Supporting Information from Sensing study of quinoxaline analogues with theoretical calculation, single-crystal X-ray structure and real application in commercial fruit juices.

Single-crystal X-ray structures of dimeric quinoxaline aldehyde (QA), quinoxaline dihydrazone (DHQ) and HQNM (Goswami S et al. 2013 Tetrahedron Lett. 54, 5075–5077. (doi:10.1016/j.tetlet.2013.07.051); Goswami S et al. 2014 RSC Adv. 4, 20 922–20 926. (doi:10.1039/C4RA00594E); Goswami S et al. 2014 New J. Chem. 38, 6230–6235. (doi:10.1039/C4NJ01498G) are reported along with the theoretical study. Among them, QA is not acting as an active probe, but DHQ and HQNM are serving as a selective and sensitive probe for the Fe³⁺ cation and the Ni²⁺ cation, respectively. DHQ can also detect the Fe³⁺ in commercial fruit juices (grape and pomegranate).