New fluorescent "off-on" behavior of 9-anthryl aromatic amides through controlling the twisted intramolecular charge transfer relaxation process by complexation with metal ions

Tatsuya Morozumi, Takahisa Anada, Hiroshi Nakamura

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Abstract

New fluorophores based on linear polyether N,N′-[oxybis(3-oxapentamethylenoxy)-2-phenyl]bis(9-anthracenecarbonamide) (3) and its analogues (2 and 4) have been synthesized, and their complexation properties with various alkali-metal and alkaline-earth-metal ions were investigated by fluorescence, UV, and 1H NMR spectroscopies. In the absence of metal ion, 2-4 showed almost no fluorescence emission (fluorescence quantum yield φ = 0.0003, fluorescence "off state) since twisted intramolecular charge transfer (TICT) occurred through the amide bond. However, 2-4 demonstrated a significant increase in fluorescence intensity around 430 nm upon complexation with alkaline-earth-metal ions. In the case of 4·Ca2+, a large enhancement effect on the fluorescence quantum yield (φ = 0.014, [Ca2+]/[4] = 5, φ4-ca2+free4 -42, fluorescence "on" state) was observed. This "off-on" fluorescence characteristic was originated from the cooperative strong binding mode between the carbonyl group and the ethylenoxy moiety for alkaline-earth-metal ions, resulting in effective inhibition of photoinduced TICT relaxation. Fluorophores 2-4 formed a 1:1 complex (the order of the complex formation constants was Ca2+ > Sr2+ ≈ Ba2+) and showed no considerable spectral changes upon complexation with alkali-metal ions and Mg2+. The 1H NMR study on 2-4 and their complexes indicated that free 2-4 formed a helical structure. After complexation, the conformational change of 2 from a helical structure to a semicircular structure was observed. The pseudocyclic form was supported as the complex structure of 3, whereas the large conformational change of 4 was not observed after the addition of metal ions.

Original languageEnglish
Pages (from-to)2923-2931
Number of pages9
JournalJournal of Physical Chemistry B
Volume105
Issue number15
Publication statusPublished - Apr 19 2001

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Relaxation processes
Complexation
Amides
amides
Metal ions
Charge transfer
metal ions
Fluorescence
Metals
charge transfer
Ions
fluorescence
Alkaline Earth Metals
Alkaline earth metals
alkaline earth metals
Alkali Metals
Fluorophores
Alkali metals
Quantum yield
alkali metals

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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title = "New fluorescent {"}off-on{"} behavior of 9-anthryl aromatic amides through controlling the twisted intramolecular charge transfer relaxation process by complexation with metal ions",
abstract = "New fluorophores based on linear polyether N,N′-[oxybis(3-oxapentamethylenoxy)-2-phenyl]bis(9-anthracenecarbonamide) (3) and its analogues (2 and 4) have been synthesized, and their complexation properties with various alkali-metal and alkaline-earth-metal ions were investigated by fluorescence, UV, and 1H NMR spectroscopies. In the absence of metal ion, 2-4 showed almost no fluorescence emission (fluorescence quantum yield φ = 0.0003, fluorescence {"}off state) since twisted intramolecular charge transfer (TICT) occurred through the amide bond. However, 2-4 demonstrated a significant increase in fluorescence intensity around 430 nm upon complexation with alkaline-earth-metal ions. In the case of 4·Ca2+, a large enhancement effect on the fluorescence quantum yield (φ = 0.014, [Ca2+]/[4] = 5, φ4-ca2+/φfree4 -42, fluorescence {"}on{"} state) was observed. This {"}off-on{"} fluorescence characteristic was originated from the cooperative strong binding mode between the carbonyl group and the ethylenoxy moiety for alkaline-earth-metal ions, resulting in effective inhibition of photoinduced TICT relaxation. Fluorophores 2-4 formed a 1:1 complex (the order of the complex formation constants was Ca2+ > Sr2+ ≈ Ba2+) and showed no considerable spectral changes upon complexation with alkali-metal ions and Mg2+. The 1H NMR study on 2-4 and their complexes indicated that free 2-4 formed a helical structure. After complexation, the conformational change of 2 from a helical structure to a semicircular structure was observed. The pseudocyclic form was supported as the complex structure of 3, whereas the large conformational change of 4 was not observed after the addition of metal ions.",
author = "Tatsuya Morozumi and Takahisa Anada and Hiroshi Nakamura",
year = "2001",
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language = "English",
volume = "105",
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journal = "Journal of Physical Chemistry B Materials",
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T1 - New fluorescent "off-on" behavior of 9-anthryl aromatic amides through controlling the twisted intramolecular charge transfer relaxation process by complexation with metal ions

