188903-14-2Relevant academic research and scientific papers
A double-functionalized cyclen with carbamoyl and dansyl groups (cyclen = 1,4,7,10-tetraazacyclododecane): A selective fluorescent probe for Y3+ and La3+
Aoki,Kawatani,Goto,Kimura,Shiro
, p. 1123 - 1132 (2001)
A cyclen (=1,4,7,10-tetraazacyclododecane) doubly functionalized with three carbamoylmethyl groups and one dansylaminoethyl (dansyl = 2-(5-(dimethylamino)-1-naphthalenesulfonyl) group (L2 = 1-(2-(5-(dimethylamino)-1-naphthalenesulfonylamido)eth
Synthesis, relaxometric and photophysical properties of a new pH-responsive MRI contrast agent: The effect of other ligating groups on dissociation of a p-nitrophenolic pendant arm
Woods, Mark,Kiefer, Garry E.,Bott, Simon,Castillo-Muzquiz, Aminta,Eshelbrenner, Carrie,Michaudet, Lydie,McMillan, Kenneth,Mudigunda, Siva D. K.,Ogrin, Doug,Tircso, Gyula,Zhang, Shanrong,Zhao, Piyu,Sherry, A. Dean
, p. 9248 - 9256 (2007/10/03)
Two gadolinium(III) chelates, GdNP-DO3A (1-methlyene-(p-NitroPhenol)-1,4,7, 10-tetraazacycloDOdecane-4,7,10-triAcetate) and GdNP-DO3AM (1-methlyene(p- NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide), containing a single nitrophenolic pendant arm plus either three acetate or three amide pendant arms were synthesized and characterized. The properties of the gadolinium, terbium, and dysprosium complexes of these ligands were examined as a function of pH. The extent and mechanism of the changes in water relaxivity with pH of each gadolinium complex was found to differ substantially for the two complexes. The water relaxivity of Gd(NP-DO3A) increases from 4.1 mM -1 s-1 at pH 9 to 7.0 mM-1 s-1 at pH 5 as a result of acid-catalyzed dissociation of the nitrophenol from the lanthanide. The nitrophenol group in Gd(NP-DO3AM) does not dissociate from the metal center even at pH 5; therefore, the very modest increase in relaxivity in this complex must be ascribed to an increase in prototropic exchange rate of the bound water and/or phenolic protons.
A tris(Zn(II)-1,4,7,10-tetraazacyclododecane) complex as a new receptor for phosphate dianions in aqueous solution
Kimura, Eiichi,Aoki, Shin,Koike, Tohru,Shiro, Motoo
, p. 3068 - 3076 (2007/10/03)
A new tris(Zn(II)-cyclen) (Zn3L3), which has three Zn(II)-macrocyclic tetraamine (cyclen) complexes connected through a 1,3,5-trimethylbenzene spacer, has been synthesized as a novel receptor for organic phosphate dianions in aqueous solution (cyclen = 1,4,7,10-tetraazacyclododecane and L3 = 1,3,5-tris(1,4,7,10-tetraazacyclododecan-1-ylmethyl)benzene). The design of Zn3L3 was based on X-ray crystal structure analysis of the 1:3 complex of 4-nitrophenyl phosphate (NPP2-) with Zn(II)-cyclen (ZnL1) complex. The potentiometric pH titration of Zn3L3.3H2O revealed the deprotonation constants of the three Zn(II)-bound H2O molecules to be 6.1 (pK1), 7.3 (pK2), and 8.6 (pK3) at 25 °C with I = 0.1 (NaNO3). These three stepwise deprotonations and 1H NMR spectra changes at various pD values in D2O suggest that strong intramolecular hydrogen bonds link each adjacent Zn(II)-OH2 (or Zn(II)-OH-) at neutral pH in aqueous solution. At higher pH (> 9), the hydrogen bond network disrupts. The 31P NMR titration of Zn3L3.3H2O with phenyl phosphate dianion (PP2-) in D2O confirmed the formation of a 1:1 complex (Zn3L3-PP2-). By potentiometric pH titrations, the 1:1 complex affinity constants, log K(aff) (K(aff) = [phosphate complex]/[Zn(II) complex] [phosphate] (M-1)), were determined to be 5.8 with NPP2-, 6.6 with PP2-, 7.0 with α-D-glucose-1-phosphate, and 7.9 with phenyl phosphonate in aqueous solution. The tris(Zn(II)-cyclen) complex is found to be a much better host toward phosphates than the parent Zn(II)-cyclen (ZnL1) (log K(aff) = 3.3 for ZnL1-NPP2-) or a bis(Zn(II)-cyclen) linked with a m-xylene spacer (Zn2L2) (log K(aff) = 4.0 for Zn2L2-NPP2-).
