Novel Water Soluble Symmetrical and Non-symmetrical 11th Group-NHC Complexes: Synthesis, Citotoxicity and SAR Study

As potential anticancer drugs, N-Heterocyclic Carbene (NHC) complexes constitute a recent and fruitful field of research. Our research group, during the last 5 years, has developed different classes of coinage metal-NHC complexes obtained from the precursors {[HB(RImH)3]Br2} (R = Benzyl, Mesityl and t-Butyl), {[H2B(BnTzH)2]Br}, {[H2B(pNO2BnTzH)2]Br}, {H2C(HTzR)2} and {H2C(HImR)2} (HTz = 1,2,4-triazole; HIm = imidazole; R = (CH2)3SO3- or (CH2)2COO-). Recently we have focused the research work on the development of new coinage metal-NHCs complexes obtained from the water soluble ligands Him1R,3RCl (R = COOCH3, COOCH2CH3 or CON(CH2CH3)2) or the zwitterionic water soluble precursor NaHIm1R,3R (R = (CH2)3SO3-). Here we report the synthesis of the novel zwitteronic symmetrical NHC ligands NaHIm1R,3R,4R’’ (R = (CH2)3SO3-, R’’ = H, CH3 or NO2), NaHBzim1R,3R (R = (CH2)3SO3-) and non-symmetrical NHC ligands NaHIm1R,3R’,4R’’ (R = (CH2)3SO3-, R’ = CH2C6H5, R’’ = H, CH3 or NO2), {[HBzim1R,3R’]Br} (R = (CH2)3SO3Na, R’ = CH2C6H5) and the related silver(I)-NHC complexes. Finally we report also the SAR study between the NHC complex classes developed by our research group.