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Shaohua Gu,
Qihan Wu,
Xueying Zhao, Wenting Wu,
Zhiqiang Gao,
Xiaoming Tan,
Ji Qian,
Hongyan Chen,
Yi Xie,
Li Jin,
Baohui Han,
Daru Lu
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ABSTRACT: Apoptosis is a distinct mode of cell death that is responsible for the deletion of cells in tumors and in normal tissues. We pursued a pathway-based approach to investigate the association of potentially functional genetic polymorphisms of the corresponding genes with the outcomes of platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC). A MALDI-TOF mass spectrometer was used for genotyping 10 polymorphisms of eight apoptosis-related genes, including BCL2 rs1801018, rs1564483, rs2279115, BAX rs4645878, caspase (CASP3) rs6948, CASP8 rs3834129, CASP10 rs13006529, rs3900115, tumor necrosis factor α (TNFα) rs1800629, and macrophage migration inhibitory factor (MIF) rs755622. The associations between these single nucleotide polymorphisms and the outcomes of 445 advanced NSCLC patients treated with platinum-based chemotherapy were evaluated. The CASP3 rs6948 polymorphism was most significantly associated with hematologic toxicity in a dose-dependent manner. The incidence of severe hematologic toxicity was significantly lower in C allele carriers (P = 0.005; odds ratio = 0.524; 95% confidence interval = 0.333-0.824) and still significant after a Bonferroni correction. The function of this single nucleotide polymorphism in gene expression was also investigated. Quantitative PCR showed that individuals with the C allele had lower levels of CASP3 transcripts in peripheral blood lymphocytes. Luciferase reporter assays showed that the minor C allele significantly decreased the reporter gene expression level. In addition, the TNFα rs1800629 mutant allele significantly elevated gastrointestinal toxicity (P = 0.020; odds ratio = 3.020; 95% confidence interval = 1.188-7.676), when compared to the wild-type homozygote. No other association was found. In conclusion, for the first time, our study suggests that CASP3 rs6948 might influence CASP3 expression and be associated with severe hematologic toxicity risk.
Cancer Science 05/2012; 103(8):1451-9. · 3.33 Impact Factor
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ABSTRACT: Polypyridyl ruthenium (Ru) complexes 1–3 were prepared. Their photophysical properties were investigated by UV-Vis absorption
and luminescence emission spectra. The luminescent lifetimes of these Ruthenium complex were prolonged by more than 5 folds
(τ = 2.50 μs for complex 3) when compared with the parent Ru complex 1 (τ = 0.45 μs). We propose that the extended luminescent
lifetime of complex 3 is due to the equilibrium between 3MLCT state and the pyrene localized 3π-π* triplet state (3IL). The luminescent O2-sensing property of the complexes in solution and the IMPEK-C polymer film were studied, and the O2 sensing was quantified with the two-site model. The oxygen-sensing property of the Ru complexes can be improved by 104-fold
with extension of the luminescent lifetimes. For example, the quenching constant K
SV was improved from 0.0023 Torr−1 of 1 to 0.2393 Torr−1 for 3. Our results demonstrated a versatile approach for the preparation of Ru (II) polypyridine complexes with extended
luminescent lifetimes as functional materials, for example, for luminescent oxygen-sensing applications.
Keywordsphosphorescence-ruthenium-oxygen sensor-quenching-intraligand triplet state
Frontiers of Chemistry in China 04/2012; 5(2):193-199.
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ABSTRACT: Ru(II)-bis-pyridine complexes typically absorb below 450 nm in the UV spectrum and their molar extinction coefficients are only moderate (ε<16,000 M(-1) cm(-1)). Thus, Ru(II)-polyimine complexes that show intense visible-light absorptions are of great interest. However, no effective light-harvesting ruthenium(II)/organic chromophore arrays have been reported. Herein, we report the first visible-light-harvesting Ru(II)-coumarin arrays, which absorb at 475 nm (ε up to 63,300 M(-1) cm(-1), 4-fold higher than typical Ru(II)-polyimine complexes). The donor excited state in these arrays is efficiently converted into an acceptor excited state (i.e., efficient energy-transfer) without losses in the phosphorescence quantum yield of the acceptor. Based on steady-state and time-resolved spectroscopy and DFT calculations, we proposed a general rule for the design of Ru(II)-polypyridine-chromophore light-harvesting arrays, which states that the (1)IL energy level of the ligand must be close to the respective energy level of the metal-to-ligand charge-transfer (MLCT) states. Lower energy levels of (1)IL/(3)IL than the corresponding (1)MLCT/(3)MLCT states frustrate the cascade energy-transfer process and, as a result, the harvested light energy cannot be efficiently transferred to the acceptor. We have also demonstrated that the light-harvesting effect can be used to improve the upconversion quantum yield to 15.2 % (with 9,10-diphenylanthracene as a triplet-acceptor/annihilator), compared to the parent complex without the coumarin subunit, which showed an upconversion quantum yield of only 0.95 %.
