Thymine-substituted nitronyl nitroxide biradical as a triplet (S = 1) component for bio-inspired molecule-based magnets

As a novel crystal engineering approach to organic molecule-based magnets, we have proposed a strategy of bio-inspired molecular assemblage based on intermolecular hydrogen bonding. Complementary hydrogen bonding between nucleobases as found in DNA is a promising non-covalent interaction for controlling the molecular arrangement of open-shell building block molecules. The hydrogen bonding of complementary nucleobases substituted with radical entities of different spin quantum numbers S, e.g., S = 1 and S = 1/2, gives rise to a heteromolecular aggregation of the S = 1 and S = 1/2 entities, leading to organic ferrimagnetics. In this study, we have designed and synthesized a thymine-substituted nitronyl nitroxide biradical (1) as a triplet (S = 1) component for the bio-inspired ferrimagnetic system. The molecular ground state of 1 has been found to be triplet (S = 1) with a singlet–triplet energy gap of 2J/kB = 21.4 K from magnetic susceptibility measurements. It has been found from X-ray structure analyses that the molecules form hydrogen-bonded aggregates in the crystalline solid state, in which the thymine moiety plays a primary role in the molecular packing. The ground-state triplet biradical serves as an S = 1 building block for bio-inspired molecule-based magnets with hydrogen-bonded nucleobase pairings.

As a building block of bio-inspired molecule-based magnets, a thymine-substituted biradical 1 has been synthesized. The biradical 1 has a triplet ground state with 2J/kB = 21.4 K. In the crystalline solid state, 1 forms hydrogen-bonded aggregates, in which the thymine moiety plays a primary role in the molecular packing.Figure optionsDownload as PowerPoint slide