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Macairan JR, de Medeiros TV, Gazzetto M, Yarur Villanueva F, Cannizzo A, Naccache R. Elucidating the mechanism of dual-fluorescence in carbon dots. J Colloid Interface Sci 2021; 606:67-76. [PMID: 34388574 DOI: 10.1016/j.jcis.2021.07.156] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/23/2021] [Accepted: 07/31/2021] [Indexed: 11/30/2022]
Abstract
Carbon dots have garnered significant attention owing to their versatile and highly tunable optical properties; however, the origins and the underlying mechanism remains a subject of debate especially for dual fluorescent systems. Here, we have prepared carbon dots from glutathione and formamide precursors via a one-pot solvothermal synthesis. Steady state and dynamic techniques indicate that these dual fluorescent dots possess distinct emissive carbon-core and a molecular states, which are responsible for the blue and red optical signatures, respectively. To further glean information into the fluorescence mechanism, electrochemical analysis was used to measure the bandgaps of the two fluorescent states, while femtosecond transient absorption spectroscopy evidenced the two-state model based on the observed heterogeneity and bimodal spectral distribution. Our findings provide novel and fundamental insights on the optical properties of dual fluorescent dots, which can translate to more effective and targeted application development particularly in bioimaging, multiplexed sensing and photocatalysis.
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Affiliation(s)
- Jun-Ray Macairan
- Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Tayline V de Medeiros
- Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Michela Gazzetto
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Francisco Yarur Villanueva
- Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Andrea Cannizzo
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
| | - Rafik Naccache
- Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada.
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Gazzetto M, Artizzu F, Attar SS, Marchiò L, Pilia L, Rohwer EJ, Feurer T, Deplano P, Cannizzo A. Anti-Kasha Conformational Photoisomerization of a Heteroleptic Dithiolene Metal Complex Revealed by Ultrafast Spectroscopy. J Phys Chem A 2020; 124:10687-10693. [PMID: 33320003 DOI: 10.1021/acs.jpca.0c07794] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated the anti-Kasha photochemistry and anti-Kasha emission of d8-metal donor-acceptor dithiolene with femtosecond UV-vis transient absorption spectroscopy and molecular modeling. Experimentally, we found a lifetime of 1.4 ps for higher excited states, which is exceptionally long when compared to typical values for internal conversion (IC) (10 s of fs or less). Consequently, a substantial emission originates from the second excited state. Molecular modeling suggests this to be a consequence of the spatially separated molecular orbitals of the first and second excited states, which gives a charge transfer character to the IC. More surprisingly, we found that the inherent flexibility of the molecule allows the metal complex to access different configurations depending on the photoexcited state. We believe that this unique manifestation of anti-Kasha photoinduced conformational isomerization is facilitated by the exceptionally long lifetime of the second excited state.
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Affiliation(s)
- Michela Gazzetto
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Flavia Artizzu
- L3-Luminescent Lanthanide Lab, Department of Chemistry, Ghent University, Krijgslaan 281-Building S3, B-9000 Gent, Belgium
| | - Salahuddin S Attar
- Department of Chemical and Soil Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy
| | - Luciano Marchiò
- Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, Parco Area delle Scienze 17/a, 43124 Parma, Italy
| | - Luca Pilia
- Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università di Cagliari, Via Marengo 2, 09123 Cagliari, Italy
| | - Egmont J Rohwer
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Thomas Feurer
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Paola Deplano
- Department of Chemical and Soil Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy
| | - Andrea Cannizzo
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
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Smolentsev G, Milne CJ, Guda A, Haldrup K, Szlachetko J, Azzaroli N, Cirelli C, Knopp G, Bohinc R, Menzi S, Pamfilidis G, Gashi D, Beck M, Mozzanica A, James D, Bacellar C, Mancini GF, Tereshchenko A, Shapovalov V, Kwiatek WM, Czapla-Masztafiak J, Cannizzo A, Gazzetto M, Sander M, Levantino M, Kabanova V, Rychagova E, Ketkov S, Olaru M, Beckmann J, Vogt M. Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays. Nat Commun 2020; 11:2131. [PMID: 32358505 PMCID: PMC7195477 DOI: 10.1038/s41467-020-15998-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 04/07/2020] [Indexed: 12/21/2022] Open
Abstract
OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu–C and Cu–P bonds represents an underexplored type of luminophore. To investigate the charge transfer and structural rearrangements in this material, we apply complementary pump-probe X-ray techniques: absorption, emission, and scattering including pump-probe measurements at the X-ray free-electron laser SwissFEL. We find that the excitation leads to charge movement from C- and P- coordinated Cu sites and from the phosphorus atoms to phenyl rings; the Cu core slightly rearranges with 0.05 Å increase of the shortest Cu–Cu distance. The use of a Cu cluster bonded to the ligands through C and P atoms is an efficient way to keep structural rigidity of luminophores. Obtained data can be used to verify computational methods for the development of luminophores. OLED materials based on thermally activated delayed fluorescence have promising efficiency. Here, the authors investigate an organometallic multicore Cu complex as luminophore, by pump-probe X-ray techniques at three different facilities deriving a complete picture of the charge transfer in the triplet excited state.
