The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Johan Hofkens - One of the best experts on this subject based on the ideXlab platform.
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single molecule spectroscopy selectively probes donor and acceptor Chromophores in the phycobiliprotein allophycocyanin
Biophysical Journal, 2004Co-Authors: Davey Loos, Johan Hofkens, Mircea Cotlet, Frans C De Schryver, Satoshi HabuchiAbstract:We report on single-molecule fluorescence measurements performed on the phycobiliprotein allophycocyanin (APC). Our data support the presence of a unidirectional Forster-type energy transfer process involving spectrally different Chromophores, alpha84 (donor) and beta84 (acceptor), as well as of energy hopping amongst beta84 Chromophores. Single-molecule fluorescence spectra recorded from individual immobilized APC proteins indicate the presence of a red-emitting chromophore with emission peaking at 660 nm, which we connect with beta84, and a species with the emission peak blue shifted at 630 nm, which we attribute to alpha84. Polarization data from single APC trimers point to the presence of three consecutive red emitters, suggesting energy hopping amongst beta84 Chromophores. Based on the single-molecule fluorescence spectra and assuming that emission at the ensemble level in solution comes mainly from the acceptor chromophore, we were able to resolve the individual absorption and emission spectra of the alpha84 and beta84 Chromophores in APC.
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Intramolecular energy hopping and energy trapping in polyphenylene dendrimers with multiple peryleneimide donor Chromophores and a terryleneimide acceptor trap chromophore.
Journal of the American Chemical Society, 2001Co-Authors: Michael Maus, Rina De, Tania Weil, Sivaprasad Mitra, Uwe-m. Wiesler, Andreas Herrmann, Johan Hofkens, Tom Vosch, Klaus MüllenAbstract:Intramolecular Forster-type excitation energy transfer (FRET) processes in a series of first-generation polyphenylene dendrimers substituted with spatially well-separated peryleneimide Chromophores and a terryleneimide energy-trapping chromophore at the rim were investigated by steady-state and time-resolved fluorescence spectroscopy. Energy-hopping processes among the peryleneimide Chromophores are revealed by anisotropy decay times of 50−80 ps consistent with a FRET rate constant of khopp = 4.6 ns-1. If a terryleneimide chromophore is present at the rim of the dendrimer together with three peryleneimide Chromophores, more than 95% of the energy harvested by the peryleneimide Chromophores is transferred and trapped in the terryleneimide. The two decay times (τ1 = 52 ps and τ2 = 175 ps) found for the peryleneimide emission band are recovered as rise times at the terryleneimide emission band proving that the energy trapping of peryleneimide excitation energy by the terryleneimide acceptor occurs via two di...
Zhen Zhen - One of the best experts on this subject based on the ideXlab platform.
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improved electro optical property by introducing stronger acceptor to thermal stable Chromophores using modified julolidine as donor
Dyes and Pigments, 2019Co-Authors: Hua Zhang, Hongyan Xiao, Fenggang Liu, Fuyang Huo, Zhuo Chen, Ling Qiu, Zhen ZhenAbstract:Abstract Two novel second order nonlinear optical Chromophores based on large steric hindrance group modified julolidine donor and CF3-Ph-TCF acceptor linked via thiophene bridge were synthesized and characterized. Density functional theory (DFT) calculations suggested that the molecular quadratic hyperpolarizability (β) value of CF3-Ph-TCF based chromophore is 18.1% and 18.8% larger than that of TCF based Chromophores, respectively. The optimized structure shows that chromophore z4-3f with stronger acceptor and larger modification group presents the best molecular configuration. UV–Vis results show great red-shift about 130 nm for Chromophores z2-3f and z4-3f compared with z2 and z4. According to cyclic voltammetry measurements, Chromophores z2-3f and z4-3f showed lower energy gap indicating better intramolecular charge-transfer (ICT) transition. Especially, chromophore z4-3f displayed good thermal stability with onset decomposition temperature at about 265 °C. The poled films containing 25 wt% Chromophores in amorphous polycarbonate (APC) afforded electro-optical(EO) coefficients (r33) of 125 and 128 pm/V at 1310 nm. Further, film containing larger group modified chromophore was more efficient to realize good EO property with an order parameter (Φ) up to 18.4%. It's confirmed that Chromophores z2-3f and z4-3f, which had good thermal stability and high r33 values after poling in films, was a promising candidate for practical use.
