Photophysical Properties of Visible‐Light‐Harvesting Pt^II Bis(acetylide) Complexes

Abstract

PtII complexes have attracted much attention due to their readily derivatizable molecular structures and efficient production of triplet excited states and have been extensively used in many areas. Conventional PtII complexes usually exhibit small molar absorption coefficients in the visible spectral region, and the triplet excited state lifetimes are short. However, for applications such as photocatalysis, triplet–triplet annihilation (TTA) upconversion, nonlinear optics, etc., visible‐light‐harvesting PtII bis(acetylide) complexes with long‐lived triplet excited state are cucial. We summarize strategies directed towards achieving these goals, through the attachment of appropriate strong visible‐light‐harvesting organic chromophores to the ligand to switch the S0→1MLCT (metal‐to‐ligand charge transfer) transition to the S0→1IL (intraligand) transition (π–π*) and to switch the lowest triplet excited state from the 3MLCT to the 3IL state. We also summarize the properties of PtII bis(acetylide) complexes that show broadband absorption and reverse saturate absorption for application in nonlinear optics. Singlet and triplet energy transfer and localization of the triplet excited state in multiple‐chromophore complexes are also discussed.

Synthesis of Platinum-Containing Conjugated Polymers Bearing Optically Active Amide Groups: A Mechanistic Study of Chiral Aggregation

“…22−33 Such complexes possibly form supramolecular metal complexes and aggregates based on intermolecular Pt−Pt interactions. 34,35 They also exhibit unusual photoproperties, such as upconversion, 36,37 near-infrared photoluminescence, 34,35 aggregationinduced emission, 38 and mechanochromic luminescence. 39 Polymers containing cis-Pt ethynyl complexes are synthesizable by employing chelating ligands, although they are thermodynamically unfavorable to the trans-isomers.…”

“…Pt–bipyridine bis­(acetylide) [Pt­(bpy)­(CC–Ar) 2 ] complexes with highly square planar conformation are utilized as components of metallacycles, metallacages, and so on. − Such complexes possibly form supramolecular metal complexes and aggregates based on intermolecular Pt–Pt interactions. , They also exhibit unusual photoproperties, such as upconversion, , near-infrared photoluminescence, , aggregation-induced emission, and mechanochromic luminescence . Polymers containing cis -Pt ethynyl complexes are synthesizable by employing chelating ligands, although they are thermodynamically unfavorable to the trans-isomers. − There are only a few reports about the synthesis and examination of secondary structures of polymers containing Pt–bipyridine complex moieties due to their low solubility in organic solvents. − We have synthesized poly­(phenyleneethynylene)­s having optically active amide groups and Pt complex moieties ligated with bipyridine in the main chain, which assemble into regularly twisted ribbonlike structures in the solid state .…”

Lewis Pair-Functionalized Pt(II) Complexes with Tunable Emission Color and Triplet-State Properties

“…Herein, we investigate two new emissive FlexLP-functionalized Pt­(II) complexes that have tunable fluorescence colors and explore the FlexLP ligand conformation’s impact on the triplet-state properties. Many cyclometalated and polymeric Pt­(II) complexes have been reported for application in phosphorescent OLEDs, − highlighting the considerable ligand modification possible with these Pt­(II) organometallic complexes while retaining interesting photophysical characteristics. Square-planar Pt­(II) complexes of the form [Pt­( n -Bu 3 P) 2 (Ar) 2 ], where Ar is a σ-bonded alkynyl-aryl ligand, have likewise been shown to exhibit ISC and may display phosphorescence; therefore, this schematic was explored. , Acetone, a weakly HBD solvent, and methanol (MeOH), a strongly HBD solvent, were chosen because they have drastically different Kamlet–Taft HBD strengths; however, both have similar polarities .…”

An N^N Platinum(II) Bis(acetylide) Complex with Naphthalimide and Pyrene Ligands: Synthesis, Photophysical Properties, and Application in Triplet–Triplet Annihilation Upconversion

“…Transition‐metal complexes, such as those containing Pt II atoms, usually show efficient intersystem crossing (ISC) properties, and these complexes have attracted increasing attention for applications in photocatalysis, photovoltaics, photodynamic therapy, oxygen sensing, and triplet–triplet annihilation (TTA) upconversion However, conventional Pt II complexes weakly absorb visible light , . To address this problem, visible‐light‐harvesting Pt II complexes have been investigated widely through coupling with organic chromophores, such as pyrene (Py), naphthalimide (NI),, perylene,, and boron–dipyrromethene (Bodipy) ligands …”