Chemistry 03/2012; 18(16):4953-64. · 5.93 Impact Factor
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ABSTRACT: [C(^)NPt(acac)] (C(^)N = cyclometalating ligand; acac = acetylacetonato) complexes in which the naphthalimide (NI) moiety is directly cyclometalated (NI as the C donor of the C-Pt bond) were synthesized. With 4-pyrazolylnaphthalimide, isomers with five-membered (Pt-2) and six-membered (Pt-3) chelate rings were obtained. With 4-pyridinylnaphthalimide, only the complex with a five-membered chelate ring (Pt-4) was isolated. A model complex with 1-phenylpyrazole as the C(^)N ligand was prepared (Pt-1). Strong absorption of visible light (ε = 21,900 M(-1) cm(-1) at 443 nm for Pt-3) and room temperature (RT) phosphorescence at 630 nm (Pt-2 and Pt-3) or 674 nm (Pt-4) were observed. Long-lived phosphorescences were observed for Pt-2 (τ(P) = 12.8 μs) and Pt-3 (τ(P) = 61.9 μs). Pt-1 is nonphosphorescent at RT in solution because of the acac-localized T(1) excited state [based on density functional theory (DFT) calculations and spin density analysis], but a structured emission band centered at 415 nm was observed at 77 K. Time-resolved transient absorption spectra and spin density analysis indicated a NI-localized intraligand triplet excited state ((3)IL) for complexes Pt-2, Pt-3, and Pt-4. DFT calculations on the transient absorption spectra (T(1) → T(n) transitions, n > 1) also support the (3)IL assignment of the T(1) excited states of Pt-2, Pt-3, and Pt-4. The complexes were used as triplet sensitizers for triplet-triplet-annihilation (TTA) based upconversion, and the results show that Pt-3 is an efficient sensitizer with an upconversion quantum yield of up to 14.1%, despite its low phosphorescence quantum yield of 5.2%. Thus, we propose that the sensitizer molecules at the triplet excited state that are otherwise nonphosphorescent were involved in the TTA upconversion process, indicating that weakly phosphorescent or nonphosphorescent transition-metal complexes can be used as triplet sensitizers for TTA upconversion.
Inorganic Chemistry 11/2011; 50(22):11446-60. · 4.60 Impact Factor
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ABSTRACT: A colorimetric and ratiometric fluorescent thiol probe was devised with diketopyrrolopyrrole (DPP) fluorophore. The probe gives absorption and emission at 523 and 666 nm, respectively. In the presence of thiols, such as cysteine, the absorption and emission band shifted to 479 and 540 nm, respectively. Correspondingly, the color of the probe solution changed from purple to yellow, and the fluorescence changed from red to yellow. The emission intensity at 540 nm was enhanced by 140-fold. The Stokes shift of probe 1 (107 nm) is much larger than the unsubstituted DPP fluorophore (56 nm). Mass spectral analysis demonstrated that besides the expected Michael addition of thiols to the C═C bonds, the CN groups of the malonitrile moieties also react with thiols to form 4,5-dihydrothiazole structure. Probe 1 was used for fluorescence imaging of intracellular thiols. In the presence of thiols, both the green and red channel of the microscopy are active. With removal of the intracellular thiols, signal can only be detected through the red channel; thus, ratiometric bioimaging of intracellular thiols was achieved. The ratiometric response of probe 1 was rationalized by DFT calculations. Our complementary experimental and theoretical studies will be useful for design of ratiometric/colorimetric molecular probes.
