Prediction of Excitation Energies for Conjugated Oligomers and Polymers from Time-Dependent Density Functional Theory

Tao, Jianmin; Tretiak, Sergei; Zhu, Jian‐Xin

doi:10.3390/ma3053430

Cited by 3 publications

(3 citation statements)

References 142 publications

(200 reference statements)

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“…High oscillator strength (>1) of these transitions is typical for 1 π,π* transitions in molecules with extensive π-conjugation. 57,58 Similar to those observed in 1 and 2, complexes 3 and 4 also possess broad weak tails above 450 nm, which are attributed to the 1,3 LLCT/ 1,3 MLCT transitions (see the NTOs for the first excited states of 3 and 4 in Table 2).…”

Section: ■ Results and Discussionsupporting

confidence: 62%

“…For complexes 3 and 4 , the strongest absorption bands around 320 and 360 nm predominantly arise from the substituted phenylpyridine (C ∧ N) ligand-based 1 π,π* transitions with some contributions from the 1 ML′CT transition (dπ(Ir)→π*(C ∧ N)), as can be seen from the NTOs of the 19th/21st states of 3 and 7th/8th states of 4 presented in Table . High oscillator strength (>1) of these transitions is typical for 1 π,π* transitions in molecules with extensive π-conjugation. , Similar to those observed in 1 and 2 , complexes 3 and 4 also possess broad weak tails above 450 nm, which are attributed to the 1,3 LLCT/ 1,3 MLCT transitions (see the NTOs for the first excited states of 3 and 4 in Table ).…”

Section: Resultsmentioning

confidence: 62%

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Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

et al. 2014

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Five new iridium(III) complexes (3,8-R-Phen)Ir(2-(3-R′-phenyl)pyridine) 2 (1, R = fluoren-2-yl, R′ = H; 2, R = 7-benzothiazolylfluoren-2-yl, R′ = H; 3, R = H, R′ = fluoren-2-yl; 4, R = H, R′ = 7-benzothiazolylfluoren-2-yl; 5, R = R′ = 7-benzothiazolylfluoren-2-yl) with fluoren-2-yl or 7-benzothiazolylfluoren-2yl substituent on the 2-phenylpyridine (C ∧ N) and/or phenanthroline (N ∧ N) ligands were synthesized and characterized. Their photophysical properties were investigated systematically via UV−vis absorption, emission, and transient difference absorption spectroscopy. Time-dependent density functional theory (TDDFT) calculations were performed to complement the experimental data and aid in our understanding of the characters of optical transitions. In addition, reverse saturable absorption was demonstrated at 532 nm for all complexes using nanosecond laser pulses. All complexes possess a weak low-energy tail that is attributed to 1,3 MLCT (metal-to-ligand charge transfer)/ 1,3 LLCT (ligand-toligand charge transfer) transitions. The major absorption bands below 475 nm for 1−5 arise from the 1 π,π* and intraligand ( 1 ILCT) transitions within the N ∧ N or C ∧ N ligands. Attachment of fluoren-2-yl or 7benzothiazolylfluoren-2-yl substituents on N ∧ N ligand results in stronger red-shifts of the main absorption band to 400 and 408 nm for 1 and 2, respectively, as compared to 321 and 361 nm in complexes 3 and 4 with the same substituents on the C ∧ N ligands. In contrast, the 1,3 MLCT/ 1,3 LLCT transitions in 1 and 2 are just slightly red-shifted as compared to those in 3 and 4. The emission of complexes 1 and 2 is attributed to the N ∧ N ligand-centered 3 π,π* state with some admixture of 3 MLCT/ 3 ILCT/ 3 LLCT characters for 1. In contrast, the emission of 3 and 4 emanates exclusively from the 3 MLCT/ 3 LLCT states. For complex 5, which contains 7-benzothiazolylfluoren-2-yl substituents on both the C ∧ N and the N ∧ N ligands, the emission predominantly arises from the 3 MLCT/ 3 LLCT states with a small portion of N ∧ N ligand-localized 3 π,π* character. All complexes exhibit broadband triplet excited-state absorption in the visible to the near-IR region, with the major absorption bands bathochromically shifted in 1 and 2 as compared to those in 3 and 4. The stronger excited-state absorption leads to dramatic reverse saturable absorption (RSA) at 532 nm for nanosecond laser pulses. The RSA strength decreases as 5 ≈ 2 > 4 ≈ 1 > 3, which is primarily determined by the ratio of the triplet excited-state absorption cross section relative to that of the ground state. Extended π-conjugation in the N ∧ N ligand obviously increases the RSA of complexes 1, 2, and 5 in comparison to those with πconjugated substituents only on the C ∧ N ligands (3 and 4).

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Section: ■ Results and Discussionsupporting

confidence: 62%

Section: Resultsmentioning

confidence: 62%

Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

et al. 2014

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“…One particular application of single molecule methods in liquid crystals is the investigation of the physical properties of conjugated polymers. Due to their high fluorescence and low cost, conjugated polymers are competing materials for the use as light emitting devices [ 58 ]. Since their fluorescence properties are closely related to conformations, liquid crystals were used as a host to study the interdependence of physical properties on conformations.…”

Section: Conjugated Polymers In Liquid Crystal Matricesmentioning

confidence: 99%

Single Molecule Studies on Dynamics in Liquid Crystals

Täuber

Borczyskowski

2013

IJMS

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Single molecule (SM) methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC). Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.

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Theoretical insight on model linear oligomers and their ring-fused analogs used in organic electronics

Cagardová

Matúška²,

Michalík³

et al. 2022

Materials Today Communications

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Prediction of Excitation Energies for Conjugated Oligomers and Polymers from Time-Dependent Density Functional Theory

Cited by 3 publications

References 142 publications

Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Single Molecule Studies on Dynamics in Liquid Crystals

Theoretical insight on model linear oligomers and their ring-fused analogs used in organic electronics

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Prediction of Excitation Energies for Conjugated Oligomers and Polymers from Time-Dependent Density Functional Theory

Cited by 3 publications

References 142 publications

Effects of Extended π-Conjugation in Phenanthroline (N∧N) and Phenylpyridine (C∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Effects of Extended π-Conjugation in Phenanthroline (N∧N) and Phenylpyridine (C∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Single Molecule Studies on Dynamics in Liquid Crystals

Theoretical insight on model linear oligomers and their ring-fused analogs used in organic electronics

Contact Info

Product

Resources

About

Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Effects of Extended π-Conjugation in Phenanthroline (N^∧N) and Phenylpyridine (C^∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes