Self‐Assembly of Chalcogenolato‐Bridged Ester and Amide Functionalized Dinuclear Re(I) Metallacycles: Synthesis, Structural Characterization and Preliminary Cytotoxicity Studies

Abstract

Functionalized pyridyl ditopic ligands 1,2‐phenylene diisonicotinate (pdi) (L1) and N,N′‐4‐pyridylcarboxamide‐4‐pyridylcarboxyl‐1,2‐benzene (pcpcb) (L2) comprising ester/ester and amide backbone have been synthesized and utilized for the preparation of novel series of chalcogenolato‐bridged rhenium(I) metallacycles [(CO)3Re(μ‐ER)2Re(CO)3(μ‐pdi)] (1–4) and [(CO)3Re(μ‐ER)2Re(CO)3(μ‐pcpcb)] (5–8) (E=S, Se and Te; R=butyl and phenyl). Synthesis of metallacycles 1‐8 has been accomplished by the oxidative addition of dialkyl/diaryl dichalcogenide to rhenium carbonyl with ester/ester and amide functionalized pyridyl ditopic ligand in one‐pot reaction. The pyridyl ligands and metallacycles were characterized by elemental analysis, IR, NMR and UV‐Vis absorption spectroscopic techniques. Molecular structure of the metallacycles 2–4 and 7 were determined by single‐crystal X‐ray diffraction methods. Preliminary cytotoxic activities of the ligands and metallacycles were studied on various cancer and normal cells. The results revealed that the metallacycles selectively inhibited certain cancer cells but not the normal cells.

Therapeutic and Diagnostic Applications of Multimetallic Rhenium(I) Tricarbonyl Complexes

“…A large library of complexes of this type was studied for their anticancer activities (16-37) (Figure 5). [41][42][43][44] An early example is a library of metallacyclophanes with ester linkages (16)(17)(18)(19)(20). Within this class of compounds, those containing longer alkyl chains exhibit higher cytotoxicity (16 < 18 < 20).…”

“…Chalcogenolato-bridged compounds (30)(31)(32)(33)(34)(35)(36)(37) are generally less potent than the aforementioned complexes, with the exceptions of 31 and 33, which display significant cytotoxicity against Hep G2 cells. [44] Compound 24 is the most potent complex among these equatorially linked complexes, with cytotoxicity profiles similar to cisplatin. The longer, more flexible alkyl chain (n = 8) may contribute to its high activity.…”

“…Structures of para-linked pyridyl-bridged homonuclear compounds (16-37). [41][42][43][44] pyridyl-1,2,3-triazole ligands that are attached with different alkyl or aryl linkers. The axial ligands are either 4-dimethylaminopyridine (DMAP) (39)(40)(41)(42), chloride (43)(44)(45)(46), or bromide (47)(48)(49)(50).…”

“…[41][42][43][44] pyridyl-1,2,3-triazole ligands that are attached with different alkyl or aryl linkers. The axial ligands are either 4-dimethylaminopyridine (DMAP) (39)(40)(41)(42), chloride (43)(44)(45)(46), or bromide (47)(48)(49)(50). In general, the cationic complexes bearing the DMAP ligand (39)(40)(41)(42) are more active than the neutral complexes (43-50) against both Gram-positive (S. aureus) and Gram-negative (E. coli) microorganisms, presumably due to their greater lipophilicity and charge.…”

Alkyl 2-Benzothiazolyl Sulfide Ligated Dirhenium Complexes: Syntheses, Structure and Computational Study of [Re2(CO)8{μ,η1,η1-(R)SCNSC6H4}] (R = CH3 and C2H5)

“…For example, the reactions of Re2(CO)10 with pyridine-2-thiol [1], thioacetamide [2], thiobenzamide [2], diaryl disulfides [3], pyrimidine-2-thiol [4], 2-mercaptothiazoline [5], 2mercaptobenzimidazole [5], 2-mercapto-1-methylimidazole [5], and 2-mercaptobenzoxazole [6] have been reported. Recent advances in research reveal the isolation of mixed metal [7][8][9] and mixed ligand [10][11][12][13] rhenium complexes of sulfur-containing ligands. These reactions often involve the oxidative cleavage of the rhenium-rhenium bond together with the reductive S─H, N─H or S─S bond scission in the ligands [1][2][3][4][5][6].…”