Green‐Emissive Zn2+ Complex Supported by a Macrocyclic Schiff‐Base/Calix[4]arene‐Ligand: Crystallographic and Spectroscopic Characterization. Issue 36 (12th September 2021)

• Record Type: Journal Article
• Authors: Ullmann, Steve; Börner, Martin; Kahnt, Axel; Abel, Bernd; Kersting, Berthold
• Is Part Of: European journal of inorganic chemistry. Issue 36(2021)
• Page Start: 3691
• Page End: 3698
• Publication Date: 2021-09-12
• Subjects: Calixarenes -- Photophysical properties -- Salicylaldiminato ligand -- Self-assembly -- Zinc; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202100442
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The macrocyclic calix[4]arene ligand H2 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 [ZnL]2 structures comprising two five‐coordinated Zn 2+ ions. The absorption and emission wavelengths are bathochromically shifted upon going from the liquid (λmax, abs (CH2 Cl2 )=404 nm, λmax, em (CH2 Cl2 )=484 nm) to the solid state (λmax, abs =424 nm (4 wt%, BaSO4 pellet), λmax, em =524 nm (neat solid)). Insights into the electronic nature of the UV‐vis transitions were obtained with time‐dependent density functional theory (TD‐DFT) calculations for a truncated model complex. Abstract : Zn 2+ complexes of hybrid bis(iminomethyl)phenol/calix[4]arene macrocycles dimerize in the absence of external coligands to afford bright green fluorescent complexes (λem =524 nm) The fluorescence enhancement is attributed to the inhibition of photo‐induced electron transfer processes in the Zn 2+ ‐bound bis(iminomethyl)phenolate chromophores.