. Author manuscript; available in PMC: 2009 Oct 2.

Published in final edited form as: Eur J Inorg Chem. 2007 Jul 31;2007(27):4340–4349. doi: 10.1002/ejic.200700354

Table 2.

Stability constants (log K) of DOTA-(amide)₄ complexes with selected divalent metal ions (I = 1.0 M KCl, T = 25 °C).

Ligand	Species	Mg²⁺	Ca²⁺	Cu²⁺	Zn²⁺
DOTAM	ML	4.65(4)	10.32(1)	14.50(1)	13.77(1)
			7.54^a	16.31^a	10.47^a
	MLH₋₁	–	–	8.41(4)	10.57(6)
	MLH₋₂	–	–	8.82(2)	–
DOTA-(MeAm)₄	ML	4.33(2)	10.11(1)	14.61(4)	13.66(2)
			9.47^b	14.12^b	13.00^b
	MLH₋₁	–	–	8.78(7)	10.71(3)
	MLH₋₂	–	–	10.31(6)	–
DOTA-(EtAm)₄	ML	4.49(1)	10.74(2)	16.40(8)	16.55(10)
	MLH₋₁	–	–	8.96(9)	10.86(10)
	MLH₋₂	–	–	11.27(9)	–
DOTA-(gly-OEt)₄^c	ML	3.97(7)	9.09(5)	17.18(9)	11.44(5)
DOTA^d	ML	11.15	16.37	22.72	18.17
	MHL	4.09	3.54	3.78	4.18
	MLH₋₁	–	–	10.54	10.62
DOTA-(gly)₄^e	ML	4.34	10.39	13.39	–
	MHL	–	4.23^f	4.38^f	–

Ref.[12]

Ref.[14,15]

The constant MLH_–1 cannot be evaluated for any of the metal ions studied due to slow hydrolysis of the ester bonds.

Ref.[20]

Ref.[11]

Three and two more protonated species are known for the Ca²⁺ and Cu²⁺ complexes, respectively (protonation of the acetate pendant arms).