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Luminescent Platinum Complexes with π‑Extended Aryl Acetylide Ligands Supported by Isocyanides or Acyclic Diaminocarbenes
journal contributionposted on 2023-10-17, 03:33 authored by Juan Carlos López-López, Yennie H. Nguyen, Chenggang Jiang, Thomas S. Teets
In this work, we present a series of luminescent platinum acetylide complexes with acetylides that are electronically modified and/or π-extended. Six isocyanide-supported complexes with the general formula cis-[Pt(CNAr)2(CCR)2] and six acyclic diaminocarbene (ADC) complexes of the form trans-[Pt(ADC)2(CCR)2], all using the same five acetylide ligands, are described. The compounds are characterized by multinuclear NMR, FT-IR, and single-crystal X-ray diffraction. In most cases, the phosphorescence arises from an acetylide-centered 3(π → π*) excited state, although in one of the isocyanide compounds there is evidence for a charge-transfer excited state. The photoluminescence wavelength depends strongly on the substitution pattern and extent of the π conjugation on the acetylide, with maxima spanning the range of ca. 460–540 nm. Most photoluminescence lifetimes are long, beyond 50 μs, and quantum yields are low to moderate, 0.043–0.27. The photoluminescence quantum yields and lifetimes in these compounds do not systematically improve in the ADC complexes compared to the isocyanide versions, suggesting the neutral ligand σ-donor character does not play a large role in the excited-state dynamics when the triplet excited state is delocalized over a large π system.
neutral ligand σbeyond 50 μsluminescent platinum complexestriplet excited statetransfer excited statesix acyclic diaminocarbenefive acetylide ligands043 – 0photoluminescence quantum yieldslarge π systemadc complexes comparedquantum yieldsstate dynamicssix isocyanidelarge roleacyclic diaminocarbenessupported complexesπ conjugationtrans systematically improvesubstitution patternray diffractionphotoluminescence lifetimesphosphorescence arisesmultinuclear nmrmaxima spanningisocyanide versionsgeneral formulaelectronically modifieddonor charactercrystal xcis