Monolayer aggregation of a series of atypical amphiphilic beta-diketone rare earth complexes at air/liquid interface

Monolayer aggregation of a series of atypical amphiphilic rare earth comple xes REL(3)Phen [RE = Eu(III), Sm(III), Tb(III); L = acac (acetylacetone), T FA (trifluoroacetylacetone), HFA (hexafluoroacetylacetone), TTA (thenoyltri fluoroacetone); Phen = 1, 10-phenanthroline] were investigated at the air/l iquid interface by pi -A isotherms, Brewster angle microscopy (BAM) and tra nsmission electron microscopy (TEM). When the complexes were mixed with ara chidic acid (AA), respectively, stable monolayers could be formed. The rare earth complexes could be divided into two classes according to the pi -A i sotherm shape that whether there was a plateau period or not. Complexes wit h beta -diketones acac, TFA and HFA were in one class, while complexes with the P-diketone TTA were in another. All the rare earth complexes formed mi crocrystals at the air/liquid interface. However, the former complex microc rystals oriented with the same crystal plane facing to all directions upon compression; while the latter complex microcrystals oriented with the same crystal plane facing to the same direction. Differences between monolayer b ehaviors of the two classes of complexes were discussed by comparing the st ructure of P-diketone ligands. A possible structural model of the rare eart h complexes in the mixed monolayers with AA at air/liquid interface was pro posed. (C) 2001 Elsevier Science B.V. All rights reserved.