Photo-physical properties of 2-(1-ethynylpyrene)-adenosine: influence of hydrogen bonding on excited state properties

Abstract

The photo-physical properties of 2-(1-ethynylpyrene)-adenosine (PyA), a fluorescent probe for RNA dynamics, were examined by solvation studies. The excited-state dynamics display the influence of the vicinity on the spectral features. Combining improved transient absorption and streak camera measurements along with a new analysis method provide a detailed molecular picture of the photophysics. After intramolecular vibrational energy redistribution (IVR), two distinct states are observed. Solvent class (protic/aprotic) and permittivity strongly affect the properties of these states and their population ratio. As a result their emission spectrum is altered, while the fluorescence quantum yield and the overall lifetime remain nearly unchanged. Consequently, the hitherto existing model of the photophysics is herein refined and extended. The findings can serve as basis for improving the information content of measurements with PyA as a label in RNA.

The Three Possible 2‐(Pyrenylethynyl) Adenosines: Rotameric Energy Barriers Govern the Photodynamics of These Structural Isomers

“…This has been observed also in the spectra of other closely related systems . Pyrenes electron density has a node at the 2‐position, both in its HOMO and LUMO, which leads to a weak electronic coupling at the 2‐position between the pyrene and adenosine moiety. As a consequence the vibrational redistribution of excitation energy is hindered and a relatively slow vibrational relaxation is observed.…”

“…Thus, substitution at position 4 appears to lift the symmetry constraints that cause the S 0 →S 1 transition to be forbidden in pyrene. In 1PyA, the absorption is even more redshifted (394 nm) with unstructured emission in MeOH in a spectral range comparable to 2PyA and 4PyA …”

“…For 1PyA, the 2′OH‐group of the ribose is known to form an intramolecular hydrogen bond with the N3 atom of adenine. The impact of this intramolecular hydrogen bond on the presence of the fine structure (aprotic solvents) or its absence (protic ones) is established . In protic solvents, the additional hydrogen bonds partially replace the intramolecular one, stabilizing an additional excited‐state signal visible in ultrafast transient absorption experiments.…”

Evidence for hydrogen-bonded ammonia wire influencing the ESMPT process of the 7-hydroxy-4-methylcoumarin·(NH3)3 cluster

“…[1][2][3][4][5][6][7][8] A series of excited-state hydrogen bonding dynamics mechanisms have been demonstrated. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The photoinduced proton and hydrogen atom transfer (PT/HT) processes are the main reactions associated with hydrogen bonded wires, and the transferring of the proton is usually accompanied by the charge transfer. 2,[9][10][11][12][13][14][15][16] As we know, hydrogen-bonded wires are commonly found in a large variety of biological systems and chemical processes.…”

Implementation and Evaluation of Data Analysis Strategies for Time-Resolved Optical Spectroscopy

“…The capabilities of the LDA module were demonstrated in a recent study on the complex excited state dynamics of a pyrene-adenosine derivative. 30 …”