The Journal of Organic Chemistry 11/2011; 76(22):9294-304. · 4.45 Impact Factor
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ABSTRACT: Pt(II) Schiff base complexes containing pyrene subunits were prepared using the chemistry-on-complex approach. This is the first time that supramolecular photochemical approach has been used to tune the photophysical properties of Schiff base Pt(II) complexes, such as emission wavelength and lifetimes. The complexes show intense absorption in the visible region (ε = 13100 M(-1) cm(-1) at 534 nm) and red phosphorescence at room temperature. Notably, much longer triplet excited state lifetimes (τ = 21.0 μs) were observed, compared to the model complexes (τ = 4.4 μs). The extension of triplet excited state lifetimes is attributed to the establishment of equilibrium between the metal-to-ligand charge-transfer ((3)MLCT) state (coordination centre localized) and the intraligand ((3)IL) state (pyrene localized), or population of the long-lived (3)IL triplet excited state. These assignments were fully rationalized by nanosecond time-resolved difference absorption spectra, 77 K emission spectra and density functional theory calculations. The complexes were used as triplet sensitizers for triplet-triplet-energy-tranfer (TTET) processes, i.e. luminescent O(2) sensing and triplet-triplet annihilation (TTA) based upconversion. The O(2) sensitivity (Stern-Volmer quenching constant) of the complexes was quantitatively evaluated in polymer films. The results show that the O(2) sensing sensitivity of the pyrene containing complex (K(SV) = 0.04623 Torr(-1)) is 15-fold of the model complex (K(SV) = 0.00313 Torr(-1)). Furthermore, significant TTA upconversion (upconversion quantum yield Φ(UC) = 17.7% and the anti-Stokes shift is 0.77 eV) was observed with pyrene containing complexes being used as triplet sensitizers. Our approach to tune the triplet excited states of Pt(II) Schiff base complexes will be useful for the design of phosphorescent transition metal complexes and their applications in light-harvesting, photovoltaics, luminescent O(2) sensing and upconversion, etc.
Dalton Transactions 09/2011; 40(43):11550-61. · 3.84 Impact Factor
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ABSTRACT: Triplet-triplet annihilation (TTA) based upconversions are attractive as a result of their readily tunable excitation/emission wavelength, low excitation power density, and high upconversion quantum yield. For TTA upconversion, triplet sensitizers and acceptors are combined to harvest the irradiation energy and to acquire emission at higher energy through triplet-triplet energy transfer (TTET) and TTA processes. Currently the triplet sensitizers are limited to the phosphorescent transition metal complexes, for which the tuning of UV-vis absorption and T(1) excited state energy level is difficult. Herein for the first time we proposed a library of organic triplet sensitizers based on a single chromophore of boron-dipyrromethene (BODIPY). The organic sensitizers show intense UV-vis absorptions at 510-629 nm (ε up to 180,000 M(-1) cm(-1)). Long-lived triplet excited state (τ(T) up to 66.3 μs) is populated upon excitation of the sensitizers, proved by nanosecond time-resolved transient difference absorption spectra and DFT calculations. With perylene or 1-chloro-9,10-bis(phenylethynyl)anthracene (1CBPEA) as the triplet acceptors, significant upconversion (Φ(UC) up to 6.1%) was observed for solution samples and polymer films, and the anti-Stokes shift was up to 0.56 eV. Our results pave the way for the design of organic triplet sensitizers and their applications in photovoltaics and upconversions, etc.
The Journal of Organic Chemistry 08/2011; 76(17):7056-64. · 4.45 Impact Factor
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ABSTRACT: Light out of darkness? Most sensitizers for triplet-triplet annihilation (TTA) upconversion are strongly phosphorescent. A new Ru(II) -coumarin dyad, on the other hand, has a non-emissive (3) IL excited state (Φ(P) =0.2 %) but shows a good upconversion quantum yield (Φ(UC) =2.7 %, see picture, TTET=triplet-triplet energy transfer).
