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Spectroscopic and structural investigations reveal the signaling mechanism of a luminescent molybdate sensor

V.A. Corden ; A-K. Duhme-Klair ; S. Hostachy ; R.N. Perutz ; N. Redding ; Hans-Christian Becker (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; L. Hammarström
Inorganic Chemistry (0020-1669). Vol. 50 (2011), 3, p. 1105-1115.
[Artikel, refereegranskad vetenskaplig]

A heteroditopic ligand H 2-L consisting of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit and its methyl-protected precursor Me 2-L were synthesized, characterized, and their photophysical properties investigated. The three accessible protonation states of the ligand, H 2-L+, H 2-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(H 2-L)]+. It was found that upon deprotonation of the 2-hydroxy group of H 2-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(H 2-L)]+ with molybdate was shown to give the zwitterionic Mo(VI) complex [MoO 2{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-MoO 2 center.

Denna post skapades 2012-09-20.
CPL Pubid: 163629


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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)


Fysikalisk kemi

Chalmers infrastruktur