scholarly journals Luminescent polypyridyl heteroleptic CrIII complexes with high quantum yields and long excited state lifetimes

2020 ◽  
Vol 49 (39) ◽  
pp. 13528-13532
Author(s):  
Juan-Ramón Jiménez ◽  
Maxime Poncet ◽  
Benjamin Doistau ◽  
Céline Besnard ◽  
Claude Piguet
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Quantum Yields ◽  
High Quantum ◽  
Excited State Lifetimes ◽  
Chelate Rings

Heteroleptic CrIII complexes combining tridentate 6-membered chelate rings: enhancing quantum yield and excited state lifetimes.

Steric Effects in the Electronic Spectra of the 3,5-Diarylaminobenzene Derivatives

1986 ◽  
Vol 41 (11) ◽  
pp. 1311-1314 ◽  
Author(s):  
A. Balter ◽  
W. Nowak ◽  
P. Milart ◽  
J. Sepioł
Keyword(s):  
Excited State ◽  
Electronic Spectra ◽  
Fluorescence Properties ◽  
Steric Effects ◽  
Quantum Yields ◽  
Spectroscopic Behaviour ◽  
Fluorescence Quantum Yields ◽  
Excited State Lifetimes ◽  
Methyl Phenyl

Absorption and fluorescence properties, excited state lifetimes and fluorescence quantum yields were determined for a series of 3,5-diarylaminobenzene derivatives in solvents of different polarities. The role of the nitrile, methyl, phenyl and naphthyl substituents is discussed. Especially the steric effects on the spectroscopic behaviour of the investigated molecules are studied.

scholarly journals Mono- Versus Bicyclic Carbene Metal Amide Photoemitters: Which Design Leads to Best Performance?

2020 ◽  
Author(s):  
Florian Chotard ◽  
Vasily Sivchik ◽  
Mikko Linnolahti ◽  
Manfred Bochmann ◽  
Alexander Romanov
Keyword(s):  
Excited State ◽  
State Energy ◽  
Conformational Flexibility ◽  
Quantum Yields ◽  
Carbene Ligands ◽  
Lumo Energy ◽  
Excited State Energy ◽  
Excited State Lifetimes

New luminescent “carbene-metal-amide” (CMA) Cu, Ag and Au complexes based on monocyclic (C6) or bicyclic six-ring (BIC6) cyclic (alkyl)(amino)carbene ligands illustrates the effects of LUMO energy stabilization, conformational flexibility and excited state energy on the photoemission properties, leading to near-quantitative quantum yields, short excited state lifetimes Cu > Au > Ag down to 0.5 µs and high radiative rates of 10<sup>6</sup> s<sup>–1</sup>.

scholarly journals Driving high quantum yield NIR emission through proquinoidal linkage motifs in conjugated supermolecular arrays

2020 ◽  
Vol 11 (31) ◽  
pp. 8095-8104
Author(s):  
Erin J. Viere ◽  
Wei Qi ◽  
Ian N. Stanton ◽  
Peng Zhang ◽  
Michael J. Therien
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Structural Relaxation ◽  
Ground State ◽  
Building Blocks ◽  
High Quantum Yield ◽  
High Quantum ◽  
Nir Emission

Incorporation of proquinoidal BTD building blocks into conjugated porphyrin oligomers minimizes the extent of excited-state structural relaxation relative to the ground-state conformation, elucidating new classes of impressive NIR fluorophores.

Tunable RGB luminescence of a single molecule with high quantum yields through a rational design

2016 ◽  
Vol 4 (7) ◽  
pp. 1527-1532 ◽  
Author(s):  
Wen Li ◽  
Yu-Mo Zhang ◽  
Ting Zhang ◽  
Weiran Zhang ◽  
Minjie Li ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Single Molecule ◽  
Rational Design ◽  
Quantum Yields ◽  
High Quantum Yield ◽  
Fluorescent Switch ◽  
High Quantum

An organic single-molecule RGB luminescence material with a high quantum yield was realized by introducing the ESIPT and TBET mechanisms and combining an AIEE luminophore with a fluorescent switch.

scholarly journals Towards Prediction of Non-Radiative Decay Pathways in Organic Compounds I: The Case of Naphthalene Quantum Yields

