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postgraduate thesis: Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications

TitleStrongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications
Authors
Advisors
Advisor(s):Che, CM
Issue Date2017
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Ang, W. [洪偉鴻]. (2017). Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.
AbstractCyclometallated platinum(II) and palladium(II) complexes possess rich photophysical properties and are promising candidates in materials science. Three types of platinum(II) complexes supported by tetradentate (N^C^C^N and two types of O^N^C^N) ligands, and palladium(II) complexes supported by tetradentate (N^C^C^N) ligands, are described in this thesis. These complexes exhibit blue to orange-red emission over the spectral range and their syntheses together with characterizations are discussed. The complexes have also been applied as emitters in organic light-emitting diodes (OLEDs), catalysts in photochemical reactions and probes for bio-imaging. Structurally robust platinum(II) complexes supported by two types of dianionic tetradentate O^N^C^N ligands, [Pt(O^N^C^N)], have been synthesized and characterized. The complexes of both types possess good thermal stabilities (Td up to 420 oC) and show green to orange emission (em = 503−583 nm) with high quantum efficiency (em up to 80%). The complexes are featured by incorporation of spiro-compound on the ligand framework to suppress intermolecular interactions; their crystal structures show highly distorted square planar geometry compared with the reported [Pt(O^N^C^N)] complexes without short contact between Pt centers. DFT/TDDFT calculations and fs-TRF experiment revealed that there are minimal excited state distortion and efficient intersystem crossing (ISC) dominants at rate of 6.7 × 1012 s-1. Green OLED based on [Pt(O^N^C^N)] complex has been achieved (PEmax = 126.0 lm W-1; CEmax = 104.2 cd A-1; EQEmax = 26.2%) with performance comparable to that of best reported Ir(III) emitter. A new class of platinum(II) complexes with emission spanning 429613 nm have been synthesized by using tetradentate N^C^C^N ligands with oxygen bridge and spiro-linkage. These strongly phosphorescent complexes (em up to 81%) are applied as dopant in R/G/B-emitting OLEDs. Particularly, OLEDs based on the green emitting [Pt(N^C^C^N)] complex showed PAL standard green emission with luminous efficacy of 63 lm W-1 and EQE of up to 20.6%. The complexes are also active in converting aryl boronic acid to aryl alcohol in the presence of oxygen with conversions and product yields of up to 100% and 87%, respectively. Upon irradiation with Xenon lamp ( > 370 nm), Pt(IV) complex is formed via oxidative addition with methyl iodide. The cytoxtoxicity of the Pt(IV) complex against two human cancer cell lines (HCT-116 colorectal carcinoma and NCl-H460 non-small cell lung carcinoma) were examined using MTT assay. Interestingly, the Pt(IV) complex is non-cytotoxic relative to cisplatin and able to label cytosolic region after incubation in both cell lines for 24–48 hours. Palladium(II) complexes containing the tetradentate N^C^C^N ligands have been prepared. The rigid ligand scaffolds afford complexes possessing high thermal stability (Td up to 430 oC) and high emission quantum yield (em up to 47%). DFT/TDDFT calculations suggest essentially ligand-centered emissive state of the Pd(II) complexes. Sky-blue emitting OLED based on such complex has been achieved with EQE up to ca. 17% at low dopant concentrations (2 wt%). These complexes having high triplet energy and long-lived excited state are also good candidates for photocatalysis as found to be active in visible-light driven reductive C−C bond formation of alkyl bromide and [2+2] cycloaddition of styrene.
DegreeDoctor of Philosophy
SubjectLuminescence
Palladium compounds
Platinum compounds
Transition metal complexes
Dept/ProgramChemistry
Persistent Identifierhttp://hdl.handle.net/10722/265031

 

