Pyrrolo-[3,2‑b]pyrroles for Photochromic Analysis of Halocarbons

Dramatic photochromic-change of 2,5-bis­(triphenylamine)-substituted N,N′-diphenylpyrrolo-[3,2-b]­pyrrole (1) with halocarbons provides an effective route for halocarbon analysis with the naked eye. The visual detection range can reach as low as 10–4 ∼ 10–5 M (1–10 ppm) in CH3CN. This method can also be applied for detection of CHCl3 in water. Fabrication of a disposable paper test cartridge along with using a camera flash as the light source allows on-site halocarbon detection in seconds. Quantitative analysis for CHCl3 and CH2Cl2 have also been demonstrated.