Synthesis and photophysical studies of porphyrin-ferrocene conjugates

2007 ◽  
Vol 11 (10) ◽  
pp. 719-728 ◽  
Author(s):  
Hanaa Mansour ◽  
Mohamed E. El-Khouly ◽  
Shaban Y. Shaban ◽  
Osamo Ito ◽  
Norbert Jux
Keyword(s):  
Transient Absorption ◽  
Heavy Atom ◽  
Solvent Polarity ◽  
Separation System ◽  
Excited Singlet ◽  
Time Resolved ◽  
Quenching Efficiency ◽  
Donor Acceptor ◽  
Photophysical Studies ◽  
Atom Effect

The porphyrin-ferrocene conjugates ( P-nFc; n = 1, 2 and 4 ), which are simple examples of a donor-acceptor charge separation system, were synthesized. Their photoindued intramolecular and intermolecular processes have been investigated by time-resolved emission and nanosecond transient absorption techniques. Upon excitation of the porphyrins ( H 2P and ZnP ) moieties, an efficient fluorescence quenching of the excited singlet porphyrin is observed. It was found that the quenching efficiency increases with increasing number of attached ferrocene moieties and solvent polarity. The main quenching pathway involves (i) electron transfer from ferrocene to the singlet excited porphyrin and (ii) the heavy-atom effect.

scholarly journals Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

2019 ◽  
Vol 15 ◽  
pp. 2438-2446 ◽  
Author(s):  
Alessandro Iagatti ◽  
Baihao Shao ◽  
Alberto Credi ◽  
Barbara Ventura ◽  
Ivan Aprahamian ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Transient Absorption ◽  
Solvent Polarity ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Time Resolved ◽  
Two Photon Absorption ◽  
Two Photon

In this work we apply a combination of steady state and time resolved luminescence and absorption spectroscopies to investigate the excited-state dynamics of a recently developed molecular photoswitch, belonging to the hydrazone family. The outstanding properties of this molecule, involving fluorescence toggling, bistability, high isomerization quantum yield and non-negligible two-photon absorption cross section, make it very promising for numerous applications. Here we show that the light induced Z/E isomerization occurs on a fast <1 ps timescale in both toluene and acetonitrile, while the excited state lifetime of the Z-form depends on solvent polarity, suggesting a partial charge transfer nature of its low lying excited state. Time-resolved luminescence measurements evidence the presence of a main emission component in the 500–520 nm spectral range, attributed to the Z-isomer, and a very short living blue-shifted emission, attributed to the E-isomer. Finally, transient absorption measurements performed upon far-red excitation are employed as an alternative method to determine the two-photon absorption cross-section of the molecule.

An exceptionally long-lived triplet state of red light-absorbing compact phenothiazine-styrylBodipy electron donor/acceptor dyads: a better alternative to the heavy atom-effect?

2020 ◽  
Vol 56 (11) ◽  
pp. 1721-1724 ◽  
Author(s):  
Yuqi Hou ◽  
Qingyun Liu ◽  
Jianzhang Zhao
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Electron Donor ◽  
Heavy Atom ◽  
Red Light ◽  
Intersystem Crossing ◽  
Spin Orbital ◽  
Heavy Atom Effect ◽  
Donor Acceptor ◽  
Atom Effect

Heavy atom-free dyads showing a red light-absorbing and exceptionally long-lived triplet state based on a spin–orbital charge transfer intersystem crossing mechanism.

Synthesis, characterization and photophysical properties of ferrocenyl and mixed sandwich cobaltocenyl ester linked meso-triaryl corrole dyads

2017 ◽  
Vol 21 (10) ◽  
pp. 646-657 ◽  
Author(s):  
B. Shivaprasad Achary ◽  
A. R. Ramya ◽  
Rajiv Trivedi ◽  
P. R. Bangal ◽  
L. Giribabu
Keyword(s):  
Transient Absorption ◽  
Photophysical Properties ◽  
Heavy Atom ◽  
Parent Compound ◽  
Fluorescence Emission ◽  
Soret Band ◽  
Transient Absorption Spectroscopy ◽  
Ferrocene Derivatives ◽  
Time Resolved ◽  
Design And Synthesis

