Generation of chemiluminescence upon reaction of aliphatic amines with tris(2,2'-bipyridine)ruthenium(III)

Abstract

Tris(2,2'-bipyridine)ruthenium(III) (Ru(bpy)/sub 3//sup 3 +/) will undergo an electron-transfer reaction with an appropriate reducing agent to form Ru(bpy)/sub 3//sup 2 +/, which upon achieving an excited state can result in chemiluminescence. Aliphatic amines with an increasing number of carbon atoms were tested between a pH of 4 and 6 and found to act as chemiluminescent reducing agents. In addition, some diamines and phosphines were also found to react. Linear range and detection limit studies were done for the mono-, di-, and tri-n-propylamines as well as other selected compounds. Linear range values for these amines varied between approximately 3 and 5 orders of magnitude. The lowest detection limit of 0.28 pmol was found for tri-n-propylamine. Ionization potentials taken from photoelectron spectroscopy data for aliphatic amines were related linearly with the log of the chemiluminescent signal intensity. In addition, it appeared that assignment of the first ionization potential from a nonbonding orbital of the heteroatom was required for chemiluminscence.