Enhanced inverted singlet–triplet gaps in azaphenalenes and non-alternant hydrocarbons

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(15), P. 2070 - 2073

Published: Jan. 1, 2024

A substituent-based design strategy induces and enhances inversions in the excited state singlet–triplet gaps a wide range of potential organic light-emitting molecules.

Language: Английский

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Artificial design of organic emitters via a genetic algorithm enhanced by a deep neural network

Chemical Science, Journal Year: 2024, Volume and Issue: 15(7), P. 2618 - 2639

Published: Jan. 1, 2024

An artificial molecular design workflow using a genetic algorithm with strings and neural networks applied to organic molecules inverted singlet-triplet gaps finds 1000 candidates appreciable fluorescence rates.

Language: Английский

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Ultrafast Computational Screening of Molecules with Inverted Singlet–Triplet Energy Gaps Using the Pariser–Parr–Pople Semiempirical Quantum Chemistry Method

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(12), P. 2445 - 2456

Published: March 14, 2024

Molecules with an inverted energy gap between their first singlet and triplet excited states have promising applications in the next generation of organic light-emitting diode (OLED) materials. Unfortunately, such molecules are rare, only a handful examples currently known. High-throughput virtual screening could assist finding novel classes these molecules, but current efforts hampered by high computational cost required quantum chemical methods. We present method based on semiempirical Pariser–Parr–Pople theory augmented perturbation show that it reproduces gaps at fraction employed excited-state calculations. Our study paves way for ultrahigh-throughput inverse design to accelerate discovery development this new OLED

Language: Английский

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Experimental and computational studies of the optical properties of 2,5,8-tris(phenylthiolato)heptazine with an inverted singlet–triplet gap

Physical Chemistry Chemical Physics, Journal Year: 2024, Volume and Issue: 26(7), P. 5922 - 5931

Published: Jan. 1, 2024

The calculated energy inversion of the first excited states a heptazine phenylthiolate molecule is consistent with intense blue fluorescence in solid state and toluene solution.

Language: Английский

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Molecular Geometry Impact on Deep Learning Predictions of Inverted Singlet–Triplet Gaps

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(12), P. 2417 - 2426

Published: March 14, 2024

We present a deep learning model able to predict excited singlet–triplet gaps with mean absolute error (MAE) of ≈20 meV obtain potential inverted (IST) candidates. exploit cutting-edge spherical message passing graph neural networks designed specifically for generating 3D representations in molecular learning. In nutshell, the takes as input list unsaturated heavy atom Cartesian coordinates and atomic numbers, producing output. exploited available large data collections train on ≈40,000 heterogeneous density functional theory (DFT) geometries ADC(2)/cc-pVDZ gaps. ascertain predictive power from quantitative perspective obtaining predictions test set ≈14,000 molecules, whose have been generated at DFT level (the same employed training set), GFN2-xTB level, through Molecular Mechanics. notice performance degradation upon switching lower-quality geometries, ones maintaining satisfactory results (MAE ≈ 50 MAE 180 generalized AMBER force field geometries), hinting caution when dealing specific chemical classes. Finally, we verify qualitative point view, different ≈15,000 molecules already used identify new IST molecules. obtained using both experimental X-ray candidates similar those provided by quantum methods, clear hints path toward improved performance.

Language: Английский

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Reverse Intersystem Crossing Dynamics in Vibronically Modulated Inverted Singlet–Triplet Gap System: A Wigner Phase Space Study

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 15(30), P. 7603 - 7609

Published: July 19, 2024

We inspect the origin of inverted singlet-triplet gap (INVEST) and slow change in reverse intersystem crossing (rISC) rate with temperature, as recently observed. A Wigner phase space study reveals that, though INVEST is found at equilibrium geometry, variation exchange interaction doubles-excitation for other geometries harmonic region leads to non-INVEST behavior. This highlights importance nuclear degrees freedom phenomenon, this case, geometric puckering studied molecule determines associated rISC dynamics.

Language: Английский

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Benchmark computations of nearly degenerate singlet and triplet states of N-heterocyclic chromophores. II. Density-based methods

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(2)

Published: Jan. 8, 2025

In this paper, we demonstrate the performance of several density-based methods in predicting inversion S1 and T1 states a few N-heterocyclic triangulene based fused ring molecules (popularly known as INVEST molecules) with an eye to identify well performing but cost-effective preliminary screening method. Both conventional linear-response time-dependent density functional theory (LR-TDDFT) ΔSCF (namely maximum overlap method, square-gradient minimization restricted open-shell Kohn–Sham) are considered for excited state computations using exchange–correlation (XC) functionals from different rungs Jacob’s ladder. A well-justified systematism is observed when compared against fully internally contracted multireference configuration interaction singles doubles and/or equation motion coupled-cluster (EOM-CCSD), most important feature being capture spin-polarization presence correlation. set least mean absolute error proposed both approaches, LR-TDDFT ΔSCF, which can be more alternatives on synthesizable larger derivatives templates studied here. We have our findings extensive studies three cyclazine-based molecular templates, additional six related templates. Previous benchmark subsets were conducted domain-based local pair natural orbital-similarity transformed EOM-CCSD (STEOM-CCSD), resulted inadequate evaluation due deficiencies theory. The role exact-exchange, spin-contamination, context DFT comes forefront supports numerical XC these applications. Suitable connections drawn two exciton models, minimal physics governing interactions molecules.

