The kinetics of triplet state decay and concomitant delayed fluorescence of tetraphenylporphyrin
(TPP) incorporated into the multilayers of n-decanol adsorbed on the external surface of zeolites at different
temperatures were studied by the laser flash photolysis via monitoring the emission and diffuse-reflectance.
In deoxygenated samples, the kinetics of diffusion-controlled bimolecular triplet-triplet annihilation (TTA)
has been used to probe the multilayers. A very large local concentration of reactants may be obtained using
small bulk amounts. A fast TTA rate constant demonstrated the triplet energy migration in TPP assemblies
formed at the liquid/solid interface. The TTA in aerated samples is mediated by molecular oxygen leading
to 1O2 feedback—induced delayed fluorescence. Singlet oxygen works as an efficient mobile energy carrier
between TPP triplets. The parameters of both TTA may be modified by multilayer, which acts as microreactor
with supramolecular organization. The freezing of n-decanol results in dramatic apparent acceleration of
both direct and 1O2 mediated TTA due to the increase in local TPP concentration because of displacement
of TPP molecules into the residual liquid domains in polycrystalline matrix. The concentration of TPP in
those microreactors can be three orders of magnitude larger than the solubility limit in a particular neat
liquid solvent demonstrating the unique features of solid solution, which seems to be due to the presence
of crystal/liquid interfaces.
