Photochemical studies of molecules in the organized voids of microporous frameworks is an area of considerable research interest. In this study, we have examined the spectroscopy and photochemistry of trans-azobenzene introduced into the 8 A channels of an aluminophosphate framework, AlPO4-5. The acidity of aluminophosphates is considered to be very weak, based on their poor catalytic performance in transformations of organic compounds. However, we report that the Bronsted acidity of the AlPO4-5 is enough to protonate the azo groups in azobenzene. This leads to appearance of a band at 418 nm. Also, room temperature emission observed at 518 nm, an unusual spectroscopic feature for azobenzene, is due to the protonated form. Photolysis of the azobenzene/AlPO4-5 sample leads to the formation of benzo[c]cinnoline and benzidine. The Lewis acid sites of AlPO4-5 are proposed to play an important role in the photocyclization chemistry. Because the number of such acid sites in AlPO4-5 is limited, only a fraction of...

Photochemistry of Azobenzene in Microporous Aluminophosphate AlPO4-5

This chapter gives an overview of the macrocyclic chemistry of lanthanide ions. It emphasizes on functional compounds, but most of the examples given belong to biomedical, luminescence, and extraction applications; the chemical applications have been somewhat shadowed. This part of the chapter is devoted to lanthanide complexes and its aim is to maintain or enhance their unique physicochemical and chemical properties. The first step in the study of metal complexes is the synthesis or preparation of the complex followed by physicochemical characterization of the complex. Lanthanides rarely behave like transition metal cations and hence, the need for different precautions in handling them. Highly pure lanthanide oxides that are commercially available can be used as starting materials for the preparation of lanthanide complexes after treatment at 1100 °C to convert residual carbonates into the oxides. Synthesis of several lanthanide complexes requires anhydrous conditions. Hydrated lanthanide salts undergo decomposition in the process of dehydration under vacuum at elevated temperatures.

Jamil Ahbad

Papers

4,4′-Diamino-diphenyl complexes with rare-earth(III) chlorides