Green‐Emissive Zn ²⁺ Complex Supported by a Macrocyclic Schiff‐Base/Calix[4]arene‐Ligand: Crystallographic and Spectroscopic Characterization

Abstract The macrocyclic calix[4]arene ligand H 2 L comprises two non‐fluorescent 2,6‐bis‐(iminomethyl)phenolate chromophores, which show a chelation‐enhanced fluorescence enhancement upon Zn 2+ ion complexation. Macrocyclic [ZnL] complexes aggregate in the absence of external coligands via intermolecular Zn−N bonds to give dimeric structures comprising five‐coordinated ions. absorption and emission wavelengths are bathochromically shifted going from liquid (λ max,abs (CH Cl )=404 nm, λ max,em )=484 nm) solid state =424 nm (4 wt%, BaSO 4 pellet), =524 (neat solid)). Insights into electronic nature UV‐vis transitions were obtained with time‐dependent density functional theory (TD‐DFT) calculations for truncated model complex.