Columnar mesomorphism in molecular alloys based on Halogen-Bridged PtII/PtIV mixed valence complexes. The key role of the PtII/PtIV ratio
Year: 2025
Type: article
Abstract: In this paper, we studied the thermotropic behavior and phase diagrams of blends of two platinum-based metallomesogens with different oxidation states and ligands, which are prone to self-association through the formation of a mixed-valence system via Pt II ···Cl-Pt IV interactions. The constituent molecules are cis- [PtCl 2 (CNL) 2 ] (CNL = 2-(6-(4-isocyanophenoxy)hexyloxy)-3,6,7,10,11-pentakisdodecyloxytriphenylene) and [PtCl 4 (Bipy)] (Bipy = didodecyl 2,2′-bipyridyl-4,4′-dicarboxylate), which display an organic/inorganic segregated multicolumnar mesophase and a lamellar mesomorphism, respectively. Firstly, the phase diagram was constructed using polarized optical microscopy, differential scanning calorimetry and X-ray scattering data. The results indicated that compositions exceeding 50 % of [PtCl 2 (CNL) 2 ] led to columnar mesophases very similar to the one of pure [PtCl 2 (CNL) 2 ], where triphenylene cores and platinum moieties are segregated into different columnar units. Then, employing tight-binding quantum chemical methods, we studied the supramolecular organization in the columnar mesophases, as well as the electronic structure properties of mixtures with compositions larger than 50 % of [PtCl 2 (CNL) 2 ]. The results revealed that the formation of the metal–organic columns relies on a fine balance between Pt II ···Pt II and Pt II ···Cl-Pt IV intermolecular interactions, which strongly depend on the composition of the system. A deep analysis of the density of states showed that lower concentrations of [PtCl 4 (Bipy)] result in a hole-doped system, while at higher [PtCl 4 (Bipy)] concentrations the intervalence charge transfer between the metal center in different oxidation states significantly changes the electronic structure.
Source: Journal of Molecular Liquids
Institution: Universidad de Valladolid
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,480
OpenAlex ID: W4409760823