Insights into the unusual dual fluorescence of the ortho-amino analogue of green fluorescent protein chromophore

Robert Sung, Kuang-Sen Sung

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Even though both p-aminobenzonitrile (p-ABN) and o-ABDI [o-amino analogue of green fluorescent protein (GFP)] have the same electron-donating amino group, o-ABDI displays dual fluorescence while p-ABN exhibits single fluorescence. Even though both o-AABDI (o-acetamido analogue of GFP) and o-ABDI have the similar intramolecular hydrogen bonding, o-ABDI displays dual fluorescence while o-AABDI shows single fluorescence. To explore the unusual phenomenon of dual fluorescence for o-ABDI, we used the time-dependent density functional theory (TD-DFT) method with the polarizable continuum model (PCM) to study the S1 excited state of o-ABDI in acetonitrile. What we found is that o-ABDI in acetonitrile has two isomeric conformations (minima) in the S1 excited state, the twisted intramolecular charge transfer (TICT) and the localized excited (LE) states. The TICT state involves a large dipole moment change during fluorescence emission, while the LE state with a flat structure involves only a slight dipole moment change without a charge transfer during fluorescence emission. Even though both o-DMABDI (o-dimethylamino analogue of GFP) and o-ABDI have the TICT excited state, o-DMABDI does not have the stabilized LE S1 state while o-ABDI does. It is because the intramolecular hydrogen bonding of o-ABDI makes its LE S1 state highly stabilized, and that leads its LE S1 state to become a global minimum. That is why o-ABDI displays dual fluorescence.

Original languageEnglish
Pages (from-to)163-167
Number of pages5
JournalJournal of Luminescence
Volume202
DOIs
Publication statusPublished - 2018 Oct 1

Fingerprint

Chromophores
Green Fluorescent Proteins
Excited states
chromophores
Fluorescence
analogs
proteins
fluorescence
Charge transfer
charge transfer
excitation
Dipole moment
Hydrogen Bonding
acetonitrile
Hydrogen bonds
dipole moments
hydrogen
Density functional theory
Conformations
Electrons

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Biochemistry
  • Condensed Matter Physics

Cite this

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title = "Insights into the unusual dual fluorescence of the ortho-amino analogue of green fluorescent protein chromophore",
abstract = "Even though both p-aminobenzonitrile (p-ABN) and o-ABDI [o-amino analogue of green fluorescent protein (GFP)] have the same electron-donating amino group, o-ABDI displays dual fluorescence while p-ABN exhibits single fluorescence. Even though both o-AABDI (o-acetamido analogue of GFP) and o-ABDI have the similar intramolecular hydrogen bonding, o-ABDI displays dual fluorescence while o-AABDI shows single fluorescence. To explore the unusual phenomenon of dual fluorescence for o-ABDI, we used the time-dependent density functional theory (TD-DFT) method with the polarizable continuum model (PCM) to study the S1 excited state of o-ABDI in acetonitrile. What we found is that o-ABDI in acetonitrile has two isomeric conformations (minima) in the S1 excited state, the twisted intramolecular charge transfer (TICT) and the localized excited (LE) states. The TICT state involves a large dipole moment change during fluorescence emission, while the LE state with a flat structure involves only a slight dipole moment change without a charge transfer during fluorescence emission. Even though both o-DMABDI (o-dimethylamino analogue of GFP) and o-ABDI have the TICT excited state, o-DMABDI does not have the stabilized LE S1 state while o-ABDI does. It is because the intramolecular hydrogen bonding of o-ABDI makes its LE S1 state highly stabilized, and that leads its LE S1 state to become a global minimum. That is why o-ABDI displays dual fluorescence.",
author = "Robert Sung and Kuang-Sen Sung",
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Insights into the unusual dual fluorescence of the ortho-amino analogue of green fluorescent protein chromophore. / Sung, Robert; Sung, Kuang-Sen.

In: Journal of Luminescence, Vol. 202, 01.10.2018, p. 163-167.

Research output: Contribution to journalArticle

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AU - Sung, Kuang-Sen

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AB - Even though both p-aminobenzonitrile (p-ABN) and o-ABDI [o-amino analogue of green fluorescent protein (GFP)] have the same electron-donating amino group, o-ABDI displays dual fluorescence while p-ABN exhibits single fluorescence. Even though both o-AABDI (o-acetamido analogue of GFP) and o-ABDI have the similar intramolecular hydrogen bonding, o-ABDI displays dual fluorescence while o-AABDI shows single fluorescence. To explore the unusual phenomenon of dual fluorescence for o-ABDI, we used the time-dependent density functional theory (TD-DFT) method with the polarizable continuum model (PCM) to study the S1 excited state of o-ABDI in acetonitrile. What we found is that o-ABDI in acetonitrile has two isomeric conformations (minima) in the S1 excited state, the twisted intramolecular charge transfer (TICT) and the localized excited (LE) states. The TICT state involves a large dipole moment change during fluorescence emission, while the LE state with a flat structure involves only a slight dipole moment change without a charge transfer during fluorescence emission. Even though both o-DMABDI (o-dimethylamino analogue of GFP) and o-ABDI have the TICT excited state, o-DMABDI does not have the stabilized LE S1 state while o-ABDI does. It is because the intramolecular hydrogen bonding of o-ABDI makes its LE S1 state highly stabilized, and that leads its LE S1 state to become a global minimum. That is why o-ABDI displays dual fluorescence.

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