The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Joseph M Fox - One of the best experts on this subject based on the ideXlab platform.
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improved metabolic stability for 18f pet probes rapidly constructed via Tetrazine trans cyclooctene ligation
Bioconjugate Chemistry, 2015Co-Authors: Ramajeyam Selvaraj, Li-peng Yap, Benjamin C Giglio, Shuanglong Liu, Hui Wang, Mengzhe Wang, Hong Yuan, Srinivasa R Chintala, Peter S Conti, Joseph M FoxAbstract:The fast kinetics and bioorthogonal nature of the Tetrazine trans-cyclooctene (TCO) ligation makes it a unique tool for PET probe construction. In this study, we report the development of an 18F-labeling system based on a CF3-substituted diphenyl-s-Tetrazine Derivative with the aim of maintaining high reactivity while increasing in vivo stability. c(RGDyK) was tagged by a CF3-substituted diphenyl-s-Tetrazine Derivative via EDC-mediated coupling. The resulting Tetrazine-RGD conjugate was combined with a 19F-labeled TCO Derivative to give HPLC standards. The analogous 18F-labeled TCO Derivative was combined with the diphenyl-s-Tetrazine-RGD at μM concentration. The resulting tracer was subjected to in vivo metabolic stability assessment, and microPET studies in murine U87MG xenograft models. The diphenyl-s-Tetrazine-RGD combines with an 18F-labeled TCO in high yields (>97% decay-corrected on the basis of TCO) using only 4 equiv of Tetrazine-RGD relative to the 18F-labeled TCO (concentration calculated based...
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Improved Metabolic Stability for 18F PET Probes Rapidly Constructed via Tetrazine trans-Cyclooctene Ligation
2015Co-Authors: Ramajeyam Selvaraj, Li-peng Yap, Shuanglong Liu, Hui Wang, Mengzhe Wang, Hong Yuan, Srinivasa R Chintala, Peter S Conti, Benjamin Giglio, Joseph M FoxAbstract:The fast kinetics and bioorthogonal nature of the Tetrazine trans-cyclooctene (TCO) ligation makes it a unique tool for PET probe construction. In this study, we report the development of an 18F-labeling system based on a CF3-substituted diphenyl-s-Tetrazine Derivative with the aim of maintaining high reactivity while increasing in vivo stability. c(RGDyK) was tagged by a CF3-substituted diphenyl-s-Tetrazine Derivative via EDC-mediated coupling. The resulting Tetrazine-RGD conjugate was combined with a 19F-labeled TCO Derivative to give HPLC standards. The analogous 18F-labeled TCO Derivative was combined with the diphenyl-s-Tetrazine-RGD at μM concentration. The resulting tracer was subjected to in vivo metabolic stability assessment, and microPET studies in murine U87MG xenograft models. The diphenyl-s-Tetrazine-RGD combines with an 18F-labeled TCO in high yields (>97% decay-corrected on the basis of TCO) using only 4 equiv of Tetrazine-RGD relative to the 18F-labeled TCO (concentration calculated based on product’s specific activity). The radiochemical purity of the 18F-RGD peptides was >95% and the specific activity was 111 GBq/μmol. Noninvasive microPET experiments demonstrated that 18F-RGD had integrin-specific tumor uptake in subcutaneous U87MG glioma. In vivo metabolic stability of 18F-RGD in blood, urine, and major organs showed two major peaks: one corresponded to the Diels–Alder conjugate and the other was identified as the aromatized analog. A CF3-substituted diphenyl-s-Tetrazine displays excellent speed and efficiency in 18F-PET probe construction, providing nearly quantitative 18F labeling within minutes at low micromolar concentrations. The resulting conjugates display improved in vivo metabolic stability relative to our previously described system
Audebert Pierre - One of the best experts on this subject based on the ideXlab platform.
