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Updated: May 23, 2026

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry
Published on: February 4, 2017
Novel estradiol based metal complexes of Tc-99m
Carina Neto1, Maria Cristina Oliveira, Lurdes Gano
1Unidade de Ciências Químicas e Radiofarmacêuticas, Instituto Tecnológico e Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, Sacavém, Portugal.
Abstract:
Aiming to contribute to the design of technetium imaging agents for estrogen receptor (ER) positive breast tumors, we have synthesized and evaluated the novel organometallic estradiol complexes (fac-[M(CO)(3)(κ(3)-10)](+) and fac-[M(CO)(3)(κ(3)-12) M=Re/(99m)Tc) using two different bifunctional tridentate ligands (4 and 8). The rhenium complexes (13 and 14) were fully characterized by IR, (1)H NMR, (13)C NMR, mass spectrometry and elemental analyses. The (99m)Tc complexes (15 and 16) were obtained with high radiochemical purity and exhibited high in vitro radiochemical stability. To get a first insight into the relevance of these complexes for targeting ER positive tumors, ER binding affinity assays and cellular internalization studies in an ER expressing cell line, MCF-7, have also been performed suggesting a non ER mediated uptake.
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Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.

