Synthesis and characterization of two polydentate pyridylamines, their acidified salts and late first-row transition metal complexes

Abstract

Synthesis and characterization of a new tripodal polydentate pyridylamine C L and an improved synthesis of analogue N L were developed.Acidified salts of the two polyamines ( C LH and N LH), one trizinc (1), and two monometallic complexes (2 and 3) were synthesized and structurally characterized.Protonation of the polyamines occurred at the pyridine N atoms, strongly supported by the hydrogen bonds between the cations and anions in the extended network. Structural analysis of the three complexes supported by N L demonstrated its versatile coordination modes. Graphic abstract:Convenient synthesis of two tripodal polydentate pyridylamines was accomplished.Structural analysis of their acidified salts determined that protonation of the polyamines occurred at the pyridine N atoms. Versatile coordination modes of one pyridylamine with late first-row transition metal atoms were also revealed.

Anticancer, antioxidant, and antimicrobial studies and molecular docking of a new hexanuclear Zn(ii) complex, together with its X-ray crystal analysis

“…Several metal complexes containing this ligand have been reported, including Cd, 36 Li, 37 and Ag, 38,39 all displaying a polymeric nature, and with Zn, 40 which forms a dimer. Additionally, there have been instances of compounds containing a trimeric Zn 3 (OH) 3 unit, [41][42][43][44][45] though none of these compounds exhibit hexanuclear characteristics. The bond lengths and angles of the present [L 3 Zn 6 (OH) 6 ][ClO 4 ] 6 •3MeOH, none of these compounds exhibit hexanuclear characteristics.…”

An efficient transition-metal-free route to oligo-α-pyridylamines via fluoroarenes

“…Inspirational to our work were literature methods for the synthesis of H 3 py 3 tren, which are summarized in Scheme S1 (Electronic Supporting Information). They are based on the prolonged heating of H 6 tren with 2-bromopyridine (Brpy) [22] or Fpy [31,32] and excess inorganic base (K 2 CO 3 [22,31] or Cs 2 CO 3 [32]) under inert atmosphere, so as to promote three consecutive arylations of H 6 tren primary amino groups. The reported procedures involve the use of DMSO [22] or acetonitrile [32] as solvents, or even solventless conditions [31] which facilitate the work-up step.…”

“…They are based on the prolonged heating of H 6 tren with 2-bromopyridine (Brpy) [22] or Fpy [31,32] and excess inorganic base (K 2 CO 3 [22,31] or Cs 2 CO 3 [32]) under inert atmosphere, so as to promote three consecutive arylations of H 6 tren primary amino groups. The reported procedures involve the use of DMSO [22] or acetonitrile [32] as solvents, or even solventless conditions [31] which facilitate the work-up step. The highest isolated yield (86%) was obtained using Fpy, K 2 CO 3 , and solventless conditions [31], presumably as a consequence of the greater electrophilicity of fluorinated versus brominated pyridines, hence the easier formation of an Fcontaining σ complex [23].…”

“…H 6 tren(dpa) 3 proved to be synthetically accessible in substantial yields under similar, but not identical, conditions to those used to prepare H 3 py 3 tren [22,31,32], as shown in Scheme 3a-c,e. Prolonged heating of H 6 tren, HBrdpa, and K 2 CO 3 (4.0 equiv.)…”

“…The first route (Scheme 1c) is similar to that in Scheme 1b and consists in heating NH 2 py, F 2 py, and t BuOK (1:1:1.6 MR) to 85 °C in toluene for three days. Surprisingly, the reaction proved to be significantly less efficient than with Br 2 py (∼45-50% isolated yield), despite the expectedly higher electrophilicity of fluorinated versus brominated pyridines [22,31,32]. The use of a larger excess of t BuOK (2.2 equiv.)…”