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Tetrazine molecules as efficient electronic diversion channel in 2D organic-inorganic perovskites
'Royal Society of Chemistry (RSC)', 2021Co-Authors: Lédée Ferdinand, Galmiche Laurent, Audebert Pierre, Trippé-allard Gaëlle, Garrot Damien, Marrot Jérome, Lauret Jean-sebastien, Deleporte Emmanuelle, Katan Claudine, Even JackyAbstract:International audienceTaking advantage of an innovative design concept for layered halide perovskites with active chromophores acting as organic spacers, we present here the synthesis of two novel two-dimensional (2D) hybrid organic-inorganic halide perovskites incorporating for the first time 100% of a photoactive Tetrazine Derivative as organic component. Namely, the use of a heterocyclic ring containing a nitrogen proportion imparts a unique electronic structure to the organic component, with lowest energy optical absorption in the blue. The present compound, a Tetrazine, presents several resonances between the organic and inorganic components, both in terms of single particle electronic levels and exciton states, providing the ideal playground to discuss charge and energy transfer mechanisms at the organic/inorganic interface. Photophysical studies along with hybrid Time-Dependent DFT simulations demonstrate partial energy transfer and rationalise the suppressed emission from the perovskite frame in terms of different energy-transfer diversion channels, potentially involving both singlet and triplet states of the organic spacer. Periodic DFT simulations also support the feasibility of electron transfers from the conduction band of the inorganic component to the LUMO of the spacer as potential quenching mechanism, suggesting the coexistence and competition of charge and energy transfer mechanisms in these heterostructure. Our work proves the feasibility of inserting photoactive small rings in a 2D perovskite structure, meanwhile providing a robust frame to rationalize the electronic interactions between the semiconducting inorganic layer and organic chromophores, with the prospects of optimizing the organic moiety according to the envisaged application
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A theoretical perspective on the electronic and optical properties of layered halide perovskites:Symmetry analysis of quantum-well electronic structure and charge/energy transfer processes beyond thequantum-well picture
HAL CCSD, 2021Co-Authors: Quarti Claudio, Audebert Pierre, Lédée Ferdinand, Deleporte Emmanuelle, Even Jacky, Kepenekian Mikael, Pedesseau Laurent, Traore Boubacar, Mercier Nicolas, Katan ClaudineAbstract:International audienceLayered halide perovskites are a class of semiconductors produced via chemical approaches andshowing unique opto-electronic properties. Pioneered by Prof. David Mitzi in the 1990s, these materials have anatural quantum-well electronic structure (the band-gap of the inorganic frame is embedded into that of theorganic spacers) and feature positive transport properties, effective visible-light absorption, narrow excitonicemission, etc.The full exploitation of these perovskites cannot go without deep understanding of their native electronic andoptical properties, as accessible, via complex experimental set-ups and computationally expensive ab-initiocalculations. However, interpretation of experimental and theoretical results can greatly benefit from basic“pencil-and-paper” symmetry analysis. Based on group-theory, we discuss how the change in thedimensionality influences the corresponding electronic and optical properties. In the direct band gap quantumwellscenario, we highlight how the breaking of the chemical connectivity influences the electronic structure, interms of hybridization of the composing atoms (see Figure a). We also discuss the corresponding evolution ofthe optical properties, with focus on the lowest energy exciton fine structure. The present analysis will be thenextended to the case of defective-halide perovskite frames, a class of systems recently reported in theliterature.As an alternative scenario, substitution of commonly used saturated organic spacers with molecules featuringextended π-conjugation breaks the quantum-well picture. Indeed, the band-gap closing due to extended π-system can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of theinorganic frame, leading to the formation of a type II heterojunction at the organic/inorganic interface (seeFigure b). We discuss the related charge/energy transfer processes on the basis of recently reportedPbX (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as spacer. Featuring resonancesboth for the single particle states and excitonic states, these systems allow to discuss several diversionchannels for the relaxation of carriers generated in the perovskite, in the detail
