83809-94-3Relevant academic research and scientific papers
Influencing the stability of diaminomethane-containing azacrown ether ligands in the presence of transition-metal ions
Gee, William J.,Batten, Stuart R.
, p. 3240 - 3248 (2013)
The evaluation of a new azacrown ether ligand bis{[3-(pyridin-4-yl)-1H- pyrazol-1-yl]methyl}diaza-18-crown-6 (b3pd), which contains pendant p-pyridylpyrazole arms connected by diaminomethane linkers, identified a tendency to undergo retro-Mannich fragmentation in the presence of transition-metal ions. However, treatment of b3pd with potassium perchlorate or potassium iodide prior to complexation with transition-metal ions imparted a resistance to fragmentation, such that crystallisation of coordination polymers from concentrated solutions after several weeks was possible. Four solid-state structures containing Kb3pd were isolated: a perchlorate salt (1), a divalent manganese 1D coordination polymer [Mn(Kb3pd)(DMF)4]·2ClO 4·I3 (2, DMF = N,N-dimethylformamide), a cuprous 2D coordination network [Cu2(Kb3pd)2(I3)(I) 3]·3H2O (3) and a cuprous 1D coordination polymer [Cu(Kb3pd)(I)2] (4). Additionally, the retro-Mannich process was investigated by in situ FTIR spectroscopy, mass spectrometry, crystallography and by the isolation of a cobalt complex ligated by a partially fragmented ligand, mono{[3-(pyridin-4-yl)-1H-pyrazol-1-yl]methyl}diaza-18-crown-6 (m3pd). The composition of the cobalt complex was found to be [CoCl3(Hm3pd)] ·H2O (5). Diaza-18-crown-6 ligands functionalised with diaminomethane linkers are unstable in the presence of selected divalent transition-metal ions. Pretreatment of the ligands with potassium salts prevents degradation by blocking the central coordination region. Iodide redox chemistry also affects the coordination-polymer motif. Copyright
Azacrown ethers containing oximic an Schiff base sidearms - Potential heteronuclear metal ion receptors
Bordunov, Andrei V.,Bradshaw, Jerald S.,Pastushok, Victor N.,Zhang, Xian X.,Kou, Xiaolan,Dalley, N. Kent,Yang, Zhaoxia,Savage, Paul B.,Izatt, Reed M.
, p. 17595 - 17606 (2007/10/03)
A simple synthetic pathway for the preparation of oxime- and Schiff base-containing aza- and diazacrown ethers is reported. N-Methoxymethyl-substituted aza-15-crown-5 and aza-18-crown-6 as well as N,N'-bis(methoxymethyl)-substituted diaza-18-crown-6 were treated with 5-bromosalicylaldehyde to produce the N-(2'-hydroxy-3'-carbonyl-5'-bromobenzyl)-substituted aza-15-crown-5 (8), aza-18-crown-6 (9) and N,N'-bis(2'-hydroxy-3'-carbonyl-5'-bromobenzyl)-substituted diaza-18-crown-6 (10) compounds. Compounds 8 and 10 were treated with hydroxylamine to give oxime-substituted ligands 12 and 13. A series of bis-Schiff base-containing diaza-18-crown-6 ligands were prepared by reacting 10 with 2-hydroxyaniline (to form 14), 5-nitro-2-hydroxyaniline (15), 2-aminopyridine (16), 2-hydrazinopyridine (17) and N-aminomorpholine (18). Compounds 12-18 are potential complexing agents for simultaneous binding of soft transition and hard alkali or alkaline earth metal ions in one molecule. These new oxime- and Schiff base-containing ligands interacted strongly with Na+ and K+ in methanol. The interaction of the aromatic portions of 9, 10, and 12-15 with transition metal ions was shown by the UV spectra of the metal ion complexes in 50% aqueous DMF. The X-ray structure of 10 is reported.
