Syntheses, structural characterizations and properties of 12-MC-4 organotin(IV) metallacrowns: [12-MCRSn(IV)N(shi)-4] and [12-MCRSn(IV)N(Clshi)-4] (R = Et, Bu, Ph; H3shi = salicylhydroxamic acid; H3Clshi = 5-chlorosalicylhydroxamic acid)

Five 12-MC-4 organotin(IV) metallacrowns(MCs) with the types of [12-MCRSn(IV)N(shi)-4] (R = Et (1), Bu (2), Ph (3); H3Shi = salicylhydroxamic acid) and [12-MCRSn(IV)N(Clshi)-4] (R = Et (4), Bu (5), H3Clshi = 5-chlorosalicylhydroxamic acid) have been synthesized and characterized by elemental analyses, IR and TGA. X-ray single-crystal diffraction analyses were also carried out and showed that all complexes 1–5 contain a neutral 12-membered metallacrown ring which is formed by the succession of four repeating units of –[Sn–N–O]–, indicating the substituents on the tin(IV) atom are uninfluential in coordination of organotin(IV) centers with hydroxamic acid. Fluorescence properties of complexes 1–5 have been investigated, where complex 3 displays strong fluorescence emissions in the blue region. In addition, antitumor activities of complexes 4 and 5 have also been tested, and both the complexes exhibit weak activity towards human hepatocellular carcinoma cell line (Bel-7402) and Hela cell line.