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Journal articles on the topic 'Fluorescence quantum yields'

Author: Grafiati

Published: 24 April 2022

Last updated: 18 July 2025

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1

Ralston, Corie Y., Xu Wu, and Oliver C. Mullins. "Quantum Yields of Crude Oils." Applied Spectroscopy 50, no. 12 (1996): 1563–68. http://dx.doi.org/10.1366/0003702963904601.

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Fluorescence quantum yield measurements are reported for visible and UV excitation for neat and dilute crude oil solutions, extending earlier work with excitation in the long wavelength visible and the NIR. Large and monotonically increasing quantum yields are found with shorter wavelength excitation (to 325 nm), and all crude oils are shown to have nearly the same relative dependence of quantum yield on excitation wavelength. These observations are explained by the energy dependence of internal conversion. Dilute solutions of light crude oils exhibit higher quantum yields than those of heavy crude oils because of their lack of large chromophores. The fraction of fluorescence emission resulting from electronic energy transfer (with subsequent fluorescence emission) for neat crude oils was previously shown to vary from ∼100% for ultraviolet excitation to ∼0% for near-infrared excitation; this large variation correlates well with and is explained by the very large variation in quantum yields with excitation wavelength. Comparison of quantum yields from neat and dilute solutions shows that quenching is the other major process which occurs with chromophore interactions. The quantum yields of a maltene and resin are large and similar, while the asphaltene exhibits much smaller quantum yields because of its lack of small chromophores.

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2

Sen, Pinar, Nnamdi Nwahara, and Tebello Nyokong. "Photodynamic antimicrobial activity of benzimidazole substituted phthalocyanine when conjugated to Nitrogen Doped Graphene Quantum Dots against Staphylococcus aureus." Main Group Chemistry 20, no. 2 (2021): 175–91. http://dx.doi.org/10.3233/mgc-210030.

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In this study, peripherally benzimidazole unit substituted ZnPc (1) and its conjugation to nitrogen doped graphene quantum dot (NGQD) as potential phthalocyanine support via π-π stacking have been presented and fully characterized. The bottom-up solution-based synthesized NGQDs was conjugated non-covalently to zinc phthalocyanine to form NGQDs-Pc nanoconjugates. The photophysical and photochemical properties of both such as absorption, fluorescence, fluorescence life time, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yield and singlet oxygen quantum yield of the nanoconjugates in comparison to the phthalocyanine complex alone. Photodynamic antimicrobial chemotherapy activities (PACT) of ZnPc alone and its nanoconjugate were determined towards Staphylococcus aureus.

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3

Hurtubise, R. J., and S. M. Ramasamy. "Comparison of Fluorescence-to-Phosphorescence Quantum Yield Ratios in Solid-Matrix Luminescence as a Function of Temperature." Applied Spectroscopy 47, no. 3 (1993): 283–86. http://dx.doi.org/10.1366/0003702934066587.

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An equation that relates the ratio of fluorescence to phosphorescence quantum yields as function of temperature to basic photophysical parameters is considered. The quantum yields were obtained from three compounds on three different solid matrices. Fluorescence quantum yields did not change much with temperature, while phosphorescence quantum yields changed more substantially with temperature. For some of the systems considered, it was possible to show that, as the temperature was lowered, the quantum yield ratio was only a function of the phosphorescence lifetime of the phosphor. However, with other systems, the quantum yield ratio was dependent on both the rate constant of intersystem crossing from the singlet state to the triplet state and the phosphorescence lifetime. The equation discussed is important in defining the fundamental parameters that cause the luminescence quantum yield ratio to change as temperature is lowered.

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4

OWENS, JOHN W., and MARSHA ROBINS. "Phthalocyanine photophysics and photosensitizer efficiency on human embryonic lung fibroblasts." Journal of Porphyrins and Phthalocyanines 05, no. 05 (2001): 460–64. http://dx.doi.org/10.1002/jpp.340.

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This study correlates the photophysical properties of aluminum phthalocyanine tetrasulfonate (AlPcTs), zinc phthalocyanine tetrasulfonate (ZnPcTs), and phthalocyanine tetrasulfonate (PcTs) with their ability to kill human embryonic lung (HEL) cells. Photofrin, a proven anti-cancer drug, was used for comparison. The photophysical properties include fluorescence emission spectra, fluorescence quantum yields, singlet state and radiative lifetimes, quantum yield for triplet formation, and fluorescence rate constants. Results indicate that photodynamic efficacy correlates inversely with fluorescence quantum yield and fluorescence lifetime and directly with quantum yield for triplet formation.

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5

Hale, S. J., and L. A. Melton. "Absolute Quantum Yields for Exciplex Fluorescence." Applied Spectroscopy 44, no. 1 (1990): 101–5. http://dx.doi.org/10.1366/0003702904085895.

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The absolute quantum yields for exciplex fluorescence in four solutions which have potential as exciplex-based vapor/liquid visualization systems have been measured. The room-temperature absolute quantum yields for 10% dibutyl-aniline/0.4%, 1-cyanonaphthalene, 12.5% 1-methyl-naphthalene/0.5% N,N,N′,N′-tetramethyl- p-phenylenediamine (TMPD), 10% trihexylamine/1.0% 1-cyanonaphthalene, and 10% naphthalene/1.0% TMPD in hexadecane or cyclohexane are 0.03 ± 0.005, 0.05 ± 0.002 (308 nm), 0.02 ± 0.001, and 0.16 ± 0.021, respectively. The temperature dependence of the absolute quantum yield for the 10% naphthalene/1% TMPD in the hexadecane system was measured over the range of 23 to 260°C and was found to decrease by 20–30% at 260°C.

