title: Aggregation properties of bis(salicylaldiminato)zinc(II) Schiff-base complexes and their Lewis acidic character.
abstract: The synthesis, characterization, (1)H NMR, optical absorption and fluorescent properties of a series of amphiphilic Schiff-base bis(salicylaldiminato)zinc(II) complexes are reported. Detailed (1)H NMR, DOSY NMR, optical absorption and fluorescence spectroscopy studies indicate the existence of aggregate species in solutions of non-coordinating solvents. The degree of aggregation is related to the nature of the bridging diamine. Chloroform solutions of complexes where the bridging diamine contains a naphthalene or the pyridine nucleus are always characterized by the presence of defined dimer aggregates, whereas oligomeric aggregates are likely formed by complexes where the bridging diamine contains a benzene ring. In coordinating solvents or in the presence of coordinating species, a complete deaggregation of the complexes occurs, because of the axial coordination to the Zn(II) ion, accompanied by considerable changes in the (1)H NMR and optical absorption spectra. The effect of the alkyl chains length seems to play a minor role in the aggregation properties, as noticed by (1)H NMR data, optical absorption and fluorescence spectra, which remain almost unaltered on changing the chain length.
authors: Dipartimento di Ingegneria Industriale e Meccanica, Università di Catania, I-95125, Catania, Italy.
authors: Giuseppe
authors: G
authors: Consiglio
authors: Salvatore
authors: S
authors: Failla
authors: Paolo
authors: P
authors: Finocchiaro
authors: Ivan Pietro
authors: IP
authors: Oliveri
authors: Santo
authors: S
authors: Di Bella
mesh_terms: D058116:Lewis Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D058116:Lewis Acids; D009942:Organometallic Compounds; D012545:Schiff Bases; D013501:Surface-Active Agents; C572363:bis(salicylaldiminato)zinc(II)