Flavin Core as Electron Acceptor Component in a Zinc(II)-Phthalocyanine-Based Dyad

2008 ◽  
Vol 61 (4) ◽  
pp. 256 ◽  
Author(s):  
Andreas Gouloumis ◽  
G. M. Aminur Rahman ◽  
Julia Abel ◽  
Gema de la Torre ◽  
Purificación Vázquez ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Ground State ◽  
Charge Separation ◽  
Photoinduced Electron Transfer ◽  
Significant Interaction ◽  
Transient Absorption ◽  
Cross Coupling ◽  
Ion Pair ◽  
Donor Acceptor ◽  
Recombination Dynamics

A zinc(ii)-phthalocyanine-flavin dyad has been synthesized by Heck-type cross-coupling between a flavin that bears a p-iodophenyl group and a phthalocyanine functionalized with a vinyl moiety. Electrochemical experiments reveal that no significant interaction occurs at the ground state between the two electroactive subunits. However, the occurrence of a photoinduced electron transfer in this donor–acceptor conjugate is observed in transient absorption experiments. Charge-separation (i.e., 4.0 × 1011 s–1) and charge-recombination dynamics in benzonitrile (2.2 × 1010 s–1) reveal a remarkable stabilization of the radical ion pair in this solvent.

REVERSIBLE, METASTABLE, ULTRAFAST PHOTOINDUCED ELECTRON TRANSFER FROM SEMICONDUCTING POLYMERS TO BUCKMINSTERFULLERENE AND IN THE CORRESPONDING DONOR/ACCEPTOR HETEROJUNCTIONS

1994 ◽  
Vol 08 (03) ◽  
pp. 237-274 ◽  
Author(s):  
N. S. SARICIFTCI ◽  
A. J. HEBGER
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Ground State ◽  
Charge Separation ◽  
Photoinduced Electron Transfer ◽  
Semiconducting Polymers ◽  
Time Resolved ◽  
Degenerate Ground State ◽  
Photoinduced Charge Separation ◽  
Donor Acceptor

The results of comprehensive studies of photoinduced electron transfer from semiconducting (conjugated) polymers to buckminsterfullerene are reviewed. Steady state and femtosecond time-resolved photoinduced absorption (photoexcitation spectroscopy), steady state and picosecond time-resolved photoluminescence, steady state and picosecond photoconductivity, and steady state light-induced electron spin resonance measurements are summarized as experimental evidence which demonstrates ultrafast, long lived photoinduced electron transfer. Comparative studies with different semiconducting polymers as donors demonstrate that in degenerate ground state polymers, soliton excitations form before the electron transfer can occur; thereby inhibiting charge transfer and charge separation. In non-degenerate ground state systems, photoinduced electron transfer occurs in less than 10−12 s , quenching the photoluminescence as well as the intersystem crossing into the triplet manifold. The importance of electron–phonon coupling and structural relaxation following photoexcitation in these quasi-one-dimensional semiconducting polymers is proposed as a principal contribution to the stabilization of the charge separated state. Utilizing thin films of the semiconducting polymer (donor) and buckminsterfullerene (acceptor) to form a heterojunction interface, we have fabricated bilayers which functioned as photodiodes and as photovoltaic cells. The results are discussed in terms of opportunities for solar energy conversion, for photodiode detector devices, and for a variety of other applications which use photoinduced charge separation.

scholarly journals Hypsochromic solvent shift of the charge separation band in ionic donor–acceptor Li+@C60⊂[10]CPP

2019 ◽  
Vol 55 (75) ◽  
pp. 11195-11198 ◽  
Author(s):  
Anton J. Stasyuk ◽  
Olga A. Stasyuk ◽  
Miquel Solà ◽  
Alexander A. Voityuk
Keyword(s):  
Electron Transfer ◽  
Charge Separation ◽  
Photoinduced Electron Transfer ◽  
Blue Shift ◽  
Polar Medium ◽  
Solvent Shift ◽  
Donor Acceptor

Photoinduced electron transfer in CPP-based donor–acceptor complexes C60⊂[10]CPP and Li+@C60⊂[10]CPP was studied using DFT/TDDFT. Unusual blue shift of charge separated states for Li+@C60⊂[10]CPP complexes in the polar medium is predicted.

