M 2158 (OTTO) 5-Methyl-2-pyrazinecarboxylic acid, 98% Cas 5521-55-1 - used in the preparation of novel europium(III) complexes, (5-methyl-2-pyrazinecarboxylato) (phenanthroline)europium(III). M 2158 (OTTO) 5-Methyl-2-pyrazinecarboxylic acid, 98% Cas 5521-55-1 - used in the synthesis of Ln-metal organic frameworks (MOFs).