The isolation and purification of tris-2,2′-bipyridine complexes of ruthenium(ii) containing unsymmetrical ligands

Abstract

Monomeric ruthenium() complexes [Ru(L) 3 ] 2ϩ containing unsymmetric bipyridine ligands [Where L = 5-methyl-2,2Ј-bipyridine (L 1 ), 5-ethyl-2,2Ј-bipyridine (L 2 ), 5-propyl-2,2Ј-bipyridine (L 3 ), 5-(2-methylpropyl)-2,2Ј-bipyridine (L 4 ), 5-(2,2-dimethylpropyl)-2,2Ј-bipyridine (L 5 ) or 5-(carbomethoxy)-2,2Ј-bipyridine (L 6 )] have been studied and the meridional and facial isomers isolated by the use of cation-exchange column chromatography (SP Sephadex C-25) eluting with either sodium toluene-4-sulfonate or sodium hexanoate. The relative yield of the facial isomer was found to decrease with increasing steric bulk, preventing the isolation of fac-[Ru(L 5 ) 3 ] 2ϩ . The two isomeric forms were characterized by 1 H NMR spectroscopy, with the complexes [Ru(L 1-3 ) 3 ] 2ϩ demonstrating an unusually large coupling between the H 6 and H 4 protons. Crystals suitable for X-ray structural analysis of [Ru(L 1 ) 3 ] 2ϩ were obtained as a mixture of the meridional and facial isomers, indicating that separation of this isomeric mixture could not be achieved by fractional crystallisation. The optical isomers of the complex [Ru(L 3 ) 3 ] 2ϩ were chromatographically separated on SP Sephadex C-25 relying upon the inherent chirality of the support. It is apparent that chiral interactions can inhibit geometric isomer separation using this technique.

Beyond catalysis: N-heterocyclic carbene complexes as components for medicinal, luminescent, and functional materials applications

“…1 Despite this rapid evolution and the widespread attention these ligands have received, 20 application of NHCs in other areas has been scarce. This is particularly remarkable since NHCs combine a number of properties 2 of potential interest for the fabrication of materials (Fig.…”

Chiral recognition ability of cellulose derivatives bearing pyridyl and bipyridyl residues as chiral stationary phases for high-performance liquid chromatography

“…Enantioseparation on cellulose derivatives bearing pyridyl and bipyridyl groups Pyridinecarboxylic acid chlorides and 2,2¢-bipyridine-5-carboxylic acid chloride were synthesized according to reported procedures [27][28][29][30][31] and reacted with cellulose to obtain the derivatives 1a-d and 2-6 bearing pyridyl and bipyridyl residues, respectively. The derivatives 1-6 except for 1a were adsorbed onto aminopropyl silica gel, and the obtained packing materials were packed in stainless steel tubes by the slurry method.…”

“…Compound 10 (0.7 g) was stirred in SOCl 2 (40 ml) and the mixture was heated at 70 1C. 31 After 3 h, the remaining SOCl 2 was removed under reduced pressure. The obtained acid chloride 11 was used for the synthesis of cellulose derivatives without further purification.…”

“…31 After heating at 70 1C for 3 h and at 90 1C for 12 h, the mixture was filtered and washed with hot water. The pale pink filtrate was then slowly acidified with 1 M HCl to obtain a white precipitate.…”

Ru(II) Tris(bipyridyl) Complexes with Six Oligonucleotide Arms as Precursors for the Generation of Supramolecular Assemblies

“…Although [Ru(bpy) 3 ] 2+ exists in two enantiomeric forms, substitution at all three 4 and 4' sites results in an octahedral arrangement of the substituents in both enantiomers. First, enantiomerically pure DNA-[Ru(bpy) 3 ] 2+ conjugates should be attainable by appropriate chromatographic resolution of the Ru complexes as has been described for related ruthenium complexes, [30][31][32] followed by their incorporation into DNA conjugates. However, such chromatographic separations are not yet routine, and successful isomer resolution still depends in part upon the nature of the complex.…”