Angewandte Chemie International Edition 07/2011; 50(36):8283-6. · 13.45 Impact Factor
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ABSTRACT: We studied four cyclometallated Pt(II) complexes, in which the thiazo-coumarin ligands (Pt-2, Pt-3 and Pt-4) or the phenylthiazo ligand (Pt-1) were directly cycloplatinated. Pt-2 shows intense absorption in visible region but other complexes show blue-shifted absorption. Room temperature phosphorescence was observed for all the complexes, and the emission wavelength is dependent on the size of the π-conjugation, not the intramolecular charge transfer (ICT) feature of the C^N ligands. Pt-2 shows longer phosphorescence lifetime (τ = 20.3 μs) than other complexes (below 2.0 μs). Furthermore, Pt-2 shows phosphorescence quantum yield Φ = 0.37, whereas Pt-3 and Pt-4 show much smaller Φ values (0.03 and 0.01, respectively). DFT/TDDFT calculations indicate (3)IL triplet excited states for the complexes. The complexes were used as for luminescence O(2) sensing and triplet-triplet-annihilation (TTA) based upconversion. Stern-Volmer quenching constant K(SV) = 0.026 Torr(-1) was observed for Pt-2, ca. 89-fold of that of Pt-3. TTA upconversion is achieved with Pt-2 (λ(em) = 400 nm with λ(ex) = 473 nm, anti-Stokes shift is 0.47 eV, excitation power density is at 70 mW cm(-2)). The upconversion quantum yield with Pt-2 as triplet sensitizer is up to 15.4%. The TTET efficiency (K(SV) = 1.33 × 10(5) M(-1), k(q) = 6.57 × 10(9) M(-1) s(-1). DPA as quencher) of Pt-2 is 34-fold of the model complex [Ru(dmb)(3)][PF(6)](2). Our results show that the (3)IL state can be readily accessed by direct cyclometallation of organic fluorophores and this approach will be useful for preparation and applications of transition metal complexes that show intense absorption in visible region and the long-lived emissive (3)IL excited states.
Dalton Transactions 06/2011; 40(22):5953-63. · 3.84 Impact Factor
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ABSTRACT: A dbbpy platinum(II) bis(coumarin acetylide) complex (Pt-1, dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was prepared. Pt-1 shows intense absorption in the visible region (λ(abs) = 412 nm, ε = 3.23 × 10(4) M(-1) cm(-1)) compared to the model complex dbbpy Pt(II) bis(phenylacetylide) (Pt-2, λ(abs) = 424 nm, ε = 8.8 × 10(3) M(-1) cm(-1)). Room temperature phosphorescence was observed for Pt-1 ((3)IL, τ(P) = 2.52 μs, λ(em) = 624 nm, Φ(P) = 2.6%) and the emissive triplet excited state was assigned as mainly intraligand triplet excited state ((3)IL), proved by 77 K steady state emission, nanosecond time-resolved transient absorption spectroscopy and DFT calculations. Complex Pt-1 was used for phosphorescent oxygen sensing and the sensitivity (Stern-Volmer quenching constant K(SV) = 0.012 Torr(-1)) is 12-fold of the model complex Pt-2 (K(SV) = 0.001 Torr(-1)). Pt-1 was also used as triplet sensitizer for triplet-triplet-annihilation based upconversion, upconversion quantum yield Φ(UC) up to 14.1% was observed, vs. 8.9% for the model complex Pt-2.
Dalton Transactions 06/2011; 40(31):7834-41. · 3.84 Impact Factor
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Angewandte Chemie International Edition 02/2011; 50(7):1626-9. · 13.45 Impact Factor
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ABSTRACT: The long-lived room temperature (RT) intra-ligand phosphorescence ((3)IL) of dbbpy Pt(II) bis(acetylide) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) complexes Pt-1 (λ(em) = 629 nm, τ = 118 μs, quantum yield φ = 17.5%) and Pt-3 (λ(em) = 658 nm, τ = 73.6 μs, φ = 2.1%) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine), containing naphthalimide (NI) and pyrene subunits, respectively, were used for enhanced luminescent oxygen sensing, compared to the model complex dbbpyPt (bisphenylacetylide) (Pt-2, λ(em) = 559 nm, τ = 0.7 μs, φ = 49.6%) with the normal (3)MLCT excited state (metal-to-ligand-charge-transfer). The luminescent lifetimes of Pt-1 and Pt-3 are greatly extended by 168-fold and 105-fold, respectively, when compared to that of Pt-2. The (3)IL features of the photoluminescence of Pt-1 and Pt-3 are supported by DFT/TDDFT calculations, which indicated a NI localized triplet excited state but a normal (3)MLCT/(3)LLCT excited state for Pt-2. The luminescent oxygen sensing properties of the complexes in solution as well as in polymer films were studied. In polymer films, the O(2) sensitivity of Pt-1 (quenching constant K(SV) = 0.085 Torr(-1)) and Pt-3 (K(SV) = 0.062 Torr(-1)) is 70-fold and 50-fold of Pt-2 (K(SV) = 0.0012 Torr(-1)), respectively.
