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.

Fluorescence emission and polarization analyses for evaluating binding of ruthenium metalloglycoclusters to lectins and tetanus toxin C-fragment

“…[2][3][4][5] The use of metalloglycoclusters as a probe molecule is an attractive proposition because the metal center furnishes photochemical and electrochemical properties that can be employed as useful analytical indicators in kinetic studies. Gottschaldt et al 6 reported on metalloglycoclusters that contain a rhenium or technetium metal center, and Kobayashi et al 2 and Kikkeri et al 3 reported on ruthenium metalloglycoclusters. Because the clusters can possess a variety of coordination numbers, in addition to providing useful photochemical and electrochemical properties, unique geometrical features can be imparted to the carbohydrate probe.…”

Synthesis of Iridium(III) Complex Bearing 1-Thio-β-D-glucose Tetraacetate Moieties and its Photogeneration of Singlet Oxygen

“…However, the reported sugar-containing Ir(III) complex (1) is hardly soluble in benzene; thus, we synthesized a novel Ir(III) complex coordinated with bipyridyl ligands bearing acetyl-protected glucose by following a modified version of our reported method (Scheme 4) [9][10][11].…”

“…The starting bipyridyl ligands bearing acetyl-protected glucose were prepared according to a reported method [9]. Bromomethyl-2,2′-bipyridine (160 mg, 0.47 mmol) was dissolved in DMF (2 mL), followed by the addition of 1-thio-β-D-glucose tetraacetate (350 mg, 0.97 mmol) and Na 2 CO 3 (350 mg, 3.3 mmol) at room temperature.…”

“…We already established the synthetic method of acetyl-protected bipyridyl ligands and their complexes with rhenium(I), technetium(I), and ruthenium [9,10], followed by deprotection of acetyl groups affording sugar-conjugated metal complexes. Ir(III) has also been reported in a pioneering synthetic study [11,12].…”

Water‐Soluble and Biocompatible Cyclometalated Iridium(III) Complexes: Synthesis, Luminescence and Sensing Application

“…The 1 H NMR and 13 C NMR spectroscopic data were identical to the literature. [8] The dichloro-bridged dimer [Ir(C N) 2 -μ-Cl] 2 was conveniently prepared from a reaction of the respective ligand and IrCl 3 ·xH 2 O.…”