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Affiliation(s)
| | | | - Alexander Guda
- The Smart Materials Research Institute, Southern Federal University, 344090, Rostov-on-Don, Russia
| | - Kristoffer Haldrup
- Physics Department, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Jakub Szlachetko
- Institute of Nuclear Physics, Polish Academy of Sciences, 31-342, Kraków, Poland
| | | | | | - Gregor Knopp
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Rok Bohinc
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Samuel Menzi
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | | | - Dardan Gashi
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Martin Beck
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | | | - Daniel James
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Camila Bacellar
- Paul Scherrer Institute, 5232, Villigen, Switzerland.,Laboratory for Ultrafast Spectroscopy, Lausanne Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Giulia F Mancini
- Paul Scherrer Institute, 5232, Villigen, Switzerland.,Laboratory for Ultrafast Spectroscopy, Lausanne Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Andrei Tereshchenko
- The Smart Materials Research Institute, Southern Federal University, 344090, Rostov-on-Don, Russia
| | - Victor Shapovalov
- The Smart Materials Research Institute, Southern Federal University, 344090, Rostov-on-Don, Russia
| | - Wojciech M Kwiatek
- Institute of Nuclear Physics, Polish Academy of Sciences, 31-342, Kraków, Poland
| | | | - Andrea Cannizzo
- Institute of Applied Physics, University of Bern, 3012, Bern, Switzerland
| | - Michela Gazzetto
- Institute of Applied Physics, University of Bern, 3012, Bern, Switzerland
| | - Mathias Sander
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Matteo Levantino
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Victoria Kabanova
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Elena Rychagova
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina, 49, Nizhny Novgorod, 603950, Russia
| | - Sergey Ketkov
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina, 49, Nizhny Novgorod, 603950, Russia
| | - Marian Olaru
- Institute of Inorganic Chemistry and Crystallography, University of Bremen, Leobenerstr. 7, 28359, Bremen, Germany
| | - Jens Beckmann
- Institute of Inorganic Chemistry and Crystallography, University of Bremen, Leobenerstr. 7, 28359, Bremen, Germany
| | - Matthias Vogt
- Institute of Inorganic Chemistry and Crystallography, University of Bremen, Leobenerstr. 7, 28359, Bremen, Germany. .,Martin-Luther-Universität Halle-Wittenberg Naturwissenschaftliche Fakultät II, Institut für Chemie, Anorganische Chemie, D-06120, Halle, Germany.
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Sciortino A, Gazzetto M, Buscarino G, Popescu R, Schneider R, Giammona G, Gerthsen D, Rohwer EJ, Mauro N, Feurer T, Cannizzo A, Messina F. Disentangling size effects and spectral inhomogeneity in carbon nanodots by ultrafast dynamical hole-burning. Nanoscale 2018; 10:15317-15323. [PMID: 30069566 DOI: 10.1039/c8nr02953a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Carbon nanodots (CDs) are a novel family of nanomaterials exhibiting unique optical properties. In particular, their bright and tunable fluorescence redefines the paradigm of carbon as a "black" material and is considered very appealing for many applications. While the field keeps growing, understanding CDs fundamental properties and relating them to their variable structures becomes more and more critical. Two crucial problems concern the effect of size on the electronic structure of CDs, and to what extent their optical properties are influenced by structural disorder. Furthermore, it remains largely unclear whether traditional concepts borrowed from the photo-physics of semiconductor quantum dots can be applied to any type of CDs. We used femtosecond optical hole burning to address the excited-state properties of a family of CDs with the specific structure of β-C3N4. The experiments provide compelling evidence of the dramatic effects of structural heterogeneity on the optical spectra, and reveal the remarkably simple pattern of the electronic transitions of these CDs, normally obscured by disorder. Moreover, the data conclusively clarify the different effects of the nanometric size and of the disordered surface structure on the fluorescence tunability, ruling out for these CDs any quantum confinement effect comparable to semiconductor quantum dots.
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Affiliation(s)
- Alice Sciortino
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Via Archirafi 36, 90123 Palermo, Italy.
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Sciortino A, Madonia A, Gazzetto M, Sciortino L, Rohwer EJ, Feurer T, Gelardi FM, Cannas M, Cannizzo A, Messina F. The interaction of photoexcited carbon nanodots with metal ions disclosed down to the femtosecond scale. Nanoscale 2017; 9:11902-11911. [PMID: 28660936 DOI: 10.1039/c7nr03754f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fluorescent carbon nanodots are a novel family of carbon-based nanoscale materials endowed with an outstanding combination of properties that make them very appealing for applications in nanosensing, photonics, solar energy harvesting and photocatalysis. One of the remarkable properties of carbon dots is their strong sensitivity to the local environment, especially to metal ions in solution. These interactions provide a testing ground for their marked photochemical properties, highlighted by many studies, and frequently driven by charge transfer events. Here we combine several optical techniques, down to femtosecond time resolution, to understand the interplay between carbon nanodots and aqueous metal ions such as Cu2+ and Zn2+. We find that copper inhibits the fluorescence of carbon dots through static and diffusional quenching mechanisms, and our measurements allow discriminating between the two. Ultrafast optical methods are then used to address the dynamics of copper-dot complexes, wherein static quenching takes place, and unveil the underlying complexity of their photocycle. We propose an initial increase of electronic charge on the surface of the dot, upon photo-excitation, followed by a partial electron transfer to the nearby ion, with 0.2 ps and 1.9 ps time constants, and finally a very fast (≪1 ps) non-radiative electron-hole recombination which brings the system back to the ground state. Notably, we find that the electron transfer stage is governed by an ultrafast water rearrangement around photo-excited dots, pointing out the key role of solvent interactions in the photo-physics of these systems.
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Affiliation(s)
- A Sciortino
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Via Archirafi 36, 90123 Palermo, Italy
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