Herein, we report as eries of unsymmetrical bispyrazolate-typeP t II compounds that exhibit mesomorphism at low temperatures and photophysicalm ulti-stimuli-responsive properties.T hese Pt II compounds show a great ability to be self-assembled by intermolecular Pt···Pt interactions in the solid state,s og enerating ac olumnar stackingo fm olecules that is responsible for the formation of the mesophases. By controlling the nature of the molecular assembly through external stimuli such as the temperature, the pressure, or the presenceo fv apours or solvents, it is possible to modulate the luminescence behaviour of thesem aterials.T he Pt II monomers emit ag reenish light, whereas aggregation of molecules produces ar edshifted emission. These metallomesogens also show a high stability ands uccessive grinding/fuming cycles can be performedw ithoutd egradation of the sample. The applicationo ft hese materials is very attractive as rewritable luminescent platforms, and their use is already demonstrated.Metallomesogensa re consideredsoft materials in which the establishment of intermolecular interactions and short contacts is favoured. [1] Therefore, the self-assembly of molecules will determinet he energy levelso ft he HOMOa nd LUMO orbitals, this fact openingawide range of possibilities in relationw ith the photophysical behaviour of this kind of nanomaterials. [2] It is well known that the luminescence emission in such systems can be originated from ag reat variety of excited states, such as ligand centre charge transfer (LCT), intraligand charge transfer (ILCT), metal-to-ligand charge transfer (MLCT), and metalmetal-to-ligand charget ransfer (MMLCT). [3] Here the nature of the coordinated ligands, as well as that of the counter-ions (in the case of ionic species), play ak ey role. As mall modification in the molecular structure can induce the formation of new intermolecular interactions, and this can originaten otable changes in its properties ande ven give rise to stimuli-responsive behaviours. [4] Many authors have demonstratedt he versatility of the Pt II metallomesogens to emit light in aw ide spectral range of 400-800nm, simply by introduction of ab ulky substituent group, for example;o rb ym odification of the number of terminal alkyl chains. [5] Particularly,the study of species in which the platinum centre is coordinated to delocalised p-systems is arousing speciali nterest becauset he phosphorescent nature of the emission is boosted at room temperature. [6] Materials that exhibit both liquid crystal and stimuli-responsive properties have been reported in the literature, but are very scarce. [4b,c, 7] Herein, we describe as eries of unsymmetrically four-coordinated Pt II metallomesogens bearing one pyridylpyrazolate and one isoquinolinylpyrazolate ligands, both being additionally carriers of dicatenar alkyloxyphenyl substituents. The compounds are, thus, four-chained, decorated with alkyl chain lengthsf rom four to 18 carbona toms (compounds 1-8; Scheme 1). The introductiono fa symmetryi se xpected to fa...