Effect of salts on the quantum yield and the decay of lons produced by photoinduced electron transfer from zinc tetraphenylporphyrin to 1,4-benzoquinone in 4-methylpentan-2-one

1992 ◽  
Vol 88 (1) ◽  
pp. 35 ◽  
Author(s):  
Hiroshi Seki
2003 ◽  
Vol 56 (9) ◽  
pp. 917 ◽  
Author(s):  
Jason P. Geue ◽  
Nicholas J. Head ◽  
A. David Ward ◽  
Stephen F. Lincoln

The formation of fluorescent alkali metal and alkaline earth complexes of 1-(2-{10-[2-piperazinoethyl]-9-anthryl}ethyl)piperazine (1) and alkaline earth complexes by 4-(2-{10-[2-(1,4-thiazinan-4-yl)ethyl]-9-anthryl}ethyl)thiomorpholine (2) in acetonitrile is reported. Both (1) and (2) have ‘fluorophore–spacer–receptor’ structures in the sequences ‘anthracene–dimethylene–piperazine’ and ‘anthracene–dimethylene–thiomorpholine’, respectively. Complexation by alkali metal ions and alkaline earth ions, Mm+, modulate photoinduced electron transfer (PET) to increase the fluorescence of (1) and complexation of alkaline earth ions similarly increases the fluorescence of (2). The two receptors of (1) and (2) may either complex Mm+ singly to form [ML]m+ or cooperatively to form a ‘sandwich’ complex [ML′]m+ characterized together by complexation constant K1 and quantum yield φ1. They may also complex two Mm+ in [M2L]2m+ characterized by K2 and φ2. Typical data are exemplified for (1) and Mm+ = Na+ by K1 = 1.33 × 105 dm3 mol–1 (φ1 = 0.02) and K2 = 4.20 × 102 dm3 mol–1 (φ1 = 0.07), for (1) and Mm+ = Ca2+ by K1 = 3.2 × 106 dm3 mol–1 (φ1 = 0.34) and K2 = 1.32 × 104 dm3 mol–1 (φ2 = 0.54), and for (2) and Mm+ = Ca2+ by K1 = 2.29 × 104 dm3 mol–1 (φ1 = 0.20) and K2 = 8.0 × 102 dm3 mol–1 (φ2 = 0.57) at 298.2 K and I = 0.05 mol dm–3 (NEt4ClO4). These data are compared with those for the alkaline earth complexes of 4-{2-[10-(2-morpholinoethyl)-9-anthryl]ethyl}morpholine. In 40 : 60 (v/v) 1,4-dioxan/water, protonation modulates PET to increase the fluorescence of (1)H44+ and (2)H22+. (The pKa values of (1)H44+ are 9.02, 8.06, 4.32, and 2.96 at 298.2 K and I = 0.05 mol dm–3 (NEt4ClO4).) The syntheses of (1) and (2) are reported.


2020 ◽  
Author(s):  
Rishikesh Kulkarni ◽  
Anneliese Gest ◽  
Chun Kei Lam ◽  
Benjamin Raliski ◽  
Feroz James ◽  
...  

<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>


Author(s):  
Anton J Stasyuk ◽  
Olga A. Stasyuk ◽  
Miquel Solà ◽  
Alexander Voityuk

Suitanes, a new class of two-component mechanically interlocked systems, have recently been developed. In this work, we report a detailed study of photoinduced electron transfer processes in the suit[3]anes consisting...


2021 ◽  
Vol 154 (5) ◽  
pp. 054104
Author(s):  
D. Wellnitz ◽  
G. Pupillo ◽  
J. Schachenmayer

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