Document Detail

Cucurbit[10]uril binding of dinuclear platinum(II) and ruthenium(II) complexes: association/dissociation rates from seconds to hours.
MedLine Citation:
PMID:  20148228     Owner:  NLM     Status:  MEDLINE    
A simpler method for the purification of cucurbit[10]uril (Q[10]) from the Q[10].Q[5] inclusion complex is reported. 1,12-Diaminododecane was used to displace Q[5], as opposed to the synthetic melamine derivative currently used. The binding of trans-[{PtCl(NH(3))(2)}(2)(micro-NH(2)(CH(2))(8)NH(2))](2+) (CT008) and [{Ru(phen)(2)}(2)(micro-bb(5))](4+) {phen = 1,10-phenanthroline; bb(5) = 1,5-bis[4(4'-methyl-2,2'-bipyridyl)]pentane} (Rubb(5)) to Q[10] was studied by (1)H NMR and luminescence spectroscopy, cyclic voltammetry and molecular modelling. The (1)H NMR resonances of the methylene protons in the bridging ligands of CT008 and Rubb(5) exhibited large upfield chemical shift changes upon addition of Q[10]. These shifts are indicative of encapsulation of the bridging ligand within the Q[10] cavity, with the metal centres positioned outside the portals. (1)H NMR-based kinetics experiments with Rubb(5) show the presence of a portal-bound intermediate which progresses to a completely encapsulated inclusion complex only after many hours. The large metal centres of Rubb(5) provide a restriction to the movement of the complex in and out of the cavity and result in binding kinetics that are slow on both the (1)H NMR and biological timescales. This result was consistent with molecular modelling simulations. Cyclic voltammetry showed that the Ru(III/II) couple of free Rubb(5) appeared at +1.058 V (vs Ag/AgCl), with the first ligand reduction observed as a shoulder ( approximately -1.38 V) on the edge of the solvent (water) front. The Q[10]-bound complex exhibited an anodic shift of 48 mV compared to the free metal complex. Luminescence spectroscopy of the binding of Rubb(5) to Q[10] yielded an approximate binding constant of 1.9 x 10(9) M(-1). Although CT008 was encapsulated within Q[10], the inclusion complex was not soluble in several buffers at pH 7.0. These results indicate that Q[10] is not an effective delivery vehicle for dinuclear platinum(II) anti-cancer drugs; however, due to the strong binding affinity and slow exchange rates, Q[10] does show considerable promise as a delivery mechanism for controlled slow release of large dinuclear ruthenium(II) complexes.
Michelle J Pisani; Yunjie Zhao; Lynne Wallace; Clifford E Woodward; F Richard Keene; Anthony I Day; J Grant Collins
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Publication Detail:
Type:  Journal Article     Date:  2010-01-07
Journal Detail:
Title:  Dalton transactions (Cambridge, England : 2003)     Volume:  39     ISSN:  1477-9234     ISO Abbreviation:  Dalton Trans     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-02-11     Completed Date:  2010-05-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101176026     Medline TA:  Dalton Trans     Country:  England    
Other Details:
Languages:  eng     Pagination:  2078-86     Citation Subset:  IM    
School of Physical, Environmental and Mathematical Sciences, University College, University of New South Wales, Australian Defence Force Academy, Campbell, ACT 2600, Australia.
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MeSH Terms
Coordination Complexes / chemical synthesis,  chemistry*
Diamines / chemistry
Macrocyclic Compounds / chemistry*
Magnetic Resonance Spectroscopy
Phenanthrolines / chemistry
Platinum / chemistry*
Ruthenium / chemistry*
Reg. No./Substance:
0/Coordination Complexes; 0/Diamines; 0/Macrocyclic Compounds; 0/Phenanthrolines; 0/cucurbituril; 2783-17-7/1,12-dodecamethylenediamine; 66-71-7/1,10-phenanthroline; 7440-06-4/Platinum; 7440-18-8/Ruthenium

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