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6

Swarts, Jannie C., and M. David Maree. "The observation of room temperature delayed fluorescence in various non-peripherally substituted phthalocyanines." Journal of Porphyrins and Phthalocyanines 11, no. 08 (2007): 613–17. http://dx.doi.org/10.1142/s1088424607000710.

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The first observation of direct room temperature delayed fluorescence from non-peripherally substituted phthalocyanines is reported. The quantum yields of delayed fluorescence and delayed fluorescence lifetimes were determined and are discussed. The normal fluorescence quantum yields and photodegradative quantum yields of these compounds were also determined.

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7

Zhang, Xian-Fu, and Xiaojie Sun. "Germanium triazatetrabenzcorrole and germanium phthalocyanine: Synthesis, fluorescence and singlet oxygen generation." Journal of Porphyrins and Phthalocyanines 22, no. 09n10 (2018): 847–52. http://dx.doi.org/10.1142/s1088424618500670.

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The synthesis, fluorescence properties and singlet oxygen generation capability of germanium tetrabenzotriazacorrole (LGeTBC), germanium phthalocyanine (Cl[Formula: see text]GePc) and their derivatives are described. Measurements include UV-vis absorption spectra, fluorescence emission spectra, fluorescence quantum yields fluorescence lifetimes, and singlet delta oxygen quantum yields. LGeTBC and its derivatives exhibit quite different spectral and fluorescence properties from their phthalocyanine precursor. Both LGeTBC and Cl[Formula: see text]GePc show high singlet delta oxygen quantum yields and suitable fluorescence quantum yields, indicating that they can act as good singlet oxygen photosensitizers for photodynamic therapy.

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8

Downare, Taggart D., and Oliver C. Mullins. "Visible and Near-Infrared Fluorescence of Crude Oils." Applied Spectroscopy 49, no. 6 (1995): 754–64. http://dx.doi.org/10.1366/0003702953964462.

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Fluorescence emission spectra and absolute quantum yields have been measured for ten diverse crude oils at various concentrations over a broad range of excitation and emission wavelengths in the visible and the near-infrared. Energy transfer produces large red shifts and large widths in the fluorescence emission spectra for shorter wavelength excitation particularly for heavier crude oils. However, the effects of energy transfer are nearly absent for near-infrared excitation; all crude oils exhibit nearly the same emission spectra for long wavelength excitation. In addition, the fraction of emission resulting from collisional energy transfer relative to nascent emission is almost independent of oil type; it is governed by quantum yield characteristics. Absolute fluorescence quantum yields of ten crude oils (and three rhodamine dyes for validation) were measured with respect to scattering of latex microspheres in distilled water. Fluorescence quantum yields vary systematically with crude oil type as well as excitation wavelength; quantum yields are lower for high fluorophore concentrations (heavy crude oils) and for longer wavelength excitation. Stern-Volmer analyses of the quantum yields indicate that simple models apply and show the relative quenching rates for different excitation wavelengths.

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9

Tayfuroğlu, Ömer, Fatma Aytan Kılıçarslan, Göknur Yasa Atmaca, and Ali Erdoğmuş. "Synthesis, characterization of new phthalocyanines and investigation of photophysical, photochemical properties and theoretical studies." Journal of Porphyrins and Phthalocyanines 22, no. 01n03 (2018): 250–65. http://dx.doi.org/10.1142/s1088424618500281.

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This work describes the synthesis, spectral, aggregation and fluorescence properties of bis 4-[(4-tert-butylbenzyl)oxy substituted metal free (2), magnesium (3), zinc (4) and nickel (5) phthalocyanines. The syntheses of the novel compounds were confirmed by FT-IR, UV-vis, mass and NMR spectroscopy techniques, as well as elemental analysis. The effects of the nature of the central metal on the photophysical parameters of the phthalocyanine complexes are reported in this study. The photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence behavior and fluorescence quantum yield) of the complexes were reported in different solutions (dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) and tetrahydrofuran (THF)). However, energy minimized structure, vibrational frequency, molecular orbital levels and electronic absorption spectra were obtained by DFT calculations which supported the experimental results.

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10

Starukhin, A. S., V. V. Kouhar, and V. S. Shershan. "Dependence of the values of fluorescence quantum yields for porphyrins and phthalocyanines from the effects of reabsorption." Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ 88, no. 6 (2024): 935–40. https://doi.org/10.31857/s0367676524060143.

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The values of fluorescence quantum yield upon using by the procedures of relative and of absolute quantum yields were measured for a set of porphyrins and phthalocyanines with different activities of bands in the absorption spectrum. The correlations between of the values quantum yields and optical densities at the absorption bands of the samples has been estimated that provides an opportunity to estimate the nature of the internal filter effects.

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11

Hott, J. L., and R. F. Borkman. "The non-fluorescence of 4-fluorotryptophan." Biochemical Journal 264, no. 1 (1989): 297–99. http://dx.doi.org/10.1042/bj2640297.

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The derivative 4-fluorotryptophan was confirmed to have negligible fluorescence at 25 degrees C and 285 nm (tryptophan/4-fluorotryptophan quantum-yield ratio greater than 100:1). However, photolysis experiments on tryptophan and 4-fluorotryptophan, in which loss of starting material was measured by reverse-phase h.p.l.c., demonstrated that 4-fluorotryptophan was significantly more photochemically active than the parent tryptophan, with the 4-fluorotryptophan photolysis quantum yield being 7 times larger than that of tryptophan at 25 degrees C and 285 nm. In addition, at 77 K and 275 nm 4-fluorotryptophan displayed strong fluorescence and phosphorescence, with emission quantum yields comparable with those of tryptophan at 77 K and 275 nm.

