Semi-synthetic antibiotics: Titanium(IV), zirconium(IV) and mercury(II) complexes of 6-amino penicillinic acid

Abstract

A number of organometallic derivatives involving 6-amino penicillinic acid ( I), of the types η 5-R) 2M- (Cl)L −Et 3NH + ( II), (η 5-R) 2M(Cl)L ( III) and R′HgL [R = cyclopentadienyl (C 5H 5), indenyl (C 9H 7), R′ = phenyl (C 6H 5), p-acetoxyphenyl ( p-CH 3COOC 6H 4), o-hydroxyphenyl ( o-HOC 6H 4), p-hydroxyphenyl ( p-HOC 6H 4); M = Ti(IV), Zr(IV); LH = 6-amino penicillinic acid] have been synthesized and characterized. Conductance measurements indicate that while the (η 5-R) 2M(Cl)L −Et 3NH + complexes are 1:1 electrolytes, the remaining compounds are non-electrolytes. From IR and UV spectral studies it is concluded that the penicillin moiety is bidentate. PMR and CMR studies support the stoichiometry of the complexes. Fluorescence studies have been carried out for o- and p-HOC 6H 4HgL complexes and relevant photochemical parameters have been elucidated. X-ray diffraction studies have been made for the o-HOC 6H 4HgL complex. For the C 6H 5HgL, p-CH 3COOC 6H 4HgL and p-HOC 6H 4HgL complexes, thermal studies (TG and DTA) have been carried out and kinetic parameters for thermal degradation have been enumerated. In addition, the fragmentation pattern of these complexes has been analysed on the basis of mass spectra. The C 6H 5HgL and p-CH 3COOC 6H 4HgL complexes show positive bactericidal activities.