Fluorescent materials based on main-group metal complexes have attracted a lot of interest recently, due to i.a. their potential use in optoelectronic devices, a wide range of biological applications or as chemosensors. The key advantages of such materials are their ready availability and, unlike many transition metal complexes, low toxicity. The earliest references to luminescent metal complexes can be traced back to the middle of the 19th century. However, 1987 saw a breakthrough, when an Alq3 (q-H = 8-hydroxyquinoline) compound was presented as the emitting layer in the first lightemitting diode. This seminal work provided the impetus for seeking more effective metal complexes with 8-hydroxyquinolinato scaffolds, and in particular, the group 13-based luminescent complexes. Particular attention has been paid to the use of (O,N)and (N,N)-bifunctional ligands due to the ease with which their photophysical properties can be tuned (Figure ). Over the last few decades, numerous examples of highly fluorescent Al-based compounds have been reported, e.g. salen derivatives, BODIPY framework-based complexes , asymmetric acetylacetonates and dinuclear triple-stranded helicates (ALPHY), including recently reported dinuclear dimethylaluminium β-diketiminate, (Me2Al)2BODDI, which exhibited high photoluminescence quantum yield (PLQY) in the condensed phase and solution (Figure ). Photoluminescence behaviour is often highly dependent on the aggregate state of the investigated molecular entities. In this context, the effects related to the degree of aggregation, namely aggregation-induced enhancement of emission (AIEE) and aggregation-caused quenching (ACQ), are particularly relevant. The ACQ effect, which is common for most aromatic hydrocarbons and their derivatives, can be explained by intense intermolecular π•••π stacking interactions experienced by molecules located in close proximity within the aggregate or cluster. The AIEE process can be mainly understood to operate by mechanisms based on the restriction of intramolecular rotation. Thus, as molecular packing in the solid plays an important role in determining which of the two effects, AIEE or ACQ, dominate, it is, therefore, important to constantly seek new efficient luminophores in order to gain both a deeper understanding of structure-property relationships and further insights into working mechanisms. Such information will be vital to the systematic design and development of more efficient luminogens.