A Photoinduced Electron-Transfer Reagent for Peroxyacetic Acid, 4-Ethylthioacetylamino-7- phenylsulfonyl-2,1,3-benzoxadiazole, Based on the Method for Predicting the Fluorescence Quantum Yields

2002 ◽  
Vol 74 (16) ◽  
pp. 4089-4096 ◽  
Author(s):  
Maki Onoda ◽  
Seiichi Uchiyama ◽  
Tomofumi Santa ◽  
Kazuhiro Imai
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Quantum Yields ◽  
Peroxyacetic Acid ◽  
Fluorescence Quantum Yields

Germanium(IV) phthalocyanine-porphyrin based hetero trimers: synthesis, spectroscopy and photochemistry

2012 ◽  
Vol 16 (03) ◽  
pp. 282-289 ◽  
Author(s):  
Jaipal Kandhadi ◽  
Ravi Kumar Kanaparthi ◽  
Lingamallu Giribabu
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Method Comparison ◽  
Differential Pulse ◽  
Electronic Energy ◽  
Proton Nuclear Magnetic Resonance ◽  
Quantum Yields ◽  
Electronic Energy Transfer ◽  
Fluorescence Quantum Yields ◽  
Uv Visible

The known oxophilicity of Germanium(IV) ion of Germanium(IV) phthalocyanine and porphyrins have been exploited to synthesize functionally active, "axial-bonding" -type hetero oligomers. These hetero trimers have been fully characterized by elemental analysis, FAB-MS, UV-visible, proton nuclear magnetic resonance (1D and 1 H -1 H COSY) and fluorescence spectroscopies, as well as differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data with those of the corresponding individual constituents reveals that there is no apparent π–π interactions in these "vertically" linked hetero oligomers. The fluorescence quantum yields were found to be lower of these hetero oligomers in comparison with those of the monomeric chromophores. Electronic energy transfer and photoinduced electron transfer from axial porphyrins to central metalloid phthalocyanine and photoinduced electron transfer from singlet state of axial porphyrins to central metalloid phthalocyanine is detected in these hetero oligomers.

1,3,5-Triarylpyrazolines — pH-driven off-on-off molecular logic devices based on a “receptor1-fluorophore-spacer-receptor2” format with internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms

2015 ◽  
Vol 93 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Ramon Zammit ◽  
Maria Pappova ◽  
Esther Zammit ◽  
John Gabarretta ◽  
David C. Magri
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Charge Transfer ◽  
Photoinduced Electron Transfer ◽  
Photophysical Properties ◽  
Molecular Probes ◽  
Quantum Yields ◽  
Ph Sensing ◽  
Internal Charge Transfer ◽  
Internal Charge

The excited state photophysical properties of the 1,3,5-triarylpyrazolines 1–4 were studied in methanol and 1:1 (v/v) methanol–water, as well as 1:4 (v/v) methanol–water and water by fluorescence spectroscopy. The molecules 2–4 incorporate a “receptor1-fluorophore-spacer-receptor2” format while 1 is a reference compound based on a “fluorophore-receptor1” design. The molecular probes operate according to photoinduced electron transfer (PET) and internal charge transfer (ICT) processes. At basic and neutral pHs, 2–4 are essentially nonfluorescent due to PET from the electron-donating dimethylamino moiety appended on the 5-phenyl ring to the excited state of the 1,3,5-triarylpyrazoline fluorophore. At proton concentrations of 10−3 mol/L, the dimethylamino unit is protonated resulting in a strong blue fluorescence about 460 nm with significant quantum yields up to 0.54. At acid concentrations above 10−2 mol/L, fluorescence quenching is observed by an ICT mechanism due to protonation of the pyrazoline chromophore. Symmetrical off-on-off fluorescence–pH profiles are observed, spanning six log units with a narrow on window within three pH units. Hence, 2–4 are novel examples of ternary photonic pH sensing molecular devices.

