Null Exciton-Coupled Chromophoric Dimer Exhibits Symmetry-Breaking Charge Separation

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(34), P. 13769 - 13781

Published: Aug. 9, 2021

A comprehensive understanding of the structure-property relationships in multichromophoric architectures has pushed limits for developing robust photosynthetic mimics and molecular photovoltaics. The elusive phenomenon null exciton splitting gathered immense attention recent years owing to occurrence unique chromophoric consequent emergent properties. Herein, we unveil hitherto unobserved coupling assisted highly efficient photoinduced symmetry-breaking charge separation (SB-CS) a Greek cross (+)-oriented spiro-conjugated perylenediimide dimer (Sp-PDI2). Quantum chemical calculations have rationalized infrequent manifestation behavior Sp-PDI2. Negligible contribution long-range Coulombic short-range charge-transfer mediated renders monomer-like spectroscopic signature Sp-PDI2 toluene. (+)-arranged possesses selective hole-transfer coupling, facilitating ultrafast dissociation excitons evolution charge-separated state polar solvents. Radical cationic anionic signatures were characterized by employing femtosecond transient absorption spectroscopy. substantial hole transfer electronic lower activation energy barrier accelerated rate. rate recombination (CR) markedly decelerated due falling into inverted region Marcus parabola, where driving force CR is larger than total reorganization CR. Hence, ratio rates SB-CS over exhibited an unprecedently high value 2647 acetonitrile. current study provides impeccable evidence role filtering governing thereby novel insights towards design biomimics advanced functional materials.

Language: Английский

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Newton-X Platform: New Software Developments for Surface Hopping and Nuclear Ensembles

Journal of Chemical Theory and Computation, Journal Year: 2022, Volume and Issue: 18(11), P. 6851 - 6865

Published: Oct. 4, 2022

Newton-X is an open-source computational platform to perform nonadiabatic molecular dynamics based on surface hopping and spectrum simulations using the nuclear ensemble approach. Both are among most common methodologies in chemistry for photophysical photochemical investigations. This paper describes main features of these methods how they implemented Newton-X. It emphasizes newest developments, including zero-point-energy leakage correction, complex-valued potential energy surfaces, induced by incoherent light, machine-learning potentials, exciton multiple chromophores, supervised unsupervised machine learning techniques. interfaced with several third-party quantum-chemistry programs, spanning a broad electronic structure methods.

Language: Английский

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Energy Component Analysis for Electronically Excited States of Molecules: Why the Lowest Excited State Is Not Always the HOMO/LUMO Transition

Journal of Chemical Theory and Computation, Journal Year: 2023, Volume and Issue: 19(8), P. 2340 - 2352

Published: April 6, 2023

The ability to tune excited-state energies is crucial many areas of molecular design. In cases, this done based on the highest occupied orbital (HOMO) and lowest unoccupied (LUMO). However, viewpoint incomplete neglecting many-body nature underlying wave functions. Within work, we highlight importance two terms, other than energies, that contribute excitation show how quantify them from quantum chemistry computations: a Coulomb attraction repulsive exchange interaction. Using framework, explain under which circumstances excited state molecule, either singlet or triplet multiplicity, not accessed via HOMO/LUMO transition paradigmatic examples. case push-pull molecule ACRFLCN, locally lying below charge transfer due enhanced binding. naphthalene (the 1La state) becomes second its repulsion term. More generally, why do always behave like energy gaps, providing insight into photophysical processes as well methodogical challenges in describing them.

Language: Английский

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Keeping the chromophores crossed: evidence for null exciton splitting

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 52(19), P. 6664 - 6679

Published: Jan. 1, 2023

Attempts to identify and probe atypical molecular aggregates focusing on the less explored null aggregates. The aggregate was foretold by Kasha possess exciton interaction leading spectroscopically uncoupled assembly.

Language: Английский

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Classification of doubly excited molecular electronic states

Chemical Science, Journal Year: 2023, Volume and Issue: 14(15), P. 4012 - 4026

Published: Jan. 1, 2023

A rigorous classification scheme for doubly excited states is proposed and the different possible types are exemplified in various molecules.

Language: Английский

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First-Principles Calculations of Excited-State Decay Rate Constants in Organic Fluorophores

The Journal of Physical Chemistry A, Journal Year: 2023, Volume and Issue: 127(48), P. 10033 - 10053

Published: Nov. 21, 2023

In this Perspective, we discuss recent advances made to evaluate from first-principles the excited-state decay rate constants of organic fluorophores, focusing on so-called static strategy. strategy, one essentially takes advantage Fermi's golden rule (FGR) at key points potential energy surfaces, a procedure that can be refined in variety ways. way, radiative constant straightforwardly obtained by integrating fluorescence line shape, itself determined vibronic calculations. Likewise, FGR allows for consistent calculation internal conversion (related non-adiabatic couplings) weak-coupling regime and intersystem crossing rates, therefore giving access estimates emission yields when no complex photophysical phenomenon is play. Beyond outlining underlying theories, summarize here results benchmarks performed various types highlighting both quality calculations accuracy relative energies are crucial reaching semiquantitative estimates. Finally, illustrate successes challenges determining quantum using series fluorophores.

