The preparation of substitution-inert 99Tc metal-fragments: Promising candidates for the design of new 99mTc radiopharmaceuticals

Synthesis and biological evaluation of a novel 99mTc‐cyclopentadienyltricarbonyl technetium complex as a new potential brain perfusion imaging agent

“…[8,9] Among those, 99m Tc-cyclopentadienyltricarbonyl technetium complexes of general formula RCpTc(CO) 3 (R = organic part or biomolecule, Cp = cyclopentadienyl moiety) have been extensively studied. [10 -15] The neutral and lipophilic 'piano stool' organometallic core, 'CpM(CO) 3 ' (M = 99m Tc or Re), is particularly attractive since it has a low molecular weight, exhibits a high chemical and in vivo stability resulting from the low-spin d 6 electron configuration, and unlike reported Tc(V)/Re(V) complexes, it does not possess additional stereocenters, which often complicate the purification process of radiopharmaceuticals. [16] Over the past decade, the research of the radiopharmaceutical unit of the Centre National des Sciences et Technologies Nucléaires, (Tunisia), have been focused on small Tc-cyclopentadienyl derivatives called cytectrene I and II, as highlighted in Scheme 1.…”

Ligand exchange and complex formation kinetics studied by NMR exemplified on fac-[(CO)3M(H2O)]+ (M=Mn, Tc, Re)

“…Synthesis and characterization of radiolabelled compounds for imaging and therapy has strongly expanded over the last decade [15][16][17][18][19]. An important isotope for radioactive imaging agents is 99m Tc and there is a strong interest in the development of new labelling techniques using this short-lived isotope.…”

Influence of the ligand donor atoms on the in vitro stability of rhenium(I) and technetium (I)-99m complexes with pyrazole-containing chelators: Experimental and DFT studies

“…6A, and the Re complexes (1)(2)(3)(4)(5)(6) are more stable than the corresponding Tc complexes (1a-6a) by $15-18 kcal/mol. The energy decomposition terms (Table 2) suggest that the interaction energy DE 0 almost reflects the DE elec term, with the Pauli repulsion and the orbital interaction (DE Pauli and DE orb ) practically canceling each other.…”

“…Ideally, the ligand must form a thermodynamically and kinetically stable complex and possess functional groups for further conjugation to a biologically active molecule, somehow related to a certain disease or disease type. In the last decades, a plethora of 99m Tc and 186/188 Re complexes presenting different metal cores and having different formal oxidation states (I, III-V) have been investigated aiming at the finding of compounds with increased stability, improved pharmacokinetics and enhanced biological specificity [1][2][3][4]. More recently, tricarbonyl Re and Tc complexes emerged as versatile tools in radiopharmaceutical research following the introduction by Alberto and co-workers of the air-and water-stable synthons fac-[M(CO) 3 (H 2 O) 3 ] + (M = Tc or Re) [5].…”