH2OO) with methane and ethane that yield alcohol products were investigated using dual-level variational transition state theory with multidimensional tunneling corrections (VTST/MT). Additional systems—including halogenated formaldehyde oxides (CF2OO and CCl2OO), deuterated alkanes (CD4, C2D6), and isotopically substituted formaldehyde oxide (CH218O18O)—were also examined to explore substituent and isotope effects. Bimolecular rate constants and kinetic isotope effects (KIEs) were computed over the temperature range of 100–600 K. Significant tunneling contributions were predicted, especially below room temperature, where tunneling increases the rate constants of the CH2OO + alkane reactions by up to two orders of magnitude. The computed H/D KIEs are approximately 3 at 300 K and rise to ~10 at 200 K. Notably, pronounced oxygen tunneling was also observed, giving 18O KIEs of ~1.2 at 300 K and ~2.2 at 200 K. Halogen substitution was predicted to substantially reduce reaction barriers due to the weakening of the O–O bond, leading to rate constants for CF2OO reactions that exceed those of CH2OO by more than ten orders of magnitude at 300 K. The mechanisms underlying the strong tunneling effects, the individual contributions to the calculated KIEs, and the implications of these findings for atmospheric chemistry are discussed.

Abstract: Due to their chemical structure and convenient, tunable physicochemical properties, intermetallic alloys and materials are promising for use in various fields, such as gas sensors. The aim of this study was to perform DFT GGA calculations of the adsorption energy of atomic nitrogen and the properties of partially substituted metal atoms with nitrogen in Ti3Sb supercells with an A15 cubic structure. Adsorption and doping at various adsorption sites and crystallographic orientations (110; 111; 100), as well as their electronic properties, were studied in 2 × 2, 3 × 3, and 5 × 5 supercells. The density of states (DOS) of Ti3Sb–N supercells with two different positions of partial substitution of nitrogen for Ti3Sb metal atoms was calculated: N/Ti and N/Sb. Comparative data show that the structural and energetic properties of Ti3Sb–N vary compared to pure Ti3Sb. Controlled incorporation of nitrogen atoms and partial substitution of Ti3Sb atoms allow for tuning of the properties of Ti3Sb–N. These data can be used to optimize and predict the electronic structure and response characteristics of such materials for electronics and catalysis. They are also important as potential sensor materials with exceptional properties and promising applications for nitrogen detection in targeted developments.

Abstract: Electronegativity is a cornerstone of chemical theory, yet its traditional definitions remain empirical. Here, a variational definition of electronegativity (\( χ_V \)χ_V) is proposed, derived directly from the principle of least action. In this framework, the ratio between the effective nuclear charge (Z_eff\( Z_eff \)) and the principal quantum number (\( n^* \)n*) quantifies the deviation of an atom from its stationary (minimal-action) configuration, yielding \( \) χ_V=κ[(Z_eff/n* )²-1] , with a single universal constant (κ) fixed using fluorine. The scale reproduces periodic trends without empirical fitting and shows strong linear correlations with Pauling, Mulliken, and Allen electronegativities (r = 0.91–0.97, R² ≈ 0.9). χ_V also exhibits a nearly perfect proportionality with the first ionization energy (r = 0.9999) and an inverse-square dependence on atomic radius (R² = 0.904). When applied to 47 diatomic molecules, predicted bond-dissociation energies yield a mean absolute error of 15.8 kJ mol⁻¹—slightly lower than Pauling’s classical relation. These results demonstrate that electronegativity can be interpreted as a quantified deviation from the condition of least action, bridging atomic structure, energy, and reactivity within a unified physical framework.

Abstract: A unified electromagnetic response theory has been formulated in terms of quasi-energy derivatives within the nonrelativistic single-determinant framework. The formalism is applicable to both optical and non-optical electromagnetic responses, without restriction to monochromatic fields. Electromagnetic properties are expressed through quasi-energy derivatives, providing a consistent and general description under arbitrary static or dynamic perturbations. Magnetic properties obtained from this framework are inherently gauge-invariant, since a gauge transformation of the electromagnetic potentials corresponds to a unitary phase transformation acting on both the Hamiltonian and molecular orbitals. The present theory thus offers a comprehensive foundation for evaluating (hyper)polarizabilities, (hyper)magnetizabilities, and other related response properties.

