We report here the efficient reduction of CO2 to CO by cobalt aminopyridine macrocycles. The effect of the pendant amines on catalysis was investigated. Several cobalt complexes based on the azacalix[4](2,6)pyridine framework with different substitutions on the pendant amine groups have been synthesized (R = H (1), Me (2), and allyl (3)), and their electrocatalytic properties were explored. Und...

Biphenols are important structure motifs for ligand systems in organic catalysis and are therefore included in the category of so-called "privileged ligands". We have developed a new synthetic pathway to construct these structures by the use of selenium dioxide, a stable, powerful, and commercially available oxidizer. Our new, and easy to perform protocol gives rise to biphenols and diaryl sele...

The title compound, C(24)H(32)N(2)O(4), is a polydentate Schiff base and reveals strong intra-molecular O-H⋯N hydrogen bonding between the hy-droxy O atom and the imino N atom, with an O⋯N distance of 2.570 (3) Å. In the crystal, a centre of inversion is located at the mid-point of the compound. The diimino-hexyl-ene chain is almost ideally in the anti conformation, with an average dihedral ang...

Catalytic asymmetric oxidation-chemistry involving heteroatom transfer from a reagent to a substrate is perhaps unparalleled in synthetic utility for the construction of enantioenriched materials.[1] Conversely, there is a significant deficiency of asymmetric two-electron oxidations that do not involve heteroatom transfer. Some potentially valuable reactions of this type include the oxidation o...

Abstract Catalysis by first-row transition metals is of increasing interest in the context scarcity chemical resources. For instance, iron promising due to its abundance, low toxicity and unique electronic features. Here we synthesized quinazoline alkaloids from alkynoic acids functionalized amines presence dibromide pyridine toluene or, alternatively, a solventless reaction system. We studied ...

The second-order rate constants for reaction of the Mg2+ complexes of phosphorylated pyridine monoanions with Mg(OH)+ a re 104-106-fold larger than the second-order rate constants for their reaction with water (25 OC, ionic strength 1.5). Of the 106-fold rate enhancement with the phosphorylated 4morpholinopyridine/Mg2 complex, 1 04-fold is attributed to the greater nucleophilicity of Mg(OH)+ co...

The tris(2-pyridyl)phosphine oxide (Py3PO) complex [Ru(Py3PO)(bpy)(OH2)]2+ (bpy is 2,2'-bipyridine) is a pH-dependent water oxidation electrocatalyst that accelerates dramatically with increasing pH-up to 780 s-1 at pH 10 (∼1 V overpotential). Despite retaining the pentakis(pyridine) ligand arrangement common to previously reported catalysts, the tripodal Py3PO ligand framework supports much fa...

A series of cobalt complexes with pentadentate pyridine-rich ligands is studied. An initial Co(II) amine complex 1 is prone to aerial oxidation yielding a Co(III) imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N-methyl protecting group to the ligand inhibits this oxidation and gives rise to the Co(II) species 5. Both the C...

As alternative energy sources are essential to reach a climate-neutral economy, hydrogen peroxide (H2O2) as futuristic carrier gains enormous awareness. However, seeking for stable and electrochemically selective H2O2 ORR electrocatalyst is yet challenge, making the design of—ideally—bifunctional catalysts extremely important outmost of interest. In this study, we explore application trimetalli...

An amine-catalyzed reaction has been discovered that couples alpha-allenic esters with N-acyl imines in good to excellent yields (up to 88%). Extension of this methodology from the study of achiral pyridine-based catalysis to chiral peptide-based scaffolds is presented. The approach culminated in the identification of a tetrameric peptide sequence containing an embedded pyridylalanine (Pal) res...