中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | N,N′,N″-trimethyl-1,4,7-triazanonane | 25598-89-4 | C8H21N3 | 159.275 |
The reactivity of CoIII amine-thiolate complexes with terminal and bridging thiolate functions towards oxidizing agents has been investigated. The mononuclear CoIII N3S3 complex [CoIII(L1)] (2) (H3L1 represents the hexadentate ligand N,N′,N″-Tris(2-thio-benzyl)-1,1,1 -tris- (aminomethyl)ethane) featuring three terminal thiolate ligands, and the binuclear N3CoIII- (μ-S)3CoIIIN3 complex [CoIII 2(L2)]3+ (4) (H3L2 = N,N′,N″-Tris-[2-thio-3-aminomethyl-5-terrbutyl- benzyl]-1,1,1-tris(aminomethyl)ethane) featuring three bridging thiolates were selected. Hydrogen peroxide was the oxidizing agent. Whereas the thiolato-bridged complex 4 is resistant towards oxidation by hydrogen peroxide, 2 undergoes a ligand-based oxidation reaction to give the amine-sulfinate complex [Co(L1′)] 5, where all three terminal thiolates have been oxidized to sulfinates without gross structural changes of the parent complex 2. In contrast to 4, the cyclic voltammogram of 2 reveals an irreversible oxidation wave at E = +0.52 V vs SCE which can be attributed to a ligand-centered oxidation reaction. 4 and 5 have been structurally characterized by X-ray crystallography.
A number of polydentate arylamide ligands have been prepared by coupling various acyclic tripodal or linear polyamines with derivatives of nicotinic and picolinic acids. Two synthetic procedures were utilized; tris[(2-hydroxynicotinyl)carbonyl]-2-aminoethyl}amine (H3NICTREN) was prepared by Method A, the HOSu/DCC method, and the other arylamides in this study were prepared by Method B, the CDI method. Method A involved the reaction of N-hydroxysuccinimide with 2-hydroxynicotinic acid (in the presence of dicyclohexylcarbodiimide (DCC) as a dehydrative coupling reagent) to form the succinimide ester, followed by reaction with TREN to yield H3NICTREN. Method B involved reaction of a carboxylic acid (2-hydroxynicotinic, 3-hydroxypicolinic, nicotinic, or picolinic acids) with carbonyldiimidazole (CDI) to form the N-acylimidazolide, followed by reaction with the amine (TREN, TAME, spermidine, or TRPN) to yield the desired arylamide. The X-ray structure of 1,1,1-tris[(3-hydroxypicolinyl)carbonyl]-2-aminomethyl}ethane (H3PICTAME) was determined; crystals of H3PICTAME are monoclinic, a = 10.257(2), b = 15.572(3), c = 15.208(2) Å, β = 96.124(15)°, Z = 4, space group P21/a. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.041 and Rw = 0.038 for 2506 reflections with I >= 3 sigma (I). In the solid state, H3PICTAME contains an extensive hydrogen-bonding network, with eight intra- and one intermolecular H-bonds per molecule; the ligand is partially preorganized for metal ion chelation. The acid dissociation constants of H3NICTREN and those of 1,1,1-tris[(2-hydroxynicotinyl)carbonyl]-2-
aminomethyl}ethane (H3NICTAME) have been determined; pKa1 = 11.2 (10.68), pKa2 = 10.7 (10.58), pKa3 = 10.0 (9.71), and pKa4 = 6.25 for H3NICTREN (H3NICTAME); the high phenolic pKa's are consistent with the hydrogen bonding observed in the solid state.Key words: arylamide, hydrogen bonding, preorganization.
TAME5OX can act as a good candidate with potential applications in chemical and biological fields. Fluorescence reduction due to ESIPT between protonated NH+ ∼ –OH and deprotonated N ∼ –O− forms was proven by DFT calculation.