β-Diketonate Coordination: Vibrational Properties, Electronic Structure, Molecular Topology, and Intramolecular Interactions. Beryllium(II), Copper(II), and Lead(II) as Study Cases

The Journal of Physical Chemistry A, Год журнала: 2025, Номер unknown

Опубликована: Янв. 17, 2025

Nine metal complexes formed by three symmetric β-diketonates (viz., acetylacetonate (acac), 1,1,1,3,3,3-hexafluoro-acetylacetonate (hfac), and 2,2,6,6-tetramethylheptane-3,5-dionate (tmhd)) ions (with different coordination geometries, viz., BeII - tetrahedral, CuII square planar, PbII "swing" pyramidal) were investigated. The study combines structural analyses, vibrational spectroscopic techniques, quantum chemical calculations with the aim of bridging crystal structure, electronic molecular topology, far-infrared (FIR) characteristics. effect intramolecular interactions on structural, electronic, features is center this study. structure Be(tmhd)2 also reported discussed for first time. A complete review experimental IR spectra offered; discrepancies in assignments some peaks are revealed among published works. Anharmonic effects considered acac complexes; however, they negligible FIR modes. systematic comparison between computed experimentally measured data allowed us to design an inexpensive, yet efficient computational protocol investigate large polynuclear complexes.

Язык: Английский

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Predicting fundamental gaps accurately from density functional theory with non-empirical local range separation

The Journal of Chemical Physics, Год журнала: 2024, Номер 160(18)

Опубликована: Май 8, 2024

We present an exchange–correlation approximation in which the Coulomb interaction is split into long- and short-range components range separation determined by a non-empirical density functional. The functional respects important constraints, such as homogeneous slowly varying limits, leads to correct long-range potential, eliminates one-electron self-interaction. Our approach designed for spectroscopic purposes closely approximates piecewise linearity of energy function particle number. functional’s accuracy predicting fundamental gap generalized Kohn–Sham theory demonstrated large number systems, including organic semiconductors with notoriously difficult electronic structure.

Язык: Английский

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Extending Density-Corrected Density Functional Theory to Large Molecular Systems

The Journal of Physical Chemistry Letters, Год журнала: 2025, Номер unknown, С. 939 - 947

Опубликована: Янв. 21, 2025

Practical density-corrected density functional theory (DC-DFT) calculations rely on Hartree-Fock (HF) densities, which can be computationally expensive for systems with over a hundred atoms. We extend the applicability of HF-DFT using dual-basis method, where matrix from smaller basis set is used to estimate HF solution larger set. Benchmarks many systems, including GMTKN55 database main-group chemistry, and L7 S6L data sets large molecular demonstrate efficacy our approach. apply method both DNA HIV compare literature. The details recent reparameterization HF-r2SCAN-DC4 are explained, showing no loss performance.

Язык: Английский

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Adapting hybrid density functionals with machine learning

Science Advances, Год журнала: 2025, Номер 11(5)

Опубликована: Янв. 31, 2025

Exact exchange contributions significantly affect electronic states, influencing covalent bond formation and breaking. Hybrid density functional approximations, which average exact admixtures empirically, have achieved success but fall short of high-level quantum chemistry accuracy due to delocalization errors. We propose adaptive hybrid functionals, generating optimal admixture ratios on the fly using data-efficient machine learning models with negligible overhead. The Perdew-Burke-Ernzerhof (aPBE0) improves energetics, electron densities, HOMO-LUMO gaps in QM9, QM7b, GMTKN55 benchmark datasets. A model uncertainty-based constraint reduces method smoothly PBE0 extrapolative regimes, ensuring general applicability limited training. By tuning fractions for different spin aPBE0 effectively addresses gap problem open-shell systems such as carbenes. also present a revised QM9 (revQM9) dataset more accurate properties, including stronger binding, larger bandgaps, localized dipole moments.

Язык: Английский

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The Role of Methyl Substitution in Spin Crossover of Fe(III) Complexes with Pentadentate Schiff Base Ligands

Inorganics, Год журнала: 2025, Номер 13(2), С. 57 - 57

Опубликована: Фев. 15, 2025

A series of mononuclear complexes, [Fe(L5)(bylim)](BPh4), where L5 represents a pentadentate Schiff base ligand, bylim is 1-benzyl-1-imidazole, and BPh4− the tetraphenylborate anion, was synthesized. The determined crystal structures indicate absence significant cooperative interactions, which influence properties eventual spin transition. Changes in magnetic behavior induced by substitution ligand were investigated through susceptibility measurements. It found that only complexes containing non-substituted secondary amino group exhibit some form crossover, whereas majority those with methyl substituent remain high-spin state across entire measured temperature range (2–300 K). changes amine further explored theoretical calculations at DFT CASSCF/NEVPT2 levels theory. topology energetics electron density atomic charges QT-AIM calculations.

Язык: Английский

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Excited-state methods for molecular systems: Performance, pitfalls, and practical guidance

Chemical Physics Reviews, Год журнала: 2025, Номер 6(2)

Опубликована: Май 1, 2025

Proper theoretical descriptions of ground and excited states are critical for understanding molecular photophysics photochemistry. Complex interactions in experimentally interesting systems require multiple approximations the underlying quantum mechanics to practically solve various physical observables. While high-level calculations small provide very accurate excitation energies, this accuracy does not always extend larger or other properties. Because this, “best” method study new molecules is clear, leading many researchers default inexpensive easy-to-use black-box methods. Unfortunately, even when these methods reproduce experimental it necessarily right reasons. Without physics, becomes challenging understand classes molecules. Consequently, predicted properties their trends may offer reliable mechanistic understanding. This review targeted at beginners computational chemistry who interested studying excited-state A brief overview common ground- covered easy reference during comparison The primary focus compare several important chromophores. performance each explored practitioners a road map on what work well different identify further that needs be done field.

