The School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, UK BT9 5AG.
Dalton Trans. 2012 Jun 21;41(23):7005-12. doi: 10.1039/c2dt12446g. Epub 2012 Apr 30.
The synthesis of two new tripodal complexes Ru(L3)(2) and Ru(L4)(2), encapsulating a ruthenium(II) cation, has been successfully achieved and the products fully characterized, including by X-ray structural determination. The smaller cavity, built around a tris(2-aminoethyl)amido scaffold demonstrated only moderate and predictable interactions with a range of anions and no significant spectroscopic change with nitrate, chloride and bromide, although dihydrogen phosphate did result in an almost stoichiometric precipitation. The expansion of the cavity to include the more rigid 1,3,5-benzenetricarbonylamide group creates a larger cavity, which shows a decrease in the emission on the introduction of chloride, bromide, hydrogen sulfate and nitrate salts, with the (1)H NMR titrations giving a surprisingly high binding affinity for nitrate over the smaller and simpler halides.
