Luminescent products

Fig. 4.8.3 Absorption spectra of pure mineopsin-2 (A), its luminescence product after the addition of Ca2+ (B), and the base line (C). Sample concentration 0.081 mg/ml. From Ward and Seliger, 1974b, with permission from the American Chemical Society.

Soon after the hypothetical structure was published, coelenterazine was isolated as an actual substance from the liver of the luminous squid Watasenia scintillans, and it was chemically synthesized (Inoue et al., 1975). The availability of synthetic coelenterazine led to the important discovery that the treatment of the luminescence product of aequorin with coelenterazine results in the regeneration of active aequorin (Shimomura and Johnson, 1975c), which consequently confirmed the presence of a coelenterazine moiety in the aequorin molecule. During the same period, it became increasingly evident that coelenterazine is involved as a luciferin in various bioluminescent organisms, such as the sea cactus Cavernularia, the sea pen Ptilosarcus, and the sea pansy Renilla (Shimomura and Johnson, 1975b). 

Two principal ways exist to use a dye as a sensor of local polarity (or of microscopic electric fields) (1) monitoring the polarity-induced shift of the energy levels, e.g., the red shift of the fluorescence and (2) monitoring changes in fluorescence intensity induced by the polarity- or field-induced modulation of nonradiative rates. As these compete with the fluorescence emission, the fluorescence intensity (and lifetime) is correspondingly modulated. (3) In some cases, the radiative rates are also solvent sensitive this is usually connected with the formation of luminescent products. 

W. Rettig, W. Majenz, R. Lapouyade, and M. Vogel, Adiabatic photochemistry with luminescent products, /. Photochem. Photobiol.A Chem. 65,95-110(1992). 

The luminescent production of light by living animals and bacteria, by chemical reactions occurring in special organs, is covered under bioluminescence (see Chapter 3, section 3.7). 

Methods based on chemiluminescent and bioluminescent labels are another area of nonisotopic immunoassays that continue to undergo active research. Most common approaches in this category are the competitive binding chemiluminescence immunoassays and the immunochemiluminometric assays. Chemiluminescence and heterogenous chemiluminescence immunoassays have been the subject of excellent reviews (91, 92). Detection in chemiluminescence immunoassays is based on either the direct monitoring of conjugated labels, such as luminol or acridinium ester, or the enzyme-mediated formation of luminescent products. Preparation of various derivatives of acridinium esters has been reported (93, 94), whereas a variety of enzyme labels including firefly or bacterial luciferase (70), horseradish peroxidase (86, 98), and alkaline phosphatase are commercially available. 

The free energy of the annihilation reaction can be evaluated from the one-electron potentials for oxidation and reduction of the species involved and the zero-zero emission energy, Eqq, of the luminescent product. The excited state formed can be either singlet or triplet spin multiplicity (or both). If strict spin conservation is observed in the process, the products will contain 75 % triplet and 25 % singlet however, hyperfine interactions provide alternate avenues for angular momentum conservation [13, 14]. 

The photonics of Nph molecules on the surfaces of the zeolite X as well as on aerosil has been studied. Nph in zeolite voids is present as physically adsorbed molecules and bound in donor-acceptor complexes (CTC). Water vapor admission to an adsorbed Nph causes oxidation under formation of luminescent products of a-naphthoquinon on the Na-forms and its mixture with b-naphthol in presence of the alkaline-earth cations. Assumption about participation of oxygen chemisorbed on acid centers in an oxidation reaction is substantiated. In presence of transition metal ions the Nph luminescence is totally quenched. The Nph molecules adsorbed on the dehydroxylated aerosil surface form bimolecular excimer-like associates with a stable ground state and resistance to UV irradiation. 

Figure 6 DFO and Indanedione - reagents that react with amino acids to give a luminescent product.

Industrial Applications Colored or luminescent products as geothermal tracers microfabricated electrophoresis devices porous polymer monoliths separation devices thin-film polymer light emitting diodes ... 

Miyoshi, K. Colorant compositions with good adhesion and resistance to dry conditions, and colored or luminescent products containing them. Jpn. Kokai Tokkyo Koho JR 2006265306,2006. 

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