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12

Itoh, Takao, Bryan E. Kohler та Charles W. Spangler. "Fluorescence quantum yields of α, ω-diphenylpolyenes". Spectrochimica Acta Part A: Molecular Spectroscopy 50, № 13 (1994): 2261–63. http://dx.doi.org/10.1016/0584-8539(94)e0007-w.

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13

Hurtubise, R. J., and S. M. Ramasamy. "Comparison of Solution and Solid-Matrix Luminescence Parameters." Applied Spectroscopy 47, no. 1 (1993): 116–22. http://dx.doi.org/10.1366/0003702934048433.

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A relatively large number of comparisons have been made between solution luminescence and solid-matrix luminescence parameters for several lumiphors adsorbed on a number of solid matrices. Comparisons have been made for both room-temperature and low-temperature fluorescence and phosphorescence quantum yields, fluorescence and phosphorescence lifetimes, and a variety of photophysical rate constants. The comparisons reveal that solid-matrix luminescence can give greater fluorescence and phosphorescence quantum yields in many cases at room temperature, compared to the corresponding solution quantum yields at low temperature. The comparisons of fluorescence and phosphorescence lifetimes and the photophysical rate constants for the lumiphors adsorbed on solid matrices and in solutions reveal new insights into the differences between solid-matrix luminescence and solution luminescence.

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14

Novakova, Veronika, Eva H. Mørkved, Miroslav Miletin, and Petr Zimcik. "Influence of protonation of peripheral substituents on photophysical and photochemical properties of tetrapyrazinoporphyrazines." Journal of Porphyrins and Phthalocyanines 14, no. 07 (2010): 582–91. http://dx.doi.org/10.1142/s1088424610002458.

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Octasubstituted zinc tetrapyrazinoporphyrazines with four N,N-dimethylaminophenyls and four phenyl or pyridin-3-yl substituents were synthesized and fully characterized. Their fluorescence quantum yields in DMF or pyridine were very low, almost undetectable, as a consequence of ultrafast intramolecular charge transfer. Titration of their DMF solutions with sulfuric acid led to increase of the fluorescence quantum yields by two orders of magnitude when the full protonation of peripheral substituents was achieved. Intramolecular charge transfer is no longer a favorable way of excited-state relaxation at full protonation of N,N-dimethylaminophenyl substituents because of loss of donor centers (free electron pair on its nitrogen). Similarly, singlet oxygen quantum yields also increased by two orders of magnitude when sulfuric acid was added to tetrapyrazinoporphyrazine solutions in DMF. Protonation at azomethine nitrogens of tetrapyrazinoporphyrazine macrocycle was observed at higher acid concentrations and it led to considerable decrease of fluorescence quantum yields. Octaphenyl zinc tetrapyrazinoporphyrazine and octa(pyridin-3-yl) zinc tetrapyrazinoporphyrazine were used as controls without intramolecular charge transfer. Their fluorescence and singlet oxygen quantum yields were high in DMF and decreased at higher concentrations of sulfuric acid due to protonation of azomethine nitrogens. The results suggest that the photophysical and photochemical properties of studied compounds may be controlled by changes of pH of medium.

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15

Silva, Gustavo T. M., Cassio P. Silva, Karen M. Silva, et al. "Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins." Photochem 2, no. 2 (2022): 423–34. http://dx.doi.org/10.3390/photochem2020029.

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Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.

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16

Bhunia, Asamanjoy, Dolores Esquivel, Subarna Dey, et al. "A photoluminescent covalent triazine framework: CO2 adsorption, light-driven hydrogen evolution and sensing of nitroaromatics." Journal of Materials Chemistry A 4, no. 35 (2016): 13450–57. http://dx.doi.org/10.1039/c6ta04623a.

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17

Zhang, Min, Zhi-Quan Tian, Dong-Liang Zhu, et al. "Stable CsPbBr3 perovskite quantum dots with high fluorescence quantum yields." New Journal of Chemistry 42, no. 12 (2018): 9496–500. http://dx.doi.org/10.1039/c8nj01191e.

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18

Kanematsu, Yusuke, Akiyoshi Ohta, Shunya Nagai, et al. "A Practical Application of Machine Learning for the Development of Metallole-Based Fluorescent Materials." Molecules 30, no. 8 (2025): 1686. https://doi.org/10.3390/molecules30081686.

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We have built a prediction model of the fluorescence quantum yields of metalloles. Based on the suggestion by the prediction model, we synthesized 10 fluorescent molecules to confirm the prediction accuracy. By measuring the fluorescence quantum yields of the synthesized molecules, it was demonstrated that our prediction model reasonably classified the quantum yields with an accuracy of 0.7. In particular, the low quantum yields were perfectly predicted for the synthesized molecules, demonstrating the usefulness of our prediction model to screen out weakly fluorescent molecules from the candidates. On the other hand, the low precision of 0.5 was attributed to the bias in the training dataset containing many fluorine-containing molecules with high quantum yields. Our prediction model was then revised with the generator of candidate molecular structures for more efficient development of fluorescent materials with taking the applicability domain into account, and the improvement of the applicability was confirmed owing to the increment of the dataset.

