ABSTRACT
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.
ABSTRACT
Paper-based electrochemical sensors (PESs) have been evidenced as analytical strategies for employing simple, low-cost, portable and disposable sensing platforms that can be used in many application areas. Recently, PESs have gained extensive attention because of their advantages of advanced sensitivity and selectivity during detection provided by electrochemistry, compared with microfluidic paper-based analytical devices (µPADs) that still lack these advantages. Also, it can be expected that PESs can better meet current user demands, making them a stand-out analytical tool because of their capability for multiple analyte detection and their compatibility in a variety of application areas, like clinical diagnosis, environmental monitoring and food quality control. Herein, in this mini review, we present an overview of recent developments in PESs over the last decade, focusing on existing fabrication techniques and application areas, specifically in relation to clinical diagnostics, food quality control and environmental monitoring, where simple and portable analytical devices are greatly needed. A summary and future outlooks for PESs are also discussed.
