Polypeptides with pendant porphyrins of defined sequence of chromophores: towards artificial photosynthetic systems

2008 ◽  
Vol 12 (12) ◽  
pp. 1232-1241 ◽  
Author(s):  
Farid Aziat ◽  
Régis Rein ◽  
Jorge Peón ◽  
Ernesto Rivera ◽  
Nathalie Solladié
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Amino Acid ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
Free Base ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Absorption And Fluorescence Spectroscopy ◽  
Artificial Photosynthetic

In this paper we now report our ongoing progress in the preparation of artificial photosynthetic systems through the preparation of light harvesting multi-porphyrins. A tetramer, constituted of a central dipeptide functionalized by two free-base porphyrins and surrounded by one amino-acid bearing a pendant Zn ( II ) porphyrin on each side, has been chosen. The optical and photophysical properties of this tetramer have been studied by absorption and fluorescence spectroscopy. In addition, the energy transfer phenomenon has been studied and monitored by femtosecond time-resolved fluorescence. Our results indicate that the excited state dynamics redounding in the excitation being localized in the inner free-base porphyrins takes place in the time scale of approximately 1 ps.

Synthesis and Photophysical Properties of a Conformationally Flexible Mixed Porphyrin Star-Pentamer

2009 ◽  
Vol 62 (7) ◽  
pp. 692 ◽  
Author(s):  
Toby D. M. Bell ◽  
Sheshanath V. Bhosale ◽  
Kenneth P. Ghiggino ◽  
Steven J. Langford ◽  
Clint P. Woodward
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Fluorescence Decay ◽  
High Yield ◽  
Free Base ◽  
Time Resolved ◽  
Zinc Porphyrin ◽  
Relative Contribution ◽  
Synthetic Strategy ◽  
Decay Times

The synthesis of a porphyrin star-pentamer bearing a free-base porphyrin core and four zinc(ii) metalloporphyrins, which are tethered by a conformationally flexible linker about the central porphyrin’s antipody, is described. The synthetic strategy is highlighted by the use of olefin cross metathesis to link the five chromophores together in a directed fashion in high yield. Photoexcitation into the Soret absorption band of the zinc porphyrin chromophores at 425 nm leads to a substantial enhancement of central free-base porphyrin fluorescence, indicating energy transfer from the photoexcited zinc porphyrin (outer periphery) to central free-base porphyrin. Time-resolved fluorescence decay profiles required three exponential decay components for satisfactory fitting. These are attributed to emission from the central free-base porphyrin and to two different rates of energy transfer from the zinc porphyrins to the free-base porphyrin. The faster of these decay components equates to an energy-transfer rate constant of 3.7 × 109 s–1 and an efficiency of 83%, whereas the other is essentially unquenched with respect to reported values for zinc porphyrin fluorescence decay times. The relative contribution of these two components to the initial fluorescence decay is ~3:2, similar to the 5:4 ratio of cis and trans geometric isomers present in the pentamer.

FRET Study Between Carbon Quantum Dots and Malachite Green by Steady-State and Time-Resolved Fluorescence Spectroscopy

2020 ◽  
Vol 10 (3) ◽  
pp. 178-188
Author(s):  
Bipin Rooj ◽  
Ankita Dutta ◽  
Debojyoti Mukherjee ◽  
Sahidul Islam ◽  
Ujjwal Mandal
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Fluorescence Spectroscopy ◽  
Malachite Green ◽  
Dye Degradation ◽  
Fluorescence Emission ◽  
Carbon Quantum Dots ◽  
Time Resolved Fluorescence ◽  
Physical Processes ◽  
Time Resolved

Background: Understanding the interaction between different organic dyes and carbon quantum dots helps us to understand several photo physical processes like electron transfer, energy transfer, molecular sensing, drug delivery and dye degradation processes etc. Objective: The primary objective of this study is to whether the carbon quantum dots can act as an electron donor and can participate in the different photo physical processes. Methods: In this work, Carbon Quantum Dots (CQDLs) are synthesized in most economical and simple carbonization method where petals of Nelumbo nucifera L. are used as a carbon precursor. The synthesized CQDLs were characterized by using experimental techniques like UV−Vis absorption, FT-IR, Transmission Electron Microscopy (TEM), steadystate and time-resolved fluorescence spectroscopy. Results: The spectral analysis shows that the so synthesized CQDLs are spherical in shape and its diameter is around 4.2 nm. It shows the fluorescence emission maximum at 495 nm with a quantum yield of 4%. In this work the interaction between Carbon Quantum Dots (CQDLs) and an organic dye Malachite Green (MG) is studied using fluorescence spectroscopic technique under ambient pH condition (At pH 7). The quenching mechanism of CQDLs with MG was investigated using Stern-Volmer equation and time-resolved fluorescence lifetime studies. The results show that the dominant process of fluorescence quenching is attributed to Forster Resonance Energy Transfer (FRET) having a donor acceptor distance of 53 Å where CQDLs act as a donor and MG acts as an acceptor. Conclusion: This work has a consequence that CQDLs can be used as a donor species for different photo physical processes such as photovoltaic cell, dye sensitized solar cell, and also for antioxidant activity study.

Spectral and Photoprototropic Characteristics of 4-Aminobiphenyl in β-Cyclodextrin

2004 ◽  
Vol 69 (4) ◽  
pp. 748-758 ◽  
Author(s):  
Israel V. Muthu Vijayan Enoch ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Excited State ◽  
Steady State ◽  
Fluorescence Spectroscopy ◽  
Inclusion Complex ◽  
Ground State ◽  
Time Resolved Fluorescence ◽  
Neutral Form ◽  
Time Resolved ◽  
Time Resolved Spectroscopy

The photophysical and photoprototropic behaviour of 4-aminobiphenyl (4ABP) in aqueous β-cyclodextrin (β-CDx) solution has been investigated using steady-state and time-resolved fluorescence spectroscopy. Fluorescence of the neutral form of 4ABP is enhanced due to the formation of a 1:1 complex with β-CDx. The formation of this complex has been confirmed by time-resolved spectroscopy. In the presence of β-CDx, no change was observed in the ground state pKa value but the excited state pKa value changed. Based on its photophysical and photoprototropic characteristics in β-CDx, the structure of the 1:1 inclusion complex is proposed.

Excited-state intramolecular proton transfer and conformational relaxation in 4′-N,N-dimethylamino-3-hydroxyflavone doped in acetonitrile crystals

2016 ◽  
Vol 18 (41) ◽  
pp. 28564-28575 ◽  
Author(s):  
Kazuki Furukawa ◽  
Norifumi Yamamoto ◽  
Kazuyuki Hino ◽  
Hiroshi Sekiya
Keyword(s):  
Excited State ◽  
Steady State ◽  
Fluorescence Spectroscopy ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Conformational Relaxation ◽  
Excited State Dynamics

Excited-state dynamics of 4′-N,N-dimethylamino-3-hydroxyflavone doped in acetonitrile crystals has been investigated by using steady-state and time-resolved fluorescence spectroscopy.

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