Single Molecule Magnets

What is it about?

A novel single-molecule magnet (SMM) of trans-substituted Tb(III) porphyrin, {[Tb(BIPPP)2](DBU-H)} (BIPPP: 5,15-bis(3,5-isopentoxyphenyl)porphyrin, DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene), is reported here. The alternating current magnetic susceptibility measurements showed the frequency dependence on the in-phase and out-of-phase magnetic susceptibility under both zero and 2000 Oe direct current magnetic fields. The barrier height for the reversal of the magnetic moment at the high-temperature region was estimated to be 299 cm−1, which is the same order as that of the previously reported tetraphenylporphyrin-based Tb(III) double-decker complex. Atomic force microscopy revealed that {[Tb(BIPPP)2](DBU-H)} formed self-assembled monolayers on highly oriented pyrolytic graphite using the simple drop-cast technique. The result proves the high design freedom of porphyrin-based double-decker SMMs.

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Photo by Terry Vlisidis on Unsplash

Photo by Terry Vlisidis on Unsplash

Why is it important?

a novel porphyrin double-decker complex, [Tb(BIPPP)2](DBU-H)] was synthesized. The UV-vis-NIR absorption spectrum showed that the isolated complex exists in an anionic form. The ac magnetic susceptibility measurements showed that [Tb(BIPPP)2](DBU-H)] behaves as an SMM. This is the first report on an SMM of trans-substituted porphyrins. The results show that the low-symmetry porphyrins can also be a component of SMMs, proving that the porphyrin-based SMMs may have significantly high design freedom. Furthermore, the AFM study showed that [Tb(BIPPP)2](DBU-H)] forms self-assembled monolayers on HOPG by the simple drop-cast technique. We expect that porphyrin-based SMM systems will provide a new design strategy for SMM-based molecular devices.

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