A novel pyrenyl-appended tricalix[4]arene for fluorescence-sensing of Al(III)

In acetonitrile, the tren-N-tricalix[4]arene 4 with three appended pyrenyl groups showed an enhanced fluorescence in the presence of Al3+ and, to a lesser extent, of In3+. Compound 4 was shown to form a 1:1 complex with Al3+, the metal cation being located in the tren part. The association constant (Ka) of 4 for the Al3+ cation was calculated to be 8.7×103 M−1 in acetonitrile.