2019 ◽  
Author(s):  
Alexander Kohn ◽  
Zhou Lin ◽  
Troy Van Voorhis
Keyword(s):  
Machine Learning ◽  
Excited State ◽  
Quantum Yield ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Rational Design ◽  
Radiative Decay ◽  
Quantum Yields ◽  
Equilibrium Geometry ◽  
Radiative Loss

<div>Many emerging technologies depend on human’s ability to control and manipulate the excited-state properties of molecular systems. These technologies include fluorescent</div><div>labeling in biomedical imaging, light harvesting in photovoltaics, and electroluminescence in light-emitting devices. All of these systems suffer from non-radiative loss pathways that dissipate electronic energy as heat, which causes the overall system efficiency to be directly linked to quantum yield (Φ) of the molecular excited state. Unfortunately, Φ is very difficult to predict from first principles because the description of a slow non-radiative decay mechanism requires an accurate description of long-timescale excited-state quantum dynamics. In the present study, we introduce an efficient semiempirical method of calculating the fluorescence quantum yield (Φ<sub>fl</sub>) for molecular chromophores, which, based on machine learning, converts simple electronic energies computed using time-dependent density functional theory (TDDFT) into an estimate of Φ<sub>fl</sub>. As with all machine learning strategies, the algorithm needs to be trained on fluorescent dyes for which Φ<sub>fl</sub>’s are known, so as to provide a black-box method which can later predict Φ<sub>fl</sub>’s for chemically similar chromophores that have not been studied experimentally. As a first illustration of how our proposed algorithm can be trained, we examine a family of 25 naphthalene derivatives. The simplest application of the energy gap law is found to be inadequate to explain the rates of internal conversion (IC) or intersystem crossing (ISC) – the electronic properties of at least one higher-lying electronic state (S<i><sub>n</sub></i> or T<i><sub>n</sub></i>) or one far-from-equilibrium geometry are typically needed to obtain accurate results. Indeed, the key descriptors turn out to be the transition state between the Franck–Condon minimum a distorted local minimum near an S<sub>0</sub>/S<sub>1</sub> conical intersection (which governs IC) and the magnitude of the spin–orbit coupling (which governs ISC). The resulting Φ<sub>fl</sub>’s are predicted with reasonable accuracy (±22%), making our approach a promising ingredient for high-throughput screening and rational design of the molecular excited states with desired Φ’s. We thus conclude that our model, while semi-empirical in nature, does in fact extract sound physical insight into the challenge of describing non-radiative relaxations.</div>

Photolysis of hydrogen peroxide, photocatalytic effects of Cu(II) and reaction kinetics

1986 ◽  
Vol 51 (5) ◽  
pp. 973-981 ◽  
Author(s):  
Stanislav Luňák ◽  
Petr Sedlák ◽  
Josef Vepřek-Šiška
Keyword(s):  
Hydrogen Peroxide ◽  
Thermal Decomposition ◽  
Quantum Yield ◽  
Reaction Kinetics ◽  
Copper Ions ◽  
Oxidation States ◽  
Radiation Temperature ◽  
Quantum Yields ◽  
High Quantum ◽  
Catalytically Active

The quantum yield of hydrogen peroxide photolysis has been measured as a function of the concentration of photocatalytically active Cu2+ ions, intensity of photolytic radiation, temperature, and hydrogen peroxide concentration. The results obtained are consistent with the concept that high quantum yields of hydrogen peroxide photolysis (Φ >> 1) are due to thermal decomposition of hydrogen peroxide catalyzed by photochemically generated copper ions in oxidation states which are catalytically active.

The dual pathway in photocycloaddition of 1,3-diketonatoboron difluorides: excimer reactions

1991 ◽  
Vol 69 (10) ◽  
pp. 1575-1583 ◽  
Author(s):  
Yuan L. Chow ◽  
Xianen Cheng
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Model Compound ◽  
Singlet State ◽  
Quantum Yields ◽  
Singlet Excited State ◽  
Dibenzoylmethanatoboron Difluoride ◽  
Dual Pathway ◽  
Excimer Formation ◽  
Simple Olefin

