Iron(II) Mediated Supramolecular Architectures with Schiff Bases and Their Spin-Crossover Properties.

Supramolecular architectures, which are formed through the combination of inorganic metal cations and organic ligands by self-assembly, are one of the techniques in modern chemical science. This kind of multi-nuclear system in various dimensionalities can be implemented in various applications such as sensing, storage/cargo, display and molecular switching. Iron(II) mediated spin-crossover (SCO) supramolecular architectures with Schiff bases have attracted the attention of many investigators due to their structural novelty as well as their potential application possibilities. In this paper, we review a number of supramolecular SCO architectures of iron(II) with Schiff base ligands exhibiting varying geometrical possibilities. The structural and SCO behavior of these complexes are also discussed in detail.

Spin-crossover in iron(ii)-Schiff base complexes.

The spin-crossover (SCO) phenomenon is one of the most prominent examples of bi-stability in molecular chemistry, and the SCO complexes are proposed for nanotechnological applications such as memory units, sensors, and displays. Since the discovery of the SCO phenomenon in tris(N,N-dialkyldithiocarbamato)iron(iii) complexes, numerous investigations have been made to obtain bi-stable SCO complexes undergoing spin-state switching at or around room temperature (RT). Valiant efforts have also been made to elucidate the structure-property relationship in SCO complexes to understand the factors-such as ligand-field strength, molecular geometry, and intermolecular interactions-governing the SCO. Schiff base ligands are an important class of nitrogen-rich chelating ligands used to prepare SCO complexes, because the Schiff base ligands are easy to synthesize and tailor with additional functionalities. Iron(ii)-Schiff base SCO complexes are a well-studied class of SCO active complexes due to the propensity of the complexes to undergo bi-stable SCO. In this context, this perspective attempts to elucidate the structure-SCO property relationships governing SCO in selected mono-, bi-, and multi-nuclear iron(ii)-Schiff base complexes.