Many metrics such as atom economy, molar efficiency, E-factor, and reaction mass efficiency have been developed for evaluating the efficiency or greenness of chemical reactions. While some of these have been applied to evaluating the chemical synthesis of nanoparticles, these tools have not been optimized for the evaluation of nanoparticle synthetic methods. There are complications with evaluating nanoparticle syntheses using these metrics that are not encountered when evaluating common organic reactions. A critical evaluation is provide here of existing green chemistry metrics applied to a series of published gold nanoparticle preparations. Through this, we have established a list of best practices for the use of metrics in evaluating nanoparticle syntheses. In addition, we evaluated the role of composition uncertainty in nanoparticle synthesis and how this influences efficiency metrics. In particular, while mass based metrics, such as E-factor, are insensitive to composition uncertainty other metrics provide different results depending on what assumptions are made about the molecular composition of the nanoparticles. Through this analysis we conclude that better nanoparticle metrics are needed to more accurately compare synthetic routes.

Adapting green chemistry metrics for nanoparticle synthesis

249th National Meeting (2015)

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