Excited state lifetimes and energies of okenone and chlorobactene, exemplary keto and non-keto aryl carotenoids

2015 ◽  
Vol 17 (20) ◽  
pp. 13245-13256 ◽  
Author(s):  
Dariusz M. Niedzwiedzki ◽  
Laura Cranston
Keyword(s):  
Excited State ◽  
Photophysical Properties ◽  
Time Resolved ◽  
Excited State Lifetimes

Photophysical properties of two typical aryl carotenoids, okenone and chlorobactene, were studied with application of femtosecond and microsecond time-resolved absorption spectroscopies.

scholarly journals Excited State Dynamics of 8-Vinyldeoxyguanosine in Aqueous Solution Studied by Time-Resolved Fluorescence Spectroscopy and Quantum Mechanical Calculations

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 824
Author(s):  
Lara Martinez-Fernandez ◽  
Thomas Gustavsson ◽  
Ulf Diederichsen ◽  
Roberto Improta
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Radiative Decay ◽  
Decay Channel ◽  
Photophysical Properties ◽  
Time Resolved ◽  
Td Dft ◽  
Bonding Properties ◽  
Purine Ring ◽  
Vinyl Group

The fluorescent base guanine analog, 8-vinyl-deoxyguanosine (8vdG), is studied in solution using a combination of optical spectroscopies, notably femtosecond fluorescence upconversion and quantum chemical calculations, based on time-dependent density functional theory (TD-DFT) and including solvent effect by using a mixed discrete-continuum model. In all investigated solvents, the fluorescence is very long lived (3–4 ns), emanating from a stable excited state minimum with pronounced intramolecular charge-transfer character. The main non-radiative decay channel features a sizeable energy barrier and it is affected by the polarity and the H-bonding properties of the solvent. Calculations provide a picture of dynamical solvation effects fully consistent with the experimental results and show that the photophysical properties of 8vdG are modulated by the orientation of the vinyl group with respect to the purine ring, which in turn depends on the solvent. These findings may have importance for the understanding of the fluorescence properties of 8vdG when incorporated in a DNA helix.

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.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3904
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed.

Drug-biomolecule interactions in the excited states

2006 ◽  
Vol 78 (12) ◽  
pp. 2277-2286 ◽  
Author(s):  
Virginie Lhiaubet-Vallet ◽  
Miguel Angel Miranda
Keyword(s):  
Amino Acids ◽  
Excited State ◽  
Excited States ◽  
Binding Sites ◽  
Photophysical Properties ◽  
Building Blocks ◽  
Point Of View ◽  
Time Resolved ◽  
Specific Antibodies ◽  
Chemical Mechanisms

Drug-biomolecule interactions in the excited state are relevant from a photobiological point of view as they can be correlated with a number of photosensitization disorders such as photocarcinogenicity, photoallergy, phototoxicity, etc. Nonsteroidal anti-inflammatory 2-arylpropionic acids and antibacterial fluoroquinolones have been selected as typical examples of photoactive drugs. Protein photosensitization has revealed photoadduct formation; the major amino acids involved are Tyr, Trp, and His. Generation of specific antibodies has allowed us to identify relevant structures of the drug epitopes. Then, drugs have been submitted to systematic steady-state and time-resolved studies on their photophysical properties, alone and in the presence of biomolecules: proteins, DNA, and their simple building blocks. The results are discussed in the framework of the chemical mechanisms underlying photosensitization by drugs and also in connection with the potential of drug excited states as (chiral) reporters for the binding sites of biomolecules.

scholarly journals Determining Excited-State Structures and Photophysical Properties in Phenylphosphine Rhenium(I) Diimine Biscarbonyl Complexes Using Time-Resolved Infrared and X-ray Absorption Spectroscopies

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Kiyoshi Miyata ◽  
Masataka Funaki ◽  
Tatsuki Morimoto ◽  
Shunsuke Nozawa ◽  
...  
Keyword(s):  
Excited State ◽  
Photophysical Properties ◽  
Stokes Shift ◽  
Combination Method ◽  
Acetonitrile Solution ◽  
Structural Factors ◽  
Time Resolved ◽  
X Ray ◽  
Time Resolved Infrared Spectroscopy ◽  
X Ray Absorption

We have explored the structural factors on the photophysical properties in two rhenium(I) diimine complexes in acetonitrile solution, cis,trans-[Re(dmb)(CO)<sub>2</sub>(PPh<sub>2</sub>Et)<sub>2</sub>]+ (Et(2,2)) and cis,trans-[Re(dmb)(CO)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>]+ ((3,3)) (dmb = 4,4'-dimethyl-2,2'-bipyridine, Ph = phenyl, Et = ethyl) using the combination method of time-resolved infrared spectroscopy, time-resolved extended X-ray absorption fine structure, and quantum chemical calculations. The difference between these complexes is the number of phenyl groups in the phosphine ligand, and this only indirectly affects the central Re(I). Despite this minor difference, the complexes exhibit large differences in emission wavelength and excited-state lifetime. Upon photoexcitation, the bond length of Re-P and angle of P-Re-P are significantly changed in both complexes, while the phenyl groups are largely rotated by ~20º only in (3,3). We concluded that the instability from steric effects of phenyl groups and diimine leads to the smaller Stokes shift of the lowest excited triplet state (T<sub>1</sub>) in (3,3). The large structural change between the ground and excited states causes the longer lifetime of T<sub>1</sub> in (3,3).

