Photoswitchable Magnetic Resonance Imaging Contrast by Improved Light-Driven Coordination-Induced Spin State Switch
摘要:
We present a fully reversible and highly efficient on-off photoswitching of magnetic resonance imaging (MRI) contrast with green (500 nit), and violet-blue (435 nm) light. The contrast change is based on inframolecular 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.
porphyrin and its application as a versatile precursor for building up functional ortho-substituted tetraaryl porphyrin architectures is reported. This precursor porphyrin provides the basis for efficient modular syntheses of porphyrin compounds with covalently attached axial ligands which are important as enzyme model complexes, electron transfer dyads, and many other applications. In the present study
Synthesis of Functionalized Perfluorinated Porphyrins for Improved Spin Switching
作者:M. Dommaschk、C. Näther、R. Herges
DOI:10.1021/acs.joc.5b01524
日期:2015.9.4
We have established a method to synthesize perfluorinated meso-phenylporphyrins with one phenyl group bearing a substituent in the ortho position. These novel electron-deficient porphyrins are interesting for model enzymes, catalysis, photodynamic therapy, and electron transfer. The key step is the synthesis of an iodine-substituted porphyrin and its Suzuki cross coupling with boronic acid derivatives. We applied the novel strategy to synthesize a highly electron-deficient, azopyridine-substituted Ni-porphyrin that undergoes an improved ligand-driven coordination-induced spin-state switch.