10-Methyl-9- acridinium

An HPLC-CL determination of environmentally important chlorophenols was reported by using 10-methyl-9-acridinium carboxylate as a CL label. A two-step derivatization was used to produce the CL derivatives (Fig. 10). Following the separation under reversed-phase conditions, the CL reaction was performed by the base-catalyzed postcolumn oxidation. The quantum efficiency was dependent on the species of analytes. The detection limit of chlorophenols (S/N = 3) ranged from 300 amol to 1.25 fmol per injection (Fig. 11) [52],... 

Methyl-8-hydroxyquinoline, 7 588 10-Methyl-9-acridinium carboxylate, chemiluminescence reagent, 5 846 Methyl abietate, 24 553 Methyl acetate... 

Various other miscellaneous salts have been used from time to time to initiate cationic polymerisation. These include tris-p-bromophenyl aminium hexa-chloroantimonate (97), anilinium hexafluoroantimonate (98), nitronium tetra-fluoroborate (95), thianthrenium perchlorate (99), and hexachloroantimonate (100), and N-methyl acridinium and N-methylphenazonium salts (75). In general... 

Further benzologation leads to measurable pvalues for the IV-methyl-acridinium (9.8626) and N-methylphenanthridinium (11.9441) cations however, pKR+ > 14 in aqueous solutions of the N-methyl cations of both the 5, 6- and 7, 8-benzoquinolines.41 The loss in resonance energy upon pseudobase formation is expected to be one of the major factors involved in considerations of the relative susceptibilities of heterocyclic cations to pseudobase formation. A rather crude, but informative, calculation of the loss in resonance energy (AR) upon pseudobase formation has been attempted for each of the above cations. 

Hybridize methyl acridinium ester probe with target nucleic acid (single-stranded or heat-denatured) for 10 min at 60°C in 0.1 M lithium succinate buffer (pH 5.2) containing 10% (w/v) lithium lauryl sulfate, 2 mM EDTA and 2 mM EGTA (total volume 100 xl with 0.2 pmol of probe in a 12x75 mm tube). 

The reductive dimerisation of N-methyl acridinium ion to give (125) proceeds under ultra-violet light illumination in aqueous methanol or aqueous acetonitrile in the presence of triphenyl-phosphine here electron transfer from the triphenylphosphine to the excited state of the acridinium ion to produce the N-methylacridinyl radical is implicated. 

Only one acridinium phenyl carboxylate has found significant use as a chemiluminescent label. 4-(2-succinimidyloxycarbonylethyl)-phenyl-10-methyl-acridinium-9-carboxylate fluorosulphonate has been employed for the determination of albumin and thyroxine and a-fetoprotein. 

A NOVEL CHEMILUMINESCENT IMMUNOASSAY OF TOTAL THYROXINE USING THE ACRIDINIUM ESTER 2 ,6,-DIMETHYL-4 -(N-SUCCINIMIDYLOXYCARBONYL) PHENYL-10-METHYL-ACRIDINIUM -9-CARBOXYLATE METHOSULFATE AS LABEL... 

While luminol and isoluminol require an oxidant plus a catalyst for initiation of the chemiluminescent reaction, esters derived from A -methyl acridinium carboxylic acid require only alkaline hydrogen peroxide (W4). Acridinium esters were first introduced by McCapra s group (M23, M25, S32), based on earlier work on the bioluminescence of the lucigenin/luciferase system (G18), and reviewed in McCapra and Beheshti (M21). From Fig. 19, one can see the structural similarity between lucigenin and a typical acridinium ester. 

Fig. 27. Two acridinium esters with increased stability for covalent labeling of (a) lysine groups, viz., 2, 6 -dimethyl-4 -(N-succinimidyloxycarbonyl)phenyl-10-methylacridinium-9-carboxylafe meth-osulfate (b) carboxyl groups, viz., 2, 6 -dimethyl-4 -[iV-(2-aminoethyl)carbanioyl]phenyl-10-methyl-acridinium-9-carboxylate bromide. Taken from Law et al. (L2).

The first immunoassay utilizing acridinium esters was described in 1981 (S31, S32). The p-carboxyphenyl ester of 9-carboxy-A -methyl-acridinium bromide (Fig. 24 R = HOOC-(j) A = Br) was coupled by carbodiimide chemistry to the lysine residues of sheep a-fetoprotein (AFP) antibody. Unlabeled antibodies were immobilized onto plastic tubes, and the AFP antigen was assayed in a direct two-site... 

M12. Mattingly, G., Chemiluminescent 10-methyl-acridinium-9-(N-sulphonylcarboxamide) salts. Synthesis and kinetics of light emission. 7. Biolumin. Chemilumin. 6, 107-114 (1991). 

The selectivity toward the hydride transfer from the 4 position of these compounds was also studied for the reduction of 10-methyl-acridinium cation with 38-4- , 39-4-d, and 40-4-d that were prepared by the reduction of 43, 44, and 45 with BNAH-4,4-d2, respectively. 

In 1973 Sigman showed that direct hydride transfer can occur from NADH (or d-4-NADH) by using an aromatic analogue iV-methyl acridinium salt (286). 

The weak chemiluminescence from lucigenin in alkaline DMSO solutions in the absence of O2 may involve similar reactions. Cyanide ions also react with lucigenin to give light in the presence of oxygen [7]. Again N-methyl acridone is the emitter and the biacridanyl derivative (6) appears to be an intermediate. An equilibrium between (6) and the radical (7) is proposed. Addition of cyanide ion to N-methyl acridinium chloride in air-saturated DMSO or DMF produces the same radical. 

This tendency to pseudo-base formation increases with the complexity of the heterocyclic nucleus. Thus, whereas pseudo-base formation does not occur for the i-methylpyridinium cation, and only at a very high pH for the i-methylquinolinium and 2-methylisoquinolinium ions, the reaction takes place much more readily upon further annelation (as in lo-methyl-acridinium). The insertion of an electron-attracting substituent (such as -NOg), or a second doubly-bound ring-nitrogen atom, as in quinox-alinium and quinazolinium, has the same effect. Some examples are listed in Table 10.5, in which p/Crqh is the pH at which the pseudo-base and the quaternary cation are present in equal concentrations. Formally p/Croh is similar to a piCa value, but the equilibrium is only slowly achieved. 

Heald RA et al. (2002) Antitumor polycyclic acridines. 8.(1) Synthesis and telomerase-inhibitory activity of methylated pentacyclic acridinium salts. J Med Chem 45(3) 590-597... 

Hutchinson 1 et al. (2004) Synthesis and properties of bioactive 2- and 3-amino-8-methyl-8H-quino[4,3,2-kl]acridine and 8,13-dimethyl-8H-quino[4,3,2-kl]acridinium salts. Org Biomol Chem 2(2) 220-228... 

Abbreviations SPQ 6-methoxy-N -(sulfopropyl)quinolinium SPA N-(sulfopropyl)acridinium lucigenin bis-N-methylacridinium nitrate MACA 10-methylacridinium-9-carboxamide MAMC N-methylacridinium-9-methyl carboxylate. 

A selective reaction takes place between H2O2 and 10-methyl-9-(p-formylphenyloxy-carbonyl)acridinium trifluoromethanesulfonate (123) in basic solution with CL emission at about 470 nm. A proposed mechanism for CL is depicted in Scheme 2. No catalyst other than an alkali is required for the process to take place. The LOD is about 5 nM, with linearity np to 60 (xM. It should be pointed out that the LOD is dictated by the technical capability of obtaining a blank of water devoid of H2O2. The method was applied for H2O2 determination in natural waters. ... 

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