We report here the design and synthesis of corrole-metallocene dyads consisting of a metallocene (either ferrocene (Dyad 1) or mixed sandwich [Formula: see text]-[C[Formula: see text]H[Formula: see text](COOH)]Co([Formula: see text]-C[Formula: see text]Ph[Formula: see text] (Dyad 2)) connected via an ester linkage at meso phenyl position. Both the dyads were characterized by [Formula: see text]H NMR, MALDI-TOF, UV-visible, fluorescence spectroscopies (steady-state, picosecond time-resolved), femtosecond transient absorption spectroscopy (fs-TA) and electrochemical methods. The absorption spectra of these dyads showed slight broadening and splitting of the Soret band that indicates a weak ground state interaction between the corrole macrocycle and metallocene part of the present donor–acceptor (D–A) system. However, in both the dyad systems, fluorescence emission of the corrole was quenched in polar solvents as compared to its parent compound 10-(4-hydroxyphenyl)-5,15-bis-(pentafluorophenyl ) corrole (Ph-Corr). The quenching was more pronounced in ferrocene derivatives than in cobaltocenyl derivatives. Transient absorption studies confirm the absence of photoinduced electron transfer from metallocene to correl for these dyad systems and the quenching of singlet state of corrole is found to enhance intersystem crossing due to heavy atom effect.

Phthalocyanine-corannulene conjugates: Synthesis, complexation studies with a pyridyl-functionalized C60 fullerene, and photophysical properties

2020 ◽  
Vol 24 (01n03) ◽  
pp. 410-415 ◽  
Author(s):  
Juan A. Suanzes ◽  
Sumit Chaurasia ◽  
Rafael M. Krick Calderon ◽  
Dirk M. Guldi ◽  
Giovanni Bottari ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Supramolecular Interactions ◽  
C60 Fullerene ◽  
Time Resolved ◽  
Complexation Studies ◽  
Donor Acceptor ◽  
Photophysical Studies ◽  
Covalently Linked ◽  
Photoinduced Charge

We report here the synthesis and characterization of some novel Zn(II)phthalocyanine (Pc)-corannulene conjugates and their complexation ability towards a pyridyl-functionalized C[Formula: see text] fullerene through metal-ligand supramolecular interactions. Steady-state and time-resolved photophysical studies carried out on these electron donor–acceptor (D–A) Zn(II)Pc-corannulene/C[Formula: see text] ensembles indicate the formation of photogenerated charge-separated species. Interestingly, a stabilization of the photoinduced charge-separated state is observed in the case of the D–A supramolecular complexes comprising the corannulene-substituted Zn(II)Pcs when compared to their non-corannulene functionalized Zn(II)Pc analogues. We rationalize this stabilizing effect of the charge-separated state exerted by the corannulene as a result of the increased [Formula: see text]-extension and augmented hydrophobicity of the Zn(II)Pc core by the covalently-linked polyaromatic hydrocarbon (PAH) fragment.

The internal heavy-atom effect on 3-phenylselanyl and 3-phenyltellanyl BODIPY derivatives studied by transient absorption spectroscopy

2016 ◽  
Vol 15 (2) ◽  
pp. 250-259 ◽  
Author(s):  
Jamaludin Al Anshori ◽  
Tomáš Slanina ◽  
Eduardo Palao ◽  
Petr Klán
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Heavy Atom ◽  
Transient Absorption Spectroscopy ◽  
Intersystem Crossing ◽  
Heavy Atom Effect ◽  
Atom Effect

The extent of intersystem crossing related to the heavy-atom effect of Se and Te atoms was investigated on monosubstituted 3-phenylselanyl and 3-phenyltellanyl BODIPY derivatives.