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19

Багров, И. В., А. В. Дадеко, В. М. Киселев, Т. Д. Муравьева та А. М. Стародубцев. "Сравнительные исследования фотофизических свойств димегина, фотодитазина и радахлорина". Журнал технической физики 126, № 2 (2019): 162. http://dx.doi.org/10.21883/os.2019.02.47198.259-18.

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AbstractThe photophysical properties of three photosensitizers—dimegine, photoditazine, and radachlorin—have been comparatively examined. For dimegine and photoditazine, two techniques have been used to measure the singlet oxygen generation quantum yields and the quenching constants of singlet oxygen by dimegine and photoditazine, as well as the dimegine fluorescence quantum yield.

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20

Gümrükçü, Gülşah, Gülnur Keser Karaoğlan, Ali Erdoğmuş, Ahmet Gül, and Ulvi Avcıata. "Photophysical, Photochemical, and BQ Quenching Properties of Zinc Phthalocyanines with Fused or Interrupted Extended Conjugation." Journal of Chemistry 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/435834.

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The effects of substituents and solvents on the photophysical and photochemical parameters of zinc(II) phthalocyanines containing four Schiff’s base substituents attached directly and through phenyleneoxy-bridges on peripheral positions are reported. The group effects on peripheral position and the continual and intermittent conjugation of the phthalocyanine molecules on the photophysical and photochemical properties are also investigated. General trends are described for photodegradation, singlet oxygen, and fluorescence quantum yields of these compounds in dimethylsulfoxide (DMSO), dimethylformamide (DMF), and tetrahydrofurane (THF). Among the different substituents, phthalocyanines with cinnamaldimine moieties (1cand2c) have the highest singlet oxygen quantum yields (ΦΔ) and those with nitro groups (1aand2a) have the highest fluorescence quantum yields in all the solvents used. The fluorescence of the substituted zinc(II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ) in these solvents.

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21

Xu, Zihao, Wenwen Ma, Yuchen Song, et al. "Methylsteric Effects Enhance Fluorescence in Diphenylfumaronitrile AIEgens." Molecules 30, no. 14 (2025): 2898. https://doi.org/10.3390/molecules30142898.

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The development of fluorophores with high-fluorescence quantum yields is highly desirable. To regulate photophysical properties, previous fumaronitrile-core fluorophore designs primarily employed electron-donating structure modifications and π-conjugation extension strategies. Here, we report a novel strategy to enhance the fluorescence performance of fluorophores by introducing methyl groups into fumaronitrile phenyl rings. The introduction of methyl groups reduces the ability to generate reactive oxygen species while enhancing the fluorescence quantum yield. Notably, after encapsulating DSPE-PEG2000 to form nanoparticles, TFN-Me nanoparticles exhibited superior fluorescence performance than previously reported fluorophores and successfully applied in in vivo tumor fluorescence imaging. This study indicates that the methyl introduction strategy holds the potential to become a powerful tool for developing high-brightness fluorophores with fumaronitrile structure.

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22

Lagorio, María Gabriela. "Determination of Fluorescence Quantum Yields in Scattering Media." Methods and Applications in Fluorescence 8, no. 4 (2020): 043001. http://dx.doi.org/10.1088/2050-6120/aba69c.

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23

Brune, Daniel C., Robert E. Blankenship, and Gilbert R. Seely. "FLUORESCENCE QUANTUM YIELDS AND LIFETIMES FOR BACTERIOCHLOROPHYLL c." Photochemistry and Photobiology 47, no. 5 (1988): 759–63. http://dx.doi.org/10.1111/j.1751-1097.1988.tb02776.x.

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24

Behrenfeld, M. J., T. K. Westberry, E. S. Boss, et al. "Satellite-detected fluorescence reveals global physiology of ocean phytoplankton." Biogeosciences 6, no. 5 (2009): 779–94. http://dx.doi.org/10.5194/bg-6-779-2009.

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Abstract. Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.

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25

Bakalova, Sn, L. Biczók, I. Kavrakova, and T. Bérces. "Photophysical and Photochemical Properties of 2,3-Dihydro-4(l H)-quinolinones. Part I. Fluorescence Properties." Zeitschrift für Naturforschung C 45, no. 9-10 (1990): 980–86. http://dx.doi.org/10.1515/znc-1990-9-1009.

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Abstract Absorption spectra and fluorescence properties of 2,3-dihydro-4(1 H)-quinolinone derivatives were studied at room temperature in different solvents. It has been found that the fluorescence quantum yields and fluorescence decay times strongly depend on the molecular structure and solvent polarity. The character and the energy of excited states were determined by PPP and CNDO/S quantum-chemical calculations.

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26

Chaari, Mahdi, Zsolt Kelemen, José Giner Planas, et al. "Photoluminescence in m-carborane–anthracene triads: a combined experimental and computational study." Journal of Materials Chemistry C 6, no. 42 (2018): 11336–47. http://dx.doi.org/10.1039/c8tc03741h.

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m-Carborane has demonstrated to be a perfect platform to boost the fluorescence properties of anthracene, giving rise to high fluorescence quantum yields in solution and also retaining fluorescence emission in the aggregate state.

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27

Tunç, Gülenay, Mohamad Albakour, Vefa Ahsen, and Ayşe Gül Gürek. "Peripherally carboxylic acid substituted asymmetric zinc(II) phthalocyanines: Synthesis and photophysicochemical properties." Journal of Porphyrins and Phthalocyanines 23, no. 11n12 (2019): 1355–64. http://dx.doi.org/10.1142/s1088424619501402.

