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10 results on '"Jean-Pierre Malval"'

1. Bimetallic Ruthenium Nitrosyl Complexes with Enhanced Two‐Photon Absorption Properties for Nitric Oxide Delivery

Author

Yael Juarez‐Martinez, Pablo Labra‐Vázquez, Alejandro Enríquez‐Cabrera, Andrés F. Leon‐Rojas, Diego Martínez‐Bourget, Pascal G. Lacroix, Marine Tassé, Sonia Mallet‐Ladeira, Norberto Farfán, Rosa Santillan, Gabriel Ramos‐Ortiz, Jean‐Pierre Malval, Isabelle Malfant, Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Centro de Investigacion y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Centro de Investigaciones en Optica (CIO), Consejo Nacional de Ciencia y Tecnología [Mexico] (CONACYT), Institut de Science des Matériaux de Mulhouse (IS2M), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), IRP-MCCM French-Mexican International Research Program, LIA-LCMMC International Laboratory / CNRS - CONACyT, Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), and Gulli, Marie-Hélène

Subjects
Photons, Photochemistry, Organic Chemistry, Ruthenium nitrosyl, General Chemistry, [CHIM.COOR] Chemical Sciences/Coordination chemistry, Nitric Oxide, Ligands, Ruthenium, Catalysis, Ligand design, Density functional calculations, Two-photon absorption, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Density Functional Theory
Abstract

International audience; One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl-substituted terpyridine ligand, and bpy the 2,2’-bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF-CC-TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis-RuNO2 and bis-RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one-photon absorption (OPA) correlates well with the TD-DFT computations. A spectacular effect is observed at two-photon absorption (TPA) with a large enhancement of the molecular cross-section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA-based drug delivery.

Published
2022

2. Mixture of Azolium Tetraphenylborate with Isopropylthioxanthone: A New Class of N‐Heterocyclic Carbene (NHC) Photogenerator for Polyurethane, Polyester, and ROMP Polymers Synthesis

Author

Jean-Pierre Malval, Patrick Lacroix-Desmazes, Julien Pinaud, Corine Reibel, Abraham Chemtob, Valérie Héroguez, Thi Kim Hoang Trinh, Fabrice Morlet-Savary, Institut de Science des Matériaux de Mulhouse (IS2M), Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Laboratoire de Chimie des Polymères Organiques (LCPO), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC), Team 1 LCPO : Polymerization Catalyses & Engineering, and Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)

Subjects
Isopropylthioxanthone, Tetraphenylborate, 010405 organic chemistry, Organic Chemistry, General Chemistry, ROMP, 010402 general chemistry, Metathesis, 01 natural sciences, Catalysis, 0104 chemical sciences, Adduct, chemistry.chemical_compound, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Polymerization, Polymer chemistry, Copolymer, Carbene, ComputingMilieux_MISCELLANEOUS
Abstract

In the search of smarter routes to control the conditions of N-heterocyclic carbene (NHCs) formation, a two-component air-stable NHC photogenerating system is reported. It relies on the irradiation at 365 nm of a mixture of 2-isopropylthioxanthone (ITX) with 1,3-bis(mesityl)imidazoli(ni)um tetraphenylborate. The photoinduced liberation of NHC is evidenced by reaction with a mesitoyl radical to form an NHC-radical adduct detectable by electron spin resonance spectroscopy. The NHC yield can be determined by 1 H NMR spectroscopy through the formation of a soluble and stable NHC-carbodiimide adduct. To deprotonate the azolium salt and liberate the NHC, a mechanism is proposed in which the role of base is played by ITX radical anion formed in situ by a primary photoinduced electron-transfer reaction between electronically excited ITX (oxidant) and BPh4 - (reductant). An NHC yield as high as 70 % is achieved upon starting with a stoichiometric ratio of ITX and azolium salt. Three different photoNHC-mediated polymerizations are described: synthesis of polyurethane and polyester by organocatalyzed step-growth polymerization and ring-opening copolymerization, respectively, and generation of polynorbornene by ring-opening metathesis polymerization using an NHC-coordinated Ru catalyst formed in situ.

