Enantiomerically selective vapochromic sensing

The double salt materials platinum(II)tetrakis-R-β-methylphenethylisocyanide tetracyanoplatinate(II) (R-1) and platinum(II)tetrakis-S-β-methylphenethylisocyanide tetracyanoplatinate(II) (S-1) have been synthesized with highly enantiomerically pure isocyanide ligands. The vapochromic behavior of R-1 and S-1 has been studied in the presence of a chiral probe vapor to determine if enantiomerically selective sensing is possible with these materials. The wavelength of maximum emission values (λmax) for solid-state vapoluminescence spectra of R-1 and S-1 in the presence of enriched R- and S-2-butanol vapor differ by approximately 10 nm while the λmax values for R-1 and S-1 under nitrogen are nearly identical. Principal component analysis has been performed on datasets that consist of a series of vapoluminescence spectra of R-1 and S-1 as a function of the R/S-2-butanol ratio. Plots of principal component one versus R/S-2-butanol ratio show mirror image trends for R-1 relative to S-1. While care must be taken to control water vapor and monitor R-1 and S-1 for possible decomposition, the reported results nevertheless show that R-1 and S-1 are capable of enantiomerically selective vapochromic sensing.