Hristova, S. Deneva, Vera V. Pittelkow, M. Crochet, Aurélien Kamounah, Fadhil S. Fromm, Katharina M. Hansen, P. E. Antonov, Liudmil 2018 A series of aryl azo derivatives of naphthols (1–3) were studied by means of UV–Vis and NMR spectroscopy in different solvents as well as by quantum chemical calculations and X-ray analysis. Previous studies have shown that Sudan I (1) exists as a tautomeric mixture. The effect of the solvents is minimized by the existing intramolecular hydrogen bond. Therefore, the influence on the tautomeric state in structurally modified 1 has been investigated. Structure 2 contains an additional OH- group, which deprotonates easily and affects the position of the tautomeric equilibrium by changing the electronic properties of the substituent. The implementation of a sidearm in 3 creates a condition for competition between the nitrogen from the azo group and from the piperidine unit for the tautomeric proton. In this case the use of acid as a stimulus for controlling the tautomeric process was achieved. application/pdf https://folia.unifr.ch/global/documents/307156 https://folia.unifr.ch/documents/307156/files/fro_csp.pdf https://folia.unifr.ch/documents/307156/files/fro_csp_sm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.dyepig.2018.03.070 info:eu-repo/semantics/openAccess License undefined Dyes and Pigments. - 2018, vol. 156, p. 91-99 info:eu-repo/classification/udc/54 A concept for stimulated proton transfer in 1-(phenyldiazenyl)naphthalen-2-ols http://purl.org/coar/resource_type/c_6501