AU - Morozumi, Tatsuya

AU - Anada, Takahisa

AU - Nakamura, Hiroshi

PY - 2001/4/19

Y1 - 2001/4/19

N2 - New fluorophores based on linear polyether N,N′-[oxybis(3-oxapentamethylenoxy)-2-phenyl]bis(9-anthracenecarbonamide) (3) and its analogues (2 and 4) have been synthesized, and their complexation properties with various alkali-metal and alkaline-earth-metal ions were investigated by fluorescence, UV, and 1H NMR spectroscopies. In the absence of metal ion, 2-4 showed almost no fluorescence emission (fluorescence quantum yield φ = 0.0003, fluorescence "off state) since twisted intramolecular charge transfer (TICT) occurred through the amide bond. However, 2-4 demonstrated a significant increase in fluorescence intensity around 430 nm upon complexation with alkaline-earth-metal ions. In the case of 4·Ca2+, a large enhancement effect on the fluorescence quantum yield (φ = 0.014, [Ca2+]/[4] = 5, φ4-ca2+/φfree4 -42, fluorescence "on" state) was observed. This "off-on" fluorescence characteristic was originated from the cooperative strong binding mode between the carbonyl group and the ethylenoxy moiety for alkaline-earth-metal ions, resulting in effective inhibition of photoinduced TICT relaxation. Fluorophores 2-4 formed a 1:1 complex (the order of the complex formation constants was Ca2+ > Sr2+ ≈ Ba2+) and showed no considerable spectral changes upon complexation with alkali-metal ions and Mg2+. The 1H NMR study on 2-4 and their complexes indicated that free 2-4 formed a helical structure. After complexation, the conformational change of 2 from a helical structure to a semicircular structure was observed. The pseudocyclic form was supported as the complex structure of 3, whereas the large conformational change of 4 was not observed after the addition of metal ions.

AB - New fluorophores based on linear polyether N,N′-[oxybis(3-oxapentamethylenoxy)-2-phenyl]bis(9-anthracenecarbonamide) (3) and its analogues (2 and 4) have been synthesized, and their complexation properties with various alkali-metal and alkaline-earth-metal ions were investigated by fluorescence, UV, and 1H NMR spectroscopies. In the absence of metal ion, 2-4 showed almost no fluorescence emission (fluorescence quantum yield φ = 0.0003, fluorescence "off state) since twisted intramolecular charge transfer (TICT) occurred through the amide bond. However, 2-4 demonstrated a significant increase in fluorescence intensity around 430 nm upon complexation with alkaline-earth-metal ions. In the case of 4·Ca2+, a large enhancement effect on the fluorescence quantum yield (φ = 0.014, [Ca2+]/[4] = 5, φ4-ca2+/φfree4 -42, fluorescence "on" state) was observed. This "off-on" fluorescence characteristic was originated from the cooperative strong binding mode between the carbonyl group and the ethylenoxy moiety for alkaline-earth-metal ions, resulting in effective inhibition of photoinduced TICT relaxation. Fluorophores 2-4 formed a 1:1 complex (the order of the complex formation constants was Ca2+ > Sr2+ ≈ Ba2+) and showed no considerable spectral changes upon complexation with alkali-metal ions and Mg2+. The 1H NMR study on 2-4 and their complexes indicated that free 2-4 formed a helical structure. After complexation, the conformational change of 2 from a helical structure to a semicircular structure was observed. The pseudocyclic form was supported as the complex structure of 3, whereas the large conformational change of 4 was not observed after the addition of metal ions.

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