Palladium Complexes with Tridentate N‑Heterocyclic
Carbene Ligands: Selective “Normal” and “Abnormal”
Bindings and Their Anticancer Activities
Jing-Yi Lee
Jhen-Yi Lee
Yuan-Yu Chang
Ching-Han Hu
Nancy M. Wang
Hon Man Lee
10.1021/acs.organomet.5b00586.s001
https://acs.figshare.com/articles/journal_contribution/Palladium_Complexes_with_Tridentate_N_Heterocyclic_Carbene_Ligands_Selective_Normal_and_Abnormal_Bindings_and_Their_Anticancer_Activities/2132407
A series of new imidazolium salts
was synthesized by simple quaternization
reactions of 1-benzyl-1<i>H</i>-imidazole or 1-benzyl-2-methyl-1<i>H</i>-imidazole and their derivatives with 2-chloro-<i>N</i>-(pyridin-2-ylmethyl)acetamide. These resulting imidazolium
salts were successfully employed as ligand precursors for the syntheses
of novel palladium(II) complexes bearing tridentate ligands of N-heterocyclic
carbene, amidate, and pyridine donor moieties. Simple tuning of the
reaction conditions allowed selective coordination of the N-heterocyclic
carbene moiety in either “normal” or “abnormal”
binding modes. An isomeric pair of palladium complexes with “normal”
and “abnormal” N-heterocyclic carbenes was successfully
characterized by single-crystal X-ray diffraction studies. Theoretical
calculations indicated that the palladium complex with “normal”
NHC coordination was more thermally stable than its isomeric complex
with “abnormal” NHC binding. The potential of these
two sets of palladium complexes as anticancer drugs was evaluated,
and the results showed that some of these novel complexes exhibited
promising inhibition activity against human ovarian cancer cell lines.
The inhibition activity of these novel complexes was highly structurally
dependent. While the nNHC complex bearing an <i>N</i>-3-methoxybenzyl
group appeared to be the most active compound, its isomeric aNHC complex
did not exhibit any inhibition activity toward TOV21G cells. In contrast,
in the case of an isomeric pair of palladium complexes bearing <i>N</i>-4-fluorobenzyl groups, the aNHC complex showed activity
superior to that of the nNHC complex.
2015-09-14 00:00:00
inhibition activity
pyridine donor moieties
Anticancer ActivitiesA series
carbene
palladium complexes
NHC
cancer cell lines
imidazolium salts
isomeric pair
TOV 21G cells
novel complexes