New highly fluorescent silver complexes and their thin films obtained by spin coating method

Abstract

New silver complexes with ligands obtained from 2(2-pirydyl)ethylamine (epy) or o-phenylenediamine and series of aldehydes were obtained and characterized by their crystalline, molecular and spectroscopic (UV-Vis, fluorescence, IR, NMR) features. Molecular architecture of the synthesized complexes [Ag₂(epy(5-Brthca))₂(NO₃)₂] 1 and [Ag(bzim-anthr)₂]⁺NO₃⁻2 has been determined by X-ray crystal structure analysis. ¹H NMR NOE diff. spectra of Ag complexes reveal different ligand conformations in the solution and the solid state (crystal structure). Thin (13–113 nm average thickness), homogenous layers of the studied silver(I) complexes were obtained by the spin coating method. The new materials were also characterized with AFM, SEM/EDX and ellipsometry. Calculated band-gap energies related to conformational transitions in layers of complexes 3, 1 and 2 on Si(111) were 2.83 ± 0.02 eV (438 ± 3 nm), 2.90 ± 0.01 eV (428 ± 2 nm) and 2.95 ± 0.02 eV (420 ± 3 nm), respectively. The fluorescence bands of layers observed in the range 470–580 nm revealed significant intensity and were bathochromically shifted in comparison with those observed for the complexes solutions. Influence of polarity of the solvent on fluorescence properties of the obtained complexes was studied. The highest quantum yield of the fluorescence was achieved in methylene chloride for 2 with ϕ₂ = 0.52 (λ_ex = 335–385 nm) and is related to the anthracene moiety.