Language: Английский

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Ru(II) Oligothienyl Complexes with Fluorinated Ligands: Photophysical, Electrochemical, and Photobiological Properties

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(21), P. 9735 - 9752

Published: May 10, 2024

A series of Ru(II) complexes incorporating two 4,4'-bis(trifluoromethyl)-2,2'-bipyridine (4,4'-btfmb) coligands and thienyl-appended imidazo[4,5-

Language: Английский

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Ruthenium(II) Polypyridyl Complexes Containing COUBPY Ligands as Potent Photosensitizers for the Efficient Phototherapy of Hypoxic Tumors

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: 147(9), P. 7360 - 7376

Published: Feb. 15, 2025

Hypoxia, a hallmark of many solid tumors, is linked to increased cancer aggressiveness, metastasis, and resistance conventional therapies, leading poor patient outcomes. This challenges the efficiency photodynamic therapy (PDT), which relies on generation cytotoxic reactive oxygen species (ROS) through irradiation photosensitizer (PS), process partially dependent levels. In this work, we introduce novel family potent PSs based ruthenium(II) polypyridyl complexes with 2,2′-bipyridyl ligands derived from COUPY coumarins, termed COUBPYs. Ru-COUBPY exhibit outstanding in vitro cytotoxicity against CT-26 cells when irradiated light within phototherapeutic window, achieving nanomolar potency both normoxic hypoxic conditions while remaining nontoxic dark, impressive phototoxic indices (>30,000). Their ability generate Type I II ROS underpins their exceptional PDT efficiency. The lead compound study, SCV49, shows favorable vivo pharmacokinetic profile, excellent toxicological tolerability, tumor growth inhibition mice bearing subcutaneous tumors at doses as low 3 mg/kg upon deep-red (660 nm). These results allow us propose SCV49 strong candidate for further preclinical development, particularly treating large tumors.

Language: Английский

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A New Benchmark Set for Excitation Energy of Charge Transfer States: Systematic Investigation of Coupled Cluster Type Methods

Journal of Chemical Theory and Computation, Journal Year: 2020, Volume and Issue: 16(7), P. 4213 - 4225

Published: June 5, 2020

The numerous existing publications on benchmarking quantum chemistry methods for excited states rarely include Charge Transfer (CT) states, although many interesting phenomena in, e.g., biochemistry and material physics involve the transfer of electrons between fragments system. Therefore, it is timely to test accuracy chemical CT as well. In this study we first propose a new benchmark set consisting dimers having low-energy states. On set, vertical excitation energy has been calculated with Coupled Cluster including triple excitations (CC3, CCSDT-3, CCSD(T)(a)*), well full or approximate doubles (CCSD, STEOM-CCSD, CC2, ADC(2), EOM-CCSD(2)). results show that popular CC2 ADC(2) are much less accurate than valence other hand, EOM-CCSD seems have similar systematic overestimation energies both types Among triples novel EOM-CCSD(T)(a)* method noniterative found stand out its consistently good performance all delivering essentially EOM-CCSDT quality results.

Language: Английский

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Charge Separation and Charge Transfer in the Low-Lying Excited States of Pentacene

The Journal of Physical Chemistry C, Journal Year: 2020, Volume and Issue: 124(45), P. 24653 - 24666

Published: Oct. 28, 2020

Pentacene thin films are common constituents of organic photovoltaic materials and a prototypical example material that undergoes singlet exciton fission, but significant questions remain regarding the mechanism. In particular, theoretical studies have reached differing conclusions role (and even presence) low-energy charge-transfer (CT) states in this material. Periodic electronic structure calculations predict CT crystalline pentacene correlated wave function on cluster models (typically dimers) generally failed to find evidence at energies relevant fission. Here, we use an ab initio model examine size-dependent trends states, ranging from dimer hexamer. We complement these results with additional using time-dependent density functional theory. Our support idea dielectric stabilization leads appearance absent models, which (in larger models) become accessible photon Optimally-tuned screened range-separated hybrid functionals, set frontier orbital nonempirical way, greater degree charge separation as compared other functionals. electron–hole correlations calculations, reveal underlying excited may go undetected by qualitative analysis tools. These help connect quantum chemistry periodic they suggest former inadequate for

Language: Английский

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