The biomedical chemistry of technetium and rhenium

Abstract

This review describes recent developments in the chemistry of both first and second generation 99m-technetium-based imaging agents. The material is presented according to the biological target for the agent, and where possible actual images are presented to indicate the type of information available to the clinician. Beta emitting isotopes of rhenium offer a possible method for the in situ treatment of cancerous tissue using analogous targeting strategies to those for technetium. Recent developments in the relevant coordination chemistry of rhenium and their extension to in vitro and in vivo studies are presented.

Synthesis and structural characterization of rhenium(I) tricarbonyl complexes with the bidentate ligands o-(diphenylphosphino)benzaldehyde (P∩O) and o-[(diphenylphosphino)benzylidene]analine (P∩N)

“…Complexes [ReX(CO) 3 (P ∩O)] (1, X=Cl; 2, X=Br) were isolated as air-stable red-brown needles while complexes [ReX(CO) 3 (P ∩N] (3, X=Cl; 4, X=Br) were separated as yellowish blocks. In the rhenium(I) carbonyl stretching region of t he infrared spectra, the complexes show three strong peaks consistent with a facial arrangement o f t he three carbonyl groups [33,34], which are assigned as the A′ (1), A ″ and A′(2) vibrations, respectively [35].…”

“…Perspective view of the complex [ReCl(CO) 3 (P ∩N)] (3): ORTEP drawing with 30% probability ellipsoids. Table 1 Summary of crystal data, intensity, collection, and refinement data a for complexes [ReCl(CO) 3 Table 2 Selected bond distances (Å) and angles (°) for complexes 1 and 2 1 2 Table 3 Selected bond distances (Å) and angles (°) for complexes 3 and 4 3 4…”

“…The gamma-emitting radionuclide 99m Tc and its Group VII congener 186/188 Re have found wide-ranging applications in radiodiagnosis [1][2][3][4][5][6] and radiotherapy [7,8], respectively. The optimal nuclear properties of 99m Tc (γ-emitter, E max = 140 keV, t 1/2 = 6 h), as well as its convenient availability from 99 Mo/ 99m Tc generator system [9], have made 99m Tc radiopharmaceuticals virtually ideal for imaging low capacity high density receptors by deploying SPECT (single photon emission computerized tomography), while both isotopes 186 Re (t 1/2 = 90.64 h, E max = 1.1 MeV) and 188 Re (t 1/2 = 17 h, E max = 2.1 MeV) are suitable for therapeutic use b y means of β-irradiation.…”

Pentadentate thioether-oxime macrocyclic and quasi-macrocyclic complexes of copper(II) and nickel(II)

“…Since that time, several N 4 and N 2 S 2 quasi-macrocyclic and BF 2 -macrocyclized oximes have been synthesized [3 -7]. Recently a copper -oxime complex was used to oxidize anthracene [8], while metal-containing oxime complexes are utilized in medicine as well; technetium(V)-and copper(II)-containing 6ic-oximes currently are used as cerebral and myocardial perfusion imaging agents [9][10][11][12][13][14]. This area was also recently reviewed [15,16].…”

Structural characterizations of an Re(IV) complex [ReCl4(OPPh3)2] and of an imino species [ReOCl2(PPh3)(η2-OC6H4-2-CHNH)] prepared from the reaction of [ReOCl3(PPh3)2] with salicylaldoxime

“…The widespread contemporary interest in the development of technetium and rhenium radiopharmaceuticals [1][2][3][4][5] has fostered a dramatic expansion of the coordination chemistry of these metals. One persistent strategy has focused on developing effective chelating ligands for the robust and ubiquitous {MO} 3+ core (M = Tc, Re).…”