Polynuclear lanthanide complexes of a series of bridging ligands containing two tridentate N,N’,O-donor units: structures and luminescence properties was written by Ronson, Tanya K.;Adams, Harry;Harding, Lindsay P.;Pope, Simon J. A.;Sykes, Daniel;Faulkner, Stephen;Ward, Michael D.. And the article was included in Dalton Transactions in 2007.Quality Control of 6-Acetylpicolinic acid This article mentions the following:
A set of three potentially bridging ligands containing two tridentate chelating N,N’,O-donor (pyrazole-pyridine-amide) donors separated by an o- (I = L2), m- (L3), or p-phenylene (L1) spacer has been prepared and their coordination chem. with lanthanide(III) ions investigated. Ligand L1 forms complexes with a 2:3 M:L ratio according to the proportions used in the reaction mixture The Ln2(L1)3 complexes contain two 9-coordinate Ln(III) centers with all three bridging ligands spanning both metal ions and have a cylindrical (non-helical) ‘mesocate’ architecture. The 1:1 complexes display a range of structural types depending on the conditions used including a cyclic Ln4(L1)4 tetranuclear helicate, a Ln2(L1)2 dinuclear mesocate and an infinite one-dimensional coordination polymer in which metal ions and bridging ligands alternate along the sequence. ESMS studies indicate that the 1:1 complexes form a mixture of oligonuclear species {Ln(L1)}n in solution (n up to 5) which are likely to be cyclic helicates. In contrast, ligands L2 and L3 generally form dinuclear Ln2L2 Ln(III) complexes in which the two ligands may be arranged in a helical or non-helical architecture about the two metal ions. These complexes also contain an addnl. exogenous bidentate bridging ligand, either acetate or formate, which has arisen from hydrolysis of solvent mols. promoted by the Lewis-acidity of the Ln(III) ions. Luminescence studies on some of the Nd(III) complexes showed that excitation into ligand-centered 锜?锜? transitions result in the characteristic near-IR luminescence from Nd(III) at 1060 nm. In the experiment, the researchers used many compounds, for example, 6-Acetylpicolinic acid (cas: 122637-39-2Quality Control of 6-Acetylpicolinic acid).
6-Acetylpicolinic acid (cas: 122637-39-2) belongs to pyridine derivatives. Pyridine has a conjugated system of six 锜?electrons that are delocalized over the ring. The molecule is planar and, thus, follows the H鐪塩kel criteria for aromatic systems. Pyridine, its benzo and pyridine-based compounds play diverse roles in organic chemistry. Pyridine-based materials are valued for their optical and physical properties as well as their medical potential. Quality Control of 6-Acetylpicolinic acid