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Article: Observation of low-energy metal-metal-to-ligand charge transfer absorption and emission: electronic spectroscopy of cyclometalated platinum(II) complexes with isocyanide ligands

TitleObservation of low-energy metal-metal-to-ligand charge transfer absorption and emission: electronic spectroscopy of cyclometalated platinum(II) complexes with isocyanide ligands
Authors
Issue Date2002
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallics
Citation
Organometallics, 2002, v. 21 n. 1, p. 226-234 How to Cite?
AbstractA series of luminescent mononuclear [(CNN)Pt(CNR)]X (HCNN = 6-phenyl-2,2‘-bipyridine; R = tBu (1), nBu (2), iPr (3), cyclohexyl (Cy, 4), X = ClO4; R = 2,6-Me2C6H3 (Ar‘, 5), X = PF6) and [(CNN)Pt(CO)]CF3SO3 (6(CF3SO3)) and binuclear [{(CNN)Pt}2(μ-CN(CH2)3NC)](PF6)2 (7(PF6)2) complexes were synthesized, and their spectroscopic and photophysical properties have been investigated. The crystal lattices of 1(ClO4) and 5(PF6) reveal close [CNN] π−π intermolecular contacts (3.4−3.6 Å). Additional metal−metal interactions are evident in 5(PF6) with intermolecular Pt−Pt distances of 3.3831(9) Å. At complex concentration greater than 5 × 10-3 mol dm-3, the UV−vis absorption spectrum of 2 displays a weak shoulder at 511 nm (ε = 120 dm3 mol-1 cm-1), which does not obey Beer's law. A metal−metal-to-ligand charge transfer (MMLCT) [dσ*(Pt−Pt) → π*(CN)] absorption of a dimeric species via 2[Pt(CNN)(CNnBu)]+ [(CNN)Pt(CNnBu)]22+ is proposed. The room-temperature emission spectrum of 4 for complex concentrations ≥ 7 × 10-3 mol dm-3 shows a low-energy band at 710 nm originating from a 3MMLCT excited state. A corresponding well-defined low-energy absorption at 500 nm in the excitation spectrum of 4 (λem 710 nm) is assigned to the 1MMLCT transition. The 77 K emissions of complexes 1−6 in glassy solutions are sensitive to complex concentration. Upon increasing concentrations from 5 × 10-5 to 2 × 10-3 mol dm-3 for 1−4, red emissions at 600−625 nm ascribed to π−π excimeric excited states develop at the expense of the vibronic 3MLCT emissions at λmax 502 nm. Complexes 2 and 4 show additional low-energy emissions at 739 and 710 nm, respectively, attributable to 3MMLCT states. Concentrated 77 K glassy solutions of complexes 5−7 exhibit 3MMLCT emissions (λmax 711−744 nm). The broad structureless solid-state luminescence of 2(ClO4), 3(ClO4), 5(PF6), 6(CF3SO3), and 7(PF6)2 at 298 K (λmax 701−748 nm) and 77 K (λmax 744−813 nm) are assigned to 3MMLCT excited states arising from intermolecular stacking interactions in the solid state. The spectroscopic properties of the related [(CNC)Pt(L)] (HCNCH = 2,6-diphenylpyridine; L = CO and CNAr‘) solids are compared, and no MMLCT emission is evident.
