4-Nitropyridine-N-oxide is a chemical compound, crystallizing in space group Pnma.
It is highly toxic when consumed orally.Pyridine, 4-nitro-, 1-oxide at cameochemicals.noaa.gov It is also weakly carcinogenic, requiring a pre-existing oncovirus infection to have any effect.
E. coli bacteria struggle to sense quorum in the presence of para-nitropyridine oxide, and the compound physically prevents P. aeruginosa from adhering to surfaces.
para-Nitropyridine oxide also forms cocrystals. The cocrystal with mercuric chloride links together the molecular π systems, generating a large third harmonic response.Newman, P.R., Warren, L.F., Cunningham, P. et al (1989). "Semiorganics: A New Class of NLO Materials", at the MRS Online Proceedings Library vol. 173, pp. 560–561 (1989). The 1:1 cocrystal with nitrophenol also exhibits nonlinear optical effects, presumably due to strong hydrogen bonding.
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