Self-Assembling, Chromogenic Receptors for the Recognition of Dicarboxylic Acids

Abstract

The synthesis of ligands (2,9-disubstituted phenanthrolines) bearing one or two acylaminopyridine binding sites, compounds 1 and 2 respectively, is described. Each ligand can assemble on a Cu(I) template, forming two different receptors for dicarboxylic acids, Cu(l)2+BF4-and Cu(2)2+Bp4-. These orange Cu(I) complexes are shown to bind (Xa > 10* 1234 567M-1) to a variety of dicarboxylic acids in chloroform, with a slight preference for the Cs-dicarboxylic acids, glutaric and V-CBz-glutamic acids, over shorter and longer substrates. Complexation is analyzed both by NMR chemical shift changes and UV-visible absorption changes. The data indicate formation of 1:1 complexes for Cu(l)2+BF4~a nd 2:1 complexes for Cu(2)2+Bp4-, with the dicarboxylic acid substrate hydrogen bonding simultaneously to an acylaminopyridine binding site on each ligand. For Cu(2)2+BF4-, the complexation event results in large shifts in the visible absorption bands and a color change from orange to red. The change in the visible absorbance, and therefore the chromogenicity, was found to be substrate dependent. The chromogenic effect is explained by a conformational change in the receptors resulting from hydrogen bond formation with the substrate.

Catalytic Conversions in Water. Part 23: Steric Effects and Increased Substrate Scope in the Palladium‐Neocuproine Catalyzed Aerobic Oxidation of Alcohols in Aqueous Solvents#

“…2,9-Bis(trifluoromethyl)-1,10-phenanthroline (5), [25] 2,9-di-nbutyl-1,10-phenanthroline (6), [36] 2-Methyl-1,10-phenanthroline (9), [37] 2,9-dichloro-1,10-phenanthroline (16), [38] 2-phenyl-1,10-phenanthroline (17), [39] 2,9-bis(trichloromethyl)-1,10-phenanthroline (19), [40] were prepared according to literature procedures. Previously unreported data are given below.…”

Synthesis of Two Branched Fluorescent Receptors and Their Binding Properties for Dicarboxylate Anions

“…The recognition ability of receptors 1 and 2 for dicarboxylate anions depends on whether the chain lengths of the anions match the distances between two adjacent chains of receptors. [19] As shown in Figure 6, receptors 1 and 2 can selectively recognize longer dicarboxylate anions, and bind adipate with the highest affinity. [a] Anions were used as their tetrabutylammonium salts.…”

Reaction of benzal bromides in water/dioxane system for easy access to benzaldehydes and 2-formylbenzonitriles (2-cyanobenzaldehydes)

“…2,19 On the other hand, the transformation of gem-dihalo compounds (benzal halides) into benzaldehydes is quite a common method. [20][21][22][23][24][25][26][27][28][29][30] In this case solvolytic displacement of halogen with successive replacement by hydroxyl followed by formal loss of HBr to generate the corresponding aldehyde, is favored by resonance stabilization offered by the aromatic ring. 29 Figure 2.…”

“…NaOH) at high temperatures, [25][26] conditions too harsh for the synthesis of 2-formylbenzonitriles, Therefore, the transformation of benzal halides 7 into 2-formylbenzonitriles have been reported under milder conditions only in the presence of the rather expensive AgNO3, used in large excess (> 3 eq. ), [5][6][7] with severe limitations concerning the scale of the synthetic procedure, the necessity of additional tedious purification operations and eventual metal contamination.…”