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Four asymmetric Zn(II) phthalocyanines (Pc1–Pc4) bearing a carboxylic acid group in the peripheral position have been designed and synthesized to investigate the influence of the distance between COOH group and the phthalocyanine core on their photophysical and photochemical properties. The novel phthalocyanine complexes were characterized by [Formula: see text]H, [Formula: see text]C NMR, IR, and UV-vis spectroscopies, elemental analysis and matrix-assisted laser desorption ionization mass spectrometry (MALDI). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields and singlet oxygen quantum yields of Pc1–Pc4 were explored in tetrahydrofuran (THF) to the determination of the potential use of these novel phthalocyanines as photosensitizers for different applications such as photovoltaic technologies and photodynamic therapy (PDT). Pc1–Pc4exhibited high singlet oxygen generation quantum yields (0.84, 0.66, 0.88 and 0.65, respectively). Fluorescence quantum yields could be obtained for Pc1, Pc2, Pc3 and Pc4 (0.13, 0.31, 0.10 and 0.25, respectively) in THF.

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28

Старухин, А. С., А. А. Романенко, А. Ю. Ильин та ін. "Влияние центрального иона металла на люминесцентные и фотофизические параметры фталоцианинов". Оптика и спектроскопия 131, № 4 (2023): 518. http://dx.doi.org/10.21883/os.2023.04.55557.79-22.

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Based on the data on the spectral and photophysical parameters of the metal complexes of tetraazaporphyrins and phthalocyanines, the effect of the central metal ion on the manifestation of spin-orbit interaction is considered. For complexes of phthalocyanines with Mg(II), Zn(II), Pd(II), and Pt(II) ions, the absorption spectra, luminescence spectra, and luminescence excitation spectra were measured, and the lifetimes and quantum yields of luminescence were determined. It was shown that metal phthalocyanines with Mg(II) and Zn(II) ions, as well as Mg-tetaraazaporphyrin, exhibit intense fluorescence with high quantum yields. For single molecules of Mg-tetaraazaporphyrin in a polymer film at T=6 K, the fluorescence excitation spectra consisting both exclusively of zero-phonon lines and containing phonon wings were measured. A wide distribution of the measured zero-phonon line widths was observed. It is demonstrated, that the introduction of Pd(II) and Pt(II) ions into the center of phthalocyanine macrocycles leads to a decrease in fluorescence and the appearance of intense phosphorescence even at room temperature. Based on measurements of quantum yields of photosensitized generation of singlet molecular oxygen, the quantum yield of interconversion into triplet states for the compounds under study was defined. Deactivation of the lower triplet state of phthalocyanines with Pd(II) and Pt(II) ions indicates the influence of the internal heavy atom effect on the rate of triplet state deactivation at room temperature and at 77 K.

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29

Scholz, Marek, Roman Dĕdic, Miriam Miguel, Rodolfo Lavilla, and Santi Nonell. "Thiazolyl-substituted porphyrins as standards for singlet molecular oxygen photosensitization." Journal of Porphyrins and Phthalocyanines 15, no. 11n12 (2011): 1202–8. http://dx.doi.org/10.1142/s1088424611004129.

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Thiazolyl- and bithiazolyl-substituted porphyrins have been characterized to assess their potential as new standards for singlet molecular oxygen photosensitization. Their absorption, fluorescence, phosphorescence and triplet–triplet spectra are slightly red-shifted relative to those of tetraphenylporphine (TPP), a well-established singlet molecular oxygen standard. Likewise, the singlet and triplet lifetimes, as well as the fluorescence quantum yields are roughly one order of magnitude smaller than those of TPP, while the triplet and singlet oxygen quantum yields increase concomitantly to ca. 1.

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30

Albakour, Mohamad, Gülenay Tunç, Büşra Akyol, et al. "Synthesis, characterization, photophysicochemical properties and theoretical study of novel zinc phthalocyanine containing four tetrathia macrocycles." Journal of Porphyrins and Phthalocyanines 22, no. 01n03 (2018): 77–87. http://dx.doi.org/10.1142/s1088424618500086.

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In this work, Zn(II) phthalocyanine derivative (TTU-Pc) bearing 13-membered tetrathia macrocycles was synthesized, and the novel Zn(II) phthalocyanine derivative was fully characterized by elemental analysis and general spectroscopic methods such as MALDI-TOF mass, FT-IR, UV-vis and [Formula: see text]H-NMR. The synthesized phthalocyanine derivative has quite limited solubility in most of the common organic solvents. Fluorescence measurement was conducted for this Zn(II)phthalocyanine to estimate its fluorescence quantum yields. The singlet oxygen generation ability was also examined to investigate its photosensitizer properties. General trends were described for quantum yields of fluorescence, photodegradation and singlet oxygen quantum yields of this compound. The electrochemical properties of the molecule were investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). In addition, the lowest energy structure, the electronic structure and frontier molecular orbitals were calculated in DFT and the excitation spectrum was obtained by TDDFT calculations. We found that our computational and experimental results were in agreement.

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31

Abbandonato, Gerardo, Katrin Hoffmann, and Ute Resch-Genger. "Determination of quantum yields of semiconductor nanocrystals at the single emitter level via fluorescence correlation spectroscopy." Nanoscale 10, no. 15 (2018): 7147–54. http://dx.doi.org/10.1039/c7nr09332b.

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A microscopy-based method to determine fluorescence quantum yields Φ<sub>F</sub> of dispersed semiconductor nanocrystals at ultralow concentration with fluorescence correlation spectroscopy (FCS) is presented.

