A cobalt pyrenylnitronylnitroxide single-chain magnet with high coercivity and record blocking temperature

Area of Science:

• Coordination Chemistry
• Molecular Magnetism
• Materials Science

Background:

• Single-chain magnets (SCMs) are molecular materials exhibiting magnetic properties along a single chain.
• Developing SCMs with high blocking temperatures and coercivity is crucial for potential applications.

Purpose of the Study:

• To synthesize and characterize a novel helical 1:1 chain complex.
• To investigate the magnetic properties and SCM behavior of the synthesized complex.

Main Methods:

• Coordination of a cobalt(II) [Co(hfac)2] moiety with a pyrene-linked nitronylnitroxide radical (PyrNN).
• Magnetic susceptibility measurements (frequency-dependent, field-cooled, zero-field-cooled).
• Hysteresis loop analysis at low temperatures.

Main Results:

• Formation of a helical 1:1 chain complex with strong antiferromagnetic exchange.
• Observation of SCM behavior with a record high blocking temperature (~14 K).
• Exhibition of significant hysteresis with high coercivity (32 kOe at 8 K), attributed to chain isolation by pyrene units.
• Identification of two distinct magnetic relaxation processes linked to chain length.

Conclusions:

• The synthesized helical cobalt complex demonstrates remarkable SCM properties.
• The bulky pyrene units effectively isolate magnetic chains, enhancing SCM behavior.
• The observed magnetic relaxation processes provide insights into chain dynamics and length dependence.