Poly(ϵ‐caprolactone) Decorated With One Room‐Temperature Red‐Emitting Ruthenium(II) Complex: Synthesis, Characterization, Thermal and Optical Properties

Abstract

The incorporation of room-temperature red-emissive [Ru(II)(dqp)(dqp-CH(2) OH)](2+) (dqp is 2,6-di(quinolin-8-yl)pyridine) in poly(ε-caprolactone) (PCL) is explored following two routes. First, the ring-opening polymerization of ε-caprolactone is investigated using the free ligand and the complex as initiators. Alternatively, the complexation strategy utilizing PCL-dqp as a macroligand is detailed. Both routes yield room-temperature emissive polymers centered at 400 nm (free ligand) and 680 nm (complex) in aerated solvent. DSC and TGA showed the typical properties of PCL, for example, the melting point (59 °C).

Aryl-Decorated RuII Polypyridyl-type Photosensitizer Approaching NIR Emission with Microsecond Excited State Lifetimes

“…After anion metathesis with NH 4 PF 6 , the obtained [Ru­(dqp)­(MeCN) 3 ] 2+ intermediates ( 6 ) are bench stable and can be readily purified by crystallization or chromatographic methods. Various related pyridine-functionalized [Ru­(dqp)­(MeCN) 3 ] 2+ complexes were prepared in good to high yields (55–88%) using [Ru III Cl 3 ] hydrate. ,, The coordination of the second ligand is generally achieved in alcoholic solution at elevated temperatures (115–140 °C) to give the bis -tridentate complexes in generally good yields (>50%). ,,,, Notably, only a few exceptions with lower isolated yields are reported, i.e., in the case of reactive ligand functionalities prone to oxidation (OH, NH 2 ) or hydrolysis (CO 2 Et) and in the case of a xylyl-based substituent …”

“…In this regard, microsecond excited state lifetimes can be achieved by virtue of very strong σ-donating ligands, e.g., N -heterocyclic and mesoionic carbenes, − or by inducing an improved octahedral geometry of the coordinating polyhedron around the metal center . The latter strategy has been demonstrated using tridentate ligands featuring 6-membered chelating rings either by the insertion of keto or amino groups into the tpy skeleton or by using peripheral 8-quinolines and related anellated heterocyclic rings. − This approach has been explored in detail in a series of functionalized complexes based on 2,6-di­(quinolin-8-yl)­pyridine (dqp), which display longer excited state lifetimes and enhanced photostability vs [Ru­(bpy) 3 ] 2+ . , The success of this strategy prompted the incorporation of the archetypal [Ru­(dqp) 2 ] 2+ complex ( 1 , Figure a) into various supramolecular architectures, e.g., in donor-photosensitizer-acceptor triads displaying highly efficient and long-lived light-induced charge separation, a bichromophoric anthracene-based system that prolongs the luminescence lifetime, as well as functional polymers such as dye-labeled polycaprolactones, photoredox-active macromolecular architectures, , and electropolymerized responsive metallopolymers. , Additionally, the biomedical application of a [Ru­(tpy)­(dqp)] 2+ photosensitizer for 1 O 2 generation was reported, and the utilization of the inherent helical symmetry of enantiomerically pure 1 for DNA intercalation has been suggested . Recently, related tridentate Ru II complexes containing 8-quinolyl-pyridine fragments were investigated as catalysts for water oxidation , or as versatile photosensitizers in dye-sensitized solar cells with high efficiencies (>10%). , …”

Synthesis and Characterization of Poly(phenylacetylene)s with Ru(II) Bis‐Terpyridine Complexes in the Side‐Chain

“…As a second approach, the variation of the binding angle affects a longer lifetime of the complex and, therefore, an enhanced photophysical activity. Ru(II) complexes with diquinoline pyridine (dqp) ligands, for instance, show excited‐state lifetimes in the range of microseconds . So far, the alkyne‐substituted Ru(II) bis ‐terpyridine complex [4′‐(4‐ethynylphenyl)‐2,2′;6′,2′′‐terpyridine][2,2′;6′,2′′‐terpyridine]ruthenium(II) hexa­fluoro­phos­phate, [(tpy)Ru II (tpy‐Ph‐≡)](PF 6 ) 2 ( M ) was applied in Sonogashira cross‐coupling reactions to either extend the conjugated system on the complex or to attach metal complexes to polymer backbones …”

One‐Pot Synthesis of Polyester–Polyolefin Copolymers by Combining Ring‐Opening Polymerization and Carbene Polymerization

“…Biodegradable polyesters, such as polylactide (PLA) and poly( ε ‐caprolactone) (PCL), have been extensively used as biomedical and packaging materials . An efficient and convenient method to synthesize polyesters is the ring‐opening polymerization (ROP) of cyclic esters catalyzed by metal complexes .…”