INTRAMOLECULAR EXCIMER FORMATION IN POLYESTERS FROM TEREPHTHALIC ACIDAND 6 2R,2R'-PROPANEDIOLS

Fluorescence has been measured for six polyesters derived from terepht halate and six 2R,2R'-propanediols, represented by HOCH2-CRR'-CH2OH. T he solvent effects on the emission spectra permit separation of the si x polymers into two groups. One group consists of the five polyesters in which R and R' are alkyl groups, and the other group has only one m ember, that being the polyester with R = R' = H. Modelling suggests th at the origin of the difference between the two groups lies in the acc ess by the polyester with R = R' = H to a conformation (inaccessible w hen R and R' are alkyl groups) that forms a very tight complex between two successive aromatic rings.