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A theoretical perspective on the electronic and optical properties of layered halide perovskites:Symmetry analysis of quantum-well electronic structure and charge/energy transfer processes beyond thequantum-well picture
HAL CCSD, 2021Co-Authors: Quarti Claudio, Audebert Pierre, Lédée Ferdinand, Deleporte Emmanuelle, Even Jacky, Kepenekian Mikael, Pedesseau Laurent, Traore Boubacar, Mercier Nicolas, Katan ClaudineAbstract:ACS Award in the Chemistry of Materials (2020): Symposium Honoring David Brian MitziInternational audienceLayered halide perovskites are a class of semiconductors produced via chemical approaches andshowing unique opto-electronic properties. Pioneered by Prof. David Mitzi in the 1990s, these materials have anatural quantum-well electronic structure (the band-gap of the inorganic frame is embedded into that of theorganic spacers) and feature positive transport properties, effective visible-light absorption, narrow excitonicemission, etc.The full exploitation of these perovskites cannot go without deep understanding of their native electronic andoptical properties, as accessible, via complex experimental set-ups and computationally expensive ab-initiocalculations. However, interpretation of experimental and theoretical results can greatly benefit from basic“pencil-and-paper” symmetry analysis. Based on group-theory, we discuss how the change in thedimensionality influences the corresponding electronic and optical properties. In the direct band gap quantumwellscenario, we highlight how the breaking of the chemical connectivity influences the electronic structure, interms of hybridization of the composing atoms (see Figure a). We also discuss the corresponding evolution ofthe optical properties, with focus on the lowest energy exciton fine structure. The present analysis will be thenextended to the case of defective-halide perovskite frames, a class of systems recently reported in theliterature.As an alternative scenario, substitution of commonly used saturated organic spacers with molecules featuringextended π-conjugation breaks the quantum-well picture. Indeed, the band-gap closing due to extended π-system can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of theinorganic frame, leading to the formation of a type II heterojunction at the organic/inorganic interface (seeFigure b). We discuss the related charge/energy transfer processes on the basis of recently reportedPbX (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as spacer. Featuring resonancesboth for the single particle states and excitonic states, these systems allow to discuss several diversionchannels for the relaxation of carriers generated in the perovskite, in the detail
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Tetrazine-incorporating layered halide perovskites featuring type II electronic interface: a small cation with several optical and electronic resonances
HAL CCSD, 2021Co-Authors: Lédée Ferdinand, Galmiche Laurent, Audebert Pierre, Trippé-allard Gaëlle, Garrot Damien, Lauret Jean-sebastien, Deleporte Emmanuelle, Even Jacky, Jérôme Marrot, Katan ClaudineAbstract:J.E and J.S.L acknowledges the financial support from the InstitutUniversitaire de France. Computational investigations were conducted thanks to HPC resourcesprovided by [TGCC/CINES/IDRIS] under the allocation 2020-A0010907682 made by GENCI.National audienceLayered halide perovskites are a class of semiconductors easily produced via chemical approaches and showing unique optical and electronic properties. These materials have a natural quantum-well electronic structure, that is, the band-gap of the inorganic frame is embedded into that of the organic spacers,[1] and feature effective light absorption, positive in-plane transport properties, effective narrow linewidth emission and improved stability against their 3D counterpart.[2] On the other hand, confinement of semiconducting properties in an inorganic is not ideal for applications where photogenerated species are required to effectively travel within the optically active component. This is the typical case of photovoltaics, where ineffective out-of-plane charge transport results in depleted performances for layered halide perovskites, as compared to 3D analogues.