The Analyst 11/2010; 135(11):2832-40. · 4.23 Impact Factor
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Wenting Wu,
Chuanhui Cheng,
Wanhua Wu,
Huimin Guo,
Shaomin Ji,
Peng Song,
Keli Han,
Jianzhang Zhao,
Xin Zhang,
Yubo Wu,
Guotong Du
Berichte der deutschen chemischen Gesellschaft 08/2010; 2010(29):4683 - 4696. · 2.94 Impact Factor
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Berichte der deutschen chemischen Gesellschaft 08/2010; 2010(28):4470 - 4482. · 2.94 Impact Factor
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ABSTRACT: An OFF-ON red-emitting phosphorescent thiol probe is designed by using the (3)MLCT photophysics of Ru(II) complexes, i.e., with Ru(II) as the electron donor. The probe is non-luminescent because the MLCT is corrupted by electron transfer from Ru(II) to an intramolecular electron sink (2,4-dinitrobenzenesulfonyl). Thiols cleave the electron sink, and the MLCT is re-established. Phosphorescence at 598 nm was enhanced by 90-fold, with a 143 nm (5256 cm(-1)) Stokes shift and a 1.1 mus luminescent lifetime.
Organic Letters 06/2010; 12(12):2876-9. · 5.86 Impact Factor
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ABSTRACT: We have synthesized three new carbazole-based fluorescent boronic acid sensors to investigate the fluorescence transduction efficiency of the novel d-PET effect, in which the fluorophore acts as the electron donor and the protonated amine/boronic acid group as the electron acceptor of the photoinduced electron transfer process (PET). Aryl ethynyl groups are attached at the 3,6-position of carbazole (aryl = 4-dimethylaminophenyl for sensor 1 or phenyl for sensor 2). Sensor 3 is without 3,6-substitutions. The phenylboronic acid moiety is attached at the 9-position (N-atom) of the carbazole in these sensors. We found that 1 and 3 are d-PET sensors (fluorophore as the electron donor, supported by DFT/TDDFT calculations), which show diminished emission at acidic pH but intensified emission at neutral/basic pH, which is in stark contrast to the normal a-PET (fluorophore as the electron acceptor) sensors, e.g., 2, which shows intensified emission at acidic pH but diminished emission at neutral pH. The fluorescence modulation efficiency of the d-PET effect of the new sensors, i.e., the emission intensity enhancement upon switching from acidic pH to neutral pH, is up to 10-fold, which is greatly improved compared to our previous d-PET sensors (ca. 3-fold). The efficient d-PET effect of the new sensors is attributed to the proper orientation of the electron donor/acceptor; i.e., the dipole moment and the transition moment (the direction of PET) of the new sensors are oriented in the same direction, and the dipole moment values of the new sensors along the vector direction of the PET are larger than that of the reported d-PET sensors. Selective recognition of alpha-hydroxyl carboxylic acids, such as tartaric acid, was achieved with the d-PET sensors, and a novel fluorescence transduction profile of enhancement/diminishment for chemoselectivity was observed. Herein we propose that the orientation of the electron donor/acceptor may significantly affect the fluorescence modulation efficiency of the PET effect; this discovery will be important for the future design of PET sensors with improved fluorescence transduction efficiencies.
The Journal of Organic Chemistry 03/2010; 75(8):2578-88. · 4.45 Impact Factor
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Shaomin Ji,
Wanhua Wu,
Yubo Wu,
Taiyang Zhao,
Fuke Zhou,
Yubin Yang,
Xin Zhang,
Xiaofen Liang, Wenting Wu,
Lina Chi,
Zhonggang Wang,
Jianzhang Zhao
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ABSTRACT: A cost-effective LED/photodiode(PD)-based time-domain luminescent lifetime measuring device with rugged electronics and simplified algorithms was assembled and successfully used to characterize oxygen sensing films, by continuously monitoring phosphorescence lifetime changes of phosphorescent platinum octaethylporphyrin (PtOEP) in cardo poly(aryl ether ketone) polymer (IMPEK-C) vs. variation of the oxygen partial pressure in a gas mixture (O(2)/N(2)). The results determined by both phosphorescence lifetime and intensity monitoring were compared and the lifetime mode gave results which are in good agreement with the intensity mode. The lifetime-based linear Stern-Volmer plot indicates that the PtOEP molecules are nearly homogeneously distributed in the sensing film. The phosphorescent lifetime of the PtOEP film changes from 75 micros in neat N(2) to less than 2 micros in neat O(2). The sensing system (by combination of the PtOEP sensing film with the home-assembled lifetime device) gives a high lifetime-based O(2) sensing resolution, e.g. about 2 micros Torr(-1) for low O(2) concentration (below 3.5% O(2), V/V). This feasible lifetime device configuration is affordable to most sensor laboratories and the device may facilitate the study of O(2) sensing material with the continuous lifetime monitoring method.
