FIELD: analytical chemistry; organic chemistry. SUBSTANCE: group of inventions relates to the field of organic and analytical chemistry, namely a reagent for detecting Zn2+ and Cd2+ cations as 2-(5-phenyl-2,2'-bipyridin-6-yl)-25,26,27,28-tetramethoxycalix[4]arene, as well as to a process for its preparation, comprising carrying out an aza-Diels-Alder reaction between 2-(6-phenyl-3-(2-pyridyl)-1,2,4-triazin-5-yl)-25,26,27,28-tetramethoxytikalix[4]arene and 2,5-norbornadiene at a temperature of 130–150 °C and in inert gas atmosphere. EFFECT: group of inventions provides the increase in the efficiency of detection and/or supramolecular extraction of cations Zn2+ and Cd2+, as well as the expansion of the arsenal of methods for obtaining reagents for the detection and/or supramolecular extraction of cations Zn2+ and Cd2+.