Complex Compounds of Sm(III) with Chlorhexidine Synthesis, characterization, luminescent properties and antibacterial activity

Mirela Calinescu,Catalina Stoica,Mihai Nita-Lazar

doi:10.37358/rc.19.1.6840

Abstract

Three new samarium(III) complex compounds with chlorhexidine as ligand and mixed ligands chlorhexidine/o-phenanthroline have been prepared and characterized by elemental and thermogravimetrical analyses, infrared, electronic and luminescence spectra. The complexes corresponded to the formulas: [Sm(CHX)(NO3)2]� NO3, [Sm(CHX)(o-phen)2]� (NO3)3 and [Sm2(CHX)(o-phen)2(NO3)4]�(NO3)2, where CHX was the chlorhexidine. Chlorhexidine acted as neutral tetradentate NNNN donor, coordinating through the four imine nitrogen atoms. The two mixed ligands complexes showed a strong luminescent emission in solid state, characteristic of samarium(III) ion. The metal complexes and the chlorhexidine diacetate were in vitro evaluated for their antimicrobial activity against two Gram negative bacteria. The results revealed that all compounds were very effective in reducing the bacterial growth rate, even at low concentration.

Highlights

W[Sams(tChHe Xch)(lNorOh3e)x2]id’ NinOe3.,C[Shmlor(hCeHxXid)(inoe-pahcetned)2]a’s(NneOu3)tr3aalntedt[raSdme2n(CtaHteXN)(No-NpNhedno)n2(oNr,Oc3o)o4]r×di(nNaOti3n)g2, where CHX through the four imine nitrogen atoms
Literature survey revealed the absence of any reports on the interaction of chlorhexidine with lanthanide ions. Such complexes may be important for their antimicrobial action and for their possible fluorescent properties. Taking into account these aspects, we reported in this paper the synthesis, characterization, antimicrobial studies and luminescent properties of three complex compounds of samarium(III) with chlorhexidine
Infrared spectra The assignments of the important infrared bands of the chlorhexidine diacetate monohydrate and its samarium(III) complexes were listed in table 2

Summary

Introduction

W[Sams(tChHe Xch)(lNorOh3e)x2]id’ NinOe3.,C[Shmlor(hCeHxXid)(inoe-pahcetned)2]a’s(NneOu3)tr3aalntedt[raSdme2n(CtaHteXN)(No-NpNhedno)n2(oNr,Oc3o)o4]r×di(nNaOti3n)g2, where CHX through the four imine nitrogen atoms. The metal complexes and the chlorhexidine diacetate were in vitro evaluated for their antimicrobial activity against two Gram negative bacteria. The biguanides have a remarkable ability to form chelates with transition metal ions. This interaction is of the greatest importance for coordinative chemistry and many studies have been devoted to this field [5-9]. Many studies have focused on increasing the effectiveness of chlorhexidine when combined with metal ions. Several studies have demonstrated synergistic inhibitory effect of some metal ions, such as Zn2+, Ag+, Cu2+ or Sn2+ with chlorhexidine on various bacteria and fungi [13-16]. The antimicrobial screening in vitro has shown an increase of activity for most complexes comparatively with chlorhexidine

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