Donor-acceptor conjugates derived from cobalt porphyrin and fullerene via metal-ligand axial coordination: Formation and excited state charge separation

2021 ◽  
pp. A-N
Author(s):  
Dili R. Subedi ◽  
Youngwoo Jang ◽  
Ashwin Ganesan ◽  
Sydney Schoellhorn ◽  
Ryan Reid ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Charge Separation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Cobalt Porphyrin ◽  
Axial Coordination ◽  
Cobalt Porphyrins ◽  
Donor Acceptor ◽  
Metal Ligand

Two types of cobalt porphyrins, viz., meso-tetrakis(tolylporphyrinato)cobalt(II), (TTP)Co (1), and meso-tetrakis(triphenylamino porphyrinato)cobalt(II), [(TPA)4P]Co, (2) were self-assembled via metal-ligand axial coordination of phenyl imidazole functionalized fulleropyrrolidine, ImC[Formula: see text] to form a new series of donor–acceptor constructs. A 1:2 complex formation with ImC[Formula: see text] was established in the case of (TTP)Co while for [(TPA)4P]Co only a 1:1 complex was possible to positively identify. The binding constants [Formula: see text] and [Formula: see text] for step-wise addition of ImC[Formula: see text] to (TTP)Co were found to be 1.07 × 105 and 3.20 × 104 M[Formula: see text], respectively. For [(TPA)4P]Co:ImC[Formula: see text], the measured [Formula: see text] values was found to be 6.48 × 104 M[Formula: see text], slightly smaller than that observed for (TTP)Co. Although both cobalt porphyrins were non-fluorescent, they were able to quench the fluorescence of ImC[Formula: see text] indicating occurrence of excited state events in the supramolecular donor-acceptor complexes. Electrochemistry coupled with spectroelectrochemistry, revealed the formation of cobalt(III) porphyrin cation instead of a cobalt(II) porphyrin radical cation, as the main product, during oxidation of phenyl imidazole coordinated cobalt porphyrin. With the help of computational and electrochemical results, an energy level diagram was constructed to witness excited state photo-events. Competitive energy and electron transfer from excited CoP to coordinated ImC[Formula: see text], and electron transfer from Im1C[Formula: see text]* to cobalt(II) porphyrin resulting into the formation of PCo[Formula: see text]:ImC[Formula: see text] charge separated state was possible to envision from the energy diagram. Finally, using femtosecond transient absorption spectroscopy and data analysis by Glotaran, it was possible to establish sequential occurrence of energy transfer and charge separation processes. The lifetime of the final charge separated state was [Formula: see text] 2 ns. A slightly better charge stabilization was observed in the case of [(TPA)4P]Co:ImC[Formula: see text] due to the presence of electron rich, peripheral triphenylamine substituents on the cobalt porphyrin.

A supramolecular Star Wars Tie Fighter Ship: electron transfer in a self-assembled triad composed of two zinc naphthalocyanines and a fullerene

2005 ◽  
Vol 09 (10) ◽  
pp. 698-705 ◽  
Author(s):  
Francis D'Souza ◽  
Suresh Gadde ◽  
Mohamed E. El-Khouly ◽  
Melvin E. Zandler ◽  
Yasuyaki Araki ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Ion Pair ◽  
Spectral Studies ◽  
Stable Complex ◽  
Intermolecular Electron Transfer ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Star Wars

Photoactive supramolecules composed of electron donor and electron acceptor entities are important for light energy harvesting applications. In the present study, a Star Wars Tie Fighter Ship shaped supramolecular triad was constructed by self-assembling two zinc naphthalocyanines to a fulleropyrrolidine bearing two pyridine entities using an axial coordination approach. Optical absorption and emission studies revealed stable complex formation, and the experimentally determined free-energy change revealed the possibility of electron transfer from singlet excited zinc naphthalocyanine to the fulleropyrrolidine. The picosecond time-resolved emission technique was utilized to evaluate the kinetics of charge separation while nanosecond transient absorption spectral studies provided evidence for electron transfer quenching. The measured charge-separation rate, k CS and quantum yield, Φ CS were found to be 5.7 × 109 s −1 and 0.93 in toluene, respectively, indicating an efficient process within the supramolecular triad. The charge recombination rate (k CR ) of the supramolecular ion-pair calculated from the nanosecond transient absorption technique was found to be 3.5 × 107 s −1 yielding a lifetime for the radical ion-pair (τ RIP ) of about 30 ns. Changing the solvent from the noncoordinating toluene to the coordinating benzonitrile or THF destroyed the supramolecular structure, and under these experimental conditions, only intermolecular electron transfer from the triplet excited zinc naphthalocyanine to fulleropyrrolidine could be observed. Under these conditions, the measured electron transfer rates, k et , T inter , were found to be 2.6 × 107 M −1. s −1 in benzonitrile and 1.2 × 107 M −1. s −1 in THF, respectively.