Persistent Identifierhttp://hdl.handle.net/10722/69092
ISSN
2015 Impact Factor: 4.186
2015 SCImago Journal Rankings: 2.043
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorLai, SWen_HK
dc.contributor.authorLam, HWen_HK
dc.contributor.authorLu, Wen_HK
dc.contributor.authorCheung, KKen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2010-09-06T06:10:29Z-
dc.date.available2010-09-06T06:10:29Z-
dc.date.issued2002en_HK
dc.identifier.citationOrganometallics, 2002, v. 21 n. 1, p. 226-234en_HK
dc.identifier.issn0276-7333en_HK
dc.identifier.urihttp://hdl.handle.net/10722/69092-
dc.description.abstractA series of luminescent mononuclear [(CNN)Pt(CNR)]X (HCNN = 6-phenyl-2,2‘-bipyridine; R = tBu (1), nBu (2), iPr (3), cyclohexyl (Cy, 4), X = ClO4; R = 2,6-Me2C6H3 (Ar‘, 5), X = PF6) and [(CNN)Pt(CO)]CF3SO3 (6(CF3SO3)) and binuclear [{(CNN)Pt}2(μ-CN(CH2)3NC)](PF6)2 (7(PF6)2) complexes were synthesized, and their spectroscopic and photophysical properties have been investigated. The crystal lattices of 1(ClO4) and 5(PF6) reveal close [CNN] π−π intermolecular contacts (3.4−3.6 Å). Additional metal−metal interactions are evident in 5(PF6) with intermolecular Pt−Pt distances of 3.3831(9) Å. At complex concentration greater than 5 × 10-3 mol dm-3, the UV−vis absorption spectrum of 2 displays a weak shoulder at 511 nm (ε = 120 dm3 mol-1 cm-1), which does not obey Beer's law. A metal−metal-to-ligand charge transfer (MMLCT) [dσ*(Pt−Pt) → π*(CN)] absorption of a dimeric species via 2[Pt(CNN)(CNnBu)]+ [(CNN)Pt(CNnBu)]22+ is proposed. The room-temperature emission spectrum of 4 for complex concentrations ≥ 7 × 10-3 mol dm-3 shows a low-energy band at 710 nm originating from a 3MMLCT excited state. A corresponding well-defined low-energy absorption at 500 nm in the excitation spectrum of 4 (λem 710 nm) is assigned to the 1MMLCT transition. The 77 K emissions of complexes 1−6 in glassy solutions are sensitive to complex concentration. Upon increasing concentrations from 5 × 10-5 to 2 × 10-3 mol dm-3 for 1−4, red emissions at 600−625 nm ascribed to π−π excimeric excited states develop at the expense of the vibronic 3MLCT emissions at λmax 502 nm. Complexes 2 and 4 show additional low-energy emissions at 739 and 710 nm, respectively, attributable to 3MMLCT states. Concentrated 77 K glassy solutions of complexes 5−7 exhibit 3MMLCT emissions (λmax 711−744 nm). The broad structureless solid-state luminescence of 2(ClO4), 3(ClO4), 5(PF6), 6(CF3SO3), and 7(PF6)2 at 298 K (λmax 701−748 nm) and 77 K (λmax 744−813 nm) are assigned to 3MMLCT excited states arising from intermolecular stacking interactions in the solid state. The spectroscopic properties of the related [(CNC)Pt(L)] (HCNCH = 2,6-diphenylpyridine; L = CO and CNAr‘) solids are compared, and no MMLCT emission is evident.-
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallicsen_HK
dc.relation.ispartofOrganometallicsen_HK
dc.titleObservation of low-energy metal-metal-to-ligand charge transfer absorption and emission: electronic spectroscopy of cyclometalated platinum(II) complexes with isocyanide ligandsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0276-7333&volume=21&spage=226&epage=234&date=2002&atitle=Observation+of+low-energy+metal-metal-to-ligand+charge+transfer+absorption+and+emission:++electronic+spectroscopy+of+cyclometalated+platinum(II)+complexes+with+isocyanide+ligandsen_HK
dc.identifier.emailLai, SW: swlai@hkucc.hku.hken_HK
dc.identifier.emailCheung, KK: kkcheung@hkucc.hku.hken_HK
dc.identifier.emailChe, CM: cmche@hku.hken_HK
dc.identifier.authorityLai, SW=rp00717en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.identifier.doi10.1021/om0106276-
dc.identifier.hkuros72383en_HK
dc.identifier.volume21-
dc.identifier.issue1-
dc.identifier.spage226-
dc.identifier.epage234-
dc.identifier.isiWOS:000173227400031-
dc.publisher.placeUnited States-

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