74621-40-2Relevant articles and documents
Reductive Transformations of a Pyrazolate-Based Bioinspired Diiron-Dinitrosyl Complex
Kindermann, Nicole,Schober, Anne,Demeshko, Serhiy,Lehnert, Nicolai,Meyer, Franc
, p. 11538 - 11550 (2016)
Flavo-diiron nitric oxide reductases (FNORs) are a subclass of nonheme diiron proteins in pathogenic bacteria that reductively transform NO to N2O, thereby abrogating the nitrosative stress exerted by macrophages as part of the immune response. Understanding the mechanism and intermediates in the NO detoxification process might be crucial for the development of a more efficient treatment against these bacteria. However, low molecular weight models are still rare, and only in a few cases have their reductive transformations been thoroughly investigated. Here, we report on the development of two complexes, based on a new dinucleating pyrazolate/triazacyclononane hybrid ligand L-, which serve as model systems for nonheme diiron active sites. Their ferrous nitrile precursors [L{Fe(R′CN)}2(μ-OOCR)](X)2 (1) can be readily converted into the corresponding nitrosyl adducts ([L{Fe(NO)}2(μ-OOCR)](X)2, 2). Spectroscopic characterization shows close resemblance to nitrosylated nonheme diiron sites in proteins as well as previous low molecular weight analogues. Crystallographic characterization reveals an anti orientation of the two {Fe(NO)}7 (Enemark-Feltham notation) units. The nitrosyl adducts 2 can be (electro)chemically reduced by one electron, as shown by cyclic voltammetry and UV/vis spectroscopy, but without the formation of N2O. Instead, various spectroscopic techniques including stopped-flow IR spectroscopy indicated the rapid formation, within few seconds, of two well-defined products upon reduction of 2a (R = Me, X = ClO4). As shown by IR and M?ssbauer spectroscopy as well as X-ray crystallographic characterization, the reduction products are a diiron tetranitrosyl complex ([L{Fe(NO)2}2](ClO4), 3a′) and a diacetato-bridged ferrous complex [LFe2(μ-OAc)2](ClO4) (3a″). Especially 3a′ parallels suggested products in the decay of nitrosylated methane monooxygenase hydroxylase (MMOH), for which N2O release is much less efficient than for FNORs.
A novel one-dimensional nickel(II) alternating chain from discrete pyrazolate-based dinuclear complexes
Meyer, Franc,Ruschewitz, Uwe,Schober, Peter,Antelmann, Bjoern,Zsolnai, Laszlo
, p. 1181 - 1186 (1998)
Hexadentate dinucleating ligands that are based on a bridging pyrazolate bearing chelating side arms [3,5-(R2NCH2)2C3N2H 2; R2N = Me2N(CH2)2NMe (HL1), Me2N(CH2)2NMe (HL2)] reacted with NiCl2·6H2O to yield complexes ClNi(μ-Cl)(μ-L1)NiCl 1 (Ni2L1Cl3) and ClNi(μ-Cl)(μ-L2)NiCl 2 (Ni2L2Cl3), respectively. Depending on the side-arm chain length and the solvent used for crystallisation these complexes either crystallised as dicrete bimetallic units (1) or were assembled via di-μ-chloro linkages to form a tetranuclear compound [ClNi(μ-Cl)-(μ-L2)Ni(μ-Cl) 2Ni(μ-Cl)(μ-L2)NiCl] 2a ([Ni2L2Cl3]2) or a novel bridge-alternating one-dimensional chain [Ni(μ-Cl)(μ-L1)Ni(μ-Cl)2]∞ 2b ([Ni2L2Cl3]∞) in the solid state. Variable-temperature magnetic susceptibility measurements revealed antiferromagnetic coupling within the basic μ-chloro-μ-pyrazolato bridged bimetallic framework in all cases and also suggested antiferromagnetic superexchange propagated by the di-μ-chloro linkage in 2b. The latter result is rationalised on the basis of the specific geometric findings for this di-μ-chloro linkage, in particular the unusually large Ni-Cl-Ni angle [101.37(4)°].
Chiral bisoxazoline ligands designed to stabilize bimetallic complexes
Das, Deepankar,Mal, Rudrajit,Mittal, Nisha,Zhu, Zhengbo,Emge, Thomas J.,Seidel, Daniel
, p. 2002 - 2011 (2018)
Chiral bisoxazoline ligands containing naphthyridine, pyridazine, pyrazole, and phenol bridging units were prepared and shown to form bimetallic complexes with various metal salts. X-ray crystal structures of bis-nickel naphthyridine-bridged, bis-zinc pyridazine-bridged, and bis-nickel as well as bis-palladium pyrazole-bridged complexes were obtained.
Synthesis and spectroscopy of CoII, NiII, CuII and ZnII complexes derived from 3,5-disubstituted-1H-pyrazole derivative: A special emphasis on DNA binding and cleavage studies
Budagumpi, Srinivasa,Kulkarni, Naveen V.,Kurdekar, Gurunath S.,Sathisha,Revankar, Vidyanand K.
, p. 455 - 462 (2010)
A series of novel CoII, NiII, CuII and ZnII complexes of 1H-pyrazole-3,5-dicarboxylic(2′-hydroxy-3′-hydrazinequinoxaline) has been prepared and characterized by the spectral and analytical techniques. CuII ion reacts with the ligand LH3 and forms the complex in one compartment of the ligand whereas, the other compartment remains free. In CoII, NiII and ZnII complexes both compartments of LH3 are involved in the coordination. DNA binding/cleavage studies were revealed the stronger binding capability of the present NiII complex, confirmed by the absorbance, viscometric and gel-electrophoresis studies. Similarly, remaining complexes do the same in the ligand field with lesser binding constants, subsequently, no complex was found to cleave the DNA. Finally, CuII complex shows growth inhibitory activity against biogram.
Synthesis and Biological Evaluation of Oral Prodrugs Based on the Structure of Gemcitabine
Zhao, Cuirong,Xue, Xiaoxia,Li, Gang,Sun, Cuicui,Sun, Changjun,Qu, Xianjun,Li, Wenbao
experimental part, p. 479 - 488 (2012/10/07)
A series of oral prodrugs based on the structure of gemcitabine (2′,2′-difluorodeoxycytidine) were synthesised by introducing an amide group at the N4-position of the cytidine ring. A total of 16 compounds were obtained, and their chemical and biological characteristics were evaluated. The half-maximal inhibitory concentrations (IC50s) for most of these compounds were higher than that of gemcitabine in vitro. Compounds 5d and 5m, the representative compounds, were examined in terms of their physiological stabilities and pharmacokinetics. Compound 5d showed good stability in PBS and simulated intestinal fluid, and an analysis of its pharmacokinetics in mice suggested that the introduction of an amide group to gemcitabine could greatly improve its bioavailability. Further evaluation of compound 5din vivo showed that this compound possesses higher activity than gemcitabine against the growth of HepG2 human hepatocellular carcinoma cells and HCT-116 colon adenocarcinoma cells with less toxicity to animals. These results suggest that compound 5d could be further developed as a potential oral anticancer agent for clinical applications in which gemcitabine is currently used. A series of oral prodrugs based on the structure of gemcitabine were synthesized. Physiological and metabolic stabilities, pharmacokinetics and antitumor activities were evaluated for representative compounds.
