J. N. Demas

ADVERTISEMENT RETURN TO ISSUEArticleNEXTMeasurement of photoluminescence quantum yields. ReviewGlenn A. Crosby and James N. DemasCite this: J. Phys. Chem. 1971, 75, 8, 991–1024Publication Date (Print):April 1, 1971Publication History Published online1 May 2002Published inissue 1 April 1971https://pubs.acs.org/doi/10.1021/j100678a001https://doi.org/10.1021/j100678a001research-articleACS PublicationsRequest reuse permissionsArticle Views19221Altmetric-Citations4333LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

A detailed study of the photophysics and photochemistry of
\npolymer-immobilized luminescent transition-metal complex
\noxygen sensors is presented. Emphasis is on understanding
\nthe underlying origin of the nonlinear Stern-Volmer quenching response. Microheterogeneity is important in both photophysical and photochemical behavior, and the nonlinear
\nquenching responses in RTV 118 silicone rubber can be adequately described by a two-site model, although detailed
\nlifetime measurements suggest a more complex Underlying
\nsystem. Counterion studies with quenching counterions are
\nshown to be useful probes of the structure of the complex in
\nthe polymer. While oxygen enhances photochemical instability, singlet oxygen is not directly implicated in sensor decomposition. In the photochemistry there is at least one reactive and one much less reactive site, although the photochemistry and quenching measurements probably sample different populations of sites. The existence of reactive sites suggests that stability can be enhanced by a preliminary photolysis to eliminate the more reactive sites.

Boron difluoride compounds are light emitting materials with impressive optical properties. Though their strong one- and two-photon absorption and intense fluorescence are well-known and exploited in molecular probes, lasers, and photosensitizers, phosphorescence, in contrast, is typically observed only at low temperatures. Here, we report that unusual room-temperature phosphorescence is achieved by combining a classic boron dye, difluoroboron dibenzoylmethane, BF2dbm, with poly(lactic acid) (PLA), a common biopolymer, resulting in a highly sensitive single-component oxygen sensor. Fluorescence quantum yields are enhanced, and temperature-sensitive delayed fluorescence is also observed. Multi-emissive BF2dbmPLA biomaterials show great promise as multifunctional molecular probes and sensors.

Purely organic materials with room-temperature phosphorescence (RTP) are currently under intense investigation because of their potential applications in sensing, imaging, and displaying. Inspired by certain organometallic systems, where ligand-localized phosphorescence ((3) π-π*) is mediated by ligand-to-metal or metal-to-ligand charge transfer (CT) states, we now show that donor-to-acceptor CT states from the same organic molecule can also mediate π-localized RTP. In the model system of N-substituted naphthalimides (NNIs), the relatively large energy gap between the NNI-localized (1) π-π* and (3) π-π* states of the aromatic ring can be bridged by intramolecular CT states when the NNI is chemically modified with an electron donor. These NNI-based RTP materials can be easily conjugated to both synthetic and natural macromolecules, which can be used for RTP microscopy.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of oxygen concentrations by luminescence quenching of a polymer-immobilized transition-metal complexJ. R. Bacon and J. N. DemasCite this: Anal. Chem. 1987, 59, 23, 2780–2785Publication Date (Print):December 1, 1987Publication History Published online1 May 2002Published inissue 1 December 1987https://pubs.acs.org/doi/10.1021/ac00150a012https://doi.org/10.1021/ac00150a012research-articleACS PublicationsRequest reuse permissionsArticle Views2231Altmetric-Citations309LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts