Encapsulation of Phosphorescent Pt(II) Complexes in Zn-Based Metal–Organic Frameworks toward Oxygen-Sensing Porous Materials

Abstract

In this work, we synthesized two tailored phosphorescent Pt­(II) complexes bearing a cyclometalating tridentate thiazole-based C^N*N pincer luminophore (L) and exchangeable chlorido ([PtCl­(L)]) or cyanido ([PtCN­(L)]) coligands. While both complexes showed photoluminescence from metal-perturbed ligand-centered triplet states (3MP-LC), [PtCN­(L)] reached the highest phosphorescence quantum yields and displayed a significant sensitivity toward quenching by 3O2. We encapsulated them into two Zn-based metal–organic frameworks, namely, MOF-5 and ZIF-8. The incorporation of the organometallic compounds in the resulting composites [PtCl­(L)]@ZIF-8, [PtCN­(L)]@ZIF-8, [PtCl­(L)]@MOF-5, and [PtCN­(L)]@MOF-5 was verified by powder X-ray diffractometry, scanning electron microscopy, time-resolved photoluminescence spectroscopy and microscopy, as well as N2- and Ar-gas sorption studies. The amount of encapsulated complex was determined by graphite furnace atomic absorption spectroscopy, showing a maximum loading of 3.7 wt %. If compared with their solid state forms, the solid-solution composites showed prolonged 3O2-sensitive excited state lifetimes for the complexes at room temperature, reaching up to 18.4 μs under an Ar atmosphere, which is comparable with the behavior of the complex in liquid solutions or even frozen glassy matrices at 77 K.

Modulation of Metallophilic and π–π Interactions in Platinum Cyclometalated Luminophores with Halogen Bonding

“…The syntheses of the Hphpyind proligand and of its chloroplatinate [Pt(phpyind)Cl] rely on standard procedures (see the Supporting Information). The direct metathesis of the chloride for the cyanide using AgCN [7e, 23] was ineffective due to low solubility of the target compounds and the difficulty of their separation from AgCl.…”

Ligand-controlled and nanoconfinement-boosted luminescence employing Pt(ii) and Pd(ii) complexes: from color-tunable aggregation-enhanced dual emitters towards self-referenced oxygen reporters

“…Hence, the need for ligands bearing water-soluble substituents or reactive groups from biomolecule conjugation can be avoided. [26][27][28][29][30] Moreover, this strategy can improve their luminescence properties, as a rigid environment can suppress roto-vibration-mediated non-radiative deactivation pathways and intermolecular quenching. 26,31 Furthermore, the matrix can enable the tuning of diverse optical properties by concentration-controlled metal-metal distances, resulting in the formation of aggregation-induced 3 MMLCT states that involve metal-metal interactions.…”

“…[26][27][28][29][30] Moreover, this strategy can improve their luminescence properties, as a rigid environment can suppress roto-vibration-mediated non-radiative deactivation pathways and intermolecular quenching. 26,31 Furthermore, the matrix can enable the tuning of diverse optical properties by concentration-controlled metal-metal distances, resulting in the formation of aggregation-induced 3 MMLCT states that involve metal-metal interactions. 32,33 While there is a vast bibliographic literature regarding Pt(II) complexes, reports on aggregates of luminescent Pd(II) compounds are very scarce.…”

Pyridine Detection Using Supramolecular Organic Frameworks Incorporating Cucurbit[10]uril

“…Due to the advent of new applications, for example, in the storage and separation of gas, − sensing, , drug delivery, in catalysis, and the identification of different structures, investigations on porous materials have increased, for example, on porous organic polymers (POPs), inorganic zeolites, metal– and covalent–organic frameworks (MOFs and COFs), and porous coordination polymers (PCPs). Recent developments in supramolecular chemistry have resulted in an increase in studies examining supramolecular organic frameworks (SOFs), a new porous material.…”