[3] In this frame, substituting the (usually) electronic inert organic spacer with organic chromophores featuring extended -conjugated core can pave the way for layered materials showing improved charge and energy transport properties.[4] Indeed, the band-gap closing due to extended -electronic conjugation can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of the inorganic frame, resulting in the formation of a type II heterojunction at the organic/inorganic interface. Here, we discuss the related charge/energy transfer processes on the basis of recently reported PbX4 (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as organic spacer.[5] Thanks to the various energy resonances between the inorganic and the organic component, both at the level of the single particle electronic states and at the level of many-body exciton states, this system represents the ideal test case to discuss in the detail charge and energy transfer processes at the type II interface. Furthermore, the incorporation of this novel chromophore as spacer is based on a new design concept, which exploits heterocycles with large fraction of nitrogen, rather than extending the size of carbon-based -core.[6] Photoluminescence (PL) and Photoluminescence Excitation (PLE) measurements indicate partial energy transfer from the inorganic frame to the organic component. Furthermore, cutting-edge, periodic DFT simulations suggest potential exciton ionization as potential responsible for the suppressed light emission from the perovskite frame. REFERENCES[1] C. Katan, et al. Chem. Rev. 2019, 119, 3140−3192[2] M. D. Smith, et al., Chem. Rev. 2019, 119, 3104−3139[3] H. Tsai, et al., Nature 2016, 536, 312–316[4] D. B. Mitzi, et al., Inorg. Chem. 1999, 38, 6246-6256[5] F. Ledée et al., revised manuscript submitted to Mater. Horiz.[6] Y. Gao, Nat. Chem. 2019, 11, 1151–115
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Functionalization of Graphene Oxide by Tetrazine Derivatives: A Versatile Approach toward Covalent Bridges between Graphene Sheets
'American Chemical Society (ACS)', 2015Co-Authors: Li Yuan, Alain-rizzo Valerie, Galmiche Laurent, Audebert Pierre, Miomandre Fabien, Louarn Guy, Bozlar Michael, Pope, Michael A., Dabbs, Daniel M., Aksay, Ilhan A.Abstract:We have covalently grafted Tetrazine Derivatives to graphene oxide through nucleophilic substitution. Since the Tetrazine unit is electroactive and nitrogen-rich, with a reduction potential sensitive to the type of substituent and degree of substitution, we used electrochemistry and X-ray photoelectron spectroscopy to demonstrate clear evidence for grafting through covalent bonding. Chemical modification was supported by Fourier transform infrared spectroscopy and thermal analysis. Tetrazines grafted onto graphene oxide displayed different mass losses compared to unmodified graphene and were more stable than the molecular precursors. Finally, a bridging Tetrazine Derivative was grafted between sheets of graphene oxide to demonstrate that the separation distance between sheets can be maintained while designing new graphene-based materials, including chemically bound, redox structures
Ramajeyam Selvaraj - One of the best experts on this subject based on the ideXlab platform.
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improved metabolic stability for 18f pet probes rapidly constructed via Tetrazine trans cyclooctene ligation
Bioconjugate Chemistry, 2015Co-Authors: Ramajeyam Selvaraj, Li-peng Yap, Benjamin C Giglio, Shuanglong Liu, Hui Wang, Mengzhe Wang, Hong Yuan, Srinivasa R Chintala, Peter S Conti, Joseph M FoxAbstract:The fast kinetics and bioorthogonal nature of the Tetrazine trans-cyclooctene (TCO) ligation makes it a unique tool for PET probe construction. In this study, we report the development of an 18F-labeling system based on a CF3-substituted diphenyl-s-Tetrazine Derivative with the aim of maintaining high reactivity while increasing in vivo stability. c(RGDyK) was tagged by a CF3-substituted diphenyl-s-Tetrazine Derivative via EDC-mediated coupling. The resulting Tetrazine-RGD conjugate was combined with a 19F-labeled TCO Derivative to give HPLC standards. The analogous 18F-labeled TCO Derivative was combined with the diphenyl-s-Tetrazine-RGD at μM concentration. The resulting tracer was subjected to in vivo metabolic stability assessment, and microPET studies in murine U87MG xenograft models. The diphenyl-s-Tetrazine-RGD combines with an 18F-labeled TCO in high yields (>97% decay-corrected on the basis of TCO) using only 4 equiv of Tetrazine-RGD relative to the 18F-labeled TCO (concentration calculated based...
