title: Inclusion complexes of the antitumour metallocenes Cp(2)MCl(2) (M = Mo, Ti) with cucurbit[n]urils.
abstract: The encapsulation of the aquated forms of molybdocene dichloride and titanocene dichloride by cucurbit[n]uril (Q[n], where n = 7 and 8) at different pD values has been studied by (1)H NMR spectroscopy and molecular modelling. (1)H NMR titration experiments indicate that both metallocenes form 1 : 1 host-guest complexes with both Q[7] and Q[8]. In these complexes, both the cyclopentadienyl ligands and metal centre are positioned deep within the cucurbituril cavity. In vitro cell proliferation studies using the cancer cell lines MCF-7 and 2008 showed that the encapsulated molybdocene complex was more active than the corresponding free metallocene, with GI(50) values of 210 and 400 muM respectively. However, unexpectedly the encapsulation of Cp(2)MoCl(2(aq))at pD 7 catalysed significant degradation of the cucurbituril framework in the presence of oxygen. Encapsulation of Cp(2)TiCl(2(aq)) by Q[7] greatly slowed the protonolysis of the cyclopentadienyl ligands in aqueous phosphate buffer (pD 7), while encapsulation in Q[8] only slightly retarded the hydrolytic degradation of the metallocene.
authors.affiliation: School of Physical, Environmental and Mathematical Sciences, University College, Australian Defence Force Academy, Canberra, ACT 2600, Australia.
authors.forename: Damian P
authors.initials: DP
authors.lastname: Buck
authors.forename: P Manohari
authors.initials: PM
authors.lastname: Abeysinghe
authors.forename: Carleen
authors.initials: C
authors.lastname: Cullinane
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Day
authors.forename: J Grant
authors.initials: JG
authors.lastname: Collins
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Harding
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D045744:Cell Line, Tumor; D006801:Humans; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum; D009942:Organometallic Compounds / Q000737:chemistry*; D014025:Titanium; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D000970:Antineoplastic Agents; D001952:Bridged-Ring Compounds; D007093:Imidazoles; D008982:Molybdenum; D009942:Organometallic Compounds; D014025:Titanium; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C507198:cucurbit(8)uril; C024389:molybdocene dichloride; C020528:titanocene dichloride