Language: Английский

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Double-bond delocalization in non-alternant hydrocarbons induces inverted singlet–triplet gaps

Chemical Science, Journal Year: 2023, Volume and Issue: 14(38), P. 10458 - 10466

Published: Jan. 1, 2023

Molecules where the first excited singlet state is lower in energy than triplet have potential to revolutionize OLEDs. This inverted singlet-triplet gap violates Hund's rule and currently there are only a few molecules which known this property. Here, we screen complete set of non-alternant hydrocarbons consisting 5-, 6-, 7-membered rings fused into two-, three- four-ring polycyclic systems. We identify several symmetry ground-state structure broken due bond-length alternation. Through symmetry-constrained optimizations molecular cores when higher symmetry, pentalene being example. uncover strategy stabilize their higher-symmetry structures with electron donors or acceptors. design substituted pentalenes, s-indacenes, indeno[1,2,3-ef]heptalenes gaps, among synthetically examples. In contrast emitters, double-bond delocalized conjugated as necessary condition achieve gap. enables chemical tuning paves way for rational gaps. These prospective emitters if properties can be optimized use

Language: Английский

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Computational Investigations of the Detailed Mechanism of Reverse Intersystem Crossing in Inverted Singlet–Triplet Gap Molecules

ACS Applied Materials & Interfaces, Journal Year: 2024, Volume and Issue: unknown

Published: May 10, 2024

Inverted singlet–triplet gap (INVEST) materials have promising photophysical properties for optoelectronic applications due to an inversion of their lowest singlet (S1) and triplet (T1) excited states. This results in exothermic reverse intersystem crossing (rISC) process that potentially enhances harvesting, compared thermally activated delayed fluorescence (TADF) emitters with endothermic rISCs. However, the processes phenomena facilitate conversion between states INVEST are underexplored. We investigate complex potential energy surfaces (PESs) three heavily studied azaphenalene compounds, namely, cyclazine, pentazine, heptazine using two state-of-the-art computational methodologies, RMS-CASPT2 SCS-ADC(2) methods. Our findings suggest ISC rISC take place directly S1 T1 electronic all compounds through a minimum-energy point (MECP) activation barrier 0.11 0.58 eV above state 0.06 0.36 rISC. predict higher-lying not populated, since structures these energetically accessible. Furthermore, conical intersection (CI) ground is high (between 0.4 2.0 eV) which makes nonradiative decay back relatively slow process. demonstrate spin-orbit coupling (SOC) driving S1-T1 enhanced by vibronic possessing vibrational modes proper symmetry. also rationalize experimentally observed anti-Kasha emission cyclazine inaccessible CI bright S2 dark states, hindering internal conversion. Finally, we show able qualitatively reproduce features, but consistently overpredict relative energies structural minima RMS-CASPT2. The identification features elaborates design rules new improved quantum yields.

Language: Английский

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Computational Design of Multiple Resonance-Type BN Molecules for Inverted Singlet and Triplet Excited States

The Journal of Physical Chemistry A, Journal Year: 2023, Volume and Issue: 127(48), P. 10189 - 10196

Published: Nov. 27, 2023

A computational design of linearly extended multiple resonance (MR)-type BN molecules based on DABNA-1 is proposed herein in the quest to find potential candidates that exhibit a negative singlet-triplet gap (ΔEST) and large oscillator strength value. The impact proper account electron correlation lowest singlet triplet excited states systematically investigated by using double-hybrid functionals within TD-DFT framework, as well wavefunction-based methods (EOM-CCSD SCS-CC2), since this contribution plays an essential role driving magnitude ΔEST MR-TADF inverted compounds. Our results point out gradual reduction with respect increasing sum number B N atoms, reaching values for some function their size. reproduce only slight deviation compared available experimental data DABNA-1, ν-DABNA, mDBCz nicely agree high-level quantum mechanical (e.g., EOM-CCSD SCS-CC2). Larger strengths are found azaphenalene-type molecules, also exhibiting inversion states. We hope study can serve motivation further showing boron- nitrogen-doped polyaromatic hydrocarbons.

Language: Английский

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