(S)-BINOL-derived chiral picolinate ligand as a platform for new polymer frameworks: a pilot study on the effect of the binaphthyl scaffold vs. picolinate

Abstract

This work proposes a graphical analysis based on a new chiral picolinate of the (S)-BINOL derivative, designated as the reference ligand L1. The models establish the influence of temperature on L1 and identify a new coordination polymer (CP) [Cu₂(pic)₂(OTf)₂(H₂O)₂(Py)]_n·2n(Py) 1·2(Py), where [Hpic = pyridine 2-carboxylic acid and pic = picolinate], as the predominant structure through the pathway in dioxane at room temperature or the known complex [Cu(pic)₂·2H₂O] 2·(H₂O)₂ at reflux in dioxane. This work provides a detailed description of the preparation method, the structural characteristics of the new CP containing the zinc complex [Zn₂(pic-Hpic)₃]_n·n(OTf) 3·(OTf), and density functional theory (DFT) calculations. Coordination polymer 1 2(Py) exhibits unusual magnetic properties at low temperature and high magnetic fields. This behavior may be associated with the presence of superparamagnetic particles or the influence of crystal field effects. In contrast, its origin is unlikely to be associated with common ferromagnetic impurities such as Fe, Co or Ni due to its characteristic high Curie temperature.