Effect on pK_a of Metal-Bound Water Molecules in Lanthanide Ion-Induced Cyclen “Cavities”

Abstract

[reaction: see text] The macrocyclic cyclen conjugates 1-4 were synthesized with the aim of forming lanthanide ion-based macrocyclic conjugates possessing deep cavities, formed upon complexation to various lanthanide ions. These complexes all possess metal-bound water molecules, where the pKa of the water molecules depends on the nature of the cavity.

Synthesis and f-element ligation properties of NCMPO-decorated pyridine N-oxide platforms

“…17 Syntheses of the intermediate, 9 and its hydrochloride salt have been previously reported. 28,29 However, modifications used in the present study provide 9 with a slightly higher yield (94%), and the spectroscopic data are in good agreement with data in the literature. 28,29 The phosphine oxide, 10, was obtained as a solid, in good yield (86%), from an Arbusov reaction of 9 by using Ph 2 POEt in refluxing o-xylene.…”

Helical self-assembly of 2-(1,4,7,10-tetraazacyclododecan-1-yl)cyclohexan-1-ol (cycyclen)

“…Solid-state data also show that changes in the cyclen helicity accompany the encapsulation of metal ions by cyclen-based ligands (Custelcean et al, 2002;Gunnlaugsson, Brougham et al, 2004;Niu et al, 2004;Iitaka et al, 1974;Gunnlaugsson, Leonard et al, 2004). In this study, we report the solid-state structure of the title compound, (I), known as cycyclen, which may be viewed as a derivative of CyEA in which the ethanolamine fragment is replaced by the tetraaza macrocycle 1,4,7,10-tetraazacyclododecane (cyclen).…”

“…$ (Howard et al, 1998), interconverts diastereomers of cyclen-based lanthanide complexes. Cyclen ring helicities are dependent upon: (i) the steric demand of the N-alkyl substituents (Tzeng et al, 2006;Gunnlaugsson, Leonard et al, 2004;Gunnlaugsson, Brougham et al, 2004); (ii) the bridging of the macrocyclic framework (Niu et al, 2002(Niu et al, , 2004; (iii) C-alkylation of the macrocyclic backbone (Widlicka et al, 2002); and (iv) protonation of the macrocyclic amine N atoms (Warden et al, 2004).…”

Synthesis and Herbicidal Activities of 3‐(4‐Chloro‐2‐fluoro‐5‐substituted phenyl)benzo[d][1,2,3]triazin‐4(3H)‐one Derivatives

“…All solvents used in the reactions were distilled from appropriate drying agents prior to use. The starting materials, propargyl 2‐chloroacetate, S ‐ethyl 2‐chloroethanethioate, n ‐butyl 2‐chloroacetate, N‐(1‐cyano‐2‐methylpropan‐2‐yl)2‐chloroacetamide, N‐n ‐butyl‐2‐chloroacetamide, and 2‐chloro‐ N , N ‐diisopropylacetamide, have been reported previously, and alkyl chlorides (bromides and iodides), 2‐chloroallyl chloride, 3‐chloroallyl chloride, allyl bromide, propargyl chloride, 1‐(chloromethoxy)‐2‐methoxyethane, ethyl 2‐bromoacetate, and cyclopentyl chloroacetate were commercially available. 5‐Amino‐2‐chloro‐4‐fluoro phenyl ethyl carbonate A was prepared according to the reference .…”