Structure and excited state properties of multiporphyrin arrays formed by supramolecular design

2003 ◽  
Vol 07 (11) ◽  
pp. 731-754 ◽  
Author(s):  
Eduard I. Zenkevich ◽  
Christian von Borczyskowski ◽  
Alexander M. Shulga
Keyword(s):  
Excited State ◽  
Photoinduced Electron Transfer ◽  
Spectral Properties ◽  
Photophysical Properties ◽  
Covalent Binding ◽  
Relaxation Processes ◽  
Radiative Relaxation ◽  
Time Resolved ◽  
Chemical Dimers ◽  
Femtosecond Time Scale

Structurally defined nanoscale self-assembled multiporphyrin arrays of variable geo-metry and composition (up to eight tetrapyrrole macrocycles) have been formed via two-fold extra-ligation in solutions at 77-293 K. The array formation is based on non-covalent binding interactions of the phenyl bridged Zn octaethylporphyrin chemical dimers or trimers, ( ZnOEP )2 Ph or ( ZnOEP )3 Ph 2, with di- and tetrapyridyl substituted tetrapyrrole extra-ligands (porphyrin, pentafluorophenyl substituted porphyrin, Cu porphyrin, tetrahydroporphyrin). Using steady-state and time-resolved measurements, spectral properties as well as pathways and dynamics of non-radiative relaxation processes (energy migration, photoinduced electron transfer, exchange d-π effects, realized in nano-femtosecond time scale) have been studied in these complexes upon variation of the composition, mutual geometry, redox and photophysical properties of interacting subunits as well as on the tempera-ture and polarity of surrounding.

Comparative photophysics of sapphyrin derivatives: effects of confused and fused pyrrole rings

2011 ◽  
Vol 15 (09n10) ◽  
pp. 858-864 ◽  
Author(s):  
Jong Min Lim ◽  
Iti Gupta ◽  
Hiroyuki Furuta ◽  
Dongho Kim
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Photophysical Properties ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Time Resolved ◽  
Nonradiative Decay ◽  
Two Photon Absorption ◽  
Two Photon

We have investigated the photophysical properties of [22] π-conjugated pentapyrrolic systems, sapphyrin, N-confused and N-fused sapphyrins, with a particular focus on the effects of confused and fused pyrrole rings on their electronic structures using steady-state and time-resolved spectroscopic methods, two-photon absorption cross-section (σ(2)) measurements and quantum mechanical calculations. The absorption spectra of N-confused and N-fused sapphyrins exhibit relatively red-shifted features compared to sapphyrin. In parallel with these spectral features, the reduced HOMO–LUMO gaps were observed in going from sapphyrin to N-fused sapphyrin. In the analysis of the anisotropy of the induced current density (AICD), N-confused and N-fused sapphyrins show that extra π-electrons in confused and fused pyrrole rings contribute to the extension of their π-conjugation pathways. Slightly larger twophoton absorption cross-section values of N-confused and N-fused sapphyrins (3250 and 3900 GM) than that of sapphyrin (2900 GM) also reflect an enhanced π-conjugation effect due to bicyclic and endocyclic extensions in π-conjugation pathways, respectively. The excited singlet and triplet state lifetimes of N-confused sapphyrin were determined to be 60 ps and 1 μs, respectively, due to conformational change and acceleration of nonradiative decay processes, being in a sharp contrast with those of sapphyrin (2.4 ns and 13 μs, respectively). In the case of N-fused sapphyrin, very short singlet excited-state lifetime of 5 ps was detected probably due to the excited-state NH-tautomerization process which enhances nonradiative decay processes.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

2020 ◽  
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracted tremendous interest owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we have reported a synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al, Beilstein J. Org. Chem. 2020, 16, 1154&ndash;1162.]. To further understand their RTP properties, here we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra measured at 77 K and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. A discussion of the correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is presented.

scholarly journals Characterization of Excited States in a Multiple-Resonance-Type Thermally Activated Delayed Fluorescence Molecule Using Time-resolved Infrared Spectroscopy

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Masaki Saigo ◽  
Tomohiro Ryu ◽  
Takumi Ehara ◽  
Kiyoshi Miyata ◽  
...  
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Potential Surfaces ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Multiple Resonance ◽  
Time Resolved Infrared Spectroscopy

We have investigated the correlation between the photophysical properties and the excited-state detailed characteristics in a multiple-resonance-type thermally activated delayed fluorescence (TADF) molecule, DABNA-1, using time-resolved infrared vibrational spectroscopy. In comparison of the distinctive vibrational spectra in the fingerprint region, 1000 - 1700 cm<sup>-1</sup>, to the simulated spectra by density functional theory calculations, we found the best calculation condition. On the basis of the calculations, we determined the excited-state geometries and molecular orbitals of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states as well as the ground state (S<sub>0</sub>). We revealed that the similarity of the potential surfaces between T<sub>1</sub> and S<sub>0</sub> suppresses the nonradiative decay and causes the high fluorescence quantum yield via TADF process.

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