74331-73-0Relevant academic research and scientific papers
Chiral probe development for circularly polarised luminescence: Comparative study of structural factors determining the degree of induced CPL with four heptacoordinate europium(III) complexes
Neil, Emily R.,Fox, Mark A.,Pal, Robert,P?lsson, Lars-Olof,O'Sullivan, Benjamin A.,Parker, David
, p. 14937 - 14951 (2015/08/24)
A series of bright, europium(iii) complexes has been prepared based on an achiral heptadentate triazacyclononane ligand bearing two strongly absorbing, coordinated aralkynyl pyridyl moieties. The binding of chiral carboxylates, including α-hydroxy acids such as lactate and mandelate, has been monitored by emission spectroscopy and is signalled by the switching on of strong circularly polarised emission. In each case, an R-chiral carboxylate gave rise to emission typical of a Δ complex, most clearly shown in the form of the ΔJ = 4 transition manifold around 700 nm. Variations in the sign and magnitude of the CPL allow the enantiomeric purity and absolute configuration of the acid to be assessed in a sample. Analysis of the relative energies of the parent aqua complexes and their stereoisomeric adducts has been aided by lifetime measurements and density functional theory calculations.
Linear bilateral extended 2,2′:6′,2′′-terpyridine ligands, their coordination complexes and heterometallic supramolecular networks
Veliks, Janis,Tseng, Jui-Chang,Arias, Karla I.,Weisshar, Florian,Linden, Anthony,Siegel, Jay S.
, p. 4317 - 4327 (2015/01/08)
Octahedral metal complexes of tridentate 2,2′:6′,2′′-terpyridine (terpy) fused with five-membered furan rings mimic the topology of tetrahedral metal complexes of bidentate 5,5′-functionalized 2,2′-bipyridine (bipy). Herein, we report the robust synthesis of 2,6-bis(2-substituted-furo[2,3-c]pyridine-5-yl)pyridine based ligands to access a series of linear bilateral extended terpy derivatives. This molecular design of alternating five- and six-membered rings has been applied to extend the applicability of terpy as a building block in supramolecular chemistry. The complexation of 2,6-bis(2-substituted-furo[2,3-c]pyridine-5-yl)pyridine derivatives with metal ions preferring octahedral geometry (Fe2+, Ru2+, and Zn2+) gives molecular "crossings" and "corners". Such design elements, functionalized with 4-pyridyl groups, allowed the construction of 3D and 2D heterometallic supramolecular networks containing Fe2+, Ag+or Fe2+, Cu+metal centers.
Vinyl Cation Intermediates in Solvolytic and Electrophilic Reactions. 1. Solvolysis of α-Arylvinyl Derivatives
Yates, Keith,Mandrapilias, George
, p. 3892 - 3902 (2007/10/02)
The solvolysis of 16 α-arylvinyl tosylates, bromides, and chlorides has been investigated in various alcohol-water mixtures and in acetic acid at several temperatures.All substrates were substituted with either 2-methyl or 2,6-dimethyl groups to accelerate the rates of reaction.The major or exclusive product isolated in most cases was the acetophenone arising from hydrolysis of the expected enol ethers or acetates during workup.The kinetics were simple first order in the vast majority of cases, with excess base added to prevent side reactions.Leaving group effects, Winstein-Grunwald m values, Schleyer Q values, and effects of solvent nucleophilicity all point to a limiting SN1 ionization generating a vinyl cation intermediate, in which there is little rear-side nucleophilic assistance by solvent.Substituent effects led to ρ values in the range -3.9 to -5.3 vs. ?+.Activation parameters are typical for an SN1 process, and ΔS% is insensitive to the presence of zero, one, or two o-methyl groups, as are the effects of solvent polarity on the rates.The results should therefore be directly comparable with other solvolytic or electrophilic reactions generating formally similar vinyl cation intermediates.
