Photo-responsive Compounds for Applications as Spin-Crossover Materials and Biomolecular Targeting Agents

Aims. The project will design new ligands with in-built photo-activatable switching groups that can chelate metal ions such as Fe(II)/Fe(III) and Au(III). For the iron complexes, both thermal and light-induced spin state switching are potentially feasible. For the Au(III) complexes, the primary concept to explore is whether light-induced biomolecular targeting of DNA and/or proteins can be demonstrated for the first time.

Spin crossover materials. Hybrid and multi-scale density functional theory (DFT) methods will be used to design a series of bespoke iron coordination compounds that could function as thermal- and light-induced spin state switches. The barriers to conformational switching in the ligands will be determined in silico along with spin crossover (SCO) critical temperatures (Tc). Based on the outcome of the simulations, selected compounds will be synthesized and characterized using single crystal and powder X-ray crystallography, NMR, IR, MS, Raman, and electronic spectroscopy as well as magnetometry. Consequently, there will be a balance of theory and experiment in the project.

Photoresponsive biomolecular targeting agents. The goals of this optional aspect of the work are: (i) To use hybrid and multi-scale DFT methods to design a series of bespoke water-soluble chelates of Au(III) or Fe(II/III) that can, in principle, undergo photoisomerization reactions. The compounds will be shaped to target specific biomolecules, e.g., DNA. (ii) To synthesize and characterize a select number of the compounds designed in silico for experimental investigation using single crystal X-ray crystallography, NMR, IR, MS, and electronic spectroscopy. The binding of the compounds to biomolecules will then be studied by electrophoresis and spectroscopic methods. Attempts could be made to crystallize and structurally elucidate macromolecular complexes of the compounds to understand how they might function at atomic resolution