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Improved Metabolic Stability for 18F PET Probes Rapidly Constructed via Tetrazine trans-Cyclooctene Ligation
2015Co-Authors: Ramajeyam Selvaraj, Li-peng Yap, Shuanglong Liu, Hui Wang, Mengzhe Wang, Hong Yuan, Srinivasa R Chintala, Peter S Conti, Benjamin Giglio, Joseph M FoxAbstract:The fast kinetics and bioorthogonal nature of the Tetrazine trans-cyclooctene (TCO) ligation makes it a unique tool for PET probe construction. In this study, we report the development of an 18F-labeling system based on a CF3-substituted diphenyl-s-Tetrazine Derivative with the aim of maintaining high reactivity while increasing in vivo stability. c(RGDyK) was tagged by a CF3-substituted diphenyl-s-Tetrazine Derivative via EDC-mediated coupling. The resulting Tetrazine-RGD conjugate was combined with a 19F-labeled TCO Derivative to give HPLC standards. The analogous 18F-labeled TCO Derivative was combined with the diphenyl-s-Tetrazine-RGD at μM concentration. The resulting tracer was subjected to in vivo metabolic stability assessment, and microPET studies in murine U87MG xenograft models. The diphenyl-s-Tetrazine-RGD combines with an 18F-labeled TCO in high yields (>97% decay-corrected on the basis of TCO) using only 4 equiv of Tetrazine-RGD relative to the 18F-labeled TCO (concentration calculated based on product’s specific activity). The radiochemical purity of the 18F-RGD peptides was >95% and the specific activity was 111 GBq/μmol. Noninvasive microPET experiments demonstrated that 18F-RGD had integrin-specific tumor uptake in subcutaneous U87MG glioma. In vivo metabolic stability of 18F-RGD in blood, urine, and major organs showed two major peaks: one corresponded to the Diels–Alder conjugate and the other was identified as the aromatized analog. A CF3-substituted diphenyl-s-Tetrazine displays excellent speed and efficiency in 18F-PET probe construction, providing nearly quantitative 18F labeling within minutes at low micromolar concentrations. The resulting conjugates display improved in vivo metabolic stability relative to our previously described system
Katan Claudine - One of the best experts on this subject based on the ideXlab platform.
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Tetrazine molecules as efficient electronic diversion channel in 2D organic-inorganic perovskites
'Royal Society of Chemistry (RSC)', 2021Co-Authors: Lédée Ferdinand, Galmiche Laurent, Audebert Pierre, Trippé-allard Gaëlle, Garrot Damien, Marrot Jérome, Lauret Jean-sebastien, Deleporte Emmanuelle, Katan Claudine, Even JackyAbstract:International audienceTaking advantage of an innovative design concept for layered halide perovskites with active chromophores acting as organic spacers, we present here the synthesis of two novel two-dimensional (2D) hybrid organic-inorganic halide perovskites incorporating for the first time 100% of a photoactive Tetrazine Derivative as organic component. Namely, the use of a heterocyclic ring containing a nitrogen proportion imparts a unique electronic structure to the organic component, with lowest energy optical absorption in the blue. The present compound, a Tetrazine, presents several resonances between the organic and inorganic components, both in terms of single particle electronic levels and exciton states, providing the ideal playground to discuss charge and energy transfer mechanisms at the organic/inorganic interface. Photophysical studies along with hybrid Time-Dependent DFT simulations demonstrate partial energy transfer and rationalise the suppressed emission from the perovskite frame in terms of different energy-transfer diversion channels, potentially involving both singlet and triplet states of the organic spacer. Periodic DFT simulations also support the feasibility of electron transfers from the conduction band of the inorganic component to the LUMO of the spacer as potential quenching mechanism, suggesting the coexistence and competition of charge and energy transfer mechanisms in these heterostructure. Our work proves the feasibility of inserting photoactive small rings in a 2D perovskite structure, meanwhile providing a robust frame to rationalize the electronic interactions between the semiconducting inorganic layer and organic chromophores, with the prospects of optimizing the organic moiety according to the envisaged application
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A theoretical perspective on the electronic and optical properties of layered halide perovskites:Symmetry analysis of quantum-well electronic structure and charge/energy transfer processes beyond thequantum-well picture