DC FieldValueLanguage
dc.contributor.advisorChe, CM-
dc.contributor.authorAng, Wai-hung-
dc.contributor.author洪偉鴻-
dc.date.accessioned2018-11-08T04:00:01Z-
dc.date.available2018-11-08T04:00:01Z-
dc.date.issued2017-
dc.identifier.citationAng, W. [洪偉鴻]. (2017). Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.-
dc.identifier.urihttp://hdl.handle.net/10722/265031-
dc.description.abstractCyclometallated platinum(II) and palladium(II) complexes possess rich photophysical properties and are promising candidates in materials science. Three types of platinum(II) complexes supported by tetradentate (N^C^C^N and two types of O^N^C^N) ligands, and palladium(II) complexes supported by tetradentate (N^C^C^N) ligands, are described in this thesis. These complexes exhibit blue to orange-red emission over the spectral range and their syntheses together with characterizations are discussed. The complexes have also been applied as emitters in organic light-emitting diodes (OLEDs), catalysts in photochemical reactions and probes for bio-imaging. Structurally robust platinum(II) complexes supported by two types of dianionic tetradentate O^N^C^N ligands, [Pt(O^N^C^N)], have been synthesized and characterized. The complexes of both types possess good thermal stabilities (Td up to 420 oC) and show green to orange emission (em = 503−583 nm) with high quantum efficiency (em up to 80%). The complexes are featured by incorporation of spiro-compound on the ligand framework to suppress intermolecular interactions; their crystal structures show highly distorted square planar geometry compared with the reported [Pt(O^N^C^N)] complexes without short contact between Pt centers. DFT/TDDFT calculations and fs-TRF experiment revealed that there are minimal excited state distortion and efficient intersystem crossing (ISC) dominants at rate of 6.7 × 1012 s-1. Green OLED based on [Pt(O^N^C^N)] complex has been achieved (PEmax = 126.0 lm W-1; CEmax = 104.2 cd A-1; EQEmax = 26.2%) with performance comparable to that of best reported Ir(III) emitter. A new class of platinum(II) complexes with emission spanning 429613 nm have been synthesized by using tetradentate N^C^C^N ligands with oxygen bridge and spiro-linkage. These strongly phosphorescent complexes (em up to 81%) are applied as dopant in R/G/B-emitting OLEDs. Particularly, OLEDs based on the green emitting [Pt(N^C^C^N)] complex showed PAL standard green emission with luminous efficacy of 63 lm W-1 and EQE of up to 20.6%. The complexes are also active in converting aryl boronic acid to aryl alcohol in the presence of oxygen with conversions and product yields of up to 100% and 87%, respectively. Upon irradiation with Xenon lamp ( > 370 nm), Pt(IV) complex is formed via oxidative addition with methyl iodide. The cytoxtoxicity of the Pt(IV) complex against two human cancer cell lines (HCT-116 colorectal carcinoma and NCl-H460 non-small cell lung carcinoma) were examined using MTT assay. Interestingly, the Pt(IV) complex is non-cytotoxic relative to cisplatin and able to label cytosolic region after incubation in both cell lines for 24–48 hours. Palladium(II) complexes containing the tetradentate N^C^C^N ligands have been prepared. The rigid ligand scaffolds afford complexes possessing high thermal stability (Td up to 430 oC) and high emission quantum yield (em up to 47%). DFT/TDDFT calculations suggest essentially ligand-centered emissive state of the Pd(II) complexes. Sky-blue emitting OLED based on such complex has been achieved with EQE up to ca. 17% at low dopant concentrations (2 wt%). These complexes having high triplet energy and long-lived excited state are also good candidates for photocatalysis as found to be active in visible-light driven reductive C−C bond formation of alkyl bromide and [2+2] cycloaddition of styrene.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subject.lcshLuminescence-
dc.subject.lcshPalladium compounds-
dc.subject.lcshPlatinum compounds-
dc.subject.lcshTransition metal complexes-
dc.titleStrongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications-
dc.typePG_Thesis-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplineChemistry-
dc.description.naturepublished_or_final_version-
dc.date.hkucongregation2018-
dc.identifier.mmsid991044014366603414-

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