Photoexcitation and Electron Transfer Reactions of Zinc Lipidporphyrins in DMSO

1999 ◽  
Vol 03 (01) ◽  
pp. 53-59 ◽  
Author(s):  
TAKERU OHGUSHI ◽  
ZI-CHEN LI ◽  
FU-MIAN LI ◽  
TERUYUKI KOMATSU ◽  
SHINJI TAKEOKA ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Steric Effect ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Transfer Reactions ◽  
Quantum Yields ◽  
Electron Transfer Reactions ◽  
Fluorescence Quantum Yields ◽  
Photochemical Properties

The photophysical and photochemical properties of 5,10,15,20-tetrakis{α,α,α,α-o-[2′,2′-dimethyl-20′-((2″-(trimethylammonio)ethyl)phosphonatoxy)alkanamido]phenyl}porphinatozinc(II) (zinc lipidporphyrins, ZnLPs ( C 10, C 18)) have been studied in homogeneous DMSO solution and compared with those of 5,10,15,20-tetrakis{α,α,α,α-o-pivalamidophenyl}porphinatozinc(II) ( ZnTpivPP ) and tetrakis-phenylporphinatozinc(II) ( ZnTPP ). The fluorescence quantum yields of the ZnLPs were lower than that of ZnTPP , but their fluorescence lifetimes were relatively long. The electron transfer reactions from the photoexcited states of these Zn porphyrin complexes to several quinone derivatives were evaluated by fluorescence spectroscopy and laser flash photolysis. The efficiences of oxidative quenching of the excited porphyrins via a dynamic process were significantly decreased by the presence of the bulky substituents on one side of the porphyrin macrocycle. This steric effect of the porphyrin side-chains was quantitatively examined by the Marcus classical treatment.

The Formation of Fluorescent Alkaline Earth Complexes by 4-{2-[10-(2-Morpholinoethyl)-9-anthryl]methyl}morpholine and its -Ethyl}morpholine and -Propyl}morpholine Analogues in Acetonitrile

2003 ◽  
Vol 56 (4) ◽  
pp. 301 ◽  
Author(s):  
Jason P. Geue ◽  
Nicholas J. Head ◽  
A. David Ward ◽  
Stephen F. Lincoln
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Alkaline Earth ◽  
Quantum Yields ◽  
Complexation Constants ◽  
Sandwich Complex ◽  
Complexation Constant ◽  
Receptor Structure ◽  
Alkaline Earths ◽  
Tertiary Nitrogen

The formation of fluorescent alkaline earth complexes of 4-{2-[10-(2-morpholinoethyl)9-anthryl]methyl}morpholine and its new -ethyl}morpholine and -propyl}morpholine analogues, L = (1)–(3), in acetonitrile is reported. Each L has a ‘fluorophore–spacer–receptor’ structure in the sequence ‘anthracene–(methylene)n–morpholine’ in which quenching of the anthracene fluorophore becomes less effective as the receptor tertiary nitrogen becomes more distant with an increase in n from 1 to 3. Complexation by the alkaline earths (M2+) modulates photoinduced electron transfer (PET) and enhances the fluorescence of (1)–(3). The two alkyl morpholine receptors of (1)–(3) may either complex M2+ singly to form [ML]2+ and [M2L]4+ or cooperatively to form a [ML′]2+ ‘sandwich’ complex depending on the length of the alkyl spacer. Thus, (1) dominantly forms [ML]2+ and [ML′]2+ while (2) and (3) form all three complexes as exemplified by [Mg(2)]2+ and [Mg(2)′]2+ characterized by the overall complexation constant K1 = 9.19 × 104 dm3 mol−1 and [Mg2(2)]4+ characterized by the stepwise complexation constant K2 = 1.19 × 103 dm3 mol−1 at 298.2 K and I = 0.05 mol dm−3 (NEt4ClO4). The most stable and fluorescent complexes are formed by Mg2+ and Ca2+, consistent with M2+ size being an important factor affecting complex characteristics. Eighteen complexation constants and quantum yields are reported for the (1)–(3) complexes together with those for (1)–(3) alone. In 40 : 60 (v/v) 1,4-dioxan/water, protonation modulates PET to increase the fluorescence of (1)H22+–(3)H22+. (The pKa values for (2)H22+ are 6.38 and 5.62, and for (3)H22+ are 7.00 and 6.25.) The syntheses of (2) and (3) are reported.

