Probing the Reaction of N,N-Dimethyformamide Dimethyl Acetal with p-tert-Butylthiacalix[4]arene Tetrahydrazides: A Facile Approach for the Synthesis and Application of Novel Metal Receptors

Recent developments in the field of sensing and recognition revealed that artificial receptors based on calix[4]arenes with π-conjugated fluorophoric or chromophoric moieties are efficient in enhancing selectivity/sensitivity as well as the binding affinity for ionic or molecular recognition. Herein, via studying the reaction of dimethylformamide dimethyl acetal (DMF–DMA) with p-tert-butylthiacalix[4]arene tetrahydrazides in three different conformers (i.e., cone, partial-cone, and 1,3-alternate), the formation of novel lower rim p-tert-butylthiacalix[4]arene derivative (cone, partial-cone, and 1,3-alternate) conformers in high yields (80, 95, and 85%, respectively) was achieved. The structure of isolated products was confirmed using different spectroscopic and analytical techniques such as FT-IR, H NMR, C NMR, and elemental analysis. Importantly, the synthesized receptors showed preferential uptakes of alkali (Na, K and Cs), heavy (Pb, Cd, Hg, and Ag) and transition (Ni, Co, and Cu) metal ions via liquid–liquid extraction method. The finding of this work adds new compounds to the growing family of thiacalix[4]arenes and validates their high sensitivity and selectivity in detection of heavy metal ions. INTRODUCTION Calix[n]arenes are bowl-shaped macrocyclic compounds that have been widely used in catalysis, molecular recognition, metal ion receptors, and sensors. Among the calixarene family, thiacalix[4]arenes are the most popular members as the presence of sulfur atoms in their structure HETEROCYCLES, Vol. 102, No. 1, 2021 81