Photoresponsive spin-crossover liquid crystals

This proposal aims at developing a series of photoresponsive magnetic soft materials through the combination of spincrossover (SCO) property, photochromic property and liquid crystal (LC) property in a single material.

The SCO property comes from the switchable electronic state between high-spin (HS, S = 2) and low-spin (LS, S = 0) state of the Fe(II) center in an octahedral coordination sphere under an external stimuli (e.g. temperature, light and pressure) and display an interconversion between diamagnetism and paramagnetism.

The SCO molecules will be further decorated with long alkyl chains, which are covalently inserted by azobenzene group as photochromic unit, to display both LC and photochromic properties.

The reversible cis/trans conformational change of photochromic unit is expected to change the coordination sphere of Fe(II) center and intermolecular interactions in LC systems, thus tuning the ligand field and SCO cooperativity and giving novel ligand-driven light-induced spin change effect (LD LISC) behavior.

Moreover, if compared to traditional solid crystalline materials, the obtained materials will show superior characteristics, such as reversibility, faster response, and improved fabricability, allowed by the flexible nature of LCs.

The obtained photoresponsive SCO LC materials will have multidisciplinary applications in prototypes of optical memory devices, displays, sensors, and switches, etc.

The proposal designed by the researcher and host will make a contribution and promotion in the development of multifunctional molecular magnets, especially of photomagnetic materials.