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32

Gu, Pei-Yang, Guangfeng Liu, Jun Zhao, et al. "Understanding the structure-determining solid fluorescence of an azaacene derivative." Journal of Materials Chemistry C 5, no. 34 (2017): 8869–74. http://dx.doi.org/10.1039/c7tc03089d.

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Three different single crystal forms of an azaacene derivative with different fluorescence quantum yields have been obtained and the relationship between their structures and fluorescence have been studied.

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33

Chow, Yuan L., and Xiao-Yun Liu. "The photocycloaddition of naphthoates with acetylacetone; dramatic acid promotions of product quantum yields." Canadian Journal of Chemistry 69, no. 8 (1991): 1261–72. http://dx.doi.org/10.1139/v91-189.

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In acetonitrile and methanol, methyl 1- and methyl 2-naphthoate (1- and 2-NpCO2CH3) underwent [2 + 2] photocycloaddition with acetylacetone (acacH) from a reactive species derived from the lowest spectroscopic singlet excited state to give cyclobutane derivatives such as 9 that ring-opened to afford addition products of acetyl and acetonyl moieties at the 7,8-position for 1-NpCO2CH3 (2 and 3) and the 1,2-position for 2-NpCO2CH3 (7). Further irradiation of 3 and 7 caused a deep-seated rearrangement of 3 to give 4 and an intramolecular addition of 7 to give the caged product 8. The photocycloaddition quantum yields were increased remarkably in the presence of a trace amount (< 0.001 M) of protic acids. For example, the limiting quantum yield of 2 and 3 with Фadducts = 0.033 (in the absence) increased to Фadducts > 0.5 under comparable conditions in the presence of [H2SO4] = 0.001 M, approaching the maximum asymptotically at about this concentration; the increases of the quantum yield could not be correlated with H2SO4 concentrations. The acid promotion of the product formation elevated the photocycloaddition to a significantly useful preparative reaction. The photocycloaddition of 2-NpCO2CH3 was quenched by tributylamine, dimethylaniline, and methyl iodide, and could not be initiated by typical triplet sensitization. Strong fluorescence of 2-NpCO2CH3 at 358 nm in CH3CN was quenched by acetylacetone, tributylamine, dimethylaniline, and methyl iodide, the last of which concurrently enhanced the phosphorescence intensity of 2-NpCO2CH3. In the presence of [H2SO4] > 0.005 M the fluorescence intensity at 358 nm was quenched and a new fluorescence at 470 nm corresponding to protonated 12-NpCO2CH3 appeared. However, in the [H2SO4] < 0.002 M region, the new fluorescence was not observed, indicating that the protonation scarcely occurred. The Stern–Volmer constant, obtained by the quantum yield monitor, of the 2-NpCO2CH3 photocycloaddition with acacH was more than an order of magnitude smaller than that obtained by the quenching of 2-NpCO2CH3 fluorescence by acacH. The discrepancies outlined above clearly demonstrate that the reactive intermediate of the photocycloaddition is not the exciplex of the spectroscopic singlet excited species of 12-NpCO2CH3 and acacH, but one that is derived from the exciplex. It is speculated that this unknown reactive intermediate interacts with a proton to promote the photocycloaddition. Key words: photocycloaddition of naphthoates, photorearrangement of styryl ketones, acid catalysis of quantum yields, fluorescence of protonated naphthoates, acid enhancement of singlet quenching.

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34

Falkowski, Paul G., Hanzhi Lin, and Maxim Y. Gorbunov. "What limits photosynthetic energy conversion efficiency in nature? Lessons from the oceans." Philosophical Transactions of the Royal Society B: Biological Sciences 372, no. 1730 (2017): 20160376. http://dx.doi.org/10.1098/rstb.2016.0376.

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Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

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35

Ndung’u, Caroline, Daniel J. LaMaster, Simran Dhingra, et al. "A Comparison of the Photophysical, Electrochemical and Cytotoxic Properties of meso-(2-, 3- and 4-Pyridyl)-BODIPYs and Their Derivatives." Sensors 22, no. 14 (2022): 5121. http://dx.doi.org/10.3390/s22145121.

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Boron dipyrromethene (BODIPY) dyes bearing a pyridyl moiety have been used as metal ion sensors, pH sensors, fluorescence probes, and as sensitizers for phototherapy. A comparative study of the properties of the three structural isomers of meso-pyridyl-BODIPYs, their 2,6-dichloro derivatives, and their corresponding methylated cationic pyridinium-BODIPYs was conducted using spectroscopic and electrochemical methods, X-ray analyses, and TD-DFT calculations. Among the neutral derivatives, the 3Py and 4Py isomers showed the highest relative fluorescence quantum yields in organic solvents, which were further enhanced 2-4-fold via the introduction of two chlorines at the 2,6-positions. Among the cationic derivatives, the 2catPy showed the highest relative fluorescence quantum yield in organic solvents, which was further enhanced by the use of a bulky counter anion (PF6−). In water, the quantum yields were greatly reduced for all three isomers but were shown to be enhanced upon introduction of 2,6-dichloro groups. Our results indicate that 2,6-dichloro-meso-(2- and 3-pyridinium)-BODIPYs are the most promising for sensing applications. Furthermore, all pyridinium BODIPYs are highly water-soluble and display low cytotoxicity towards human HEp2 cells.

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36

Kawski, A., G. Piszczek, and A. Kubicki. "Fluorescence Properties of p-Quaterphenyl and p-Quinquephenyl Derivatives in Liquid Solvents." Zeitschrift für Naturforschung A 51, no. 8 (1996): 905–9. http://dx.doi.org/10.1515/zna-1996-0804.

