4231-74-7Relevant articles and documents
New artificial biomimetic enzyme analogues based on Iron(II/III) schiff base complexes: An effect of (Benz)imidazole organic moieties on phenoxazinone synthase and DNA recognition
Bocian, Aleksandra,Brykczyńska, Daria,Fik-Jaskó?ka, Marta A.,Gorczyński, Adam,Kubicki, Maciej,Patroniak, Violetta,Roviello, Giovanni N.,Szymańska, Martyna,Wa??sa-Chorab, Monika
, (2019)
Elucidation of the structure and function of biomolecules provides us knowledge that can be transferred into the generation of new materials and eventually applications in e.g., catalysis or bioassays. The main problems, however, concern the complexity of the natural systems and their limited availability, which necessitates utilization of simple biomimetic analogues that are, to a certain degree, similar in terms of structure and thus behaviour. We have, therefore, devised a small library of six tridentate N-heterocyclic coordinating agents (L1–L6), which, upon complexation, form two groups of artificial, monometallic non-heme iron species. Utilization of iron(III) chloride leads to the formation of the 1:1 (Fe:Ln) ‘open’ complexes, whereas iron(II) trifluoromethanosulfonate allows for the synthesis of 1:2 (M:Ln) ‘closed’ systems. The structural differences between the individual complexes are a result of the information encoded within the metallic centre and the chosen counterion, whereas the organic scaffold influences the observed properties. Indeed, the number and nature of the external hydrogen bond donors coming from the presence of (benz)imidazole moieties in the ligand framework are responsible for the observed biological behaviour in terms of mimicking phenoxazinone synthase activity and interaction with DNA.
Supramolecular Control of the Template-Induced Selective Photodimerization of 4-Methyl-7-O-hexylcoumarin
Skene, William G.,Couzigne, Emilie,Lehn, Jean-Marie
, p. 5560 - 5566 (2003)
A symmetric ditopic molecular receptor (3), containing two identical hydrogen-bonding recognition subunits, was designed and synthesized. These subunits are capable of binding substrates with complementary donor and acceptor sites to form a supramolecular complex through hydrogen bonding, Receptor 3 was designed to accept two guest molecules, which are held in close proximity within the supramolecular species. The substrate molecule, 4-methyl-7-O-hexylcoumarin (1c), forms a 2:1 complex with a binding constant of 150M-1 for the second substrate, passing first through a 1:1 complex with an affinity constant of 510M-1. The orientation of two molecules of 1c when bound to the template leads to the selective formation of the trans-syn [2+2] photoproduct 2cB upon irradiation. Other photoproducts typically produced in the absence of the template are suppressed.
A family of readily synthesised phosphorescent platinum(ii) complexes based on tridentate: N^N^O -coordinating Schiff-base ligands
Puttock, Emma V.,Fradgley, Jack D.,Yufit, Dmitry S.,Gareth Williams
supporting information, p. 15012 - 15028 (2019/10/22)
The synthesis and photophysical properties of 22 platinum(ii) complexes featuring N^N^O-coordinating ligands are described. The complexes have the form Pt(N^N^O-Ln)Cl (n = 1 to 20). The tridentate ligands comprise lateral pyridine and phenolate rings, offering the metal N and O coordination respectively, linked via an imine or hydrazone unit that provides a further, central N atom for coordination. The proligands HLn, some of which have previously been reported for the coordination of 1st row transition metal ions in other contexts, are Schiff bases that are readily synthesised by condensation of salicylaldehydes either with 8-aminoquinoline (to generate imine-based ligands HL1-4) or with 2-hydrazinopyridines (to generate hydrazone-based proligands HL5-20). The Pt(ii) complexes are prepared under mild conditions upon treatment of the proligands with simple Pt(ii) salts. Metathesis of the chloride ligand by an acetylide is possible, as exemplified by the preparation of two further complexes of the form Pt(N^N^O-Ln)(-CC-Ar), where Ar = 3,5-bis(trifluoromethyl)phenyl. Nine of the complexes have been characterised in the solid state by X-ray diffraction. The imine-based complexes have intense low-energy absorption bands around 520 nm attributed to charge-transfer transitions. They display deep red phosphorescence in solution at ambient temperature, with λmax in the range 635-735 nm, quantum yields up to 4.6% and lifetimes in the microsecond range. The hydrazone complexes that feature a py-NH-NC-Ar linker display pH-dependent absorption spectra owing to the acidity of the hydrazone NH: these complexes have poor photostability in solution. In contrast, their N-methylated analogues (i.e., py-NMe-NC-Ar) show no evidence of photodecomposition. They are phosphorescent in solution at room temperature in the 600-640 nm region, the emission maximum being influenced by substituents in the phenolate ring. The results show how simply prepared tridentate Schiff base ligands-which offer the metal a combination of 5- and 6-membered chelate rings-can provide access to phosphorescent Pt(ii) complexes that have superior emissive properties to those of terpyridines, for example.
Nickel-catalyzed direct C-H bond sulfenylation of acylhydrazines
Li, Jun-Ming,Yu, Yang,Weng, Jiang,Lu, Gui
supporting information, p. 6047 - 6056 (2018/09/06)
A Ni-catalyzed direct C-H bond sulfenylation of acylhydrazines was developed. The reaction used N-(pyridinyl)hydrazine as the bidentate-directing group, which can be smoothly removed through reductive N-N cleavage. This system can bear various important functional groups, providing an efficient route for the preparation of diverse diaryl sulfides.
