A new class of Selenium/tellurium-bearing alicyclic Schiff-base macrocycles of β-tellurocyclohexenal with 3,3'-seleno/tellurobis(propan-1-amine)

: A new series of 22- and 32-membered Schiff-base macrocycles containing both hard nitrogen (N) and soft tellurium (Te) donor atoms has been successfully synthesized through a template-free condensation strategy. The macrocycles were obtained by the reaction of β-tellurocyclohexenal with ethylenediamine and 3,3′-seleno-/tellurobis(propan-1-amine), leading to the efficient formation of structurally diverse chalcogen-containing macrocyclic frameworks. This synthetic approach provides a straightforward route to large-ring Schiff-base systems without the need for metal-ion templates, a common requirement in macrocycle synthesis. Notably, the methodology afforded a new class of homo- and heterochalcogen-containing alicyclic 32-membered Schiff-base macrocycles, designated as compounds 11 and 12. These unique macrocycles incorporate four chalcogen centers (Se and/or Te) within a single ring, representing rare examples of highly functionalized chalcogen-rich macrocyclic architectures. The presence of multiple chalcogen donor sites is expected to influence their coordination behaviour, electronic properties, and potential applications in supramolecular and coordination chemistry. The synthesized macrocycles were comprehensively characterized using a combination of spectroscopic and analytical techniques. Infrared (IR) spectroscopy confirmed the formation of the azomethine (C=N) linkage, while ¹H, and ¹³C NMR spectra provided detailed structural information. The incorporation of selenium and tellurium atoms was further verified by ⁷⁷Se and ¹²⁵Te NMR spectroscopy, and high-resolution mass spectrometry (HRMS) confirmed the molecular compositions of the newly synthesized macrocyclic compounds.