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Article: Emissive or nonemissive? a theoretical analysis of the phosphorescence efficiencies of cyclometalated platinum(II) complexes

TitleEmissive or nonemissive? a theoretical analysis of the phosphorescence efficiencies of cyclometalated platinum(II) complexes
Authors
KeywordsDensity functional calculations
Electronic structure
Jahn-teller distortion
Platinum
Spin-orbit coupling
Issue Date2009
PublisherWiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry
Citation
Chemistry - A European Journal, 2009, v. 15 n. 29, p. 7225-7237 How to Cite?
AbstractWe herein report a theoretical analysis based on a density functional theory/time-dependent density functional theory (DFT/TDDFT) approach to understand the different phosphorescence efficiencies of a family of cyclometalated platinum(II) complexes: [Pt(NCN)Cl] (1; NCN = l,3-bis(2-pyridyl)phenyl -), [Pt-(CNN)Cl] (2; CNN=6-phenyl-2,2′- bipyridyl -), [Pt(CNC)(CNPh)] (3; CNC = 2,6-diphenylpyridyl 2-), [Pt(RCNN)Cl] (4; R-CNN = 3-(6′-(2″-naphthyl)- 2′-pyridyl)isoquinolinyl -), and [Pt(R-CNC)(CNPh)] (5; R-CNC=2,6bis(2′-naphthyl)pyridyl 2-). By considering both the spin-orbit coupling (SOC) and the electronic structures of these complexes at their respective optimized singlet ground (S 0) and first triplet (T opt 1 ,) excited states, we were able to rationalize the experimental findings that 1 ) 1 is a strong emitter while its isomer 2 is only weakly emissive in CH 2Cl 2 solution at room temperature; 2) although the cyclometalated ligand of 3 has a higher ligand-field strength than that of 1, 3 is nonemissive in CH 2Cl 2 solution at 298 K; and 3) extension of π conjugation at the lateral aryl rings of the cyclometalated ligands of 2 and 3 to give 4 and 5, respectively, leads to increased emission quantum yields under the same conditions. We found that Jahn-Teller and pseudoJahn-Teller effects are operative in complexes 2 and 3, respectively, on going from the optimized S 0 ground state to the optimized T opt 1, excited state, and thus lead to large excitedstate structural distortions and hence fast nonradiative decay. Furthermore, a strong-field ligand may push the two different occupied d orbitais so far apart that the SOC effect is small and the radiative decay rate is slow. This work is an example of electronic-structure-driven tuning of the phosphorescence efficiency, and the DFT/TDDFT approach is demonstrated to be a versatile tool for the design of phosphorescent materials with target characteristics. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.
Persistent Identifierhttp://hdl.handle.net/10722/70469
ISSN
2015 Impact Factor: 5.771
2015 SCImago Journal Rankings: 2.323
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorTong, GSMen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2010-09-06T06:23:10Z-
dc.date.available2010-09-06T06:23:10Z-
dc.date.issued2009en_HK
dc.identifier.citationChemistry - A European Journal, 2009, v. 15 n. 29, p. 7225-7237en_HK
dc.identifier.issn0947-6539en_HK
dc.identifier.urihttp://hdl.handle.net/10722/70469-
dc.description.abstractWe herein report a theoretical analysis based on a density functional theory/time-dependent density functional theory (DFT/TDDFT) approach to understand the different phosphorescence efficiencies of a family of cyclometalated platinum(II) complexes: [Pt(NCN)Cl] (1; NCN = l,3-bis(2-pyridyl)phenyl -), [Pt-(CNN)Cl] (2; CNN=6-phenyl-2,2′- bipyridyl -), [Pt(CNC)(CNPh)] (3; CNC = 2,6-diphenylpyridyl 2-), [Pt(RCNN)Cl] (4; R-CNN = 3-(6′-(2″-naphthyl)- 2′-pyridyl)isoquinolinyl -), and [Pt(R-CNC)(CNPh)] (5; R-CNC=2,6bis(2′-naphthyl)pyridyl 2-). By considering both the spin-orbit coupling (SOC) and the electronic structures of these complexes at their respective optimized singlet ground (S 0) and first triplet (T opt 1 ,) excited states, we were able to rationalize the experimental findings that 1 ) 1 is a strong emitter while its isomer 2 is only weakly emissive in CH 2Cl 2 solution at room temperature; 2) although the cyclometalated ligand of 3 has a higher ligand-field strength than that of 1, 3 is nonemissive in CH 2Cl 2 solution at 298 K; and 3) extension of π conjugation at the lateral aryl rings of the cyclometalated ligands of 2 and 3 to give 4 and 5, respectively, leads to increased emission quantum yields under the same conditions. We found that Jahn-Teller and pseudoJahn-Teller effects are operative in complexes 2 and 3, respectively, on going from the optimized S 0 ground state to the optimized T opt 1, excited state, and thus lead to large excitedstate structural distortions and hence fast nonradiative decay. Furthermore, a strong-field ligand may push the two different occupied d orbitais so far apart that the SOC effect is small and the radiative decay rate is slow. This work is an example of electronic-structure-driven tuning of the phosphorescence efficiency, and the DFT/TDDFT approach is demonstrated to be a versatile tool for the design of phosphorescent materials with target characteristics. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.en_HK
dc.languageengen_HK
dc.publisherWiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistryen_HK
dc.relation.ispartofChemistry - A European Journalen_HK
dc.subjectDensity functional calculationsen_HK
dc.subjectElectronic structureen_HK
dc.subjectJahn-teller distortionen_HK
dc.subjectPlatinumen_HK
dc.subjectSpin-orbit couplingen_HK
dc.titleEmissive or nonemissive? a theoretical analysis of the phosphorescence efficiencies of cyclometalated platinum(II) complexesen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0947-6539&volume=15&spage=7225&epage=7237&date=2009&atitle=Emissive+or+Nonemissive?+A+Theoretical+Analysis+of+the+Phosphorescence+Efficiencies+of+Cyclometalated+Platinum(II)+Complexesen_HK
dc.identifier.emailTong, GSM:tongsm@hkucc.hku.hken_HK
dc.identifier.emailChe, CM:cmche@hku.hken_HK
dc.identifier.authorityTong, GSM=rp00790en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1002/chem.200802485en_HK
dc.identifier.pmid19544517-
dc.identifier.scopuseid_2-s2.0-67650581269en_HK
dc.identifier.hkuros167107en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-67650581269&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume15en_HK
dc.identifier.issue29en_HK
dc.identifier.spage7225en_HK
dc.identifier.epage7237en_HK
dc.identifier.isiWOS:000268549400025-
dc.publisher.placeGermanyen_HK
dc.identifier.scopusauthoridTong, GSM=7102328656en_HK
dc.identifier.scopusauthoridChe, CM=7102442791en_HK

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