Photoelectronic Utility of Photoinduced Electron Transfer by Phosphorescent Ir(III) Complexes

2014 ◽  
Vol 1668 ◽  
Author(s):  
Youngmin You
Keyword(s):  
Electron Transfer ◽  
Energy Conversion ◽  
Photoinduced Electron Transfer ◽  
Chemical Energy ◽  
Quantum Yields ◽  
Intermolecular Electron Transfer ◽  
Wide Range ◽  
Electrochemically Active ◽  
Order Of Magnitude ◽  
Natural Photosynthesis

ABSTRACTIntermolecular photoinduced electron transfer (PeT) has found a wide range of photoelectronic utility. One of the most notable examples includes the natural photosynthesis, where PeT between chlorophyll and quinone triggers photon-to-chemical energy conversion. We observed that phosphorescent Ir(III) complexes exhibited efficient PeT to trigger a cascade of catalytic intermolecular electron transfer among electrochemically active molecules. To establish the photoelectronic utility of PeT, a series of cyclometalated Ir(III) complexes were prepared and evaluated for photoelectrocatalytic conversion of dithienylethene (DTE) compounds. Selective photoexcitation of the Ir(III) complexes facilitated ultrafast PeT from DTE. The oxidative PeT initiated electrocatalytic cycloreversion of DTE, yielding one order of magnitude enhancement in quantum yields relative to direct photochromic conversion.

Photoinduced Electron Transfer in Dyads with (R)-/(S)-Naproxen and (S)-Tryptophan

2017 ◽  
Vol 231 (3) ◽  
Author(s):  
Ekaterina A. Khramtsova ◽  
Alexandra A. Ageeva ◽  
Alexander A. Stepanov ◽  
Viktor F. Plyusnin ◽  
Tatyana V. Leshina
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Amino Acid ◽  
Quantum Yields ◽  
Intramolecular Electron Transfer ◽  
Active Centers ◽  
Acceptor Interaction ◽  
Enzyme Binding ◽  
Fluorescence Quantum Yields ◽  
Donor Acceptor

AbstractShort-lived intermediates arising from the donor-acceptor interaction of non-steroidal anti-inflammatory drug (NSAID) – (S)-naproxen (NPX) and its (R)-enantiomer with the tryptophan amino acid residue (Trp) have been studied by spin chemistry and photochemistry methods. The donor-acceptor interaction has caried out in a model linked system – dyad under the UV-irradiation. Interest in the NPX-Trp dyad diastereomers is connected with the possibility of using them as models of ligand-enzyme binding as long as amino acid residues are located at the enzyme’s active centers. It is these residues that interact with NSAID during the binding. It is widely thought that charge transfer processes are involved in the process of drug-enzyme binding. Withing this framework the role of charge transfer in NPX-Trp excited state quenching have been investigated. The analysis of the chemically induced dynamic nuclear polarization (CIDNP), as well as fluorescence kinetics and quantum yield in different polarity media has shown that the main channel of NPX fluorescence quenching is the intramolecular electron transfer between NPX and Trp fragments. Electron transfer rate constants and fluorescence quantum yields of diastereomers have demonstrated stereodifferentiation.

Computationally Assisted Design of High Signal-to-Noise Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes

2020 ◽  
Author(s):  
Rishikesh Kulkarni ◽  
Anneliese Gest ◽  
Chun Kei Lam ◽  
Benjamin Raliski ◽  
Feroz James ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dft Calculations ◽  
Photoinduced Electron Transfer ◽  
Density Functional ◽  
Embryonic Stem ◽  
High Sensitivity ◽  
Md Simulations ◽  
High Signal ◽  
Signal To Noise ◽  
Green Fluorescent

<p>High signal-to-noise optical voltage indicators will enable simultaneous interrogation of membrane potential in large ensembles of neurons. However, design principles for voltage sensors with high sensitivity and brightness remain elusive, limiting the applicability of voltage imaging. In this paper, we use molecular dynamics (MD) simulations and density functional theory (DFT) calculations to guide the design of a bright and sensitive green-fluorescent voltage-sensitive fluorophore, or VoltageFluor (VF dye), that uses photoinduced electron transfer (PeT) as a voltage-sensing mechanism. MD simulations predict an 11% increase in sensitivity due to membrane orientation, while DFT calculations predict an increase in fluorescence quantum yield, but a decrease in sensitivity due to a decrease in rate of PeT. We confirm these predictions by synthesizing a new VF dye and demonstrating that it displays the expected improvements by doubling the brightness and retaining similar sensitivity to prior VF dyes. Combining theoretical predictions and experimental validation has resulted in the synthesis of the highest signal-to-noise green VF dye to date. We use this new voltage indicator to monitor the electrophysiological maturation of human embryonic stem cell-derived medium spiny neurons. </p>

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