In recent years, there has been tremendous interest and explosive advances in solid-state lighting (SSL). This novel technology of lighting is based on LEDs (light emitting diodes) and is said to create a revolution in the lighting industry [1]. As compared to the conventional incandescent or fluorescent light sources, the solid-state lighting offers many advantages such as high energy conversion efficiency (~200 lm/W), long lifetime (>100000 h), being robust and environmentally friendly.For general lighting purposes, “white LEDs” are required. The industrial solution to date is to use a single LED chip, e.g. blue LED (460 nm) or near-UV LED (380 nm), combined with phosphors. Therefore, finding the efficient phosphor materials with high absorption in the near UV/blue spectral region is the key for SSL technique.Lanthanoid complexes have long been known to be luminescent. This type of compounds is of particular interest. First, luminescence occurs via the so-called “antenna” mechanism, i.e. via ligand absorption, which is highly efficient and in addition can be easily modified to tune the luminescent properties of the complexes. Second, many ligands are commercially available and are relatively cheap materials. Third, the complexes are molecular-based solid materials, which do not require highly pure rare earths as starting materials. Furthermore, recycling of the expensive rare earth metals can be readily achieved from complexes.Despite the various potential advantages, rare earth (lanthanide) complexes have received little attention in the field of lighting and display applications due mainly to low luminescent efficiency of the known complexes in comparison with oxide-based luminescent materials.Recently, several new lanthanide complexes were synthesized in CBAC. Some of them show very interesting luminescent properties. For example, the Eu- and Tb-complexes of pyridine-2,6-dicarboxylic acid (H₂pda) [2] show highly intense red and green emission under UV light of 254 nm (Fig. left); also complexes of the corresponding diamide are luminescent [3]. Furthermore, the La- and Tb-complexes of 5-tert-butyl-2-hydroxyisophthalic acid (H₃L) are highly luminescent and can be excited even with wavelengths up to 380 nm (Fig. right) [4]. The goal of the proposed study is to develop and investigate new coordination complexes as potential phosphor materials for LED-based SSL. Although several Tb- or Eu-complexes with promising luminescent properties were discovered in the past years, a systematic investigation of this type of complexes is highly beneficial.