File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Ligand π-conjunction dictated intersystem crossing in phenyleneethynylene gold(I) complexes

TitleLigand π-conjunction dictated intersystem crossing in phenyleneethynylene gold(I) complexes
Authors
KeywordsCombined method
Comparative studies
Delayed fluorescence
Excited-state decay
Excited-state dynamics
Issue Date2012
PublisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/publishing/journals/sc/About.asp
Citation
Chemical Science, 2012, v. 3 n. 6, p. 1883-1892 How to Cite?
AbstractThe excited state dynamics of gold(i) complexes containing monomeric phenyleneethynylene (PE) or oligo (p- or m-PE) ligand, namely PhCCAu(PCy 3) (1a) and PhCC(C 6H 4-1,m-CC) 2Au(PCy 3) (m = 4, 2a; m = 3, 3a) were investigated by combined methods of femtosecond transient absorption (fs-TA), fs time-resolved fluorescence (fs-TRF) and nanosecond time-resolved emission (ns-TRE). Comparative study was also performed on the corresponding metal free p- and m-PE oligomers (2b and 3b) to allow for evaluating the effect of ligand π-conjugation and the effect of gold(i) on the overall dynamics and emission pathways of the gold(i)-PE complexes. The results reveal that, although the incorporation of heavy gold(i) into PE ligand is effective in promoting the spin-forbidden ligand centered S 1 1ππ* to T 1 3ππ* intersystem crossing (ISC), the exact ISC rate constant (k ISC) is largely controlled by π-conjugation of the PE ligand in the S 1 states of 1a-3a. Upon increasing π-conjugation as from 1a to 3a and to 2a, the k ISC decreases consecutively by ∼2 orders of magnitude from ∼1.2 × 10 12 s -1 in 1a to ∼2.6 × 10 10 and ∼1.6 × 10 8 s -1 in 3a and 2a, respectively. As a result, the prompt fluorescence (PF) from the initial S 1 1ππ* state is quenched to markedly different extent, with the lifetime (τ PF) ranging from ∼0.7 ps in 1a to ∼450 ps in 2a. Aside from PF, long-lived delayed fluorescence (DF, lifetime on microsecond timescale) formed due to triplet-triplet annihilation (TTA) has also been identified to contribute to the fluorescence of 2a and 3a but not 1a. The ligand dependent behavior of both the k ISC and DF provides a rationale to the varied efficiency and unusual composition of the emissions of 1a-3a. The findings present a compelling case that impacts the conventional scenario of ISC due to the heavy-atom effect in the excited state decay of transition-metal complexes; the photophysical parameters and the deactivation pattern derived in this work are useful information for understanding the structure-property relationship of transition-metal-PE complexes. © 2012 The Royal Society of Chemistry.
Persistent Identifierhttp://hdl.handle.net/10722/168660
ISSN
2015 Impact Factor: 9.144
2015 SCImago Journal Rankings: 4.974
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorMa, Cen_US
dc.contributor.authorChan, CTLen_US
dc.contributor.authorKwok, WMen_US
dc.contributor.authorChe, CMen_US
dc.date.accessioned2012-10-08T03:24:06Z-
dc.date.available2012-10-08T03:24:06Z-
dc.date.issued2012en_US
dc.identifier.citationChemical Science, 2012, v. 3 n. 6, p. 1883-1892en_US
dc.identifier.issn2041-6520en_US
dc.identifier.urihttp://hdl.handle.net/10722/168660-
dc.description.abstractThe excited state dynamics of gold(i) complexes containing monomeric phenyleneethynylene (PE) or oligo (p- or m-PE) ligand, namely PhCCAu(PCy 3) (1a) and PhCC(C 6H 4-1,m-CC) 2Au(PCy 3) (m = 4, 2a; m = 3, 3a) were investigated by combined methods of femtosecond transient absorption (fs-TA), fs time-resolved fluorescence (fs-TRF) and nanosecond time-resolved emission (ns-TRE). Comparative study was also performed on the corresponding metal free p- and m-PE oligomers (2b and 3b) to allow for evaluating the effect of ligand π-conjugation and the effect of gold(i) on the overall dynamics and emission pathways of the gold(i)-PE complexes. The results reveal that, although the incorporation of heavy gold(i) into PE ligand is effective in promoting the spin-forbidden ligand centered S 1 1ππ* to T 1 3ππ* intersystem crossing (ISC), the exact ISC rate constant (k ISC) is largely controlled by π-conjugation of the PE ligand in the S 1 states of 1a-3a. Upon increasing π-conjugation as from 1a to 3a and to 2a, the k ISC decreases consecutively by ∼2 orders of magnitude from ∼1.2 × 10 12 s -1 in 1a to ∼2.6 × 10 10 and ∼1.6 × 10 8 s -1 in 3a and 2a, respectively. As a result, the prompt fluorescence (PF) from the initial S 1 1ππ* state is quenched to markedly different extent, with the lifetime (τ PF) ranging from ∼0.7 ps in 1a to ∼450 ps in 2a. Aside from PF, long-lived delayed fluorescence (DF, lifetime on microsecond timescale) formed due to triplet-triplet annihilation (TTA) has also been identified to contribute to the fluorescence of 2a and 3a but not 1a. The ligand dependent behavior of both the k ISC and DF provides a rationale to the varied efficiency and unusual composition of the emissions of 1a-3a. The findings present a compelling case that impacts the conventional scenario of ISC due to the heavy-atom effect in the excited state decay of transition-metal complexes; the photophysical parameters and the deactivation pattern derived in this work are useful information for understanding the structure-property relationship of transition-metal-PE complexes. © 2012 The Royal Society of Chemistry.en_US
dc.languageengen_US
dc.publisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/publishing/journals/sc/About.aspen_US
dc.relation.ispartofChemical Scienceen_US
dc.subjectCombined method-
dc.subjectComparative studies-
dc.subjectDelayed fluorescence-
dc.subjectExcited-state decay-
dc.subjectExcited-state dynamics-
dc.titleLigand π-conjunction dictated intersystem crossing in phenyleneethynylene gold(I) complexesen_US
dc.typeArticleen_US
dc.identifier.emailMa, C: macs@hkucc.hku.hken_US
dc.identifier.emailChe, CM: cmche@hku.hken_US
dc.identifier.authorityMa, C=rp00758en_US
dc.identifier.authorityChe, CM=rp00670en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1039/c2sc20038den_US
dc.identifier.scopuseid_2-s2.0-84864230192en_US
dc.identifier.hkuros205375-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84864230192&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume3en_US
dc.identifier.issue6en_US
dc.identifier.spage1883en_US
dc.identifier.epage1892en_US
dc.identifier.isiWOS:000304365000022-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridChe, CM=7102442791en_US
dc.identifier.scopusauthoridKwok, WM=7103129332en_US
dc.identifier.scopusauthoridChan, CTL=39960952700en_US
dc.identifier.scopusauthoridMa, C=7402924979en_US

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats