Abstract
A heteroditopic ligand H2-L consisting of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit and its methyl-protected precursor Me2-L were synthesized, characterized, and their photophysical properties investigated. The three accessible protonation states of the ligand, H2-L+, H2-L, and H-L-, showed distinct 1 H NMR, absorption and emission spectroscopic characteristics that allow pH-sensing. The spectroscopic signatures obtained act as a guide to understand the signaling mechanism of the luminescent pH and molybdate sensor [Re-(bpy)(CO)3(H2-L)]+. It was found that upon deprotonation of the 2-hydroxy group of H2-L, a ligand-based absorption band emerges that overlaps with the Re(dπ)-bpy metal-to-ligand charge transfer (MLCT) band of the sensor, reducing the quantum yield for emission on excitation in the 370 nm region. In addition, deprotonation of the catechol-unit leads to quenching of the emission from the Re(dn)→ bpy 3MLCT state, consistent with photoinduced electron transfer from the electron-rich, deprotonated catecholate to the Re-based luminophore. Finally, reaction of 2 equiv of [Re(bpy)(CO)3(H2-L)]+ with molybdate was shown to give the zwitterionic Mo(VI) complex [MoO2{Re(CO) 3-(bpy)(L)}2], as confirmed by electrospray ionization (ESI) mass spectrometry and X-ray crystallography. The crystal structure determination revealed that two fully deprotonated sensor molecules are bound via their oxygen-donors to a cis-dioxo-MoO2 center.
| Original language | English |
|---|---|
| Pages (from-to) | 1105-1115 |
| Number of pages | 11 |
| Journal | Inorganic Chemistry |
| Volume | 50 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Feb 7 2011 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Physical and Theoretical Chemistry
Cite this
Spectroscopic and structural investigations reveal the signaling mechanism of a luminescent molybdate sensor. / Corden, Vincent A.; Duhme-Klair, Anne K.; Hostachy, Sarah; Perutz, Robin N.; Reddig, Nicole; Becker, Hans Christian; Hammarström, Leif.
In: Inorganic Chemistry, Vol. 50, No. 3, 07.02.2011, p. 1105-1115.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Spectroscopic and structural investigations reveal the signaling mechanism of a luminescent molybdate sensor
AU - Corden, Vincent A.
AU - Duhme-Klair, Anne K.
AU - Hostachy, Sarah
AU - Perutz, Robin N.
AU - Reddig, Nicole
AU - Becker, Hans Christian
AU - Hammarström, Leif
PY - 2011/2/7
Y1 - 2011/2/7
N2 - A heteroditopic ligand H2-L consisting of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit and its methyl-protected precursor Me2-L were synthesized, characterized, and their photophysical properties investigated. The three accessible protonation states of the ligand, H2-L+, H2-L, and H-L-, showed distinct 1 H NMR, absorption and emission spectroscopic characteristics that allow pH-sensing. The spectroscopic signatures obtained act as a guide to understand the signaling mechanism of the luminescent pH and molybdate sensor [Re-(bpy)(CO)3(H2-L)]+. It was found that upon deprotonation of the 2-hydroxy group of H2-L, a ligand-based absorption band emerges that overlaps with the Re(dπ)-bpy metal-to-ligand charge transfer (MLCT) band of the sensor, reducing the quantum yield for emission on excitation in the 370 nm region. In addition, deprotonation of the catechol-unit leads to quenching of the emission from the Re(dn)→ bpy 3MLCT state, consistent with photoinduced electron transfer from the electron-rich, deprotonated catecholate to the Re-based luminophore. Finally, reaction of 2 equiv of [Re(bpy)(CO)3(H2-L)]+ with molybdate was shown to give the zwitterionic Mo(VI) complex [MoO2{Re(CO) 3-(bpy)(L)}2], as confirmed by electrospray ionization (ESI) mass spectrometry and X-ray crystallography. The crystal structure determination revealed that two fully deprotonated sensor molecules are bound via their oxygen-donors to a cis-dioxo-MoO2 center.
AB - A heteroditopic ligand H2-L consisting of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit and its methyl-protected precursor Me2-L were synthesized, characterized, and their photophysical properties investigated. The three accessible protonation states of the ligand, H2-L+, H2-L, and H-L-, showed distinct 1 H NMR, absorption and emission spectroscopic characteristics that allow pH-sensing. The spectroscopic signatures obtained act as a guide to understand the signaling mechanism of the luminescent pH and molybdate sensor [Re-(bpy)(CO)3(H2-L)]+. It was found that upon deprotonation of the 2-hydroxy group of H2-L, a ligand-based absorption band emerges that overlaps with the Re(dπ)-bpy metal-to-ligand charge transfer (MLCT) band of the sensor, reducing the quantum yield for emission on excitation in the 370 nm region. In addition, deprotonation of the catechol-unit leads to quenching of the emission from the Re(dn)→ bpy 3MLCT state, consistent with photoinduced electron transfer from the electron-rich, deprotonated catecholate to the Re-based luminophore. Finally, reaction of 2 equiv of [Re(bpy)(CO)3(H2-L)]+ with molybdate was shown to give the zwitterionic Mo(VI) complex [MoO2{Re(CO) 3-(bpy)(L)}2], as confirmed by electrospray ionization (ESI) mass spectrometry and X-ray crystallography. The crystal structure determination revealed that two fully deprotonated sensor molecules are bound via their oxygen-donors to a cis-dioxo-MoO2 center.
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U2 - 10.1021/ic1019422
DO - 10.1021/ic1019422
M3 - Article
VL - 50
SP - 1105
EP - 1115
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 3
ER -