FIELD: chemistry. SUBSTANCE: group of inventions relates to the field of organic and analytical chemistry, namely to a reagent for detecting Zn2+ cations, which is 2-(1-(pyridin-2-yl)4-phenyl-isoquinolin-3-yl)-25,26,27,28-tetramethoxycalix[4]arene, as well as a method for its preparation, comprising carrying out the aza-Diels-Alder reaction at a temperature of 105–110 °C in an inert gas atmosphere of 2-(6-phenyl-3-(2-pyridin-2-yl)-1,2,4-triazin-5-yl)-25,26,27,28-tetramethoxycalix[4]arene with 1,2-dehydrobenzene, which is generated in situ by the reaction of anthranilic acid with isoamyl nitrite. EFFECT: group of inventions provides an increase in detection efficiency and/or supramolecular extraction of Zn2+ cations, as well as an expansion of the arsenal of methods for obtaining reagents for the detection and/or supramolecular extraction of cations Zn2+.