Abstract: Machine learning is rapidly reshaping the field of chemical synthesis, influencing how chemists design, plan, and carry out reactions. Yet for many students, the role of artificial intelligence in synthesis remains abstract or inaccessible. This article introduces the current landscape of machine learning in chemistry, focusing on why these new approaches are emerging and how they complement, rather than replace, human creativity. We outline the challenges of traditional retrosynthetic planning, describe the rise of AI-driven platforms such as IBM RXN and AiZynthFinder, and discuss how they exemplify broader changes in the practice of chemistry. Practical “try it yourself” suggestions are included to help students and educators explore these developments firsthand. By highlighting both opportunities and limitations, this guide equips learners to critically understand the future of synthesis as a collaboration between chemists and computational tools.

Abstract: Every chemist knows the small heartbreak: the calculation looks beautiful; the flask does not. This paper takes that feeling seriously and names it—the reality gap—and then shows how to cross it on purpose. Our thesis is straightforward: predictive chemistry emerges when we let theory and experiment argue in public, with machine learning acting as the translator that keeps the debate honest.We first map where neat first‑principles wobble in the wild: bonds stretching and breaking, surfaces choosing a pathway, solvents shifting free energies just enough to matter, and spin states reorganizing the landscape. We then show how to correct those edges without discarding physics: hybrid QM/ML methods that learn systematic errors, uncertainty that travels with every prediction so we know when to trust and when to measure, and chemistry‑aware transfer learning so models trained on idealized inputs remain useful on real instruments.The loop closes when models talk to tools and tools talk back. Process‑analytical technologies feed real‑time signals to Bayesian optimization, multi‑objective workflows make trade‑offs visible (yield, selectivity, cost, greenness), and autonomy becomes conditional by design—robots execute, chemists steer. We focus on validation that survives deployment, not convenience: splits that reflect how chemistry varies in practice, calibrated confidence, and structured logging that treats failures as first‑class data. Finally, we detail what this buys in real laboratories: faster cycles, reproducible and information‑rich datasets, greener routes—and decisions made with eyes open.The message is practical and hopeful. Keep the physics where it is strong. Teach it where it is stubbornly wrong. Carry uncertainty forward. Let instruments help decide where to look next. Do that, and the calculation and the flask still won’t always agree—but they will disagree productively, more often, and for reasons we can understand. That is predictive chemistry in practice.

Abstract: Chemical bonds among carbon are central to Chemistry. A general working principle regarding these interactions is that these contacts get stronger as the carbon atoms become closer to each other. Nevertheless, there are long, yet strong single C–C bonds which challenge this interpretation. Herein, we perform a quantitative thorough decomposition of the electronic energy of hexaphenylethane and several derivatives of this molecule with increasingly bulkier substituents. For this purpose, we exploited state-of-the-art methods of wave function analysis for the examination of the chemical bonding scenario in the examined systems, namely the Quantum Theory of Atoms in Molecules (QTAIM) and the Interacting Quantum Atoms (IQA) electronic energy partition. Our results reveal the predominance of collective non-covalent interactions over the central, covalent one in the chemical bonding of the examined molecules, in particular for those which have been synthesised in the laboratory. The QTAIM and IQA methods also showed that besides London dispersion, electron sharing comprises and important contribution to the above mentioned collective interactions. Overall, our results give valuable insights about the importance of collective interactions in the investigated systems and they aid in the understanding of the nature or long, yet stable single C–C bonds.

Abstract: The revolutionary field of artificial intelligence (AI) has affected all aspects of our lives, including the field of chemistry. The impact of AI has been felt even more strongly in recent years, as new powerful computational tools have emerged. This review looks at the evolution of AI in chemistry, from a not-too-distant past when AI was limited to rule-based systems and simulation for simple data analyses to today's world of advanced (or powerful) machine learning. Despite the name, "advanced machine learning" refers to a highly diverse family of AI systems—most of which are not learned in the way, or with the types of data, that humans typically use to understand the world. The latest advances in AI, particularly deep learning, hold the promise of revolutionizing chemistry. The use of these advanced computational methods enables researchers to extract relationships from large datasets of molecular and chemical information. This capacity to discern pattern recognition within big data allows for the accurate prediction of molecular properties. It furthermore enables the efficient optimization of chemical reactions and the design of new materials at the molecular scale. Whether directly applied to chemistry or harnessed through interdisciplinary collaboration, AI will make a significant impact on the pace of chemical research in coming years. The review article highlights these prospects and discusses some specific areas, including drug discovery and materials science, where AI's impact will likely be felt most keenly. Moreover, AI is beginning to find applications in chemical synthesis and spectroscopy, and these have made predictions about reactions easier and enhanced data interpretation spectacularly. One of the promises going forward is the hoped-for emergence of quantum computing, which may take the not-yet-fully-realized uses of AI in chemistry even further. One of the main points made in this review is that for all this to happen, the chemistry community may need to plan a bit; interdisciplinary collaborations between chemists and AI experts will be essential to push forward the kinds of uses AI could have in our field.