Search

Foremost, practical applications of spin-crossover (SCO) materials require control of the nature of the spin-state coupling. In existing SCO materials, there is a single, well-defined dimensionality relevant to the switching behavior. A new material, consisting of 1,2,4-triazole-based trimers coordinated into 1D chains by [Au(CN)2 ]- and spaced by anions and exchangeable guests, underwent SCO defined by elastic coupling across multiple dimensional hierarchies. Detailed structural, vibrational, and theoretical studies conclusively confirmed that intra-trimer coupling was an order of magnitude greater than the intramolecular coupling, which was an order of magnitude greater than intermolecular coupling. As such, a clear hierarchy on the nature of elastic coupling in SCO materials was ascertained for the first time, which is a necessary step for the technological development of molecular switching materials.

A series of ruthenaindene complexes containing electron-donating and -withdrawing groups were synthesized and characterized. The ruthenaindenes were synthesized from ruthenium butenynyl complexes which were formed by the treatment of Me2Ru(PMe3)4 with 1,4-diaryl-1,3-butadiynes in methanol. Electrochemistry of the metal center in ruthenaindenes showed that the complexes with electron-donating groups on the aromatic ring have significantly lower oxidation potentials in comparison to complexes with electron-withdrawing groups. Even though the substitution of the aromatic ring with electron-donating/-withdrawing groups is remote from the metal center, the electronic properties of the substituents are relayed effectively to the metal center, indicating that the metal center in the ruthenaindenes is quite intimately embedded into the organic aromatic framework.