Remarkably strong magnetic response in molecules with polar groups

TL;DR

This study reveals that molecules with polar groups, such as cellulose derivatives, exhibit unexpectedly strong paramagnetism due to reduced excitation energy and aggregation effects, challenging traditional views of electromagnetism.

Contribution

The paper demonstrates that polar molecules can have significant magnetic responses, supported by DFT calculations, highlighting a novel link between polarity and magnetism in molecular systems.

Findings

Polar molecules like cellulose derivatives are strongly paramagnetic.

Polarity reduces excitation energy, enabling magnetic moments.

Aggregation amplifies the magnetic response of polar groups.

Abstract

For more than a century, electricity and magnetism have been believed to always exhibit inextricable link due to the symmetry in electromagnetism. At the interface, polar groups that have polar charges, are indispensable to be considered, which interact directly with other polar charges/external charges/external electric fields. However, there is no report on the corresponding magnetic properties on these polar groups. Clearly, such asymmetry, that is, only the interaction between the polar groups and charges, is out of bounds. Here we show that those molecules with considerable polar groups, such as cellulose acetate (CA) and other cellulose derivatives with different polar groups, can have strong magnetic response, indicating that they are strongly paramagnetic. Density functional theory (DFT) calculation shows that the polarity greatly reduces the excitation energy from the state without net spin (singlet) to the state with net spin (triplet), making the considerable existence of magnetic moments on the polar groups. We note that the hydrophobic groups in these molecules have no magnetic moments, however, they make the molecules aggregate to amply the magnetic effect of the magnetic moments in the polar groups, so that these magnetic moments can induce the strong paramagnetism. Our observations suggest a recovery of the symmetry with inextricable link between the electricity and magnetism at the interface. The findings leave many imaginations of the role of the magnetic interaction in biological systems as well as other magnetic applications considering that many of those polar materials are biological materials, pharmaceutical materials, chemical raw materials, and even an essential hormone in agricultural production.