Energy migration singlet

Singlet energy migration occurs in P2VN and PS via a random-walk process, based on the observation that the UV absorbance spectrum of the polymer is the same as that of a monochromophoric compound. 

Interesting antenna systems based on polymers have also been designed by Fox and co-workers [26], They prepared a series of well-defined block copolymers labeled with aromatic chromophores and demonstrated that directional singlet energy migration across the block interface takes place, whereas extensive exciplex formation, a decay channel which dissipates electronic energy in flexible polymers, is strongly inhibited in these special polymers. 

The preceding analysis and review of the literature indicate a need for additional types of experiments to study triplet mobility in polymers. One experiment which has been particularly useful in studies of singlet energy migration in polymers, involves determination of the quenching of donor emission by a known mole fraction of a copolymerized luminescent quencher (26). We have extended this approach to the study of triplet states. The polymers chosen for study are homopolymers of isomeric acetonaphthyl methacrylates (aceto-NMA, 1). A related monomer, 2,4-diaceto-l-naphthyl... 

These polymers were chosen for several reasons. The phosphorescence of the acetonaphthyl ester chromophore is intense at 77K, so that spectra of high quality are obtained. At the same time the quantun yield of intersystem crossing from Sj to Tj is 1.0, so that interference from singlet energy migration is not a problem. 

Webber and co-workers have proposed two equations which allow the calculation ofA/D where A is the singlet energy migration rate and D is the diffusion constant for the quencher (13). In equation 2, k e is the bimolecular rate constant for quenching of the polymer while k refers to a model compound of low molecular weight such as ethylnapnthalene. 

Polyesters bearing 9-anthryl or 1-pyrenyl groups originally prepared as photocurable and excimer forming polymers (7) exhibit the tendency of singlet energy migration. The... 

SINGLET ENERGY MIGRATION, TRAPPING AND EXCIMER FORMATION IN POLYMERS... 

ABSTRACT. Intramolecular excimer formation in synthetic polymers is reviewed. The antenna effect in macromolecules is examined and evidence for singlet energy migration and trapping is discussed. 

The degree of debate which has arisen concerning the very existence of singlet energy migration has resulted in the main from conflicting data in certain experiments and the absence of a definitive... 

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