Spectroscopic properties of lanthanoid benzene carboxylates in the solid state: Part 1

Europium and terbium complexes of benzoic acid (HBA), 9-anthracene carboxylic acid (9-HACA), 1-naphthoic acid (1-HNA), 2-naphthoic acid (2-HNA), cinnamic acid (HCA), o-phenylbenzoic acid (o-HPhBA), p-phenylbenzoic acid (p-HPhBA), o-methylbenzoic acid (o-HMeBA), m-methylbenzoic acid (m-HMeBA), p-methylbenzoic acid (p-HMeBA), p-tert-butylbenzoic acid (p-tertHBuBA), phthalic acid (H2Phth), isophthalic acid (H2-IsoPhth) and terephthalic acid (H2-TerePhth) were synthesised by aqueous metathesis reactions. The compositions were determined by microanalysis, DTA, and EDTA volumetric methods. Structural conclusions were drawn from powder XRD patterns and IR spectra. The optoelectronic properties were determined in the solid state, including reflectance, excitation, emission, and excitation efficiency, complemented by considering triplet state energies, which were derived from phosphorescence spectra of the corresponding gadolinium complexes. Besides the emission efficiencies, the splitting pattern of the 5D0 → 7FJ transitions of Eu3+ were used to derive structural information and the intensities relative to the 5D0 → 7FJ were used to gain information about the mechanism, adding electronic allowed dipole character to the forbidden emissions.