A Self-Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent

作者：Dehaen Geert; Eliseeva Svetlana V; Kimpe Kristof; Laurent Sophie; Vander Elst Luce; Muller Robert N; Dehaen Wim; Binnemans Koen; Parac Vogt Tatjana N^*

来源：Chemistry - A European Journal, 2012, 18(1): 293-302.

DOI：10.1002/chem.201101413

• gadolinium
• lanthanides
• magnetic resonance imaging
• self-assembly
• titanium

A ditopic chelating ligand (H64) that bears catechol and diethylenetriamine-N,N,N%26apos;,N%26apos;%26apos;,N%26apos;%26apos;-pentaacetate (DTPA) has been designed and shown to specifically bind lanthanide(III) ions at the DTPA core ([Ln(H24)(H2O)]-) and further self-assemble with titanium(IV), thereby giving rise to the formation of a supramolecular metallostar complex with a lanthanide(III)-to-titanium(IV) ratio of 3:1, [(Ln4)3Ti(H2O)3]5- (Ln=La, Eu, Gd). The efficacy of the metallostar complex as a potential bimodal optical/magnetic resonance imaging (MRI) agent has been evaluated. Nuclear magnetic relaxation dispersion (NMRD) measurements for the [(Gd4)3Ti(H2O)3]5- complex have demonstrated an enhanced r1 relaxivity that corresponds to 36.9 s-1?mM-1 per metallostar molecule at 20 MHz and 310 K, which is a result of a decreased tumbling rate. The ability of the complex to bind to human serum albumin (HSA) was also examined by relaxometric measurements. In addition, upon UV irradiation the [(Gd4)3Ti(H2O)3]5- complex exhibits broad-band green emission in the range 400750 nm with a maximum at 490 nm. Taking into account the high relaxivity and luminescence properties, the [(Gd4)3Ti(H2O)3]5- complex is a good lead compound for the development of efficient bimodal contrast agents.

• 出版日期2012-1