title: Synthesis and structure of novel sugar-substituted bipyridine complexes of rhenium and 99m-technetium.
abstract: Novel ligands have been obtained from the reaction of 4,4'-dibromomethyl-2,2'-bipyridine with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylthiol, 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosylthiol or 2,3,4,6-tetra-O-acetyl-alpha-D-thioacetylmannopyranoside in which the sugar residues are thioglycosidically linked to the bipyridine in the 4,4'-position. Cleavage of the acetyl groups affords hydrophilic symmetric ligands with free hydroxyl groups. Reaction of the new glycoconjugated ligands (L) with [Re(CO)(5)Cl] yields fluorescent complexes of general formula [Re(L)(CO)(3)Cl], which were characterised by mass spectrometry, elemental analysis and (1)H and (13)C NMR, IR, UV/Vis and fluorescence spectroscopy. These complexes exhibit excellent solubility and stability in organic solvents or water, depending on the residues of the sugar. One complex, namely tricarbonyl-4,4'-bis[(2,3,4,6-tetra-O-acetyl-beta-D-glycopyranosyl)thiomethyl]-2,2'-bipyridinerheniumtricarbonylo chloride, has been characterised by X-ray crystallography. A non-symmetric structure of the complexes could be assigned. Radiolabelling of the unprotected ligands with [(99m)Tc(H(2)O)(3)(CO)(3)](+) affords the corresponding water-soluble technetium complexes (in quantitative yields), which were characterised by their HPLC radiation traces. The formed complexes are stable for several hours in the presence of histidine but show partial ligand-exchange after one day.
authors.affiliation: Institute for Organic and Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstrasse 10, 07743 Jena, Germany. Michael.Gottschaldt@uni-jena.de
authors.forename: Michael
authors.initials: M
authors.lastname: Gottschaldt
authors.forename: Daniel
authors.initials: D
authors.lastname: Koth
authors.forename: Dirk
authors.initials: D
authors.lastname: Müller
authors.forename: Ingo
authors.initials: I
authors.lastname: Klette
authors.forename: Sven
authors.initials: S
authors.lastname: Rau
authors.forename: Helmar
authors.initials: H
authors.lastname: Görls
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schäfer
authors.forename: Richard P
authors.initials: RP
authors.lastname: Baum
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yano
mesh_terms: D000042:Absorption; D002241:Carbohydrates / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D012211:Rhenium / Q000737:chemistry*; D017556:Technetium Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D011725:Pyridines; D017556:Technetium Compounds; D012211:Rhenium; C023666:pyridine