Abstract
In this work, synthesis, characterization and photophysical properties of trivalent rare earth complexes with a nonsteroidal anti-inflammatory drug [the indomethacinate (indo), presenting formulas RE(indo)3(H2O)x (x = 3, for Eu3+ and Gd+3, and x = 4 for Tb+3), RE(indo)3(bipy) and RE(indo)3(phen) (bipy: 2,2'-bipyridine, and phen: 1,10-phenanthroline)] were investigated. Based on photoluminescent results, the intramolecular energy transfer process from T1 triplet states of indo, phen and bipy ligands to the 5D0 emitting level of the Eu3+ ion in the coordination compounds is discussed. Accordingly, it is proposed two possible intramolecular energy transfer mechanisms between indomethacinate ligand and rare earth ions, which involve the participation of excited electronic states of the heterocyclic ligands as intermediate ones.
Highlights
In recent decades, metallotherapeutic drugs based on transition metal and trivalent rare earth ions have attracted considerable attention owing to their potential applications in medicine as anti-inflammatory,1 antitumor,2 antiproliferative,3 antifungal,4,5 antiviral6,7 and antimicrobial.8 Many of these compounds present enhanced biomedical activity, reduced toxicity1 and diminished collateral effects as compared with non-coordinated parent drugs
Elemental analysis data of the rare earth indomethacinate complexes are in agreement with the ratios metal:indo:water and metal:indo:heteroaromatic equal to 1:3:3 for hydrated complexes (1 and 2), 1:3:4 for hydrated complex [3] and 1:3:1 for rare earth complexes [4,5,6,7,8,9] which contain bipy and phen as ancillary ligands
Non-radiative rates (Anrad) were drastically decreased when water molecules were substituted by heterocyclic ligands, which improved significantly the emission quantum efficiencies of the complexes
Summary
Metallotherapeutic drugs based on transition metal and trivalent rare earth ions have attracted considerable attention owing to their potential applications in medicine as anti-inflammatory, antitumor, antiproliferative, antifungal, antiviral and antimicrobial. Many of these compounds present enhanced biomedical activity, reduced toxicity and diminished collateral effects as compared with non-coordinated parent drugs. Metallotherapeutic drugs based on transition metal and trivalent rare earth ions have attracted considerable attention owing to their potential applications in medicine as anti-inflammatory, antitumor, antiproliferative, antifungal, antiviral and antimicrobial.. Metallotherapeutic drugs based on transition metal and trivalent rare earth ions have attracted considerable attention owing to their potential applications in medicine as anti-inflammatory, antitumor, antiproliferative, antifungal, antiviral and antimicrobial.8 Many of these compounds present enhanced biomedical activity, reduced toxicity and diminished collateral effects as compared with non-coordinated parent drugs. The molecular structures of NSAIDs are characterized by the presence of chromophore groups and low-lying triplet state with energy in the range of 20,000-25,000 cm‐1, which may act as luminescent sensitizers for trivalent rare earth ions.. It is well-known that RE3+ ions play a wide range of roles in fluoroimmunoassay methods,
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