[{Re6Q8}(SO3)6]10– (Q = S or Se): Facile Synthesis and Properties of the Most Highly Charged Octahedral Cluster Complexes and High Magnetic Relaxivity of Their Colloids with Gd3+ Ions

• Published in: Inorganic chemistry Vol. 58; no. 23; pp. 15889 - 15897
• Main Authors: Brylev, Konstantin A, Akhmadeev, Bulat S, Elistratova, Julia G, Nizameev, Irek R, Gubaidullin, Aidar T, Kholin, Kirill V, Kashnik, Ilya V, Kitamura, Noboru, Kim, Sung-Jin, Mironov, Yuri V, Mustafina, Asiya R
• Format: Journal Article
• Language: English
• Published: American Chemical Society 02.12.2019
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b02346

New octahedral rhenium cluster complexes [{Re6Q8}­(SO3)6]10– (Q = S or Se) were synthesized starting from [{Re6Q8}­(H2O)4(OH)2]·12H2O. The complexes were crystallized as sodium salts and characterized by X-ray single-crystal diffraction and elemental analyses, IR, UV/vis and luminescence spectroscopies. Magnetic relaxation data demonstrate the complex formation of the cluster units with gadolinium ions. The analysis of the magnetic relaxation rates measured at various Gd:cluster ratios and different concentrations revealed the conversion of the aggregates (Gd x [{Re6Se8}­(SO3)6] y ) n− into a nanoparticulate form even at x = 1 and y ≥ 1. Thus, the self-assembly of the cluster units into the nanoparticles is greatly facilitated by counterion binding with sodium cations. The concentration conditions were optimized for the formation and hydrophilization of Na x Gd y [{Re6Q8}­(SO3)6]-based colloids with the magnetic relaxivity values of r 1(2) = 21.0(24.1) and r 1(2) = 25.9(29.8) mM–1 s–1 for the {Re6S8}2+ and {Re6Se8}2+ derivatives, respectively.