Oxo-Titanium(IV) Complex/Polymer Composites—Synthesis, Spectroscopic Characterization and Antimicrobial Activity Test

Abstract

The emergence of a large number of bacterial strains resistant to many drugs or disinfectants currently used contributed to the search of new, more effective antimicrobial agents. In the presented paper, we assessed the microbiocidal activity of tri- and tetranuclear oxo-titanium(IV) complexes (TOCs), which were dispersed in the poly(methyl methacrylate) (PMMA) matrix. The TOCs were synthesized in reaction to Ti(OR)4 (R = iPr, iBu) and HO2CR’ (R’ = 4-PhNH2 and 4-PhOH) in a 4:1 molar ratio at room temperature and in Ar atmosphere. The structure of isolated oxo-complexes was confirmed by IR and Raman spectroscopy and mass spectrometry. The antimicrobial activity of the produced composites (PMMA + TOCs) was estimated against Gram-positive (Staphylococcus aureus ATCC 6538 and S. aureus ATCC 25923) and Gram-negative (Escherichia coli ATCC 8739 and E. coli ATCC 25922) bacteria and yeasts of Candida albicans ATCC 10231. All produced composites showed biocidal activity against the bacteria. Composites containing {Ti4O2} cores and the {Ti3O} core stabilized by the 4-hydroxybenzoic ligand showed also high activity against yeasts. The results of investigations carried out suggest that produced (PMMA + TOCs) composites, due to their microbiocidal activity, could find an application in the elimination of microbial contaminations in various fields of our lives.

The Composites of PCL and Tetranuclear Titanium(IV)-oxo Complexes as Materials Exhibiting the Photocatalytic and the Antimicrobial Activity

“…Analysis of the literature data shows that photocatalytic activity of TOCs can be controlled by way of ligand functionalization, especially of carboxylate groups [21]. The results of our previous research on the photocatalytic activity estimation of composites, which contained PMMA and TOCs consisting of {Ti 4 O 2 } cores, confirmed this [17,18]. According to these reports, systems stabilized with 9-fluorenocarboxylate and 4-aminobenzonate ligands exhibited the best properties.…”

“…In general, the dispersion of (1) and (2) grains in PCL matrix slightly reduces the decomposition temperature of most investigated composites (2-5 • C), which can be associated with the decomposition of TOCs below 320 • C (in thermograms, the weak decomposition stage below 320 • C was found (Figure 5a). The exception was the PCL + 20(2), for which the decomposition temperature was decreased and their one-stage thermal decomposition proceeded between 260 and 420 • C. For PMMA composites, it can be seen that the decomposition process takes place in two stages, as described in the publication [18]. For comparison, TGA studies of PMMA and PMMA + 20TOCs (TOCs = (1) and ( 2)) samples revealed that addition TOCs grains decreased the first stage of thermolysis temperature and increased the second one (Figure 5c, Table 2).…”

“…Moreover, the rutile form revealed lower toxicity than the anatase particles [11]. The presence of organic ligands stabilizing the {Ti a O b } cores in the structures of oxo-complexes can work as a photosensitizer and lead to the absorption range widening towards the visible light [16][17][18]. Due to this effect, the electrons transfer distance decrease between HOMO-LUMO orbitals of the ligands and the {Ti a O b } core, and the energy of the absorption band is lower [16,19,20].…”

“…Therefore, in this case, the presence of the triclosan (as a hydrolysis product) can be seen as a main bactericidal factor. [18]. According to earlier reports, it should be noted that in order to produce a composite material with suitable microbicidal properties, the TOCs of a specific core structure {Ti a O b } and/or functionalized carboxylate ligands must be introduced to the polymer matrix.…”

“…In our studies, we have focused on studying the microbicidal activity of tetranuclear titanium(IV)-oxo complexes with high photocatalytic activity [17,18]. Synthesized compounds were dispersed in the poly(ε-caprolactone) (PCL) matrix.…”