The Analyst 06/2009; 134(5):958-65. · 4.23 Impact Factor
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ABSTRACT: A dbbpy platinum(ii) bis(coumarin acetylide) complex (Pt-1, dbbpy = 4,4[prime or minute]-di-tert-butyl-2,2[prime or minute]-bipyridine) was prepared. Pt-1 shows intense absorption in the visible region ([small lambda]abs = 412 nm, [varepsilon] = 3.23 [times] 104 M-1 cm-1) compared to the model complex dbbpy Pt(ii) bis(phenylacetylide) (Pt-2, [small lambda]abs = 424 nm, [varepsilon] = 8.8 [times] 103 M-1 cm-1). Room temperature phosphorescence was observed for Pt-1 (3IL, [small tau]P = 2.52 [small mu ]s, [small lambda]em = 624 nm, [capital Phi]P = 2.6%) and the emissive triplet excited state was assigned as mainly intraligand triplet excited state (3IL), proved by 77 K steady state emission, nanosecond time-resolved transient absorption spectroscopy and DFT calculations. Complex Pt-1 was used for phosphorescent oxygen sensing and the sensitivity (Stern-Volmer quenching constant KSV = 0.012 Torr-1) is 12-fold of the model complex Pt-2 (KSV = 0.001 Torr-1). Pt-1 was also used as triplet sensitizer for triplet-triplet-annihilation based upconversion, upconversion quantum yield [capital Phi]UC up to 14.1% was observed, vs. 8.9% for the model complex Pt-2.
Dalton Transactions. 40(31):7834-7841.
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ABSTRACT: 5,10,15,20-tetraarylporphyrins TPP, TNP and TPyP (where TPP = 5,10,15,20-tetraphenylporphyrin, TNP = 5,10,15,20-tetranaphthalporphyrin and TPyP = 5,10,15,20-tetrapyrenyl-porphyrin) and the corresponding Pt(II) complexes were prepared. The photophysical properties of the porphyrin ligands and the Pt(II) complexes were studied using UV–vis absorption and photo-luminescence spectra; the geometry and electronic structure of the ligands and the complexes were studied via DFT/TDDFT calculations. UV–vis absorption and luminescence emission spectra showed that the added aryl groups did not contribute to the π-conjugation system of either the metal-free porphyrins or the Pt(II) complexes and, therefore, all ligands (and complexes) displayed similar photophysical properties. DFT/TDDFT calculations supported the proposed photophysical process and indicated very weak involvement of the aryl appendents in the low-lying electronic excited states. The luminescent oxygen sensing properties of the Pt(II) complexes were studied in solution as well as in polymer films (monitored via emission intensity and lifetime mode). The results demonstrated that in the case of both the pyrenyl and naphthyl groups, the oxygen sensing character of the complexes could be improved (quenching constant KSV = 0.068 Torr−1 for Pt–TNP vs. KSV = 0.040 Torr−1 for the parent complex Pt–TPP).
Dyes and Pigments 89(3):199-211. · 3.13 Impact Factor
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ABSTRACT: Phenylethynylene containing polypyridyl ruthenium (Ru) complexes 1 and 2 were prepared using chemistry-on-complex approach. The luminescent lifetimes of these complexes were extended by more than 2-fold (τ = 1.8 μs for complex 1) when compared to the reference complex 3 (i.e. Ru(Phen)(bpy)2, τ = 0.8 μs). Based on DFT/TDDFT calculations, we propose that 3LLCT/3MLCT mixed states are the emissive triplet states of 1 and 2. Luminescence oxygen sensitivity of the complexes are improved with extension of the lifetimes, e.g. I0/I100 = 15.4 for complex 3, but I0/I100 = 36.8 was observed for the complex 1 in MeCN solution (I0 is the emission in N2 and I100 is the emission intensity under O2 atmosphere). O2 sensitivity of the complexes were also studied in polymers IMPES-C, PES-C and polyvinyl chloride (PVC). The IMPES-C sensing film demonstrated very short response time and recovery time (3.4 and 7.5 s, respectively), which is ideal for practical O2 sensors. Modified Stern–Volmer equation and the two-sites model were used to fit the luminescent O2 sensing data. We found that with tuning the luminescence lifetimes, the luminescence O2 sensitivity of the Ru complexes (quenching constant, kSV) can be improved by up to 20-fold.
Sensors and Actuators B: Chemical.
