88 research outputs found
Photophysical characterization of light-emitting poly(indenofluorene)s
No full textTime-resolved photoluminescence spectroscopy experiments of three poly(2,8-indenofluorene) derivatives bearing different pendant groups are presented. A comparison of the photophysical properties of dilute solutions and thin films provides information on the chemical purity of the materials. The photophysical properties of poly(2,8-indenofluorene)s are correlated with the morphological characteristics of their corresponding films. Wide-angle X-ray scattering experiments reveal the order in these materials at the molecular level. The spectroscopic results confirm the positive impact of a new synthetic approach on the spectral purity of the poly(indenofluorene)s. It is concluded that complete side-chain substitution of the bridgehead carbon atoms C-6 and C-12 in the indenofluorene unit, prior to indenofluorene ring formation, reduces the probability of keto formation. Due to the intrinsic chemical purity of the arylated derivative, identification of a long-delayed spectral feature, other than the known keto band, is possible in the case of thin films. Controlled doping experiments on the arylated derivative with trace amounts of an indenofluorene-monoketone provide quantitative information on the rates of two major photophysical processes, namely, singlet photoluminescence emission and singlet photoluminescence quenching. These results allow the determination of the minimum keto concentration that can affect the intrinsic photophysical properties of this polymer. The data suggest that photoluminescence quenching operates in the doped films according to the Stern-Volmer formalism
Annihilation assisted upconversion: all-organic, flexible and transparent multicolour display
No full textLow-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin
No full text[EN] Efforts to fabricate low-power up converting solid-state systems have rapidly increased in the past decade because of their possible application in several fields such as
bio-imaging, drug delivery, solar harvesting or displays. The synthesis of upconverting cross-linked polyester rubbers with covalently tethered chromophores is presented here.
Cross-linked films were prepared by reacting a poly(mannitol- sebacate) pre-polymer with 9,10-bis(4-hydroxymethylphenyl) anthracene (DPA-(CH2OH)2) and palladium
mesoporphyrin IX. These chromophores served as emitters and sensitizers, respectively, and through a cascade of photophysical events, resulted in an anti-Stokes shifted emission. Indeed, blue emission (*440 nm) of these solid materials was detected upon excitation at 543 nm with a green laser and the power dependence of integrated unconverted intensity versus excitation was examined. The new materials display upconversion at power densities as low as 32 mW/cm2, and do not display phase de-mixing, which has been identified as an obstacle in rubbery blends comprising untethered chromophores.The authors are thankful for the financial support of the Swiss National Science Foundation (200021_13540/1 and 200020_152968), Spanish Ministry of Economy and Competitiveness (Project MAT2010/21494-C03) and the Adolphe Merkle Foundation. The authors thank Prof. Christoph Weder for his help and support.Lee, S.; Sonseca, A.; Vadrucci, R.; Giménez Torres, E.; Foster, E.; Simon, YC. (2014). Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin. Journal of Inorganic and Organometallic Polymers. 24(5):898-903. https://doi.org/10.1007/s10904-014-0063-7S898903245C. A. Parker, C. G. Hatchard. P. Chem. Soc. London, 386–387 (1962)Y.C. Simon, C. Weder, J. Mater. Chem. 22, 20817–20830 (2012)J.Z. Zhao, S.M. Ji, H.M. Guo, Rsc Adv. 1, 937–950 (2011)C. Reinhard, R. Valiente, H.U. Gudel, J. Phys. Chem. B 106, 10051–10057 (2002)M. Haase, H. Schafer, Angew. Chem. Int. Edit. 50, 5808–5829 (2011)W.H. Wu, J.Z. Zhao, J.F. Sun, S. Guo, J. Org. Chem. 77, 5305–5312 (2012)T.T. Zhao, X.Q. Shen, L. Li, Z.P. Guan, N.Y. Gao, P.Y. Yuan, S.Q. Yao, Q.H. Xu, G.Q. Xu, Nanoscale 4, 7712–7719 (2012)C. Cepraga, T. Gallavardin, S. Marotte, P.H. Lanoe, J.C. Mulatier, F. Lerouge, S. Parola, M. Lindgren, P.L. Baldeck, J. Marvel, O. Maury, C. Monnereau, A. Favier, C. Andraud, Y. Leverrier, M.T. Charreyre, Polym. Chem. 4, 61–67 (2013)J. Qian, D. Wang, F.H. Cai, Q.Q. Zhan, Y.L. Wang, S.L. He, Biomaterials 33, 4851–4860 (2012)S. Baluschev, V. Yakutkin, T. Miteva, G. Wegner, T. Roberts, G. Nelles, A. Yasuda, S. Chernov, S. Aleshchenkov, A. Cheprakov, New J. Phys. 10, 013007 (2008)S. Baluschev, T. Miteva, V. Yakutkin, G. Nelles, A. Yasuda, G. Wegner, Phys. Rev. Lett. 97, 143903 (2006)M. Samoc, A. Samoc, B. Luther-Davies, Opt. Express 11, 1787–1792 (2003)A. Monguzzi, J. Mezyk, F. Scotognella, R. Tubino, F. Meinardi, Phys. Rev. B 78(195112), 1–5 (2008)A. Monguzzi, R. Tubino, F. Meinardi, Phys. Rev. B 77, 155122-1-4 (2008)T.N. Singh-Rachford, R.R. Islangulov, F.N. Castellano, J. Phys. Chem. A 112, 3906–3910 (2008)C. Wohnhaas, A. Turshatov, V. Mailander, S. Lorenz, S. Baluschev, T. Miteva, K. Landfester, Macromol. Biosci. 