Photoswitchable Magnetic Resonance Imaging Contrast by Improved Light-Driven Coordination-Induced Spin State Switch.
We present a fully reversible and highly efficient on-off photoswitching of magnetic resonance imaging (MRI) contrast with green (500 nm) and violet-blue (435 nm) light. The contrast change is based on intramolecular light-driven coordination-induced spin state switch (LD-CISSS), performed with azopyridine-substituted Ni-porphyrins. The relaxation time of the solvent protons in 3 mM solutions of the azoporphyrins in DMSO was switched between 3.5 and 1.7 s. The relaxivity of the contrast agent changes by a factor of 6.7. No fatigue or side reaction was observed, even after >100,000 switching cycles in air at room temperature. Electron-donating substituents at the pyridine improve the LD-CISSS in two ways: better photostationary states are achieved, and intramolecular binding is enhanced.
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Marcel
M
Dommaschk
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Morten
M
Peters
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Florian
F
Gutzeit
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Christian
C
Schütt
‡Institut für Anorganische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 6/7, 24098 Kiel, Germany.
Christian
C
Näther
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Frank D
FD
Sönnichsen
§Clinic for Radiology and Neuroradiology, Arnold Heller Straße 3, 24105 Kiel, Germany.
Sanjay
S
Tiwari
§Clinic for Radiology and Neuroradiology, Arnold Heller Straße 3, 24105 Kiel, Germany.
Christian
C
Riedel
§Clinic for Radiology and Neuroradiology, Arnold Heller Straße 3, 24105 Kiel, Germany.
Susann
S
Boretius
†Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, 24098 Kiel, Germany.
Rainer
R
Herges
D003287:Contrast Media / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004583:Electrons; D008027:Light; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
D003287:Contrast Media; D056831:Coordination Complexes; D008665:Metalloporphyrins; D011725:Pyridines; C048287:3-azopyridine; D009532:Nickel; D004121:Dimethyl Sulfoxide