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Abstract Absorption, fluorescence and emission anisotropy spectra, as well as quantum yields and fluores-cence decay times of p-quaterphenyl (PQP), 4,4"'-bis-(2-butyloctyloxy)-p-quaterphenyl (BBQ), 2,5,2"",5""-tetramethyl-p-quinquephenyl (TMI) and 3,5,3"",5""-tetra-f-butyl-p-quinquephenyl (QUI) were investigated in several nonpolar and polar solvents. It was found that high quantum yield is accompanied by a short (not exceeding 1 ns) lifetime and considerable emission anisotropy in low viscosity solvents. For TMI and QUI, which incorporate as many as 5 phenyl groups, the quantum yield in dioxane is 0.98 and 0.97, respectively. In the case of molecules with 4 phenyl groups, the quantum yield is slightly lower, amounting to 0.91. Rotational motions of terminal phenyl groups cause a lower deactivation of the excitation energy of the singlet state S p the longer the linear molecule.

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37

Mohi, Ali Taher, and Haydar Abd Alkarim Abd Alreda. "Solvent Effect on the spectral and photophysical properties of the Acridone." Journal of Physics: Conference Series 2322, no. 1 (2022): 012075. http://dx.doi.org/10.1088/1742-6596/2322/1/012075.

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Abstract UV/Vis absorption, emission, and excitation spectroscopy with various solvents (dimethyl sulfoxide (DMSO), N,N-Dimethylformamide (DMF), and tetrahydrofuran (THF) and Acetone) at two concentrations (10−4 and 10−5) Mol/L were used to investigate the spectra and photophysical properties of Acridone. Using the integrated emission spectra, the fluorescence quantum yields are calculated. The emission maxima were determined using the red absorption band’s positions and bandwidths. The maximum absorption and emission wavelengths were found to be 390–399 nm and 399–413 nm, respectively, resulting in Stokes shifts of 318.05 and 1142.62 cm-1. Fluorescence spectra have a broad spectral range so that as concentration is increased, each peak shifts toward a long wavelength. It has been discovered that as concentrations increase, the quantum efficiency decreases. The fluorescence quantum yield magnitude is affected by solvents, with THF having the highest value.

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38

Enoki, Masami, and Ryuzi Katoh. "Estimation of quantum yields of weak fluorescence from eosin Y dimers formed in aqueous solutions." Photochemical & Photobiological Sciences 17, no. 6 (2018): 793–99. http://dx.doi.org/10.1039/c7pp00465f.

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39

Nyokong, Tebello. "Desired properties of new phthalocyanines for photodynamic therapy." Pure and Applied Chemistry 83, no. 9 (2011): 1763–79. http://dx.doi.org/10.1351/pac-con-10-11-22.

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The manuscript focuses on the properties of phthalocyanines (Pcs) that are required for them to be employed as photosensitizers in applications such as photodynamic therapy (PDT). High triplet-state quantum yields and lifetimes as well as high singlet-oxygen quantum yields are required for a good photosensitizer. In addition, absorption of the photosensitizer in the red region of the electromagnetic spectrum is also required, and this can be achieved by ring expansion, substitution with electron-donating ligands, and change of the central metal among others. Quantum dots (QDs) are efficient accumulators of light energy, and they can transfer this energy to molecules that possess a very efficient ability to generate singlet oxygen through a process called Förster resonance energy transfer (FRET). Thus, there is a decrease in the fluorescence quantum yield of the QDs when in the vicinity of Pcs. Triplet quantum yields of the Pcs increase in the presence of QDs.

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40

Li, Yigang, Hong Yang, Zian He, et al. "Significant Increment of Photoluminescence Quantum Yield by Efficiently Prohibiting Fluorescence Quenching in Erbium(III) Organic Complexes." Journal of Materials Research 20, no. 11 (2005): 2940–46. http://dx.doi.org/10.1557/jmr.2005.0362.

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A systematic investigation and comparison of the photoluminescence (PL) quantum yields of six erbium(III) organic complexes are reported. We demonstrated that the PL quantum yield could be significantly improved by getting rid of OH and CH groups in the complexes. Moreover, perfluooctanoic acid with neither OH nor CH groups was used as a ligand to form complex with Er3+. The quantum yield of the newly synthesized erbium(III) complex was found to be as high as 2%, 100 times higher than ever reported.

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41

Tau, Prudence, and Tebello Nyokong. "Synthesis and photophysical properties of octa-substituted phthalocyaninato oxotitanium(IV) derivatives." Journal of Porphyrins and Phthalocyanines 10, no. 08 (2006): 1040–48. http://dx.doi.org/10.1142/s1088424606000399.

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The synthesis, spectral and photophysical properties including fluorescence quenching of the following octa-substituted oxotitanium phthalocyanines are reported: 2,3,9,10,16,17,23,24-octaphenoxyphthalocyaninato titanium(IV) oxide, 2,3,9,10,16,17,23,24-[octakis(4-t-butylphenoxyphthalocyaninato)]titanium(IV) oxide, 2,3,9,10,16,17,23,24-{octakis[(4-benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide and 2,3,9,10,16,17,23,24-octaphenylthiophthalocyaninato titanium(IV) oxide. The complexes are characterized by 1 H NMR, IR and UV-vis spectroscopies. Their photophysical properties are presented where moderate fluorescence quantum yields (0.14-0.19) and lifetimes were determined. Varied triplet quantum yields were obtained and the triplet lifetimes (40-100 μs) were short.

