Inclusion compounds have gained an increasing interest in the past few decades. These compounds are composed of a combination of "host" and "guest" molecules; and some examples of organic hosts include cyclodextrins, crown ethers and calixarenes. The limited dimensions of these host molecules usually impose restrictions to the mobility and conformations of the guest, resulting in the discipline of its properties. These effects in turn are usually reflected in product distributions and reaction rates. Inclusion compounds are formed not only in solution but also in the solid state, where effects can be more dramatic.

The objective of my project is to gain insights into the role that host and guest molecules play in organic solid phototransformations. Studies will focus on inclusion effects on the photochemical behavior of carbonyl compounds within calixarene complexes. Calixarenes represent an interesting type of bridged aromatic oligomers, obtained by condensation of phenol and formaldehyde. Investigations will be carried out based on the application of time resolved diffuse reflectance laser flash photolysis techniques. Studies will be based on the use of p-tert-butylcalix[n]arene (where n= 4,6 and 8) and its derivatives and of guest molecules differing in their degree of flexibility as well as their excited state characteristics (example, xanthone and benzophenone).

29-jun-96