scholarly journals Remarkable Dependence of the Final Charge Separation Efficiency on the Donor-Acceptor Interaction in Photoinduced Electron Transfer

2015 ◽  
Vol 128 (2) ◽  
pp. 639-643 ◽  
Author(s):  
Tomohiro Higashino ◽  
Tomoki Yamada ◽  
Masanori Yamamoto ◽  
Akihiro Furube ◽  
Nikolai V. Tkachenko ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Charge Separation ◽  
Photoinduced Electron Transfer ◽  
Separation Efficiency ◽  
Acceptor Interaction ◽  
Donor Acceptor ◽  
Charge Separation Efficiency

Corrole–ferrocene and corrole–anthraquinone dyads: synthesis, spectroscopy and photochemistry

2015 ◽  
Vol 17 (40) ◽  
pp. 26607-26620 ◽  
Author(s):  
Jaipal Kandhadi ◽  
Venkatesh Yeduru ◽  
Prakriti R. Bangal ◽  
Lingamallu Giribabu
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Charge Separation ◽  
Photoinduced Electron Transfer ◽  
Charge Recombination ◽  
Transfer Rates ◽  
Donor Acceptor

Two different donor–acceptor systems based on corrole–ferrocene (Cor–Fc) and corrole–anthraquinone (Cor–AQ) have been designed and synthesized. Excited state properties of these dyads indicates intramolecular photoinduced electron transfer (PET) take place in these dyads and the electron-transfer rates (kET) was found to be ∼1011s−1. The charge separation (CS) and charge recombination (CR) are found to be identical.

Photoinduced charge separation in a PtII acetylide donor–acceptor triad based on 2-(1-pyrazole)-pyridine modified with naphthalene mono-imide electron acceptor

2013 ◽  
Vol 85 (7) ◽  
pp. 1331-1348 ◽  
Author(s):  
Igor V. Sazanovich ◽  
Mohammed A. H. Alamiry ◽  
Anthony J. H. M. Meijer ◽  
Michael Towrie ◽  
E. Stephen Davies ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Electron Acceptor ◽  
Charge Separation ◽  
Transient Absorption ◽  
Initial Population ◽  
Large Shift ◽  
Photoinduced Charge Separation ◽  
Donor Acceptor ◽  
Photoinduced Charge

A class of molecular electron transfer cascades—those based on PtII complexes of 2-(1-pyrazole)-pyridine (pzpy) ligands—are reported. The synthesis of a new electron-acceptor imide-modified pzpy ligands is reported, and their application to transition-metal chemistry demonstrated by the synthesis of the PtII chloride and acetylide complexes. These donor–acceptor assemblies are promising models for investigation of photoinduced charge separation. Accordingly, picosecond time-resolved infrared (TRIR) and femtosecond transient absorption (TA) studies have been undertaken to elucidate the nature and dynamics of the lowest excited states in Pt(NAP-pyr-pyrazole)(–CC–Ph–C7H15)2. It has been established that the initial population of an MLL'CT excited state in the chromophoric [Pt(pyridine-pyrazole)(acetylide)] core is followed by an electron transfer to the naphthalimide (NAP) acceptor, forming a charge-separated state. This state is characterized by a large shift in ν(CO) vibrations of the NAP acceptor, as well as by a very intense and broad [×10 times in comparison to ν(CO)] asymmetric acetylide stretch which incorporates –CC–Pt–CC– framework and occurs at approximately 300 cm–1 lower in energy than its ground-state counterpart. In CH2Cl2 at room temperature, the charge-separated state with the lifetime of 150 ps collapses into an almost isoenergetic NAP-localized triplet state; the rate of this transformation changes upon decreasing the temperature to 263 K. This final excited state, 3NAP-(pyr-pyrazole)Pt(–CC–Ph–C7H15)2, has an unusually long, for PtII complexes, excited-state lifetime of tens of microseconds. The work demonstrates the possibility of tuning excited-state properties in this new class of PtII chromophores designed for electron-transfer cascades.

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.

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