956-00-3Relevant academic research and scientific papers
Solvent-controlled excited state behavior: 2-(2'-pyridyl)indoles in alcohols
Herbich,Hung,Thummel,Waluk
, p. 3508 - 3518 (1996)
Efficient fluorescence quenching caused by rapid internal conversion from the first excited singlet state is observed in alcohol solutions of 2-(2'-pyridyl)indoles, molecules which may simultaneously act as hydrogen bouding donors and acceptors. Electroni
Fac-Specific syntheses of homochiral [Fe(NN′)3] 2+ complexes (NN′ = pyridine keto-hydrazone); Origins of the stereoselectivity
Sebli, Cynthia Paul,Howson, Suzanne E.,Clarkson, Guy J.,Scott, Peter
experimental part, p. 4447 - 4454 (2010/07/04)
The 2-pyridinehydrazones (from condensation of pyridine-2-carbaldehyde and hydrazines) have previously been noted to have poor ligating ability as a result of a sterically demanding planar conformation. Destabilisation of this conformation is achieved through simple use of the ketohydrazones, and as a result the diamagnetic chiral tris-bidentate diimine complexes fac-[FeL 3]2+ are readily isolated. In the solid state, inter-ligand π-π stacking and complex/counter-ion H-bonding are apparent, and these features persist in solution according to dynamic NMR spectra, which also indicate extremely high stereoselectivity for the fac isomers (>200:1). The compounds crystallise as conglomerates, and time-resolved CD spectra of non-racemic samples indicate a high degree of persistence of chirality (racemisation t1/2ca 77 min). Variations of solvent and counter-ion indicate that H-bonding is unimportant in determining the structure of the cation. The fac-selectivity arises in the induction of a chiral conformation in the coordinated ligand, and the fact that such non-planar ligands can only be accommodated about the Fe(ii) centre if they all have the same absolute configuration. Adding a hydrazine N-methyl group increases the steric demand further, while retaining the novel non-planar conformation, and as a result paramagnetic chiral bis-bidentate complexes such as [FeL7 2(CH3CN)2]2+ are readily available.