HAL CCSD, 2021Co-Authors: Quarti Claudio, Audebert Pierre, Lédée Ferdinand, Deleporte Emmanuelle, Even Jacky, Kepenekian Mikael, Pedesseau Laurent, Traore Boubacar, Mercier Nicolas, Katan ClaudineAbstract:International audienceLayered halide perovskites are a class of semiconductors produced via chemical approaches andshowing unique opto-electronic properties. Pioneered by Prof. David Mitzi in the 1990s, these materials have anatural quantum-well electronic structure (the band-gap of the inorganic frame is embedded into that of theorganic spacers) and feature positive transport properties, effective visible-light absorption, narrow excitonicemission, etc.The full exploitation of these perovskites cannot go without deep understanding of their native electronic andoptical properties, as accessible, via complex experimental set-ups and computationally expensive ab-initiocalculations. However, interpretation of experimental and theoretical results can greatly benefit from basic“pencil-and-paper” symmetry analysis. Based on group-theory, we discuss how the change in thedimensionality influences the corresponding electronic and optical properties. In the direct band gap quantumwellscenario, we highlight how the breaking of the chemical connectivity influences the electronic structure, interms of hybridization of the composing atoms (see Figure a). We also discuss the corresponding evolution ofthe optical properties, with focus on the lowest energy exciton fine structure. The present analysis will be thenextended to the case of defective-halide perovskite frames, a class of systems recently reported in theliterature.As an alternative scenario, substitution of commonly used saturated organic spacers with molecules featuringextended π-conjugation breaks the quantum-well picture. Indeed, the band-gap closing due to extended π-system can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of theinorganic frame, leading to the formation of a type II heterojunction at the organic/inorganic interface (seeFigure b). We discuss the related charge/energy transfer processes on the basis of recently reportedPbX (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as spacer. Featuring resonancesboth for the single particle states and excitonic states, these systems allow to discuss several diversionchannels for the relaxation of carriers generated in the perovskite, in the detail
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A theoretical perspective on the electronic and optical properties of layered halide perovskites:Symmetry analysis of quantum-well electronic structure and charge/energy transfer processes beyond thequantum-well picture
HAL CCSD, 2021Co-Authors: Quarti Claudio, Audebert Pierre, Lédée Ferdinand, Deleporte Emmanuelle, Even Jacky, Kepenekian Mikael, Pedesseau Laurent, Traore Boubacar, Mercier Nicolas, Katan ClaudineAbstract:ACS Award in the Chemistry of Materials (2020): Symposium Honoring David Brian MitziInternational audienceLayered halide perovskites are a class of semiconductors produced via chemical approaches andshowing unique opto-electronic properties. Pioneered by Prof. David Mitzi in the 1990s, these materials have anatural quantum-well electronic structure (the band-gap of the inorganic frame is embedded into that of theorganic spacers) and feature positive transport properties, effective visible-light absorption, narrow excitonicemission, etc.The full exploitation of these perovskites cannot go without deep understanding of their native electronic andoptical properties, as accessible, via complex experimental set-ups and computationally expensive ab-initiocalculations. However, interpretation of experimental and theoretical results can greatly benefit from basic“pencil-and-paper” symmetry analysis. Based on group-theory, we discuss how the change in thedimensionality influences the corresponding electronic and optical properties. In the direct band gap quantumwellscenario, we highlight how the breaking of the chemical connectivity influences the electronic structure, interms of hybridization of the composing atoms (see Figure a). We also discuss the corresponding evolution ofthe optical properties, with focus on the lowest energy exciton fine structure. The present analysis will be thenextended to the case of defective-halide perovskite frames, a class of systems recently reported in theliterature.As an alternative scenario, substitution of commonly used saturated organic spacers with molecules featuringextended π-conjugation breaks the quantum-well picture. Indeed, the band-gap closing due to extended π-system can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of theinorganic frame, leading to the formation of a type II heterojunction at the organic/inorganic interface (seeFigure b). We discuss the related charge/energy transfer processes on the basis of recently reportedPbX (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as spacer. Featuring resonancesboth for the single particle states and excitonic states, these systems allow to discuss several diversionchannels for the relaxation of carriers generated in the perovskite, in the detail
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Tetrazine-incorporating layered halide perovskites featuring type II electronic interface: a small cation with several optical and electronic resonances
