New Approach for Designing
Single-Chain Magnets: Organization
of Chains via Hydrogen Bonding between Nucleobases
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Abstract
Two one-dimensional (1D) manganese complexes, [Mn<sub>2</sub>(naphtmen)<sub>2</sub>(L)](ClO<sub>4</sub>)·2Et<sub>2</sub>O·2MeOH·H<sub>2</sub>O (<b>1</b>) and [Mn<sub>2</sub>(naphtmen)<sub>2</sub>(HL)](ClO<sub>4</sub>)<sub>2</sub>·MeOH
(<b>2</b>), were
synthesized by using a bridging ligand with a nucleobase moiety, 6-amino-9-β-carboxyethylpurine,
and a salen-type manganese(III) dinuclear complex, [Mn<sub>2</sub>(naphtmen)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub> (naphtmen<sup>2–</sup> = <i>N</i>,<i>N</i>′-(1,1,2,2-tetramethylethylene)bis(naphthylideneiminato)
dianion). In <b>1</b> and <b>2</b>, the carboxylate-bridged
Mn<sup>III</sup> dinuclear units are alternately linked by two kinds
of weak Mn···O interactions into 1D chains. As a result,
canted antiferromagnetic and ferromagnetic interactions are alternately
present along the chains, leading to a 1D chain with non-cancellation
of anisotropic spins. Since the chains connected via H-bonds between
nucleobase moieties are magnetically isolated, both <b>1</b> and <b>2</b> act as single-chain magnets (SCMs). More importantly,
this result shows the smaller canting angles hinder long-range ordering
in favor of SCM dynamics
