Excited-state Hund’s Rule Violations in Bridged [10]- and [14]Annulene Perimeters DOI Creative Commons
J. Terence Blaskovits, Clémence Corminbœuf, Marc H. Garner

et al.

Published: June 17, 2024

Molecules with Hund’s rule violations between low-lying singlet and triplet states may enable a new generation of fluorescent emitters. However, only few classes molecules are known this property at the current time. Here, we use high-throughput screening algorithm FORMED database to uncover class compounds where first excited state violates rule. We examine bridged [10]- [14]annulene perimeters saturated bridges, relate them conjugated polycyclic systems violations. Despite structural similarities related non-alternant hydrocarbons, mechanism is different in these annulene perimeters. two molecular orbital configurations contribute each state. Consequently, violation can be unambiguously assigned based on symmetry lowest states. With several examples synthetically realistic molecules, [14]annulenes thus provides link alternant (azaphenalene) violating rule, open avenues for design inverted singlet-triplet gaps.

Language: Английский

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

Pradipta Manna,

Ambar Banerjee

et al.

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

Citations

10
Resilience of Hund's rule in the chemical space of small organic molecules DOI
Atreyee Majumdar, Raghunathan Ramakrishnan

Physical Chemistry Chemical Physics, Journal Year: 2024, Volume and Issue: 26(20), P. 14505 - 14513

Published: Jan. 1, 2024

High-throughput ab initio calculations and data-mining reveal Hund's rule to prevail across the chemical space of small organic molecules with systematically varying compositions structures.

Language: Английский

Citations

8
The Role of Theoretical Calculations for INVEST Systems: Complementarity Between Theory and Experiments and Rationalization of the Results DOI Creative Commons
Á. J. Pérez‐Jiménez, Yoann Olivier, J. C. Sancho‐García

et al.

Advanced Optical Materials, Journal Year: 2025, Volume and Issue: unknown

Published: March 5, 2025

Abstract Here, the key role played by theoretical calculations for molecules presenting an inverted singlet‐triplet excited state (e.g. S 1 and T ) energy difference, or Δ E ST < 0, whose interest has steadily raised in recent years fostered experimental advances showing negative values a collection of real‐world systems is reviewed. The evolution computational efforts from pioneering on reduced set prototypical covered, to high‐throughput virtual screenings thousands identify new molecular scaffolds tune properties other than excitation energies, describe necessary benchmarking methods done parallel along years. Overall, complementarity prompted discovery more displaying 0 values, basic design principles are rationalized thus reviewed here too, while allowing at same time find which offer reasonable trade‐off between accuracy cost.

Language: Английский

Citations

1
Impact of Structure on Excitation Energies and S1‐T1 Energy Gaps of Asymmetrical Systems of Interest for Inverted Singlet‐Triplet Gaps DOI Open Access

Gideon Odonkor,

Samuel O. Odoh

Journal of Computational Chemistry, Journal Year: 2025, Volume and Issue: 46(8)

Published: March 26, 2025

Computational investigations of Inverted Singlet-Triplet (INVEST) emitters often rely on ADC(2) and TD-DFT excitation energies (EEs) obtained with the vertical approximation. Here, we first considered several cyclazine derivatives examine sensitivity EEs (VEEs) as well singlet-triplet gaps, ΔES1T1 to level at which ground state (S0) structure was optimized. For cyclazine, VEEs gaps from or are spread over a narrow range (< 0.064 eV) whether S0 is optimized various DFT, CCSD, RI-MP2 methods. However, for asymmetric cyclazines, depending protocol optimizing structures, not only substantially wider (up 0.75 but so 0.30 eV), leading cases where, different one obtains positive significantly negative gaps. We relate this behavior introduction significant asymmetry bond-length variations in derivatives, formed by ligand functionalization modification core. On more note, adiabatic (AEEs) display lower (7-30× less) geometry optimization protocols than their analogs. Crucially, M06-HF functional 100% non-local exchange provides closest available CCSD(T) data. show that effect exists also other frameworks (e.g., azulene, pentaazaphenalene, non-alternant polycyclic hydrocarbons) have been INVEST property, broader up 1.19 eV 0.62 eV. emitters, it therefore extremely important judiciously choose computational geometries, computing

Language: Английский

Citations

1
Computational Design of Boron-Free Triangular Molecules with Inverted Singlet-Triplet Energy Gap DOI
Magdalena W. Duszka, Michał F. Rode, Andrzej L. Sobolewski

et al.

Physical Chemistry Chemical Physics, Journal Year: 2024, Volume and Issue: 26(28), P. 19130 - 19137

Published: Jan. 1, 2024

A novel, computationally designed, class of triangular-shape organic molecules with an inverted singlet-triplet (IST) energy gap is investigated

Language: Английский

Citations

6
Rational Design of Organic Emitters with Inverted Singlet–Triplet Gaps for Enhanced Exciton Management DOI

Sanyam Sanyam,

Priyanshu Sorout,

Anirban Mondal

et al.