HAL CCSD, 2021Co-Authors: Lédée Ferdinand, Galmiche Laurent, Audebert Pierre, Trippé-allard Gaëlle, Garrot Damien, Lauret Jean-sebastien, Deleporte Emmanuelle, Even Jacky, Jérôme Marrot, Katan ClaudineAbstract:J.E and J.S.L acknowledges the financial support from the InstitutUniversitaire de France. Computational investigations were conducted thanks to HPC resourcesprovided by [TGCC/CINES/IDRIS] under the allocation 2020-A0010907682 made by GENCI.National audienceLayered halide perovskites are a class of semiconductors easily produced via chemical approaches and showing unique optical and electronic properties. These materials have a natural quantum-well electronic structure, that is, the band-gap of the inorganic frame is embedded into that of the organic spacers,[1] and feature effective light absorption, positive in-plane transport properties, effective narrow linewidth emission and improved stability against their 3D counterpart.[2] On the other hand, confinement of semiconducting properties in an inorganic is not ideal for applications where photogenerated species are required to effectively travel within the optically active component. This is the typical case of photovoltaics, where ineffective out-of-plane charge transport results in depleted performances for layered halide perovskites, as compared to 3D analogues.[3] In this frame, substituting the (usually) electronic inert organic spacer with organic chromophores featuring extended -conjugated core can pave the way for layered materials showing improved charge and energy transport properties.[4] Indeed, the band-gap closing due to extended -electronic conjugation can result in the (de)stabilization of the frontier orbitals of the spacer, compared to those of the inorganic frame, resulting in the formation of a type II heterojunction at the organic/inorganic interface. Here, we discuss the related charge/energy transfer processes on the basis of recently reported PbX4 (X=Cl,Br) layered perovskite frame incorporating Tetrazine Derivative as organic spacer.[5] Thanks to the various energy resonances between the inorganic and the organic component, both at the level of the single particle electronic states and at the level of many-body exciton states, this system represents the ideal test case to discuss in the detail charge and energy transfer processes at the type II interface. Furthermore, the incorporation of this novel chromophore as spacer is based on a new design concept, which exploits heterocycles with large fraction of nitrogen, rather than extending the size of carbon-based -core.[6] Photoluminescence (PL) and Photoluminescence Excitation (PLE) measurements indicate partial energy transfer from the inorganic frame to the organic component. Furthermore, cutting-edge, periodic DFT simulations suggest potential exciton ionization as potential responsible for the suppressed light emission from the perovskite frame. REFERENCES[1] C. Katan, et al. Chem. Rev. 2019, 119, 3140−3192[2] M. D. Smith, et al., Chem. Rev. 2019, 119, 3104−3139[3] H. Tsai, et al., Nature 2016, 536, 312–316[4] D. B. Mitzi, et al., Inorg. Chem. 1999, 38, 6246-6256[5] F. Ledée et al., revised manuscript submitted to Mater. Horiz.[6] Y. Gao, Nat. Chem. 2019, 11, 1151–115
Raffaella Rossin - One of the best experts on this subject based on the ideXlab platform.
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trans cyclooctene functionalized peptobrushes with improved reaction kinetics of the Tetrazine ligation for pretargeted nuclear imaging
ACS Nano, 2020Co-Authors: Johanna E L Steen, Dennis Svatunek, Barbara Sohr, Jesper Jorgensen, Kerstin Johann, Kamilla Norregaard, Alexander Birke, Vladimir Shalgunov, Patricia E Edem, Raffaella RossinAbstract:Tumor targeting using agents with slow pharmacokinetics represents a major challenge in nuclear imaging and targeted radionuclide therapy as they most often result in low imaging contrast and high radiation dose to healthy tissue. To address this challenge, we developed a polymer-based targeting agent that can be used for pretargeted imaging and thus separates tumor accumulation from the imaging step in time. The developed targeting agent is based on polypeptide-graft-polypeptoid polymers (PeptoBrushes) functionalized with trans-cyclooctene (TCO). The complementary 111In-labeled imaging agent is a 1,2,4,5-Tetrazine Derivative, which can react with aforementioned TCO-modified PeptoBrushes in a rapid bioorthogonal ligation. A high degree of TCO loading (up to 30%) was achieved, without altering the physicochemical properties of the polymeric nanoparticle. The highest degree of TCO loading resulted in significantly increased reaction rates (77-fold enhancement) compared to those with small molecule TCO moieties when using lipophilic Tetrazines. Based on computer simulations, we hypothesize that this increase is a result of hydrophobic effects and significant rearrangements within the polymer framework, in which hydrophobic patches of TCO moieties are formed. These patches attract lipophilic Tetrazines, leading to increased reaction rates in the bioorthogonal ligation. The most reactive system was evaluated as a targeting agent for pretargeted imaging in tumor-bearing mice. After the setup was optimized, sufficient tumor-to-background ratios were achieved as early as 2 h after administration of the Tetrazine imaging agent, which further improved at 22 h, enabling clear visualization of CT-26 tumors. These findings show the potential of PeptoBrushes to be used as a pretargeting agent when an optimized dose of polymer is used.