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The Effect of an Electric Field on the Spectroscopic Properties of the Isolated Green Fluorescent Protein Chromophore Anion
Author(s) -
Langeland Jeppe,
Kjær Christina,
Andersen Lars H.,
Brøndsted Nielsen Steen
Publication year - 2018
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800225
Subject(s) - chromophore , electric field , chemistry , betaine , ion , photochemistry , fluorescence , absorption (acoustics) , steric effects , absorption spectroscopy , dipole , chemical physics , analytical chemistry (journal) , materials science , stereochemistry , organic chemistry , optics , physics , quantum mechanics , composite material
Here we uncover the direct effect of a high electric field on the absorption by the Green Fluorescent Protein chromophore anion isolated in vacuo based on gas‐phase action spectroscopy. Betaine is a strong molecular dipole that creates an electric field of ∼70 MV/cm when attached to the ion at the phenolate oxygen, more than half the actual field from the protein matrix and pointing in the same direction. Nevertheless, the shift in absorption is limited (0.08 eV), supporting earlier conclusions, but subject to much debate, that the protein is rather innocent in perturbing the transition energy. The betaine complexes are readily made by electrospray ionization and in contrast to the bare ions, they dissociate after one‐photon absorption. Also, electron detachment is not an open channel complicating the bare ion case. As steric constraints are absent in vacuo , the possibility of turning on fluorescence by an electric field can be tested from experiments on complexes with betaine.