Язык: Английский

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NBN‐ and BNB‐Phenalenyls: the Yin and Yang of Heteroatom‐doped π Systems

Chemistry - A European Journal, Год журнала: 2024, Номер 30(27)

Опубликована: Март 1, 2024

Abstract NBN‐ and BNB‐doped phenalenyls are isoelectronic to phenalenyl anions cations, respectively. They represent a pair of complementary molecules that have essentially identical structures but opposite properties as electron donors acceptors. The NBN‐phenalenyls 1 – 4 considered here were prepared from N , N’‐ dimethyl‐1,8‐diaminonaphthalene readily available boron‐containing building blocks (i. e., BH 3 ⋅SMe 2 ( ), p ‐CF ‐C 6 H B(OH) C 5 or MesBCl / i Pr NEt )). Treatment with 4‐Me N‐2,6‐Me Li gave the corresponding NBN derivative . BNB‐phenalenyl was synthesized 1,8‐naphthalenediyl‐bridged diborane(6), PhNH MesMgBr. A computational study reveals photoemission originates locally excited (LE) states at NBN‐phenalenyl fragments, while is dominated by charge transfer (CT) fragment. Depending on dihedral angle θ between its Ph planes, compound emits mainly less polar LE >55°) more CT state <55°). In turn, energetic preference for either governed polarity solvent used. An equimolar aggregate BNB‐phenalenyls (in THF/H O) shows distinct red‐shifted emission compared individual components, which an intermolecular state.

Язык: Английский

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Benchmarking Charge-Transfer Excited States in TADF Emitters: ∆DFT outperforms TD-DFT for Emission Energies

Опубликована: Май 20, 2024

Charge-transfer excited states are crucial to modern electronics, particularly organic light-emitting diodes (OLEDs) based on thermally-activated delayed fluorescence (TADF). However, accurately modeling CT remains challenging, even with implementations of (time-dependent) density functional theory [(TD-)DFT], especially in a dielectric environment. To identify short-comings and improve the methodology, we previously established STGABS27 benchmark set highly accurate experimental references for adiabatic energy gap between lowest singlet triplet (∆EST). Here, diversify this STGABS27-EMS by including emission energies (Eem) use new (re)-evaluate various DFT-based approaches. Surprisingly, these tests demonstrate that state-specific (un)restricted open-shell Kohn-Sham (U/ROKS) DFT coupled polarizable continuum model perturbative non-equilibrium solvation (ptSS-PCM) provides exceptional accuracy predicting Eem over wide range functionals. In contrast, main workhorse field, Tamm-Dancoff-approximated TD-DFT (TDA-DFT) paired same ptSS-PCM, is distinctly less strongly dependent. More importantly, while TDA-DFT requires choice two very different functionals good performance either ∆EST or Eem, time-independent U/ROKS/PCM approaches deliver excellent both quantities variety

Язык: Английский

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Benchmarking Charge-Transfer Excited States in TADF Emitters: ΔDFT Outperforms TD-DFT for Emission Energies

The Journal of Physical Chemistry A, Год журнала: 2024, Номер 128(30), С. 6324 - 6335

Опубликована: Июль 19, 2024

Charge-transfer (CT) excited states are crucial to organic light-emitting diodes (OLEDs), particularly those based on thermally activated delayed fluorescence (TADF). However, accurately modeling CT remains challenging, even with modern implementations of (time-dependent) density functional theory [(TD-)DFT], especially in a dielectric environment. To identify shortcomings and improve the methodology, we previously established STGABS27 benchmark set highly accurate experimental references for adiabatic energy gap between lowest singlet triplet (ΔEST). Here, diversify this STGABS27-EMS by including emission energies (Eem) use new (re)-evaluate various DFT-based approaches. Surprisingly, these tests demonstrate that state-specific (un)restricted open-shell Kohn–Sham (U/ROKS) DFT coupled polarizable continuum model perturbative nonequilibrium solvation (ptSS-PCM) provides exceptional accuracy predicting Eem over wide range functionals. In contrast, main workhorse field, Tamm–Dancoff-approximated TD-DFT (TDA-DFT) paired same ptSS-PCM, is distinctly less strongly functional-dependent. More importantly, while TDA-DFT requires choice two very different functionals good performance either ΔEST or Eem, time-independent U/ROKS/PCM approaches deliver excellent both quantities variety

Язык: Английский

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Correcting Dispersion Corrections with Density-Corrected DFT

Journal of Chemical Theory and Computation, Год журнала: 2024, Номер unknown

Опубликована: Авг. 9, 2024

Almost all empirical parametrizations of dispersion corrections in DFT use only energy errors, thereby mixing functional and density-driven errors. We introduce density dispersion-corrected (D2C-DFT), a dual-calibration approach that accounts for delocalization errors when parametrizing interactions. simply exclude density-sensitive reactions from the training data. find significant reduction both variation among several semilocal functionals their global hybrids tailored are employed with Hartree–Fock densities.

Язык: Английский

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