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Article: Probing d8-d8 interactions in luminescent mono- and binuclear cyclometalated platinum(II) complexes of 6-phenyl-2,2′-bipyridines

TitleProbing d8-d8 interactions in luminescent mono- and binuclear cyclometalated platinum(II) complexes of 6-phenyl-2,2′-bipyridines
Authors
Issue Date1999
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/ic
Citation
Inorganic Chemistry, 1999, v. 38 n. 18, p. 4046-4055 How to Cite?
AbstractA series of luminescent mono- and binuclear cyclometalated platinum(II) complexes, namely [Pt(L1-6)Cl] (1a-6a; HL1-6 = 4-(aryl)-6-phenyl-2,2′-bipyridine; aryl = H (1), phenyl (2), 4-chlorophenyl (3), 4-tolyl (4), 4-methoxyphenyl (5), 3,4,5-trimethoxyphenyl (6)), [Pt(L1)E]+ (E = py (7), PPh3 (8)), [Pt2(L1-6)2(μ-dppm)]2+ (1b-6b, dppm = bis(diphenylphosphino)methane), [Pt2(L1)2(μ-pz)]+ (9, Hpz = pyrazole), and [Pt2(L1)2(μ-dppCn)]2+ (dppCn = bis(diphenylphosphino)propane (10, n = 3) and -pentane (11, n = 5)), were synthesized in order to examine fluid- and solid-state oligomeric d8-d8 and ligand-ligand interactions. The molecular structures of 4b(ClO4)2 and 9(PF6) reveal intramolecular Pt-Pt distances of 3.245(1) and 3.612(2) Å, respectively. While minimal metal-metal communication is expected for 9, weak π-π interactions are possible. All complexes described in this work are emissive in fluid solution at room temperature. Negligible changes in emission energy are detected by incorporating different aryl substituents into the 4-position of 6-phenyl-2,2′-bipyridine, and this indicates little electronic delocalization between them. Self-quenching of the 3MLCT emission by the mononuclear derivatives are observed in CH2Cl2 at 298 K, and a red shift in the emission energy is exhibited by complex 7 in acetonitrile at 77 K. The fluid emissions of the μ-dppm species 1b-6b at λmax 652-662 nm appear at substantially lower energies than their mononuclear counterparts and show dramatic solvatochromic effects. These emissions are ascribed to 3[dσ*, π*] excited states. In contrast, the emission of 10 and 11, bearing long bridging diphosphine ligands, are attributed to 3MLCT states of non-interacting [Pt(L1)] moieties. Significantly, the luminescence of the μ-pyrazolate complex 9 displays transitional features which are reminiscent of both 3[dσ*, π*} and 3MLCT excited states. Hence a relationship is observed between emission energy, the nature of the lowest energy excited state, and metal-metal interactions. The excited-state redox potential [E(*Pt2 2+/Pt2 +)] of 1b has been estimated by electrochemical studies (1.61 V vs NHE) and by quenching experiments with aromatic hydrocarbons (1.63 V vs NHE). © 1999 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/167333
ISSN
2015 Impact Factor: 4.82
2015 SCImago Journal Rankings: 1.873
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLai, SWen_HK
dc.contributor.authorChan, MCWen_HK
dc.contributor.authorCheung, TCen_HK
dc.contributor.authorPeng, SMen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2012-10-08T03:05:45Z-
dc.date.available2012-10-08T03:05:45Z-
dc.date.issued1999en_HK
dc.identifier.citationInorganic Chemistry, 1999, v. 38 n. 18, p. 4046-4055en_HK
dc.identifier.issn0020-1669en_HK
dc.identifier.urihttp://hdl.handle.net/10722/167333-
dc.description.abstractA series of luminescent mono- and binuclear cyclometalated platinum(II) complexes, namely [Pt(L1-6)Cl] (1a-6a; HL1-6 = 4-(aryl)-6-phenyl-2,2′-bipyridine; aryl = H (1), phenyl (2), 4-chlorophenyl (3), 4-tolyl (4), 4-methoxyphenyl (5), 3,4,5-trimethoxyphenyl (6)), [Pt(L1)E]+ (E = py (7), PPh3 (8)), [Pt2(L1-6)2(μ-dppm)]2+ (1b-6b, dppm = bis(diphenylphosphino)methane), [Pt2(L1)2(μ-pz)]+ (9, Hpz = pyrazole), and [Pt2(L1)2(μ-dppCn)]2+ (dppCn = bis(diphenylphosphino)propane (10, n = 3) and -pentane (11, n = 5)), were synthesized in order to examine fluid- and solid-state oligomeric d8-d8 and ligand-ligand interactions. The molecular structures of 4b(ClO4)2 and 9(PF6) reveal intramolecular Pt-Pt distances of 3.245(1) and 3.612(2) Å, respectively. While minimal metal-metal communication is expected for 9, weak π-π interactions are possible. All complexes described in this work are emissive in fluid solution at room temperature. Negligible changes in emission energy are detected by incorporating different aryl substituents into the 4-position of 6-phenyl-2,2′-bipyridine, and this indicates little electronic delocalization between them. Self-quenching of the 3MLCT emission by the mononuclear derivatives are observed in CH2Cl2 at 298 K, and a red shift in the emission energy is exhibited by complex 7 in acetonitrile at 77 K. The fluid emissions of the μ-dppm species 1b-6b at λmax 652-662 nm appear at substantially lower energies than their mononuclear counterparts and show dramatic solvatochromic effects. These emissions are ascribed to 3[dσ*, π*] excited states. In contrast, the emission of 10 and 11, bearing long bridging diphosphine ligands, are attributed to 3MLCT states of non-interacting [Pt(L1)] moieties. Significantly, the luminescence of the μ-pyrazolate complex 9 displays transitional features which are reminiscent of both 3[dσ*, π*} and 3MLCT excited states. Hence a relationship is observed between emission energy, the nature of the lowest energy excited state, and metal-metal interactions. The excited-state redox potential [E(*Pt2 2+/Pt2 +)] of 1b has been estimated by electrochemical studies (1.61 V vs NHE) and by quenching experiments with aromatic hydrocarbons (1.63 V vs NHE). © 1999 American Chemical Society.en_HK
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/icen_HK
dc.relation.ispartofInorganic Chemistryen_HK
dc.titleProbing d8-d8 interactions in luminescent mono- and binuclear cyclometalated platinum(II) complexes of 6-phenyl-2,2′-bipyridinesen_HK
dc.typeArticleen_HK
dc.identifier.emailLai, SW: swlai@hku.hken_HK
dc.identifier.emailChe, CM: cmche@hku.hken_HK
dc.identifier.authorityLai, SW=rp00717en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/ic990238s-
dc.identifier.scopuseid_2-s2.0-0001247525en_HK
dc.identifier.hkuros51132-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0001247525&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume38en_HK
dc.identifier.issue18en_HK
dc.identifier.spage4046en_HK
dc.identifier.epage4055en_HK
dc.identifier.isiWOS:000082525000015-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLai, SW=7402937200en_HK
dc.identifier.scopusauthoridChan, MCW=7402598116en_HK
dc.identifier.scopusauthoridCheung, TC=7103334175en_HK
dc.identifier.scopusauthoridPeng, SM=35464852200en_HK
dc.identifier.scopusauthoridChe, CM=7102442791en_HK

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