Pyridine binding

Radish KM, Shao J, Ou Z, Zhan R, Burdet E, Barhe J-M, Gros CP, Guilard R. 2005. Electrochemistry and spectroelectrochemistry of heterobimetalUc porphyrin-corrole dyads. Influence of the spacer, metal ion, and oxidation state on the pyridine binding ability. Inorg Chem 44, 9023-9038. 

Results Summary for the UV-Visible/Job s Plot Analysis of Pyridine Binding to A, V -disal icy I aldehyde-1,3-prop ancdiimincnickel (II)... 

EXPERIMENT 3.7 DETERMINATION OF THE FORMATION CONSTANT FOR PYRIDINE BINDING TO A/,A/ -DISALICYLALDEHYDE-1,3-PROPANEDI IMINENICKEL(II), [Ni(salpd)], USING THE DOUBLE RECIPROCAL (BENESI-HILDEBRAND) METHOD... 

An interesting example of the effect of introducing chirality into the bridging unit has been given by Suzuki et al. [8]. The ligand 3 contains two pyridine binding units separated by a chiral spacer. If (RJl)-3 is reacted with Ag(I), crystals of an extended... 

The final system in which racemization has been studied in detail concerns the ligands 23 and 24. The complex [Cu2(23)2] has a double-helical structure in which the pyridine binds weakly to both copper ions [49], whereas the complex [Cu2(24)2] adopts a side-by-side meso- structure [50]. Figure 14 shows the two structures. 

The (acac-<9,0)2Ir(acac-C3) pyridine complex is quite soluble in methanol, dichloromethane, and chloroform, and moderately soluble in THF. It is slightly soluble in water, benzene, and toluene. The complex is also soluble in acetic and trifluoroacetic acids. It is insoluble in hexanes and diethyl ether. The complex is air and water stable for extended periods. Addition of pyridine to complex from procedure A or B in organic or acid media leads to formation of (acac-(9,<9)2Ir (acac-C3)pyridine in situ, which drastically inhibits C-H activation however, it does not stop it completely. Pyridine binds strongly through o-donation to help stabilize the electrophilic iridium(III). 

However, the outcome of such reactions does depend on the entering ligand, as the above reaction performed with the aromatic monodentate amine pyridine instead of 1,2-ethanediamine leads to only four pyridines binding, with [V(py)4(S04)] as the product. 

N-pyridme 25.3 Cm and N-benzimidazole" tuted-2-(2-benzimidazolyl)pyridine binding... 

Molecular squares define cavities that are potential hosts for appropriate molecular guests. In methylene chloride as solvent, pyridine binds to the available Zn(II) sites of IZn with an association constant of 10 M Whether binding occurs on the square interior or exterior (or a combination of both) has not been established. Recall, however, that Zn porphyrins generally axially bind only one ligand. The free base form of the dipyridyl porphyrin used to assemble the squares binds to IZn with an equilibrium constant of 3 x 10 [7]. The stronger association is a consequence of... 

Figure 13.48. Pyridine-binding to zinc porphyrins leads to assemblies with four and eight porphyrins.

The influence of pyridine binding and spin state on the spectroscopic properties and electrochemistry of aryl iron porphyrin complexes has been studied. The reduction of styrene to ethylbenzene and 2,3-diphenylbutane catalysed by [(TPP)FeCl] is proposed to proceed via a o-Fe-CHMeRi intermediate. The phthalocyanine anion Na2[FePc] reacts with ROCBr to give Na(PcFeC R] (R = Ph, Pr), and similar alkynyl anions have been prepared with a hemin-like iron centre.55... 

The original lead structure, SCH28080 (3-cyanomethyl-2-methyl-8-[phenylmethoxy] imidazo[1,2a]pyridine), binds to the enzyme largely in its protonated form and to a site accessed from the luminal surface of the pump. A photoaffinity analog, MeDAZIP, after photolysis binds within the membrane domain in the region of TM1 and TM2. Its inhibition constant (K,), calculating for the protonated form, is in the region of 10 nM. It does not inhibit the Na,K ATPase, as ouabain does not inhibit the H,K ATPase. 

Another approach has been used by an AU20 cluster which was determined by photoelectron spectroscopy in combination with relativistic DPT calculations to appear in tetrahedral geometry where the four faces represent (111) surfaces of bulk face-centered cubic (fee) gold. Two binding models to the AU20 cluster have been considered, one where pyridine binds to the centre of a surface facet and one where p5Tidine binds to the corner of the tetrahedron (see Fig. 20). The binding mode of... 

The formation of neutral (P)Fe(C6Hs)(L) from (P)Fe(C6Hs) has been monitored both spectrally and electrochemically . Formation constants of 10 to lO - were calculated for pyridine binding by the five-coordinate Fe(III) complexes while the six coordinate (P)Fe(C6H9)dm) adducts were characterized by NMR studies . The reduction of P)Fe(C H3)(py) is electrochemically reversible and the products of reduction can be spectroscopically identified . Potentials for the reduction of (P)Fe(C6Hs)(py) are shifted in a negative direction from those of (P)Fe(C6Hs), consistent with stabilization of the six coordinate species. 

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