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(34), P. 7114 - 7123

Published: Aug. 19, 2024

In organic light-emitting diodes (OLEDs), the pursuit of efficient molecular emitters has led to development thermally activated delayed fluorescence (TADF) molecules. While TADF compounds have promising properties, they face challenges such as energy gap constraints and uphill exciton transfer. Inverted (INVEST) offer a novel solution with an inverted singlet–triplet (ΔEST) gap, enabling utilization excitons. This study examines design computational analysis array molecules, including 23 INVEST remaining positive gaps. Within STEOM-DLPNO–CCSD framework, we explore role various fragments in determining ΔEST. We also assess importance dynamic spin-polarization (DSP) obtained via Pariser–Parr–Pople (PPP) scheme determination. Exciting trends emerged from our results, pentalene-containing consistently manifesting negative ΔEST values while their naphthalene counterparts exhibited contrasting behavior. Moreover, observed DSP correlates Overall, this research advances OLED materials through analysis, offering avenues for optimizing management enhancing device performance.

Language: Английский

Citations

6
Searching the Best Double-Hybrid Density Functional to Correctly Predict the Singlet–Triplet Excited-State Inversion in Organic Systems DOI
Amel Derradji, Danillo Valverde, Éric Brémond

et al.

The Journal of Physical Chemistry C, Journal Year: 2024, Volume and Issue: 128(43), P. 18313 - 18327

Published: Oct. 18, 2024

The theoretically disclosed, and experimentally confirmed, energy inversion of the lowest singlet (S1) triplet (T1) excited states organic molecules (i.e., Hund's rule violation) is investigated herein with aid modern nonempirically derived double-hybrid (DH) density functionals, in search best trade-off between accuracy computational cost viable electronic structure methods. For that purpose, we have selected a family parameter-free expressions differing their specific formulation (DFT-0DH, DFT-QIDH, DFT0-2, SOS1-DFT-0DH, SOS1-DFT-QIDH, SOS1-DFT0-2, RSX-DFT-0DH, RSX-DFT-QIDH, SOS1-RSX-DFT-0DH, SOS1-RSX-DFT-QIDH) as well underlying exchange–correlation functional used (PBE vs r2SCAN). sake evaluating which DH can correctly describe singlet–triplet excited-state inversion, second-order approximate singles doubles method spin-component scaling (SCS-CC2) equation-of-motion coupled cluster (EOM-CCSD) calculations are also carried out. results highlight importance delicate balance all terms composing correlation part being particularly significant for achieving most accurate results. We new (PBE-DH-INVEST) exploiting relationship, providing low error metrics expected to yield robust in, e.g., high-throughput studies.

Language: Английский

Citations

6
Singlet–Triplet Inversions in Through-Bond Charge-Transfer States DOI Creative Commons
J. Terence Blaskovits, Clémence Corminbœuf, Marc H. Garner

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: unknown, P. 10062 - 10067

Published: Sept. 26, 2024

Molecules where the lowest excited singlet state is lower in energy than triplet are highly promising for a number of organic materials applications as efficiency limitations stemming from spin statistics overcome. All molecules known to possess such singlet-triplet inversions exhibit pattern spatially alternating but nonoverlapping HOMO and LUMO orbitals, meaning states local character. Here, we demonstrate that derivatives bicyclic hydrocarbon calicene Hund's rule violations charge-transfer (CT) between its rings. These CT can be tuned with substituents, so first energetically inverted. This provides conceptual connection emerging fields inverted gap existing molecular design rules state-of-the-art thermally activated delayed fluorescence materials.

Language: Английский

Citations

4
Singlet-Triplet Inversion DOI
Liam Wrigley, Cody W. Schlenker

Annual Review of Physical Chemistry, Journal Year: 2025, Volume and Issue: 76(1), P. 329 - 355

Published: April 21, 2025

The inversion of singlet and triplet states is a rare phenomenon, where, in opposition to Hund's first rule, electronic are stabilized relative their counterparts. recent discovery organic molecules exhibiting this presents exciting new technological opportunities, such as addressing stability issues light-emitting diodes (OLEDs). In review, we describe fundamental molecular properties that can yield singlet-triplet inversion, generally ascribed phenomenon known dynamic spin polarization. We discuss the systems which was theoretically proposed, experimentally verified, implemented an OLED device. highlight key insights from extensive computational work being carried out understand intricacies these systems. Finally, consider outlook for future inverted (IST) emitters.

Language: Английский

Citations

0
Addressing the High-Throughput Screening Challenges of Inverted Singlet–Triplet Materials by MRSF-TDDFT DOI
Alireza Lashkaripour, Woojin Park, Mohsen Mazaherifar

et al.

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: May 20, 2025

A new computational protocol utilizing mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT) and the DTCAM-STG exchange-correlation has been developed to identify materials with inverted singlet-triplet (INVEST) energy levels. This surpasses existing quantum chemical methods in both accuracy efficiency for predicting ΔEST, addressing challenges high-throughput screening INVEST materials. Based on this approach, novel heptazine derivatives have proposed, which are anticipated outperform currently known systems. Additionally, dynamic spin polarization (DSP) identified as a critical factor influencing phenomena. insight provides foundation design principles, enabling discovery of superior performance compared alternatives.

Language: Английский

Citations

0