Uwe Bunz and colleagues, University of Heidelberg, Germany, used digital photography to study the optical changes occurring when different pyridine-substituted cross-conjugated fluorophores (XF) were subjected to protonation.

Upon protonation of the pyridine nitrogen, the XFs with a para or ortho substitution pattern show similar bathochromic shifts in the emission. The meta XF features a smaller bathochromic shift. The color changes of XFs in the presence of carboxylic acids were used to identify them by digital photography.

Data extraction of the photographs is done using a statistical model based on RGB color.

Future challenges include making a ‘pocket fluorimeter’ by transferring this technology to a mobile phone app for automatic interpretation of complex spectroscopic data to study various analytes of clinical or environmental importance.

• Digital photography for the analysis of fluorescence responses,
  Thimon Schwaebel, Oliver Trapp, Uwe H. F. Bunz,
  Chem. Sci. 2013.
  DOI: 10.1039/c2sc21412a