Effect of coordination environment of Eu2+ ion on the 5d-4f luminescence of molecular compounds EuL2(THF)x (L = Cl, Br, I, NO3, Ac, fod, tmhd, and acac; x=0, 2)

The photoluminescence spectra of crystalline europium dihalides EuL2 (L = Cl, Br, and I) and solutions of complexes of divalent europium EuL2(THF)(2) (L = Cl, NO3, fod, tmhd, acac, Ac) in tetrahydrofuran were registered. The bathochmmic shift of the Eu2+ 5d-4f luminescence maxima is typical for all studied compounds. Its value decreases in the series Cl- > Br- > NO3- > Ac- > acac- > fod- > tmhd- and correlates well with the mean polarizabilities of the anionic ligands.