Spectroscopic Elaboration and Structural Characterizations of New Fe(III), Pd(II), and Au(III) Ampicillin Complexes: Metal-Antibiotic Ligational Behaviors

New Aspects Concerning the Ampicillin Photodegradation

New aspects concerning the photodegradation (PD) of ampicillin are reported by photoluminescence (PL), Raman scattering and FTIR spectroscopy. The exposure of ampicillin in the absence (AM) and in the presence of the excipient (AMP) to UV light leads to an intensity diminution of the photoluminescence excitation (PLE) and photoluminescence (PL) spectra and the emergence of a new IR band at 3450 cm⁻¹. The photoluminescence studies demonstrate that the AM PD is amplified in the presence of excipients and an alkaline medium. In this last case, the PD process of AM involves the emergence of new compounds, whose presence is highlighted by: (i) the emergence of the isosbestic point at 300 nm in the UV-VIS spectra; (ii) a change in the ratio between the absorbance of IR bands situated in the spectral ranges 1200–1660 and 3250–3450 cm⁻¹; and (iii) a change in the ratio between the intensities of the Raman lines localized in the spectral ranges 1050–1800 and 2750–3100 cm⁻¹. A chemical mechanism of the PD processes of AM in an alkaline medium is proposed.

Synthesis, spectroscopic, thermal, antimicrobial and electrochemical characterization of some novel Ru(iii), Pt(iv) and Ir(iii) complexes of pipemidic acid

Three new solid complexes of pipemidic acid (Pip-H) with Ru3+, Pt4+ and Ir3+ were synthesized and characterized. Pipemidic acid acts as a uni-dentate chelator through the nitrogen atom of the -NH piperazyl ring. The spectroscopic data revealed that the general formulas of Pip-H complexes are [M(L) n (Cl) x ]·yH2O ((1) M = Ru3+, L: Pip-H, n = 3, x = 3, y = 6; (2) M = Pt4+, L: Pip-NH4, n = 2, x = 4, y = 0 and (3) M = Ir3+, L: Pip-H, n = 3, x = 3, y = 6). The number of water molecules with their locations inside or outside the coordination sphere were assigned via thermal analyses (TG, DTG). The DTG curves refer to 2-3 thermal decomposition steps where the first decomposition step at a lower temperature corresponds to the loss of uncoordinated water molecules followed by the decomposition of Pip-H molecules at higher temperatures. Thermodynamic parameters (E*, ΔS*, ΔH* and ΔG*) were calculated from the TG curves using Coats-Redfern and Horowitz-Metzeger non-isothermal models. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were carefully used to assign properly the particle sizes of the prepared Pip-H complexes. The biological enhancement of Pip-H complexes rather than free chelate were assessed in vitro against four kinds of bacteria G(+) (Staphylococcus epidermidis and Staphylococcus aureus) and G(-) (Klebsiella and Escherichia coli) as well as against the human breast cancer (MCF-7) tumor cell line.