Published
2019

3. Visible light-emitting diode-sensitive thioxanthone derivatives used in versatile photoinitiating systems for photopolymerizations

Author

Hongting Pu, Ming Jin, Wu Xingyu, Jean-Pierre Malval, and Decheng Wan

Subjects
Polymers and Plastics, Chemistry, Radical, Organic Chemistry, Radical polymerization, Photodissociation, Cationic polymerization, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, Thioxanthone, 01 natural sciences, 0104 chemical sciences, Photopolymer, Materials Chemistry, 0210 nano-technology, Photoinitiator, Visible spectrum
Abstract

Novel thioxanthone (TX) derivatives are used as versatile photoinitiators upon visible light-emitting diode (LED; e.g., 405, 425, and 450 nm) exposure. The mechanisms for the photochemical generation of reactive species (i.e., cations and free radicals) produced from photoinitiating systems based on the photoinitiator and an iodonium salt, tris(trimethylsilyl)silane, or an amine, were studied by UV–vis spectroscopy, fluorescence, cyclic voltammetry, steady-state photolysis, and electron spin resonance spin-trapping techniques. The reactive species are particularly efficient for cationic, free radical, hybrid, and thiol-ene photopolymerizations upon LED exposure. The optimized photoinitiating systems exhibit higher efficiency than those of reference systems (i.e., isopropyl TX-based photoinitiating systems), especially in the visible range. According to their beneficial features, these photoinitiating systems have considerable potential in photocuring applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

Published
2017

4. Dual roles for promoting monomers to polymers: A conjugated sulfonium salt photoacid generator as photoinitiator and photosensitizer in cationic photopolymerization

Author

Hongting Pu, Wu Xingyu, Ming Jin, Jean Pierre Malval, and Decheng Wan

Subjects
Polymers and Plastics, Chemistry, Sulfonium, Organic Chemistry, Cationic polymerization, Epoxide, 02 engineering and technology, Conjugated system, Vinyl ether, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, 0104 chemical sciences, chemistry.chemical_compound, Photopolymer, Polymer chemistry, Materials Chemistry, medicine, Photosensitizer, 0210 nano-technology, Photoinitiator, medicine.drug
Abstract

An efficient strategy for comprehensive utilization of the conjugated sulfonium salt photoacid generator (PAG), namely, 3-{4-[4-(4-N,N′-diphenylamino)-styryl]phenyl}phenyl dimethyl sulfonium hexafluoroantimonate, was developed through photoinitiated cationic photopolymerization (CP) of epoxides and vinyl ether upon exposure to near-UV and visible light-emitting diodes (LEDs; e.g., 365, 385, 405, and 425 nm). Photochemical mechanisms were investigated by UV–vis spectra, molecular orbital calculations, fluorescence, cyclic voltammetry, and electron spin resonance spin-trapping analyses. Compared with commercial PAGs, the prepared conjugated sulfonium salt generated H+, which can be used as photoinitiator. Moreover, the fluorescent byproducts from photodecomposition can be used as photosensitizer of commercial iodonium salt in the photoinitiating systems of CP. These novel D-π-A type sulfonium-based photoinitiating systems are efficient (epoxide conversion = 85–90% and vinyl conversion >90%; LEDs upon exposure to 365–425 nm) even in low-concentration initiators (1%, w/w) and low curing light intensities (10–40 mW cm−2). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2722–2730

Published
2016

5. Photoisomerisation in Aminoazobenzene-Substituted Ruthenium(II) Tris(bipyridine) Complexes: Influence of the Conjugation Pathway