11, 772–778 (2011)R.R. Islangulov, J. Lott, C. Weder, F.N. Castellano, J. Am. Chem. Soc. 129, 12652–12653 (2007)Y.C. Simon, C. Weder, Chimia 66, 878 (2012)Y.C. Simon, S. Bai, M.K. Sing, H. Dietsch, M. Achermann, C. Weder, Macromol. Rapid Commun. 33, 498–502 (2012)S.H. Lee, J.R. Lott, Y.C. Simon, C. Weder, J. Mater. Chem. C 1, 5142–5148 (2013)S. Baluschev, P.E. Keivanidis, G. Wegner, J. Jacob, A.C. Grimsdale, K. Mullen, T. Miteva, A. Yasuda, G. Nelles, Appl. Phys. Lett. 86, 1–3 (2005)S. Baluschev, J. Jacob, Y.S. Avlasevich, P.E. Keivanidis, T. Miteva, A. Yasuda, G. Nelles, A.C. Grimsdale, K. Mullen, G. Wegner, ChemPhysChem 6, 1250–1253 (2005)P.C. Boutin, K.P. Ghiggino, T.L. Kelly, R.P. Steer, J. Phys. Chem. Lett. 4, 4113–4118 (2013)C.A. Sundback, J.Y. Shyu, Y.D. Wang, W.C. Faquin, R.S. Langer, J.P. Vacanti, T.A. Hadlock, Biomaterials 26, 5454–5464 (2005)Z.J. Sun, C. Chen, M.Z. Sun, C.H. Ai, X.L. Lu, Y.F. Zheng, B.F. Yang, D.L. Dong, Biomaterials 30, 5209–5214 (2009)A. Mahdavi, L. Ferreira, C. Sundback, J.W. Nichol, E.P. Chan, D.J.D. Carter, C.J. Bettinger, S. Patanavanich, L. Chignozha, E. Ben-Joseph, A. Galakatos, H. Pryor, I. Pomerantseva, P.T. Masiakos, W. Faquin, A. Zumbuehl, S. Hong, J. Borenstein, J. Vacanti, R. Langer, J.M. Karp, Proc. Natl. Acad. Sci. USA 105, 2307–2312 (2008)A. Sonseca, S. Camarero-Espinosa, L. Peponi, C. Weder, E.J. Foster, J.M. Kenny, E. Giménez, J. Polym. Sci. Part A. (2014). doi: 10.1002/pola.27367R. Vadrucci, C. Weder, Y.C. Simon, J. Mater. Chem. C 2, 2837–2841 (2014)F.A. Lara, U. Lins, G.H. Bechara, P.L. Oliveira, J. Exp. Biol. 208, 3093–3101 (2005)R. Maliger, P.J. Halley, J.J. Cooper-White, J. Appl. Polym. Sci. 127, 3980–3986 (2013)S. H. Lee, M. A. Ayer, R. Vadrucci, C. Weder, Y. C. Simon, Polym. Chem. (2014)T.W. Schmidt, Y.Y. Cheng, B. Fuckel, T. Khoury, R.G.C.R. Clady, M.J.Y. Tayebjee, N.J. Ekins-Daukes, M.J. Crossley, J. Phys. Chem. Lett. 1, 1795–1799 (2010)R. R. Islangulov, T. N. Singh, J. Lott, C. Weder, F. N. Castellano. Abstr. Pap. Am. Chem. Soc. 235 (2008
Upconverting nanovesicles for the activation of ruthenium anti-cancer prodrugs with red light
No full text
Ruthenium complexes are promising prodrugs in photoactivated chemotherapy (PACT): to prevent systemic therapeutic side-effects, a non-toxic version of the drug is introduced in the body and is only activated at the place of the tumor by means of visible light irradiation. However, most of these PACT compounds are only sensitive for UV or blue light, while this light does not permeate the body very well, in contrast to red or near-infrared light. To circumvent this problem, the principle of light-upconversion can be used to "upgrade" red light to blue light in a drug carrier such as a nanovesicle: the tumor is irradiated with red light, after which blue light is generated locally and used to activate the prodrug. Among the various methods of light-upconversion, triplet-triplet annihilation upconversion (TTA-UC) was selected as the most promising. In this thesis it is described that green-to-blue and red-to-blue upconverting nanovesicles were prepared. The red-to-blue upconverted light was successfully used to activate a ruthenium polypyridyl complex that was anchored to the same vesicle. Finally, the inherent oxygen-sensitivity of TTA-UC was greatly mitigated by the addition of water-soluble and biocompatible anti-oxidants. We expect that the results of this thesis will lead to exciting applications in PACT.NWO Vidi grantMetals in Catalysis, Biomimetics & Inorganic Material
Blue-emitting poly(2,7-pyrenylene)s: Synthesis and optical properties
