Introduction The chemistry of the lanthanoids is strongly stamped by the trivalent oxidation state and by the fact that the f-electrons of these elements are strongly shielded and are essentially not involved in chemical bonding.1-4 On the other hand, the well-shielded electrons lead to unique physical properties of the Ln3+-ions, and especially their luminescence and their magnetism have attracted significant attention that has led to various applications.5-9 The luminescence of most...
