Toward control of electron transfer in donor-acceptor molecules by bond-specific infrared excitation

Science ◽  
2014 ◽  
Vol 346 (6216) ◽  
pp. 1492-1495 ◽  
Author(s):  
Milan Delor ◽  
Paul A. Scattergood ◽  
Igor V. Sazanovich ◽  
Anthony W. Parker ◽  
Gregory M. Greetham ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Quantum Control ◽  
Pulse Sequence ◽  
Chemical Reactivity ◽  
Vibronic Interactions ◽  
Electronically Excited ◽  
Donor Acceptor ◽  
Infrared Excitation ◽  
A Charge ◽  
Bridge Vibrations

Electron transfer (ET) from donor to acceptor is often mediated by nuclear-electronic (vibronic) interactions in molecular bridges. Using an ultrafast electronic-vibrational-vibrational pulse-sequence, we demonstrate how the outcome of light-induced ET can be radically altered by mode-specific infrared (IR) excitation of vibrations that are coupled to the ET pathway. Picosecond narrow-band IR excitation of high-frequency bridge vibrations in an electronically excited covalent trans-acetylide platinum(II) donor-bridge-acceptor system in solution alters both the dynamics and the yields of competing ET pathways, completely switching a charge separation pathway off. These results offer a step toward quantum control of chemical reactivity by IR excitation.

scholarly journals Donor-Acceptor Pyridinium Salts for Photo-Induced Electron Transfer Driven Modification of Tryptophan in Peptides, Proteins, and Proteomes using Visible Light

2021 ◽  
Author(s):  
Caleb Hoopes ◽  
Francisco Garcia ◽  
Akash Sarkar ◽  
Nicholas Kuehl ◽  
David Barkan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Chemical Reactivity ◽  
Live Cells ◽  
Quantum Yields ◽  
Cell Labelling ◽  
Pyridinium Salts ◽  
Donor Acceptor ◽  
Photo Induced Electron Transfer

Tryptophan (Trp) plays a variety of critical functional roles in protein biochemistry however, owing to its low natural frequency and poor nucleophilicity, the design of effective methods for both single protein bioconjugation at Trp as well as for in situ chemoproteomic profiling re-mains a challenge. Here, we report a method for covalent Trp modification that is suitable for both scenarios by invoking photo-induced electron transfer (PET) as a means of driving efficient reactivity. We have engineered biaryl N-carbamoyl pyridinium salts that possess a donor-acceptor relationship enabling optical triggering with visible light whilst simultaneously attenuating the probe’s photo-oxidation potential in order to prevent photodegradation. This probe was assayed against a small bank of eight peptides and proteins, where it was found that micromolar concentrations of probe and short irradiation times (10-60 min) with violet light enabled efficient reactivity towards surface exposed Trp residues. The carbamate transferring group can be used to transfer useful functional groups to proteins including affinity tags and click handles. DFT calculations and other mechanistic analyses reveal correlations between excited state lifetimes, relative fluorescent quantum yields, and chemical reactivity. Biotinylated and azide-functionalized pyridinium salts were used for Trp profiling in HEK293T lysates and in situ in HEK293T cells using 450 nm LED irradiation. Peptide level enrichment from live cell labelling experiments identified 290 Trp modifications, with an 82% selectivity for Trp modification over other π-amino acids; demonstrating the ability of this method to identify and quantify reactive Trp residues from live cells.

scholarly journals The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

2014 ◽  
Vol 10 ◽  
pp. 1006-1016 ◽  
Author(s):  
Sarah Bay ◽  
Gamall Makhloufi ◽  
Christoph Janiak ◽  
Thomas J J Müller
Keyword(s):  
Electron Transfer ◽  
Excited Singlet ◽  
Gibbs Energies ◽  
Singlet States ◽  
Vis Spectroscopy ◽  
Donor Acceptor ◽  
Photo Induced Electron Transfer ◽  
Excited Singlet States ◽  
A Charge ◽  
Electronic Ground

