2-Picolyl-amine

Chromium(II) complexes of bipyridyls, terpyridyl and the phenanthrolines have been discussed in Section 35.2.2.1. Complexes of the ligands 2-aminomethylpyridine (pic, 2-picolyl-amine) and 8-aminoquinoline (amq), which have one heterocyclic and one amino nitrogen donor atom, have been prepared by methods similar to those in Scheme 10. The bis(amine) complexes are typical high-spin, distorted octahedral complexes, and the mono(amine) complexes, from their antiferromagnetic behaviour and reflectance spectra, are six-coordinate, halide-bridged polymers (Table 15).103 No tris(amine) complexes could be prepared so the attempt to find spin isomeric systems in octahedral chromium(II) systems was unsuccessful ([Cr(en)3]X2 are high-spin and [Cr(bipy)3]X3 and [CrX2(bipy)2] low-spin). 

The methanolysis of amides of N,N-di(2-picolyl)amine (Scheme 12) also illustrates the leaving group effect.216 Addition of the p-nitrophenyl derivative to a hot solution of CuCl2 in methanol... 

Macroporous glycidyl methacrylate-ethylene glycol dimethacrylate (GMA-EGDM) copolymer beads were synthesised and characterised for pore volume and surface area. These reactive copolymers were derivatised with 2-picolyl amine and coordinated with chromium and vanadium ions. The peroxocomplexes of these supported metal complexes were generated by the addition of hydrogen peroxide / tertiary butyl hydroperoxide(tert. -BHP) and shown to catalyse a variety of oxidation reactions. 

GMA-EGDM copolymer beads were synthesised as reported earlier [16]. The surface area and pore volume were determined by mercury porosimetry. 2-Picolyl amine copolymers were generated by reacting 17 mmole of 2-picolyl amine with 5g (8.5 mmole) of GMA-EGDM copolymer in ethanol at 70°C for 24 hours. 

The GMA-EGDM copolymer was synthesised from a GMA EGDM molar feed ratio of 31.5 68.5. The crosslinking density of the copolymer beads was 128%. Particle size of copolymer was in the range of 250-420 pm and the surface area estimated by single point BET method was 152 M / g. The pore volume estimated by mercury porosimetry was 0.74 cm /g. The polymer bound 2-picolyl amine was generated by the reaction of 2-picolyl amine... 

Other ligands incorporated into oligonncleotides that showed cleavage activity npon addition of metal ions inclnde bpy (2,2 -bipyridine) [ 122-124], tpy (2,2 6, 2"-terpyridine) [122,124-127], and 2,6-dicarboxypicoline or AA -bis(2-picolyl)amine [128, 129]. 

Kim aud coworkers explored a known receptor 2,6-bis(bis(2-pyridylmethyl)aminomelhyl)-4-meihyl-phenol (H-bpmp) for naked-eye detection of phosphate anion in aqueous solution." Zn + coordination with bis(2-picolyl)amine (Dpa) together with the formation of a phenoxo-bridged dinuclear metal complex (32) affords the anion binding pocket The pH-sensitive dye pyrocatechol violet (8) was chosen as the indicator for the competition assay. When [Zn2(H-bpmp)] + was titrated into a solution of 8 at pH 7.0, the solution color changed from yellow (444 nm) to blue... 

The bis(2-picolyl)amine (Dpa) unit designed for zinc complexation has also been incorporated into various receptors for pyrophosphate sensing and detection. Smith and coworkers studied a series of dinuclear zinc receptors (34, 35, and 36) and found that receptor 35 shows high selectivity and affinity for pyrophosphate under physiological conditions. " Other receptors with only one appended Dpa arm (34) or jiara-substituted Dpa arms (36) show no binding toward pyrophosphate. The binding constant for this receptor with pyrophosphate and phosphate was determined to be 1.52 X 10 and 7.3 x 10 M , respectively. A fluorescent IDA was developed for pyrophosphate using a coumarin-derived indicator 37. A more recent study... 

Acyclic tridentate nitrogen donor ligands are able to occupy three facial or meridional coordination sites of Pt complexes. Protonation of the dimethylplatinum(ii) complex of bidentate bis(2-picolyl)amine 1010 and... 

The mechanism of the Cu(II)-promoted methanolysis of A-acyl derivatives of AA-bis(2-picolyl)amine (119) has been thoroughly investigated by a kinetic study of the Cu(n) complex of the A-acetyl derivative (120) in MeOH at a range of pH values at 298 K. The mechanism, which is supported by DFT calculations, involves initial replacement of the triflate groups by two molecules of MeOH to yield a complex (121), which upon deprotonation to (121 ) facilitates an intramolecular attack by MeO to form a tetrahedral intermediate (122), which collapses to a square planar complex (P) and... 

Our own studies on these systems started with an investigation of the Cu -promoted methanolysis of substituted N-benzoyl-N,N-bis(2-picolyl) amides (41a—g) under pH-controlled conditions. The preliminary studies with 40 (R = CH3), formed in situ by the addition of a slight excess of Cu(OTf)2 to a buffered methanol solution of N-acetyl-N,N-bis(2-picolyl)amide, involved determining the kinetics of methanolysis as a function of pH. The plot of the log kots versus pH profile is bowed downward indicative of a saturation process that suggests the active form is the mono-methoxylated species 40a (R = CH3, formed by ionization of a Cu -bound methanol in 40 having a kinetic pK of <6.5) that spontaneously decomposes to methyl-p-nitrobenzoate and Cu -complexed N,N-bis(2-picolyl)amine (P or Cu DPA) as in Eqn (8). Further mechanistic studies shed additional hght on the catalytic pathway from three sets of data (1) A plot of the log kmax versus values of the substituents on 41... 

Metal Ion-Promoted LGA In Bis(2-picolyl)amine-Derlved Ureas and Carbamates 4.2.1 Ureas... 

It is also notable that the cleavage reactions occur in a variety of other organic solvents and water. To estabhsh a relative rate of each process, we placed one equivalent each of 45a, Cu(OTf2), and methoxide (along with 0.2% of methanol from the stock solutions of metal ion and base) into the various solvents and determined the reaction rates that varied by 150-fold over the series ethanol (0.70 s ) > methanol > 1-propanol > 2-propanol > acetonitrile > water (0.0046 s ). In the case of water, the hydrolysis products were Cu bis(2-picolyl)amine and p-nitroaniline, the latter probably being formed by spontaneous decarboxylation of the first-formed hydrolytic product, 48, as in Eqn (10). This latter result is important since the metal ion-promoted hydrolysis of ureas in aqueous solution is a very challenging problem due to the high solvation of the metal ion by water and difficulties in its bimolecular complexation of the very stable urea. 

Belzde M-N, Neverov AA, Brown RS. Cu(II) ion catalyzed solvolysis of N,N-bis(2-picolyl)ureas in alcohol solvents evidence for a cleavage involving nucleophilic addition and strong assistance of bis(2-picolyl)amine leaving group departure. Inorg Chem. 2014 53 7916-7925. 

Copper-catalyzed azide-alkyne cycloaddition has been used to couple the phenazine luminescent probe and an Af,Af-bis(2-picolyl)amine moiety in a 75% yield by using copper acetate (0.01 mol%) and sodium ascorbate in CH3CN/H2O (10 1) [94]. The cycloaddition of l,3-diethynyl-6-fluoroisoquinohne with 1-(2-azidoethyl)pyrrohdine has been applied to the synthesis of a soluble click fluorescent chemosensor (Scheme 3.5). The molecule displays good sensitivity toward heavy and transition metal ions such as Fe ", or Cu in water at pH 7.0 [95]. 

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