title: Rhenium(I) tricarbonyl complexes of salicylaldehyde semicarbazones: synthesis, crystal structures and cytotoxicity.
abstract: A series of N,N-disubstituted salicylaldehyde semicarbazones (SSCs), HOC(6)H(4)CHN-NHCONR(2), and their rhenium(I) tricarbonyl complexes, [ReBr(CO)(3)(SSC)], have been synthesised and characterised by IR and (1)H NMR spectroscopy. Crystallographic analysis of the complex [ReBr(CO)(3)(H(2)Bu(2))] (H(2)Bu(2)=SSC where R=Bu(n)) showed that the SSC acts as a bidentate ligand via its imino nitrogen and carbonyl oxygen atoms. The [ReBr(CO)(3)(SSC)] complexes exhibit moderate to high cytotoxicities towards MOLT-4 cells (IC(50)=1-24μM, cf. 18μM for cisplatin), and the majority of them are virtually non-toxic against non-cancerous human fibroblasts. Apoptotic assays of [ReBr(CO)(3)(H(2)Bnz(2))] (Bnz=benzyl) revealed that it mediates cytotoxicity in MOLT-4 cells via apoptosis. The complex [ReBr(CO)(3)(H(2)Bnz(2))] reacts with guanosine by proton transfer from the phenolic OH group to N(7) of guanosine. In (CD(3))(2)SO, [ReBr(CO)(3)(H(2)Bnz(2))] undergoes facile conversion to the dimeric complex, [Re(CO)(3)(HBnz(2))](2), via bromide dissociation.
authors.affiliation: Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Singapore.
authors.forename: Junming
authors.initials: J
authors.lastname: Ho
authors.forename: Wan Yen
authors.initials: WY
authors.lastname: Lee
authors.forename: Kelvin Jin Tai
authors.initials: KJ
authors.lastname: Koh
authors.forename: Peter Peng Foo
authors.initials: PP
authors.lastname: Lee
authors.forename: Yaw-Kai
authors.initials: YK
authors.lastname: Yan
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D012211:Rhenium / Q000737:chemistry*; D012664:Semicarbazones / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000970:Antineoplastic Agents; D056831:Coordination Complexes; D012664:Semicarbazones; C013243:salicylaldehyde; D012211:Rhenium