Synthesis and Chemiluminescence Properties of 6-(4-Methoxyphenyl)-2-methylimidazo[1,2-a]pyrazin-3(7H)-one and 2-Methyl-6-(2-naphthyl)imidazo[1,2-a]pyrazin-3(7H)-one

Abstract

New Cypridina luciferin analogues, 6-(4-methoxyphenyl)-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (MCLA) and 2-methyl-6-(2-naphthyl)imidazo[1,2-a]pyrazin-3(7H)-one (NCLA), were prepared together with their oxyluciferin analogues, 2-acetamido-5-(4-methoxyphenyl)pyrazine (MCOLA) and 2-acetamido-5-(2-naphthyl)pyrazine (NCOLA). Various chemiluminescence properties of these compounds were compared with those of known luciferin analogues, 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (CLA) and 6-(3-indolyl)-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (ICLA). The light yields obtained from ICLA, MCLA, and NCLA were much higher than CLA in diethylene glycol dimethyl ether (diglyme), in which triplet oxygen was the oxidant. In aqueous solution, employing superoxide ion as the oxidant, NCLA emitted light weaker than CLA and MCLA. ICLA gave almost no light on account of no fluorescence intensity of the emitter (oxyluciferin analogue ICOLA) in aqueous solution. For applications to the detection of active oxygen species produced during enzymatic reactions, MCLA is superior to conventionally used CLA because of its higher chemiluminescence quantum yield and its emission maximum in visible region.

Electrogenerated chemiluminescent behavior of MCLA at an indium-tin-oxide electrode

“…The result showed that the maximum emission wavelength was 460 nm (see Fig. 5), which was equal to the emission maximum of chemiluminescence of MCLA [1]. The results indicated that the ECL of MCLA was similar to its chemiluminescence.…”

“…6-(4-Methoxyphenyl)-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (MCLA) is one of the analogues of Cypridina hilgendorfii luciferin, and has been prepared by Goto and co-workers as chemiluminescent compound that exhibits chemiluminescence in aqueous solutions [1]. Its molecule structure is shown in Scheme 1.…”

Effect of conformation on the chemiluminescence efficiency of light‐producing 2‐methyl‐6‐(4‐methoxyphenyl)imidazo[1,2‐α]pyrazin‐3(7H)‐ones

“…During these investigations, it was revealed that 1a reacts with triplet oxygen in aqueous solutions to generate a neutral singlet excited-state amide molecule 2a*, as shown in Scheme 1. A comparable chemiluminescence mechanism has been described for a reaction with superoxide anion in an aqueous solution (6). In general, the overall chemiluminescence efficiency is dependent on: (a) emitter-formation efficiency; (b) singlet excited-state formation efficiency; and (c) fluor- escence efficiency of the emitter, such as 2a*.…”

“…Goto et al have developed Cypridina luciferin analogues, 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (CLA) (3,5) and 2-methyl-6-(4methoxyphenyl)imidazo [1,2-a]pyrazin-3(7H)-one (1a; MCLA; Figure 1) (6), as chemiluminescence probes, which were shown to emit light in aqueous solutions. The chemiluminescence efficiency of MCLA in acetate buffer in the presence of superoxide anion is about 1.3 times greater than that of CLA (6) and, therefore, the MCLA chemiluminescence method in aqueous solutions is widely utilized.…”

Development of imidazopyrazinone red‐chemiluminescent probes for detecting superoxide anions via a chemiluminescence resonance energy transfer method

“…Since the use of 2-methyl-6-phenylimidazo [1,2-a] pyrazin-3(7H)-one (CLA) 1 (1) for the detection of superoxide anions was first reported, various imidazopyrazinone-type chemiluminescent probes have been developed (2)(3)(4)(5)(6)(7). One such probe, 2-methyl-6-(4-methoxyphenyl)imidazo[1,2-a] pyrazin-3(7H)-one (MCLA) (1; Fig.…”