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Results for “Diazonium Compounds”

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At least 19 recordsLinked to original sources
PubMed1978

Photolytic inhibition and labeling of proteins with aryl diazonium compounds.

In the course of preparing aryl azide derivatives for use as photoprobes, we have observed significant light sensitivity in the precursor aryl diazonium compounds. The photosensitive properties of this class of compounds are of interest since they will seek out cationic binding sites in biological targets, and can be employed to inhibit complementary targets at acid pH. The relationship between photolytic change in the structure of diazonium compounds and the corresponding change in function of a biological target are presented. Experiments are described in which the dark and light sensitive properties of a model diazonium compound, diazobenzene sulfonate (DBS), were determined. The ultraviolet spectra were used to evaluate the dark stability and light sensitivity of DBS. Chymotrypsin and trypsin served as functioning targets for further evaluation of the photochemical properties. Both enzymes are stable to the probe in the dark at acid pH. A rapid loss of enzyme activity was observed following flash photolysis of DBS-enzyme solutions. Photolytic incorporation of radioactive DBS into chymotrypsin was observed. Aryl diazonium salts can be employed to probe the availability of complementary sites in biological targets at different acid pH values.

Chymotrypsin↗
PubMed1976

A colour reaction for the differentiation of ascomycetous and hemibasidiomycetous yeasts.

Seventy yeast strains, representative of twenty-six ascogenous genera, four saprobic hemibasidiomycetous genera and thirteen genera of the Cryptococcales were tested for their reaction with the stabilized aromatic diazonium compound, Diazonium Blue B salt. An aqueous, buffered solution of this compound gave a characteristic red colouration with the colonies of the hemibasidiomycetous species and those Cryptococcales characterized by the hemibasidiomycetous cell-wall type. The characteristic colour reaction was not observed with colonies of either the ascomycetous yeasts or those Cryptococcales characterized by the ascomycetous cell-wall type. The possibly taxonomic use of the colour reaction with Diazonium Blue B salt as an affinitive characteristic is discussed.

Ascomycota↗
PubMed1987

Aryl diazo compounds and diazonium salts as potential irreversible probes of the gamma-aminobutyric acid receptor.

The synthesis of different diazonium salts derived from homo- and heterocyclic aromatic amines bearing anionic residues is described. The chemical stabilities of these compounds were established at different pH's, and the compounds were tested accordingly in binding experiments for the rat brain gamma-aminobutyric acid (GABA) receptor, for which they could ultimately be used as irreversible affinity or photoaffinity probes. The aromatic heterocyclic series studied were 2-aminoimidazole, 2-aminothiazole, and 4-aminopyridine N-oxide. The derived diazonium salts are unstable compounds at neutral pH unless they are able to be deprotonated to the corresponding diazo form. As such, the 2-diazoimidazole-4(5)-acetic acid (3b) is stable in neutral medium and recognizes the GABA receptor (IC50 = 70 microM). The homocyclic aromatic diazonium salts showed sufficient stability to be tested in binding experiments. The diazonium salts derived from m-sulfanilic acid and 8-sulfonaphthylamine were the most interesting (10b, IC50 = 10 microM; 15b, IC50 less than 100 microM). In this series, the compounds that deprotonate at neutral pH (hydroxybenzenediazonium derivatives 12b-14b) showed increased chemical stability but decreased affinity for the GABA receptor. This difference between the diazoimidazole and the diazohydroxybenzene series is attributed to a different charge distribution between the two series. The ligands 3b, 10b, and 15b can be used as potential irreversible probes for the GABA receptor.

Affinity Labels↗
PubMedDate not supplied

The use of 4,4'-biphenylbisdiazonium fluoroborate as a coupling agent for passive haemolysis tests.

The possibility of use a stable diazonium compound, to replace bisdiazotized benzidin (BDB) for conjugating antigens to red blood cells was investigated. Five different batches of 4,4'-biphenylbisdiazonium fluoroborate (BDF) were prepared and tested in conjugation experiments. The sensitivity to specific lysis of red cells coated with different antigens (EG cells) was assayed by both direct and indirect passive haemolysis tests. Optimal conditions for the preparation of EG cells with different protein antigens were established. With the exception of the concentration of the bifunctional reagent, these conditions were similar to those previously reported for BDB. The antibody content of different anti-protein sera could be determined, with a 10 % error, by using EG cells prepared under optimal conditions in indirect passive haemolysis tests. The amount of antibody detected by this method varied from 7 to 12 ng N Ab/ml, depending upon the nature of the antigen fixed to red cell. The content of BSA in dilute solutions could be estimated by the specific inhibition of the indirect passive haemolysis tests. Testing different samples of BDF maintained at different conditions showed that the compound could be kept at room temperature, during the least four years, without appreciable loss of the conjugating properties, provided it was kept in the dry state and in the dark.

Animals↗
PubMed2006

Electronic properties of Si surfaces and side reactions during electrochemical grafting of phenyl layers.

The electrochemical grafting process of 4-nitrobenzene and 4-methoxybenzene (anisole) from diazonium salt solutions has been investigated in situ by monitoring the current density, the band bending, and the nonradiative surface recombination during grafting at different potentials and different concentrations of the diazonium salt in the solution. Ex situ infrared spectroscopic ellipsometry has been used to inspect the Si surface species before and after the grafting process. The band bending decreases with either increasing concentration of diazonium salt or when the redox potential of the diazonium compound (anisole) is nearer to the competing H+/H2 couple. The surface recombination increases at more cathodic potentials if an electron donor group is present at the phenyl ring (nitrobenzene) and vice versa for the electron acceptor group (anisole). The influence of side reactions can be reduced by use of moderate concentration and moderate or strong cathodic potential, depending on the redox potential of the diazonium compound.

Diazonium Compounds↗