MONOLAYER ASSEMBLIES INCORPORATING 2 TYPES OF CYANINE DYES - POSSIBILITY OF FORMATION OF AN AMALGAMATION-TYPE J-AGGREGATE

The J-aggregates of four types of cyanine dyes-5,6,5',6'-dibenzol,1'-d iethyl-2,2'-cyanine chloride (Dye I), 5'-dichloro-3,3'-diethyl-9-pheny l-thiacarbocyanine chloride (Dye II), dimethyl9-phenyl-4,5,4',5'-napht hothiacarbocyanine chloride (Dye III), and 1-methyl-1'-octadecyl-2,2'- cyanine perchlorate (S120-in monolayer assemblies have been fabricated . Mixed assemblies, donor/acceptor, which incorporate two types of cya nine dyes in the same layer plane, are classified into four groups acc ording to the structure of the mixed aggregate; separate aggregate, mo saic aggregate, homogeneous aggregate of persistence type, and homogen eous aggregate of amalgamation type. Spectroscopic properties of the D ye II/Dye III assembly are completely different from those of the Dye I/Dye II assembly and the S120/Dye I assembly. A single J-band and a s ingle peak of resonance fluorescence in the Dye II/Dye III assembly, i n contrast to two J-bands and two peaks of resonance fluorescence in t he other assemblies, suggest that the Dye II/Dye III assembly can form an amalgamation-type J-aggregate. An empirical parameter, Delta(DA)/T -DA, introduced to visualize the electronic requirement for the format ion of the amalgamation-type J-aggregate, is examined.