Author

Huriye Akdas-Kilig, Jean-Luc Fillaut, Claudine Katan, Hacène Meghezzi, Abdou Boucekkine, Jean-Pierre Malval, Paul Savel, Anissa Amar, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Thermodynamique et Modélisation Moléculaire, USTHB, BP 32 El Alia, 16111 Bab Ezzouar Alger, Algeria (USTHB), Université des Sciences et de la Technologie Houari Boumediene = University of Sciences and Technology Houari Boumediene [Alger] (USTHB), Institut de Science des Matériaux de Mulhouse (IS2M), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), P. Savel was supported by a MESR grant. This work was granted access to the HPC resources of CINES and of IDRIS under the allocations 2013-[x2013080649] made by GENCI (Grand Equipement National de Calcul Intensif)., Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Laboratoire de Thermodynamique et Modélisation Moléculaire, USTHB, BP 32 El Alia, 16111 Bab Ezzouar Alger, Algeria, and Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)

Subjects
Azo compounds, chemistry.chemical_element, 010402 general chemistry, Photochemistry, 01 natural sciences, Ruthenium, Catalysis, Coordination complex, Bipyridine, chemistry.chemical_compound, Photochromism, Moiety, [CHIM.COOR]Chemical Sciences/Coordination chemistry, chemistry.chemical_classification, 010405 organic chemistry, Organic Chemistry, General Chemistry, Acceptor, Coordination chemistry, 0104 chemical sciences, Density functional calculations, chemistry, Azobenzene, Linker
Abstract

International audience; Transition-metal complexes containing stimuli-responsive systems are attractive for applications in optical devices, photonic memory, photosensing, as well as luminescence imaging. Amongst them, photochromic metal complexes offer the possibility of combining the specific properties of the metal centre and the optical response of the photochromic group. The synthesis, the electrochemical properties and the photophysical characterisation of a series of donor-acceptor azobenzene derivatives that possess bipyridine groups connected to a 4-dialkylaminoazobenzene moiety through various linkers are presented. DFT and TD-DFT calculations were performed to complement the experimental findings and contribute to their interpretation. The position and nature of the linker (ethynyl, triazolyl, none) were engineered and shown to induce different electronic coupling between donor and acceptor in ligands and complexes. This in turn led to strong modulations in terms of photoisomerisation of the ligands and complexes.

Published
2015

6. Direct Laser Writing of Crystallized TiO2 and TiO2 /Carbon Microstructures with Tunable Conductive Properties

Author

Karine Mougin, Shang Yu Yu, Hsiao-Wen Zan, Arnaud Spangenberg, Olivier Soppera, Jean Pierre Malval, Gautier Schrodj, Joseph Dentzer, Institut de Science des Matériaux de Mulhouse (IS2M), Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Département de Photochimie Générale (DPG), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS), Spangenberg, Arnaud, Compréhension de la polymérisation biphotonique utilisée en écriture laser directe via la combinaison de différentes méthodes d'analyse résolues temporellement et spatialement - - 2PhotonInsight2016 - ANR-16-CE08-0020 - AAPG2016 - VALID, Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), National Chiao Tung University (NCTU), ANR, Projet Région Grand Est MIPPI4D, Ministry of Science and Technology, Taiwan (Project 104-2923-E-009-001-MY3), and ANR-16-CE08-0020,2PhotonInsight,Compréhension de la polymérisation biphotonique utilisée en écriture laser directe via la combinaison de différentes méthodes d'analyse résolues temporellement et spatialement(2016)

Subjects
Materials science, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, conductive micropattern, Context (language use), Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, TiO2 / carbon nanocomposite, law.invention, law, [CHIM]Chemical Sciences, General Materials Science, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Thin film, ComputingMilieux_MISCELLANEOUS, Microscale chemistry, miniaturized pressure sensor, [CHIM.MATE] Chemical Sciences/Material chemistry, Nanocomposite, Mechanical Engineering, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Laser, Piezoresistive effect, 0104 chemical sciences, Amorphous solid, functional metal oxide, femtosecond direct laser writing, Mechanics of Materials, Femtosecond, 0210 nano-technology
Abstract

