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Half‐sandwich ruthenium, rhodium and iridium complexes featuring oxime ligands: Structural studies and preliminary investigation of in vitro and in vivo anti‐tumour activities
Author(s) -
Palepu Narasinga Rao,
Adhikari Sanjay,
J Richard Premkumar,
Verma Akalesh K.,
Shepherd Samantha L.,
Phillips Roger M.,
Kaminsky Werner,
Kollipara Mohan Rao
Publication year - 2017
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3640
Subject(s) - chemistry , ruthenium , iridium , rhodium , denticity , stereochemistry , in vivo , ligand (biochemistry) , in vitro , medicinal chemistry , metal , biochemistry , catalysis , organic chemistry , receptor , microbiology and biotechnology , biology
Half‐sandwich ruthenium, rhodium and iridium complexes ( 1 – 12 ) were synthesized with aldoxime ( L1 ), ketoxime ( L2 ) and amidoxime ( L3 ) ligands. Ligands have the general formula [PyC(R)NOH], where R = H ( L1 ), R = CH 3 ( L2 ) and R = NH 2 ( L3 ). Reaction of [{(arene)MCl 2 } 2 ] (arene = p ‐cymene, benzene, Cp*; M = Ru, Rh, Ir) with ligands L1 – L3 in 1:2 metal precursor‐to‐ligand ratio yielded complexes such as [{(arene)MLκ 2 (N∩N) Cl}]PF 6 . All the ligands act as bidentate chelating nitrogen donors in κ 2 (N∩N) fashion while forming complexes. In vitro anti‐tumour activity of complexes 2 and 10 against HT‐29 (human colorectal cancer), BE (human colorectal cancer) and MIA PaCa‐2 (human pancreatic cancer) cell lines and non‐cancer cell line ARPE‐19 (human retinal epithelial cells) revealed a comparable activity although complex 2 demonstrated greater selectivity for MIA PaCa‐2 cells than cisplatin. Further studies demonstrated that complexes 3 , 6 , 9 and 12 induced significant apoptosis in Dalton's ascites lymphoma (DL) cells. In vivo anti‐tumour activity of complex 2 on DL‐bearing mice revealed a statistically significant anti‐tumour activity ( P = 0.0052). Complexes 1 – 12 exhibit HOMO–LUMO energy gaps from 3.31 to 3.68 eV. Time‐dependent density functional theory calculations explain the nature of electronic transitions and were in good agreement with experiments.