Spectroscopy and excited state dynamics of nearly infinite polyenes

2020 ◽  
Vol 22 (32) ◽  
pp. 17867-17879
Author(s):  
Václav Šebelík ◽  
Miroslav Kloz ◽  
Mateusz Rebarz ◽  
Martin Přeček ◽  
Eun-Hye Kang ◽  
...  
Keyword(s):  
Excited State ◽  
Spectroscopic Properties ◽  
Excited State Dynamics ◽  
Linear Polyenes

The spectroscopic properties of long, constrained, linear polyenes indicate conjugated units with N > 50, approaching the infinite polyene limit.

Intramolecular fluorescence energy transfer in nitrobenzoxadiazole derivatives of polyene antibiotics

1985 ◽  
Vol 63 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Nils O. Petersen
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Quantum Yield ◽  
Spectroscopic Properties ◽  
Fluorescence Energy Transfer ◽  
Polyene Antibiotics ◽  
Weak Symmetry ◽  
Linear Polyenes ◽  
Parinaric Acid ◽  
Fluorescence Energy

Spectroscopic properties of the polyene antibiotic Nystatin and its nitrobenzoxadiazole derivative have been characterized by lifetime and quantum yield measurements. The data suggest that Nystatin and other polyene antibiotics exhibit spectral features common to other linear polyenes such as diphenylhexatriene and parinaric acid, and support the conclusion that the strong absorption (εmax ~70 000 M−1 cm−1; λ = 306 nm) is due to a symmetry-allowed transition to a higher excited state while the red-shifted emission occurs from a lower lying excited state through a weak, symmetry-forbidden transition.Nitrobenzoxadiazole derivatives also exhibit efficient intramolecular fluorescence energy transfer from the polyene chromophore to the nitrobenzoxadiazole chromophore (λcm = 535 nm). The lifetime and quantum yield measurements suggest that the predominant mechanism of energy transfer is via a Dexter type transfer in a fraction of molecules with appropriate conformations.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

Modulation of Excited State Dynamics in Lead Halide Perovskite Films with Electrical Bias

2019 ◽  
Author(s):  
Gergely Samu ◽  
R.A. Scheidt ◽  
A. Balog ◽  
C. Janáky ◽  
P.V. Kamat
Keyword(s):  
Excited State ◽  
Excited State Dynamics ◽  
Halide Perovskite ◽  
Electrical Bias ◽  
Lead Halide
Sign in / Sign up

Export Citation Format

Share Document