The work described in this thesis focuses on two classes of luminophores: tetraarylethene-based polymers and Ir(III) complexes with orthometalated ligands. Tetraarylethene-based polymers show aggregation-induced emission (AIE) and they are of interest for applications in sensing, imaging, and material science. Ir(III) complexes with orthometalated ligands, on the other hand, can be used as components for light-emitting diodes, and they have been employed as photocatalysts, as building blocks for supramolecular complexes, and as chemo- and bio-sensors. Chapter 2 describes a novel procedure for the synthesis of hyperbranched polyarylethenes via successive electrophilic C-H vinylation reactions of aromatic cores with a triazene. The hyperbranched polyarylethenes display size-dependent luminescence and unusual ratiometric AIE behaviour and they can be applied as sensors for alkali metal cations. In Chapter 3, a clean, fast, and simple procedure for the conversion of fac-Ir(C^N)3 complexes into the thermodynamically less stable mer isomers by a consecutive reaction with first acid (TFA or HNTf2) and then base (NEt3) is reported. The process enables the interconversion of luminophores with distinct photophysical properties and allows accessing mer complexes, which are difficult to synthesize with standard procedures. The possibility of the autonomous fac-to-mer switching was also studied. Chapter 4 describes that the fac isomers of Ir(III) complexes with metalated N heterocyclic carbene ligands, Ir(C^C:)3, can be converted cleanly into the mer isomers when solutions of the complexes are treated with first HNTf2 and then NEt3. The procedure allows obtaining mer-Ir(C^C:)3 in high yields and enables the direct conversion of the mixture of fac and mer isomers of Ir(C^C:)3 into the pure mer isomers. The substituent effect was also studied, and acid-base-induced fac-to-mer isomerization of the bulky Ir(C^C:)3 complex was investigated.