A New Series of Moisture Stable Metallacyclic Heteroleptic Titanium(IV) Complexes of 8-Hydroxyquinoline: Synthesis, Characterization, Stability Study and Cytotoxicity Evaluation

Abstract

A new series of moisture resistant metallacyclic titanium(IV) derivatives prepared from 8-hydroxyquinoline of the general formulae [(Q2)Ti{(L1)(L2OR)}] (3a-b, 3d-e), [(Q2)Ti{(L1)(L3)}] (3c and 3f) and [(Q2)Ti(L4)] (3g and 3h) is synthesized by interacting the precursor molecule [(Q2)Ti(OiPr)2] (2) with various 2-heteroaryl methyl ketone oximes and various alkoxyalkanols/2-hydroxypyridine or only with catechol/resorcinol in 1:1:1 or in 1:1 molar ratios in anhydrous boiling toluene (where, HQ = 8-hydroxyquinoline; iPr = isopropyl; L1H = HONC(Me)py-2/HONC(Me)fu-2; L2 = O-CH2-CH2-; R = CH3, C2H5; L3H = 2-hydroxypyridine and L4H = catechol/resorcinol). Stability study revealed that these molecules were stable for a period of 72 h. Mononuclear nature of the complexes was confirmed through mass spectral analysis. Thermogravimetric results explain the multistage fragmentation of the complexes at 900 ºC. NMR, FTIR, and UVvisible spectral data suggested that titanium-ligands attachment is in a hexa-coordinated manner. Additionally, all these molecules were tested for their tumour inhibiting potential against MDA-MB-231 human breast carcinoma cell line.