Stilbazoles, ligands

Another approach to get new liquid crystals is the lateral fluorination of the stilbazole ligands,337 which is a common and highly effective tool to exert control over mesomorphism, crystal phase stability, and physical properties. Other modifications include the use of more alkoxy substituents and other alkyl sulfate anions.338-344 Ionic silver amino complexes also display liquid crystalline behavior at rather low temperatures they are of the form [Ag(NH2 -CJl +OJX (X = N03, n = 6,8,10,12,14 X = BF4, = 8,10,12,14).345... 

The EFISHG technique has also been applied to some pyridyl carbonyls of Rh1 or Ir1 by Bruce et al72,13 These complexes (e.g., (9) and (10)) contain stilbazole ligands bearing resolved 2-methylbutyloxy substituents, incorporated with the aim of encouraging noncentrosymmetric crystal packing structures. The observed 1.5- to 3-fold enhancements of (3 of the free stilbazole on complexation are attributable to the er-electron-withdrawing abilities of the metal centers.72,73... 

Metal perturbation of IL photochemistry appears to be less important in [Ru(bipy)2(h- n.s-4-stilbazole)2]2+ and [Ru(bipy)2(cw-4-stilbazole)2]2+. Both complexes undergo wavelength-dependent isomerization of the coordinated stilbazole ligands as the only important photoreaction."4 This wavelength dependence has beep attributed to the presence of two different types of reactive excited states, aRu-t stilbazole CT state which favors formation of the trans isomer and a higher energy IL state localized on stilbazole which decays with nearly equal probability to the two isomers. The latter pathway is qualitatively similar to the isomerization process that obtains upon direct photolysis of the free ligand. Thus coordination to Ru has not altered the characteristic photoreaction mode of the stilbazole molecule. 

Mean Linear Polarizabilities (a) and Polarizability Anisotrophies (Aa) for a Stilbazole Ligand and Its Iridium (I) Complex ... 

Systems Based on Poly(alkoxy)stilbazole Ligands... 

Complexes with Amine, Pyridine, and Stilbazole Ligands... 

The only photoreaction which the 4-styrylpyridine (4-stilbazole) complexes [Ru(bipy)(cw-4-stilbazole)] + and [Ru(bipy)(/ ra 5-4-stilbazole)] + undergo is that of cis trans isomerization of the stilbazole ligands there is no significant photodissociation. The anion [Pt(NH3)4(NH2)(N02)] " photoisomerizes to [Pt(NH3)4(NHa)(ONO)]. The quantum yield has been determined for this process, but no kinetic results are available. ... 

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