A responsive Co(II) ¹⁹F PARAShift probe: activation of Fermi contact interactions triggered by pH-dependent...

Area of Science:

• Fluorine chemistry
• Magnetic Resonance Imaging (MRI)
• Biophysical chemistry

Background:

• ¹⁹F MR imaging offers unique advantages for molecular imaging due to its high sensitivity and absence of background signal.
• Developing novel ¹⁹F probes with significant responsiveness to physiological parameters is crucial for advancing MRI applications.
• pH is a critical physiological parameter that changes in various disease states, making pH-sensitive probes highly desirable.

Purpose of the Study:

• To report a novel ¹⁹F MR imaging probe, CoNO2ASF5.
• To characterize the probe's response to physiological pH changes.
• To elucidate the mechanism behind the probe's chemical shift changes.

Main Methods:

• Synthesis and characterization of the CoNO2ASF5 probe.
• ¹⁹F MR spectroscopy experiments to measure chemical shift changes in response to pH variations.
• Computational calculations (e.g., density functional theory) to investigate the electronic structure and interactions.

Main Results:

• The CoNO2ASF5 probe exhibited a large ¹⁹F chemical shift change exceeding 30 ppm with physiological pH fluctuations.
• Computational analysis identified Fermi contact interactions as the primary mechanism responsible for the enhanced ¹⁹F MR shift.
• The probe demonstrates significant sensitivity and responsiveness to pH changes.

Conclusions:

• CoNO2ASF5 is a promising novel ¹⁹F MR imaging probe with substantial pH sensitivity.
• The identified mechanism provides insights for designing future ¹⁹F probes with tailored properties.
• This probe has potential applications in pH-based molecular imaging for disease diagnosis.