International audience; Metal oxides are an important class of materials for optoelectronic applications. In this context, developing simple and versatile processes for integrating these materials at the microscale and nanoscale has become increasingly important. One of the major remaining challenges is to control the microstructuration and electro-optical properties in a single step. It is shown here that near-infrared femtosecond laser irradiation can be successfully used to prepare amorphous or crystallized TiO2 microstructures in a single step using a direct laser writing (DLW) approach from a TiO2 precursor thin film doped with a suitable dye. When laser writing is conducted under a nitrogen atmosphere, simultaneous to the crosslinking of the Tioxide precursor, the graphitization of the organic species embedded in the initial film is observed. In this case, a carbon network is generated within the TiO2 matrix, which significantly increases the conductivity. Moreover, the TiO2/C nanocomposite exhibits piezoresistive behavior that is used in a pressure sensor device. Using this route, it is possible to use DLW to fabricate microsized pressure sensors.

Published
2018

7. ChemInform Abstract: Nonlinear Photochemistry and 3D Microfabrication with Q-Switched Nd:YAG Microchip Lasers

Author

Teodora Scheul, Olivier Stéphan, Chang Li Tseng, Michel Bouriau, Patrice L. Baldeck, Chin Te Lin, Tien-Tung Chung, Jean Pierre Malval, Chih-Lang Lin, and Cheng Huang

Subjects
chemistry.chemical_classification, Fabrication, General Medicine, Polymer, Laser, Microstructure, Photochemistry, law.invention, Silver nitrate, chemistry.chemical_compound, chemistry, Polymerization, law, Photoinitiator, Microfabrication
Abstract

We review our recent advances in two-photon induced photochemistry to fabricate three-dimensional micro-objects made in polymers, proteins and noble metals using Q-switched Nd:YAG microchip lasers. We have synthesized a new photoinitiator that is about 4 times more sensitive for two-photon polymerisation with sub-nanosecond pulses at 532 nm. We describe the improvement of our fabrication process and strategies to obtain solid microstructures that correspond to their models. We report on our progress to make silver microstructures by the photoreduction of silver nitrate with microchip lasers at 1064nm.

Published
2012

10. Derivatization of 4-(Dimethylamino)benzamide to Dual Fluorescent Ionophores: Divergent Spectroscopic Effects Dependent on N or O Amide Chelation

Author

Jean-Pierre Malval and René Lapouyade

Subjects
inorganic chemicals, Quenching (fluorescence), Organic Chemistry, Biochemistry, Fluorescence, Medicinal chemistry, Catalysis, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Intramolecular force, Amide, Excited state, Drug Discovery, Pyridine, Chelation, Physical and Theoretical Chemistry, Lone pair
Abstract

Starting from the pentafluorophenyl ester of 4-(dimethylamino)benzoic acid, two dual fluorescent amide ligands with aza-15-crown-5 and 2-(aminomethyl)pyridine were obtained for sensing, respectively, alkali (alkaline-earth) and transition (heavy) metal cations. The crystal structure of the copper(II) complex is reported. The Cu2+ is coordinated through the pyridine N- and amide O-atoms of two symmetry-related ligands. The azacrown-directed Ca-chelation to the N-atom of the amide leads to a slight quenching of the two fluorescence bands. In contrast, the pyridine directed CuII-chelation to the O-atom of the amide enhances the short-wavelength emission 17-fold over the locally excited state (LE), quenching the twisted intramolecular charge-transfer (TICT) emission, and, as a result, the intensity ratio I(LE)/I(TICT) provides an accurate and sensitive measurement of the CuII concentration. These different cation effects are dependent on which atom (N vs. O) of the amide function participates in cation coordination: while the Ca2+ interaction with the N-atom electron pair leads to the deconjugation of the amide N-atom from the fluorophore, Cu2+ interaction with the lone pair of the O-atom of the carbonyl group increases the energy of the n-π* but also of the 1La transition and therefore close the channel to the TICT state.

Published
2001

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