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structure function relationship exploration for enhanced electro optic activity in isophorone based organic nlo Chromophores
Dyes and Pigments, 2018Co-Authors: Hua Zhang, Shuhui Bo, Huajun Xu, Zhen Zhen, Shujie Chen, Hongyan Xiao, Jiahai WangAbstract:Abstract Four isophorone-based Chromophores FLD1-FLD4 has been synthesized and investigated based on julolidinyl donors, with modified isophorone-derived bridges and tricyanovinyldihydrofuran or phenyl-trifluoromethyl-tricyanofuran acceptors. The chromophore FLD3 was modified with a 2-((tert-butyldimethylsilyl)oxy)ethanethiol group covalently attached to the π-conjugate bridge to ensure its all-trans conformation and prevent close packing of molecules, which benefit the macroscopic electro-optic efficiency. The chromophore FLD3 possesses better thermal stability than chromophore FLD1 without the isolation group on the bridge. Moreover, density functional theory calculations suggested that the hyperpolarizability (β) value of chromophore FLD3 is larger than that of chromophore FLD1. Polymers doped with chromophore FLD3 have been poled to afford ultrahigh electro-optic coefficient (r33) of 238 pm/V at 1.31 μm, which is nearly 60% higher than that obtained from chromophore FLD1 and three times higher than that of analogue Chromophores FLD2 and FLD4.
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synthesis of novel nonlinear optical Chromophores achieving excellent electro optic activity by introducing benzene derivative isolation groups into the bridge
Journal of Materials Chemistry C, 2015Co-Authors: Fenggang Liu, Hongyan Xiao, Yuhui Yang, Haoran Wang, Hua Zhang, Fuyang Huo, Zhuo Chen, Jialei Liu, Ling Qiu, Zhen ZhenAbstract:Three novel second order nonlinear optical (NLO) Chromophores based on julolidinyl donors and tricyanofuran (TCF) acceptors linked together via modified polyene π-conjugation with rigid benzene derivative steric hindrance groups (chromophore CL1 and CL2) or unmodified polyene π-conjugation (Chromophores CL) moieties as the bridges have been synthesized in good overall yields and systematically characterized. Density functional theory (DFT) was used to calculate the HOMO–LUMO energy gaps and first-order hyperpolarizability (β) of these Chromophores. Besides, to determine the redox properties of these Chromophores, cyclic voltammetry (CV) experiments were performed. Compared with CL, after introducing benzene derivative steric hindrance groups into the bridge, Chromophores CL1 and CL2 had good thermal stabilities with high thermal decomposition temperatures which were 32 °C and 24 °C higher than chromophore CL, respectively. Most importantly, the introduction of rigid steric hindrance groups can effectively reduce dipole–dipole interactions to translate their relatively small β values into bulk high EO activities. By doping Chromophores CL, CL1 and CL2 with a high loading of 45 wt% in APC, EO coefficients (r33) of up to 121, 197 and 202 pm V−1 at 1310 nm can be achieved, respectively. The r33 values of new Chromophores CL1 and CL2 were about 1.6 times of chromophore CL. The high r33 value, good thermal stability and high yield suggest the potential use of the new Chromophores in an nonlinear optical area.
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Novel Chromophores with excellent electro-optic activity based on double-donor Chromophores by optimizing thiophene bridges
Dyes and Pigments, 2015Co-Authors: Yuhui Yang, Shuhui Bo, Haoran Wang, Zhen ZhenAbstract:Abstract Three novel nonlinear optical Chromophores based on the same bis( N,N -diethyl)aniline donor have been synthesized and systematically characterized. These Chromophores showed good thermal stability and chromophore y1 showed the best thermal stability of 249 °C. Besides, compared with the chromophore (y1) without the substituted group, Chromophores y2 and y3 show better intramolecular charge-transfer absorption. Most importantly, the high molecular hyperpolarizability of these Chromophores can be effectively translated into large electro-optic coefficients. The electro-optic coefficient of poled films containing 25% wt of Chromophores y1–y3 doped in amorphous polycarbonate afforded values of 149, 138 and 157 pm/V at 1310 nm for Chromophores y1–y3 respectively. These results indicated that the double donors of bis( N,N -diethyl)aniline unit can efficiently improve the electron-donating ability and the special structure can reduce intermolecular electrostatic interactions, thus enhancing the macroscopic electro-optic activity. These properties, together with good solubility, suggest the potential use of these Chromophores as advanced materials.