The lowest singlet excited state of dibenzoylmethanatoboron difluoride DBMBF2, a model compound of the BF2 complexes of 1,3-diketones, reacted with various simple olefins to give regiospecific and stereospecific photocycloadducts of 1,5-diketones similar to those from the de Mayo type reaction. DBMBF2 in acetonitrile exhibited two discrete fluorescences at 398 and 416 nm for the monomer and at 522 nm for the excimer; they were both quenched, but in different proportions, by a simple olefin. An "oxygen test" showed that the excimer of DBMBF2 is formed irreversibly in acetonitrile. The quantum yields of the photocycloaddition were shown to be proportional not only to olefin concentrations but also to DBMBF2 concentrations. Kinetic analysis has established that the total quantum yield is the sum of those arising from the interactions of the singlet excited DBMBF2 and its excimer, respectively, with an olefin, i.e., the sum of the quantum yields of exciplex and triplex pathways. The contributions from the two pathways are determined by the type of olefins and the range of DBMBF2 concentrations. For endocyclic olefins, the triplex pathway is more important and the corresponding photocycloaddition becomes very efficient as soon as the excimer starts to form in [DBMBF2] > 0.001 M. For the monosubstituted olefins, on the contrary, the exciplex pathway is always more important than the triplex pathway; they react primarily from the singlet excited state of DBMBF2. Key words: singlet state photocycloaddition, irreversible excimer formation, excimer cycloaddition, triplex and exciplex reactions.

scholarly journals A Highly Fluorescent Dinuclear Aluminium Complex with Near-Unity Quantum Yield

2021 ◽  
Author(s):  
Flavio Luis Portwich ◽  
Yves Carstensen ◽  
Anindita Dasgupta ◽  
Stephan Kupfer ◽  
Ralf Wyrwa ◽  
...  
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Quantum Yields ◽  
Photoluminescence Properties ◽  
Excited State Lifetime ◽  
One Pot ◽  
Nonwoven Fabrics ◽  
Enhanced Photoluminescence ◽  
Photoluminescence Quantum Yield ◽  
Optical Applications

The high natural abundance of aluminium makes the respective fluorophores attractive for various optical applications, but photoluminescence quantum yields above 0.7 have yet not been reported for solutions of aluminium complexes. In this contribution, a dinuclear aluminium(III) complex featuring enhanced photoluminescence properties is described. Its facile one-pot synthesis originates from a readily available precursor and trimethyl aluminium. In solution, the complex exhibits an unprecedented photoluminescence quantum yield near unity (Φabsolute 1.0 ± 0.1) and an excited-state lifetime of 2.3 ns. In the solid state, J-aggregation and aggregation-caused quenching are noticed, but still quantum yields of 0.6 are observed. Embedding the complex in electrospun nonwoven fabrics yields a highly fluorescent fleece possessing a quantum yield of 0.9 ± 0.04.

Synthesis, photophysicochemical studies of adjacently tetrasubstituted binaphthalo-phthalocyanines

2005 ◽  
Vol 09 (05) ◽  
pp. 316-325 ◽  
Author(s):  
Itumeleng Seotsanyana-Mokhosi ◽  
Ji-Yao Chen ◽  
Tebello Nyokong
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Zinc Phthalocyanine ◽  
Quantum Yields ◽  
Triplet Excited State ◽  
General Increase ◽  
Photochemical Behavior

Adjacent binaphthalo-phthalocyanines tetra-substituted with phenoxy (4a), 4-carboxyphenoxy (4b) and 4-t-butylphenoxy (4c) groups, as well as the di-substituted 4-carboxyphenoxy (5b) have been synthesized and characterized. The photophysical and photochemical behavior of 4a-c, were compared with those of the corresponding di-substituted derivatives, (5a-c). The secondary substituents on the phenoxy ring have an influence on the aggregation of the molecules and hence on their photophysical properties. All of the complexes exhibit a relatively good conversion of energy from the triplet-excited state to the singlet oxygen. The less aggregated molecule (4c), has the highest singlet oxygen quantum yield. For all the molecules, fluorescence yields are low and they all have relatively shorter triplet lifetimes compared with the unsubstituted zinc phthalocyanine. Increasing the number of ring substituents on these rigid MPc complexes (from complexes 5 to 4) showed a general increase in the triplet state lifetimes and singlet oxygen quantum yields, and a decrease in stability.

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