The purpose of this study is to determine substituent and solvent effects on the spin state of iron(II) complexes to increase the sensitivity of a selective barbiturate sensor (Figure 1). Iron(II) is part of a subset of spin crossover (SCO) transition metal species that can readily access both a high and low spin state at the same time. This means that their magnetic properties can be pushed between these two states, thereby modulating their level of paramagnetism. We are interested in exploiting an iron(II)-diaminotriazine-functionalized bipyridine that is able to selectively detect barbiturates by undergoing SCO during hydrogen-bonding self-assembly with the desired substrate. Although these sensors are selective, their detection limits are poor due to background SCO behavior, as well as their poor solubility in solvents that favor hydrogen bonding between the donor-acceptor-donor diaminotriazine and the acceptor-donor-acceptor barbiturates. Our first goal was to explore how the choice of solvent could be used to modulate the SCO behavior through hydrogen bonding with the diaminotriazine moiety. Once this was achieved, the next goal was to install different functional groups to see how perturbing the Δ<sub>O</sub> value with different electron donating and withdrawing substituents could be used to further control the level of SCO and the value of the system as a selective barbiturate sensor.

Substituent and solvent effects on the magnetic properties of iron-based spin crossover complexes bearing hydrogen bonding groups

255th National Meeting (2018)

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