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using phenoxazine and phenothiazine as electron donors for second order nonlinear optical chromophore enhanced electro optic activity
Dyes and Pigments, 2015Co-Authors: Haoran Wang, Shuhui Bo, Huajun Xu, Yuhui Yang, Dan Yang, Zhen ZhenAbstract:Abstract Two novel Chromophores based on the phenoxazine (chromophore L1) or phenothiazine (chromophore L2) donor, and tricyanofuran acceptors linked together via thiophene as the bridges have been synthesized and systematically investigated. Cyclic voltammetry measurements showed that chromophore L1 had smaller energy gap than chromophore L2 due to the stronger electron-donating ability. Moreover, Density functional theory calculations suggested that the β value of chromophore L1 is 17% larger than that of chromophore L2. The doped film containing the chromophore L1 showed an r 33 value of 49 pm/V at the concentration of 25 wt% which is two times higher than the EO activity of the chromophore L2 (23 pm/V) and the traditional aryl chromophore (10–20 pm/V). High r 33 value, high thermal stability (onset decomposition temperatures higher than 220 °C) suggests the potential use of the new chromophore in nonlinear optical materials.
Mingqian He - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of New Electrooptic Chromophores and Their Structure−Property Relationship†
Journal of Physical Chemistry B, 2004Co-Authors: Mingqian He, Thomas M Leslie, Michael E. Derosa, Sean M. Garner, Jeffery CitesAbstract:Several new high μβ Chromophores have been synthesized. These Chromophores were intentionally designed to study structure-property relationships. The synthetic strategy that was followed has been described in our previouspublications. Chromophore photostability was investigated from a structural point of view. Contact and corona poling of the Chromophores have also been accomplished with a 70 pm/V r 3 3 being achieved at λ = 1550 nm. The same Chromophores were also studied in two different polymer host systems to compare their dependence of the electrooptic coefficient and stability on the matrix material.
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Synthesis of Chromophores with Extremely High Electro-optic Activities. 2. Isophorone- and Combined Isophorone−Thiophene-Based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
Leon D Reed - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Chromophores with Extremely High Electro-optic Activities. 2. Isophorone- and Combined Isophorone−Thiophene-Based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
Sean M. Garner - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of New Electrooptic Chromophores and Their Structure−Property Relationship†
Journal of Physical Chemistry B, 2004Co-Authors: Mingqian He, Thomas M Leslie, Michael E. Derosa, Sean M. Garner, Jeffery CitesAbstract:Several new high μβ Chromophores have been synthesized. These Chromophores were intentionally designed to study structure-property relationships. The synthetic strategy that was followed has been described in our previouspublications. Chromophore photostability was investigated from a structural point of view. Contact and corona poling of the Chromophores have also been accomplished with a 70 pm/V r 3 3 being achieved at λ = 1550 nm. The same Chromophores were also studied in two different polymer host systems to compare their dependence of the electrooptic coefficient and stability on the matrix material.
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Synthesis of Chromophores with Extremely High Electro-optic Activities. 2. Isophorone- and Combined Isophorone−Thiophene-Based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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synthesis of Chromophores with extremely high electro optic activities 2 isophorone and combined isophorone thiophene based Chromophores
Chemistry of Materials, 2002Co-Authors: Mingqian He, Thomas M Leslie, John A Sinicropi, Sean M. Garner, Leon D ReedAbstract:Four new isophorone and combined isophorone and thiophene bridged Chromophores have been synthesized. All of these new high μβ Chromophores possess our newly synthesized tricyanovinyldihydrofuran acceptors. Because of our unique acceptor design, all of our Chromophores show high solubility in all organic solvents due to minimized chromophore−chromophore electrostatic interactions. These Chromophores have also been studied with respect to their solvatochromism and thermal behavior by TGA in air. Preliminary EO characterization of one of these Chromophores in polycarbonate has demonstrated an extremely high r33 of 70 pm/V at 1550 nm. We believe that this is the largest r33 reported at this wavelength.
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Translating microscopic optical nonlinearity into macroscopic optical nonlinearity: the role of chromophore chromophore electrostatic interactions
Journal of The Optical Society of America B-optical Physics, 1998Co-Authors: Aaron W. Harper, Srinath Kalluri, Antao Chen, William H. Steier, Sean M. Garner, Larry R Dalton, Bruce H. RobinsonAbstract:It has been commonly assumed that electrostatic interactions between Chromophores that exhibit large second hyperpolarizabilities β can be neglected in estimating electro-optic and second-harmonic coefficients, which can be achieved by electric-field poling of chromophore-containing polymers. Macroscopic optical nonlinearity has been assumed to scale as μβ/molecular weight, where μ is the dipole moment. Synthesis of Chromophores with μβ values of the order of 10-44 esu has led to expectations of electro-optic coefficients for organic materials that substantially exceed those of lithium niobate. Expected values have not been easily realized; thus the utility of the above-mentioned scaling factor or chromophore figure of merit has been brought into question. We demonstrate that macroscopic optical nonlinearities are attenuated at high chromophore loading for Chromophores characterized by electrostatic interactions that, at close approach distances, exceed thermal energies (kT) and poling energies (μF), where F is the effective electric field.