Phenothiazinyl and carbazolyl-donor moieties can be covalently coupled to an anthraquinone acceptor unit through an Ugi four-component reaction in a rapid, highly convergent fashion and with moderate to good yields. These novel donor–acceptor dyads are electronically decoupled in the electronic ground state according to UV–vis spectroscopy and cyclic voltammetry. However, in the excited state the inherent donor luminescence is efficiently quenched. Previously performed femtosecond spectroscopic measurements account for a rapid exergonic depopulation of the excited singlet states into a charge-separated state. Calculations of the Gibbs energy of photo-induced electron transfer from readily available UV–vis spectroscopic and cyclovoltammetric data applying the Weller approximation enables a quick evaluation of these novel donor–acceptor dyads. In addition, the X-ray structure of a phenothiazinyl–anthraquinone dyad supports short donor–acceptor distances by an intramolecular π-stacking conformation, an important assumption also implied in the calculations of the Gibbs energies according to the Weller approximation.

Fluorescence Quenching of Aminodiphenylamines with Chloromethanes

2002 ◽  
Vol 67 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Nachiappan Radha ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Ground State ◽  
Rate Constants ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
Charge Transfer Interaction ◽  
Electronically Excited ◽  
A Charge

The fluorescence quenching of 2-aminodiphenylamine (2ADPA), 4-aminodiphenylamine (4ADPA) and 4,4'-diaminodiphenylamine (DADPA) with tetrachloromethane, chloroform and dichloromethane have been studied in hexane, dioxane, acetonitrile and methanol as solvents. The quenching rate constants for the process have also been obtained by measuring the lifetimes of the fluorophores. The quenching was found to be dynamic in all cases. For 2ADPA and 4ADPA, the quenching rate constants of CCl4 and CHCl3 depend on the viscosity, whereas in the case of CH2Cl2, kq depends on polarity. The quenching rate constants for DADPA with CCl4 are viscosity-dependent but the quenching with CHCl3 and CH2Cl2 depends on the polarity of the solvents. From the results, the quenching mechanism is explained by the formation of a non-emissive complex involving a charge-transfer interaction between the electronically excited fluorophores and ground-state chloromethanes.

Photoelectrochemical properties of supramolecular composites of an anionic zinc chlorin and Li+@C60 on SnO2

2014 ◽  
Vol 18 (10n11) ◽  
pp. 982-990 ◽  
Author(s):  
Kei Ohkubo ◽  
Yuki Kawashima ◽  
Kentaro Mase ◽  
Hayato Sakai ◽  
Taku Hasobe ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Photovoltaic Cells ◽  
Lithium Ion ◽  
Transparent Electrode ◽  
Supramolecular Complex ◽  
Photoelectrochemical Properties ◽  
Triplet Excited State ◽  
Optically Transparent ◽  
Donor Acceptor

An electron donor–acceptor supramolecular complex was formed between an anionic zinc chlorin carboxylate ( ZnCh -) and lithium-ion-encapsulated [60]fullerene ( Li +@ C 60) by an electrostatic interaction in benzonitrile ( PhCN ). Photoinduced electron transfer in the supramolecular complex of ZnCh -/ Li +@ C 60 resulted in the formation of the charge-separated state via electron transfer from the triplet excited state of ZnCh - to Li +@ C 60. We report herein photovoltaic cells using ZnCh -/ Li +@ C 60 nanoclusters, which are assembled on the optically transparent electrode (OTE) of nanostructured SnO 2 (OTE/ SnO 2). The photoelectrochemical behavior of the nanostructured SnO 2 film of supramolecular nanoclusters of ZnCh - and Li +@ C 60 denoted as OTE/ SnO 2/( ZnCh -/ Li +@ C 60)n is significantly higher than the single component films of ZnCh - or Li +@ C 60 clusters, denoted as OTE/ SnO 2/( ZnCh -)n or OTE/ SnO 2/( Li +@ C 60)n.

Through-bond modulation of intramolecular electron transfer in rigidly linked donor-acceptor systems

1989 ◽  
Vol 164 (2-3) ◽  
pp. 120-125 ◽  
Author(s):  
James M. Lawson ◽  
Donald C. Craig ◽  
Michael N. Paddon-Row ◽  
Jan Kroon ◽  
Jan W. Verhoeven
Keyword(s):  
Electron Transfer ◽  
Intramolecular Electron Transfer ◽  
Donor Acceptor
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