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postgraduate thesis: Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications
Title | Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications |
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Authors | |
Advisors | Advisor(s):Che, CM |
Issue Date | 2017 |
Publisher | The 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. |
Abstract | Cyclometallated 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 429613 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. |
Degree | Doctor of Philosophy |
Subject | Luminescence Palladium compounds Platinum compounds Transition metal complexes |
Dept/Program | Chemistry |
Persistent Identifier | http://hdl.handle.net/10722/265031 |
DC Field | Value | Language |
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dc.contributor.advisor | Che, CM | - |
dc.contributor.author | Ang, Wai-hung | - |
dc.contributor.author | 洪偉鴻 | - |
dc.date.accessioned | 2018-11-08T04:00:01Z | - |
dc.date.available | 2018-11-08T04:00:01Z | - |
dc.date.issued | 2017 | - |
dc.identifier.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. | - |
dc.identifier.uri | http://hdl.handle.net/10722/265031 | - |
dc.description.abstract | Cyclometallated 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 429613 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.language | eng | - |
dc.publisher | The University of Hong Kong (Pokfulam, Hong Kong) | - |
dc.relation.ispartof | HKU Theses Online (HKUTO) | - |
dc.rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works. | - |
dc.rights | This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | - |
dc.subject.lcsh | Luminescence | - |
dc.subject.lcsh | Palladium compounds | - |
dc.subject.lcsh | Platinum compounds | - |
dc.subject.lcsh | Transition metal complexes | - |
dc.title | Strongly luminescent tetradentate platinum(II) and palladium(II) complexes : structures, photophysics and material applications | - |
dc.type | PG_Thesis | - |
dc.description.thesisname | Doctor of Philosophy | - |
dc.description.thesislevel | Doctoral | - |
dc.description.thesisdiscipline | Chemistry | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.5353/th_991044014366603414 | - |
dc.date.hkucongregation | 2018 | - |
dc.identifier.mmsid | 991044014366603414 | - |