scholarly journals Substitution Effects of C-C Triple Bonds on Deactivation Processes from the Fluorescent State of Pyrene Studied by Emission and Transient Absorption Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Minoru Yamaji ◽  
Hajime Maeda ◽  
Yasuaki Nanai ◽  
Kazuhiko Mizuno
Keyword(s):  
Triple Bond ◽  
Transient Absorption ◽  
Heavy Atom ◽  
Substitution Effects ◽  
Triple Bonds ◽  
Pyrene Derivatives ◽  
Fluorescent State ◽  
Atom Effect ◽  
Absorption Measurements ◽  
Triplet Absorption

Pyrenes substituted with tert-butylethynyl, trimethylsilylethynyl, and trimethylsilylbutadiynyl groups were prepared, and the fluorescence yields (Φf), lifetimes, and triplet-triplet absorption were measured in cyclohexane. Upon introduction of the groups possessing triple bond(s) to the pyrene skeleton, the fluorescence rate (kf) increased. The variation of the terminating groups did not appreciably affect the Φf and kf values. Increasing the number of the triple bond, the kf values increased by the magnitude of order whereas the Φf were not varied. The effect of the ethynyl groups on the kf values was rationalized by the Strickler-Berg equation considering an increase of the 1La transition moment. Triplet-triplet absorption spectra of pyrene derivatives were obtained. The intersystem crossing rates (kisc) increased upon increasing the number of triple bonds terminated with the trimethylsilyl group whereas those between ethynylpyrenes were independent of the terminating groups. Heavy atom effect failed to rationalize the enhancement of the kisc values upon adding the triple bond to the pyrene moiety.

Einfluß des Silberkations auf das Fluoreszenzverhalten polyzyklischer aromatischer Kohlenwasserstoffe

1994 ◽  
Vol 49 (4-5) ◽  
pp. 578-584
Author(s):  
Michael Komfort ◽  
Jörn Küster ◽  
Herbert Dreeskamp
Keyword(s):  
Triplet State ◽  
Energy Gap ◽  
Dynamic Equilibrium ◽  
Heavy Atom ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Exciplex Emission ◽  
Atom Effect ◽  
Absorption Measurements

Abstract Combining the results of fluorescence and triplet-triplet absorption measurements, the influence of silver perchlorate on the excited states of pyrene, phenanthrene, 9-cyanophenanthrene, 9,10-diphenylanthracene and 9,10-dicyanoanthracene in fluid solutions has been investigated. In corre­ spondence with a small energy gap between the lowest excited singlet state and the nearest lower triplet state an external heavy atom effect has been found to be responsible for the fluorescence quenching in the case of pyrene, phenanthrene and 9-cyanophenanthrene. In the case of 9,10-diphenylanthracene and 9,10-dicyanoanthracene, where this energy gap is large, an exciplex emission is observed with no significant increase of triplet state formation. Furthermore, 9-cyanophenanthrene and 9,10-dicyanoanthracene under similar experimental conditions form ground state complexes with AgCIO4 with a red-shifted fluorescence. From time-resolved fluorescence measurements a dynamic equilibrium of association in the excited state is deduced.

scholarly journals Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

2019 ◽  
Author(s):  
Alessandro Iagatti ◽  
Baihao Shao ◽  
Alberto Credi ◽  
Barbara Ventura ◽  
Ivan Aprahamian ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Transient Absorption ◽  
Solvent Polarity ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Time Resolved ◽  
Two Photon Absorption ◽  
Two Photon

In this work we apply a combination of steady state and time resolved luminescence and absorption spectroscopies to investigate the excited-state dynamics of a recently developed molecular photoswitch, belonging to the hydrazone family. The outstanding properties of this molecule, involving fluorescence toggling, bistability, high isomerization quantum yield and non-negligible two-photon absorption cross section, make it very promising for numerous applications. Here we show that the light induced Z/E isomerization occurs on a fast <1 ps timescale in both toluene and acetonitrile, while the excited state lifetime decreases with increasing solvent polarity, suggesting a partial charge transfer nature of its low lying excited state. Time resolved luminescence measurements evidence the presence of a main emission component in the 500-520 nm spectral range, attributed to the Z isomer, and a very short living blue-shifted emission, attributed to the E isomer. Finally, transient absorption measurements performed upon far-red excitation are employed as an alternative method to determine the two-photon absorption cross-section of the molecule.

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