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42

Boszczyk, Wojciech, and Tadeusz Latowski. "Photochemical Reactions of Primary Aromatic Amines with Chloromethanes in Solution. I. Spectrochemical Studies." Zeitschrift für Naturforschung B 44, no. 12 (1989): 1585–88. http://dx.doi.org/10.1515/znb-1989-1220.

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Interactions were studied of aniline, 4-methoxyaniline and 4-ethoxyaniline with tetrachloromethane, chloroform and dichloromethane in their ground and first excited singlet states. Stability constants of the complexes of these amines with the chloromethanes in cyclohexane were determined as well as their quantum yields of fluorescence in this solvent. The quenching of fluorescence of aniline and its derivatives by the chloromethanes was ascertained and characterized. Quantum yields of the formation of hydrogen chloride, ψΗCl, were measured during photochemically induced reaction of the amines in tetrachloromethane, chloroform and dichloromethane.

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43

Yadav, Priyanka, Abhineet Verma, Vishal Prasad Sharma та ін. "The development of a robust folded scaffold as a fluorescent material using butylidine-linked pyridazinone-based systems via aromatic π⋯π stacking interactions". New Journal of Chemistry 46, № 12 (2022): 5830–38. http://dx.doi.org/10.1039/d2nj00083k.

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Fluorescence-capable robust folded pyridazinone-based homo- and heterodimers linked with butylidine linkers, whose crystals exhibit fluorescence with quantum yields of 11% (1CN) and 28% (2CN) due to intramolecular stacking, were synthesized.

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44

Buck, C., B. Gramlich, and S. Wagner. "Light propagation and fluorescence quantum yields in liquid scintillators." Journal of Instrumentation 10, no. 09 (2015): P09007. http://dx.doi.org/10.1088/1748-0221/10/09/p09007.

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45

Ruetten, S. A., and J. K. Thomas. "Fluorescence and Triplet Quantum Yields of Arenes on Surfaces." Journal of Physical Chemistry B 102, no. 3 (1998): 598–606. http://dx.doi.org/10.1021/jp972934o.

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46

Yaşa, Göknur, Ali Erdoğmuş, Ahmet Lütfi Uğur, M. Kasım Şener, Ulvi Avcıata, and Tebello Nyokong. "Photophysical and photochemical properties of novel phthalocyanines bearing non-peripherally substituted mercaptoquinoline moiety." Journal of Porphyrins and Phthalocyanines 16, no. 07n08 (2012): 845–54. http://dx.doi.org/10.1142/s1088424612500940.

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The synthesis, photophysical and photochemical properties of nonperipherally (α) mercaptoquinoline substituted Zn(II) , TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, 1H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl3 , DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.

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47

Rosenberg, M., K. R. Rostgaard, Z. Liao, et al. "Design, synthesis, and time-gated cell imaging of carbon-bridged triangulenium dyes with long fluorescence lifetime and red emission." Chemical Science 9, no. 12 (2018): 3122–30. http://dx.doi.org/10.1039/c8sc00089a.

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Introduction of an isopropyl bridge in the triangulenium skeleton leads to a new series of redshifted triangulenium dyes with high fluorescence quantum yields and remarkable long fluorescence lifetime allowing for time-gated cell imaging.

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48

Tuhl, Ahmad, Wadzanai Chidawanayika, Hamada Mohamed Ibrahim, et al. "Tetra and octa(2,6-di-iso-propylphenoxy)-substituted phthalocyanines: a comparative study among their photophysicochemical properties." Journal of Porphyrins and Phthalocyanines 16, no. 01 (2012): 163–74. http://dx.doi.org/10.1142/s1088424612004495.

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This work reports on the synthesis of novel metal free, zinc, aluminum, gallium and indium tetra and octa (2,6-di-iso-propylphenoxy)-substituted phthalocyanine derivatives. UV-visible and 1H NMR analyses confirm that a non-planar conformation, adapted by the phenoxy substituents due to steric interaction in both derivative series, perfectly discourage cofacial aggregation. Fluorescence quantum yields vary as a function of the number of substituents on the ring periphery, while the fluorescence lifetimes display no distinct trend. Triplet quantum yields are significantly larger for the tetra 2,6-di-iso-propylphenoxy- substituted derivatives relative to their corresponding octa-substituted species. However there was no overall trend in the triplet lifetime values. For almost all of the phthalocyanine derivatives, singlet oxygen was produced with relatively good quantum yields. This study explores the possibility of fine-tuning their physicochemical properties by simple structural modification.

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49

Kawski, A., K. Nowaczyk, and B. Kuklinski. "Fluorescence Quantum Yields of 2-Substituted 3-Methylquinoxalines in Liquid Solutions at Room Temperature." Zeitschrift für Naturforschung A 46, no. 8 (1991): 700–702. http://dx.doi.org/10.1515/zna-1991-0808.

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AbstractA sensitivity modulation method was employed to measure the fluorescence spectra and quantum yields of weakly fluorescent 2-substituted (NH2, O, OCH3, CI, Br) 3-methylquinoxalines in n-hexane and methanol at room temperature. A strong decrease in the quantum yield with increasing atomic weight of the substituents was observed in n-hexane. In polar solvents, the CI substituent is the strongest quencher although its atomic weight is 2.254 times smaller than that of Br

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50

Cai, Yuanjing, Kerim Samedov, Brian S. Dolinar, et al. "AEE-active cyclic tetraphenylsilole derivatives with ∼100% solid-state fluorescence quantum efficiency." Dalton Transactions 44, no. 29 (2015): 12970–75. http://dx.doi.org/10.1039/c5dt01846c.

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