Fig. 1: Automated reaction platform and optical yield determination.
From: Robot-assisted mapping of chemical reaction hyperspaces and networks
a, Parts of the house-built, inexpensive (about $25K) system: (1) horizontal gantry; (2) liquid-handling module; (3) racks of pipette tips; (4) stock solutions; (5) 54-vial plates; (6) UV-Vis spectrophotometer; (7) balance for weighing of solutions (see Supplementary Videos 1 and 2). b, Hypothetical A + B → C reaction space defined by initial concentrations [A]0 and [B]0 and temperature T. c, UV-Vis spectra of the HPLC-isolated species are measured at different concentrations (here for Claisen–Schmidt condensation from Fig. 2a). d, At each point of the conditions’ space, the UV-Vis spectrum (grey) is decomposed—here nearly perfectly—into the component spectra from c, quantifying the concentrations/yields of these components in the crude mixture. e, Stoichiometry of reaction places constraints on possible concentrations (blue) of components in the crude mixture (see Methods). f, Example of a perfect linear dependence (‘multicollinearity’), in which the brown spectrum in the top subplot happens to be a linear sum of the cyan and purple ones (scaled by, respectively, 0.50 and 0.25). Consequently, unmixing is an ill-conditioned problem, as the spectrum of the entire mixture (black) can be decomposed into infinitely many combinations of the brown, cyan and purple components (1:1:1 in the top and 0.5:0.75:2 in the bottom subplots). g, Correlation matrix for components A, B and C of the Claisen–Schmidt condensation from d. Low off-diagonal elements indicate no strong multicollinearity. h, Statistical distributions of yields with respect to the limiting reagent. Relative standard deviations are 2% between repeated optical detection performed on the same crude mixture (n = 54) and 5% between experimental repeats (n = 27) of the entire workflow for the same conditions (data from Fig. 5). i, Differences between experimental and modelled spectra (from d) as a function of wavelength. The fit is adequate, as this trace closely resembles uncorrelated (‘white’) noise.
