Excited state dynamics of PPI dendrimers functionalized with 4-(4′-ethoxybenzoyloxy)salicylaldehyde chromophores

Abstract

Femtosecond transient absorption spectroscopy has been applied for the investigation of the excited state dynamics of poly(propyleneimine) dendrimers functionalized with 4-(40-ethoxybenzoyl-oxy)salicylaldehyde (SA) promesogenic units. Different transient absorption dynamics of three different tautomeric forms of SA chromophore groups have been distinguished. Cis-keto and enol-closed tautomeric forms experience opening of pseudo-aromatic ring and fast relaxation to the conformationally distorted ground state of trans-keto tautomeric form. No tautomeric changes take place under direct excitation of the trans-keto tautomers.