David F. Roswell

[36] The chemiluminescence of luminol and related hydrazides

Publisher Summary This chapter focuses on chemiluminescence of luminol [5-amino-2,3-dihydrophthalazine- 1,4-dione], and some derivatives and analogs of related hydrazides. Chemiluminescence is the production of light by chemical reactions. Electronically excited states are formed in the chemical reaction, and light emission from these completes the process. The chemiluminescent reactions of luminol are all oxidations. A wide variety of reaction conditions is employed; the reaction can be carried out either in protic media or in aprotic solvents such as dimethyl sulfoxide (DMSO), hexamethylphosphoric acid triamide (HMPT), or dimethylformamide (DMF). Water is the most common protic solvent, although the reaction has been studied in the lower alcohols as well. Hypochlorite, ferricyanide, and persulfate are commonly used oxidizing agents. The dianion is involved in aprotic oxidations, the radical anion in protic ones, and the azaquinones very probably are involved in the light pathway.

ANALOGS AND DERIVATIVES OF FIREFLY OXYLUCIFERIN, THE LIGHT EMITTER IN FIREFLY BIOLUMINESCENCE

Abstract— The 5‐methyl analog of firefly oxyluciferin, two isomeric O‐methyl ether derivatives of it and an O, OÓ‐dimethyl ether derivative were synthesized and their UV absorption and fluorescence emission spectra were determined. Comparisons of the emission data with the emission wavelength in bioluminescence indicate that the mono‐anions of firefly oxyluciferin are candidates for the light‐emitters in bioluminescence. Further, we have found that the chemiluminescence of active esters of firefly luciferin produces (from the keto form of oxyluciferin) only red light emission under a variety of conditions; a yellow‐green light emission (from the enolic forms of the oxyluciferin product) could not be elicited.

[18] Active site-directed inhibition with substrates producing carbonium ions: Chymotrypsin

Publisher Summary Irreversible enzyme inhibition can result from compounds with little or no intrinsic derivatizing power but which carry “primed” functional groups. If at the active site this group can be uncoupled to yield an active species, derivatization can occur. The first report of this type of specific inhibition was made by Bloch, who used the enzymic conversion of an acetylenic analog of the substrate to a reactive allenic form, which then rapidly alkylated the enzyme at the active site. This chapter examines the approach that involves the production of carbonium ions, as a result of enzyme action, at the active site of the enzyme; the carbonium ions are capable of alkylating the enzyme. It examines the general properties, synthesis and inhibition studies.

The chemiluminescence of amides and monoacyl hydrazides based on firefly dehydroluciferin.

Abstract— Monoacyl hydrazides based on 5‐methyldehydroluciferin and simpler analogs have been synthesized; they proved to be chemiluminescent on treatment with a strong base in DMSO in the presence of oxygen. The light emitters in these cases appear to be the corresponding carboxylate ions; a pathway involving an oxidative decarboxylation was eliminated as a possibility by consideration of the fluorescence wavelengths of the corresponding oxyluciferins. A reaction mechanism for the luminescence involving the possible intermediacy of an azadioxetane is proposed. The corresponding amides were also synthesized; they proved to be equally chemiluminescent to the hydrazides in the dehydroluciferin series.

On the Apparent Lack of Oxygen Quenching of Triplet Excited States

The early observation that excited triplet states obtained chemically from trimethyldioxetane (and subsequent energy transfers) appeared not to be quenched by oxygen is now shown to be an artifact; acetaldehyde is a product of the reaction and via chemical reactions it scavenges oxygen present in the medium; the attendant extended lifetime of the triplet states then permits their employment in photochemical‐type reactions. The effect of the aldehyde can be over‐ridden through an efficient introduction of an excess of oxygen into the liquid reaction phase.