No full textThe first 2,7-linked conjugated polypyrene tethering four aryl groups has been synthesized, and the photophysical properties of the polymer have been characterized. Due to the unique substitution with bulky aryl groups at the 4,5,9,10-positions of pyrene, the polymer although comprising large ??-units is readily soluble in common organic solvents. The polymer has a blue fluorescence in solution with an emission band maximum at X = 429 nm, fulfilling the requirements for a blue-emitting polymer. To a first approximation, this can be attributed to electronically decoupled pyrene subunits due to the nodal properties of their frontier orbitals. Furthermore, in solution the intriguing blue fluorescence is combined with solvent-dependent features, which could be used as a probe for local solvent polarity. Finally, in the solid state, the red-shifted emission of the polymer could be strongly reduced by blending with a nonconjugated polymer such as polystyrene.close373
Solution-related in Vitro Dewetting Behavior of Various Daily Disposable Contact Lenses
No full textThe dewetting process of contact lenses (CLs) is a result of material and solution properties as well as environmental factors. This article describes an investigational approach to observe and describe dewetting characteristics of different CL material and solution combinations. PURPOSE: This study aimed to determine the in vitro dewetting characteristics of various daily disposable CLs that were assessed using a noninvasive keratograph dewetting procedure (noninvasive keratograph dry-up time). In vitro dewetting data of the same CL materials soaked in saline solution and artificial tear solution (ATS) were measured to determine additional dewetting characteristics. METHODS: Noninvasive keratograph dry-up time was measured for six different soft CL materials and three different test conditions, in their specific blister solution, after exposure to saline and an ATS. Twenty CLs of each solution/material combination were assessed after an 8-hour soaking, during a 180-second dewetting observation, and the results were expressed by area under the curve values. RESULTS: Fastest dewetting occurred for all materials when measured out of saline, indicated by the highest averaged area under the curve value of 9243.3 ± 38.3 over all lens materials. Slower dewetting was detected for all materials when measured out of their specific blister solution (7755.9 ± 37.1) and out of ATS (7988.8 ± 40.0). Intragroup results were statistically significantly different for all solutions showing the smallest differences within the ATS group (P < .001, Kruskal-Wallis test). CONCLUSIONS: A pure saline thin film is not an ideal representation of a complex tear film layer of a healthy human because it lacks any evaporative protection by a lipid layer. The use of an ATS, which more likely mimics the natural tear film, allowed in this experimental in vitro project to decrease the gap to the in vivo field. In vitro dewetting information in connection with the blister solution allows only a theoretical conclusion about the initial lens wear after lens insertion
Ultrasensitive two-photon spectroscopy based on long spin-relaxation time in a dark optical trap
No full textWe propose a new spectroscopic method for measuring weak transitions in cold
and trapped atoms, which exploits the long spin relaxation times and tight
spatial confinement offered by dark optical traps to achieve extremely high
sensitivity. We demonstrate our scheme by measuring a two-photon transition in cold Rb atoms trapped in a new
single-beam dark optical trap, using an extremely weak probe laser power of
25
\mu {\ab W}. We were able to measure transitions with as small excitation
rate as
<0.1\un{s}^{-1}, using 107 fold quantum amplification of the transition
rate due to spin shelving and normalized detection with a strong cycling
transition
Aggregachromic Fluorogenic Asymmetric Cyanine Probes for Sensitive Detection of Heparin and Protamine
No full textThe precise and fast detection of heparin, the most widely used anticoagulant, remains a significant challenge for assessing its use in a clinical setting. In this work, we adapt a well-established asymmetric cyanine fluorogenic platform for the purpose of ultrasensitive heparin detection in the presence of common interferant chemical species. Three analogous fluorescence probes are synthesized in order to optimize for the number of binding moieties. Their interaction with heparin is studied using steady-state absorption, fluorescence, and circular dichroism spectroscopy. The obtained probes exhibit a highly sensitive “turn-on” fluorescence response to heparin, with a LOD in the 10–25 nM range, well within practical requirement, as well as a visible colorimetric change. The heparin–probe complex is also employed as a sensitive detection platform for protamine, both in the “turn-off” fluorescence and ratiometric detection schemes
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