Roca-Sabio, Adrian published the artcileThe effect of ring size variation on the structure and stability of lanthanide(III) complexes with crown ethers containing picolinate pendants, Synthetic Route of 1128304-86-8, the publication is Dalton Transactions (2011), 40(2), 384-392, database is CAplus and MEDLINE.
The coordination properties of the macrocyclic receptor N,N’-bis(6-carboxy-2-pyridylmethyl)-1,10-diaza-15-crown-5 (H2bp15c5) towards the lanthanide ions are reported. Thermodn. stability constants were determined by pH-potentiometric titration at 25° in 0.1M KCl. A smooth decrease in complex stability is observed upon decreasing the ionic radius of the LnIII ion from La [log KLaL = 12.52(2)] to Lu [log KLuL = 10.03(6)]. Luminescence lifetime measurements recorded on solutions of the EuIII and TbIII complexes confirm the absence of inner-sphere H2O mols. in these complexes. 1H and 13C NMR spectra of the complexes formed with the diamagnetic LaIII metal ion were obtained in D2O solution and assigned with the aid of HSQC and HMBC 2-dimensional heteronuclear experiments, as well as standard 2-dimensional homonuclear COSY and NOESY spectra. The 1H NMR spectra of the paramagnetic CeIII, EuIII and YbIII complex suggest nonadentate binding of the ligand to the metal ion. The syn conformation of the ligand in [Ln(bp15c5)]+ complexes implies the occurrence of two helicities, one associated with the layout of the picolinate pendant arms (absolute configuration Δ or Λ), and the other to the five five-membered chelate rings formed by the binding of the crown moiety (absolute configuration δ or λ). A detailed conformational anal. performed with the aid of DFT calculations (B3LYP model) indicates that the complexes adopt a Λ(λδ)(δδλ) [or Δ(δλ)(λλδ)] conformation in aqueous solution The authors’ calculations show that the interaction between the LnIII ion and several donor atoms of the crown moiety is weakened as the ionic radius of the metal ion decreases, in line with the decrease of complex stability observed on proceeding to the right across the lanthanide series.
Dalton Transactions published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Synthetic Route of 1128304-86-8.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem