Papers by Arnaud Spangenberg
Physical Chemistry Chemical Physics, 2020
This contribution aims at investigating the branching effect on the steady state, time resolved f... more This contribution aims at investigating the branching effect on the steady state, time resolved fluorescence and two-photon absorption (2PA) properties of dimethylamino and diphenylamino substituted styrylpyrimidine derivatives, by means of a combined experimental and theoretical study. In contrast to classical branched molecules with a triphenylamine central core and electron accepting groups at the periphery, here, branched molecules with the reverse topology and different symmetry are examined, namely a styrylpyrimidine group is used as the electron withdrawing core and dimethylamino or diphenylamino donors are incorporated at the periphery. Besides, compared to the great A c c e p t e d M a n u s c r i p t majority of existing branched systems, the herein studied molecules do not have the C 3 symmetry. For that reason, the spectral region of the linear and non-linear optical spectra of the two and three branched chromophores remains actually similar. Interestingly, whereas the one-photon absorption spectra of the one-branched systems versus the two-or three-branched ones are spectrally shifted, there is almost no spectral shift for the main 2PA spectral region. Meanwhile, there is still an enhancement of both linear and nonlinear optical responses. Overall, here we developed a strategy that enhances the 2PA response while maintaining the spectral position. Specifically, 2PA cross section values as high as 500 GM have been obtained for the diphenylamino A-(π-D) 3 molecule in dichloromethane. C. K. acknowledges support by the Grand Equipement National de Calcul Intensif (GENCI) through HPC resources of CINES and IDRIS (grant 2019-A0060800649). M. F. acknowledges the Région Bretagne for her Ph. D. Funding. 1 (a) S.
Shape influence on the ultrafast plasmonic properties of gold nanoparticles
Optics Express, Jul 14, 2022
The aim of shape-controlled colloidal synthesis of gold (Au) is to produce Au nanoparticles (NPs)... more The aim of shape-controlled colloidal synthesis of gold (Au) is to produce Au nanoparticles (NPs) with fine control of shapes, sizes, and dispersities. We show how transient absorption spectroscopy (TAS) can be used to rapidly and accurately quantify the vast ensemble of shapes of Au NPs in solution within minutes, including the synthesized nanorods, decahedra, and nanospheres. Colloidal solutions containing Au NPs were measured in TAS and their localized surface plasmon resonance (LSPR) modes were classified according to the shape, wavelength and number of peaks. Then their excited-state relaxation dynamics were used to ascertain their electron-phonon ( e-ph ) coupling time constant and frequency of optomechanical modes. TAS can quickly show that an Au nanosphere sample contains a tiny fraction of Au nanorods, whereas steady-state absorbance is totally blind to the presence of nanorods. Additionally, the TAS experiments indicate that the characteristic e-ph coupling time constants ...
Enhancement of Two-Photon Initiating Efficiency of a 4,4′-Diaminostyryl-2,2′-bipyridine Derivative Promoted by Complexation with Silver Ions
Macromolecules, Jan 25, 2012
ABSTRACT We report on the two-photon-induced polymerization (TPIP) ability of a new class of free... more ABSTRACT We report on the two-photon-induced polymerization (TPIP) ability of a new class of free radical two-photon initiator based on a cationic silver(I) complex incorporating 4,4′-diaminostyryl-2,2′-bipyridine (DES) derivatives as ligands. Coordination with Ag+ induces a strong increase of the charge transfer character at excited state, which enhances the two-photon absorption properties of the complex with respect to that of the free ligand. A comparative analysis of the photophysical properties of DES and DES2Ag+ shows that the presence of silver cation increases the efficiency for the generation of radical cations (DES•+), which can be used as hydrogen abstractor in free radical photopolymerization. We show that the addition of an aliphatic amine used as hydrogen donor also opens a parallel route for the regeneration of DES. The improvement of the two-photon polymerization efficiency is then evidenced by the fabrication of microstructures. We finally demonstrate that the use of DES2Ag+ as two-photon initiator offers new opportunities for the fabrication of functional nanostructures composed of metal–polymer nanocomposites.
Journal of Materials Chemistry C, Jul 21, 2014
interchromophore coupling within the oligomer which exhibits a highly distorted geometry resultin... more interchromophore coupling within the oligomer which exhibits a highly distorted geometry resulting in a strong reduction of the effective conjugation length. The recursive implementation of nine monomers into a three-dimensional architecture leads however to a cooperative enhancement of the two-photon absorption (2PA) cross-section with a MAX of 5093 GM at 800 nm. This very high 2PA ability has been oriented to improve the two-photon induced polymerization efficiency of a bicomponent photoinitiator system implying a hexaarylbiimidazole used as H-abstractor and an aliphatic amine used as H-donor. The photosensitizing mechanism is investigated and we clearly show that the intrinsic photoinitiation efficiency with the oligomer is increased by a factor 3 as compared to its corresponding monomer. We therefore demonstrate that such a two-photon sensitizing strategy leads to a synergy effect combining a higher photoinitiation reactivity and a very large two-photon absorption cross-section.
Switching properties of nanomaterials based on organic photochromism
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2007
<i>N</i>-(3,5-Di-<i>tert</i>-butylsalicylidene)-4-iodobenzene, a peculiar case of a nonlinear optical photoswitch
Journal of Physical Organic Chemistry, Nov 1, 2007
ABSTRACT N-(3,5-Di-tert-butylsalicylidene)-4-iodobenzene (1) is photochromic in the solid state, ... more ABSTRACT N-(3,5-Di-tert-butylsalicylidene)-4-iodobenzene (1) is photochromic in the solid state, owing to its ability to yield enol–keto tautomerism. Despite its centrosymmetric structure (P21/c), polycrystalline thin films of 1 show second harmonic generation (SHG). Moreover, this SHG can be reversibly switched by light. Investigations using confocal microscopy showed that a morphology change occurs when the fundamental beam of a Ti:sapphire (990 nm, 1.3 ps) is focused on the material, yielding an SHG-active solid. Copyright © 2007 John Wiley &amp; Sons, Ltd.
Physical Chemistry Chemical Physics, 2013
Chemical Communications, 2019
Dyes and Pigments, 2016
A series of five octupolar molecules with central triphenylamine donor and peripheral diazine ele... more A series of five octupolar molecules with central triphenylamine donor and peripheral diazine electron-withdrawing groups has been prepared. These structures possess extended π-spacer comprising multiple bonds in a combination with 1,4-phenylene and 2,5-thienylene subunits. Starting from tris(4-ethynylphenyl)amine, the key step in the preparation of the chromophores involves triple Sonogashira cross-coupling reaction. The photophysical properties of the compounds are described. A strong positive emission solvatochromism, typical for dyes featuring Intramolecular Charge Transfer (ICT), is observed, two-photon absorption (2PA) properties were also measured. Linear and nonlinear optical properties as well as electronic
A Versatile Method for Preparing Metal Oxide Nanostructures via Laser Direct Patterning
Organic crystals for second harmonic generation switching based on anil photochromes
Research on Chemical Intermediates, Feb 1, 2008
... de Photochimie Supramoléculaires et Macromoléculaires (PPSM, CNRS UMR8531), Institutd'Al... more ... de Photochimie Supramoléculaires et Macromoléculaires (PPSM, CNRS UMR8531), Institutd'Alembert, 61 avenue ... In photochromic materials, we demonstrated that non-linear optical (NLO) properties ... design of materials fulfilling the prerequisites for SHG activity (pushpull and ...
CCDC 687883: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Surface Color on Demand: Chameleon Effect
JOM, 2022
CCDC 635611: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
2018 20th International Conference on Transparent Optical Networks (ICTON), 2018
Microscopy techniques based on recording of the optical field diffracted by the specimen, in ampl... more Microscopy techniques based on recording of the optical field diffracted by the specimen, in amplitude and phase, like Digital Holographic Microscopy (DHM) have been a growing research topic in recent years. Tomographic acquisitions are possible if one is able to record information, while controlling variations of the specimen illumination. Classical approaches consider either illumination variation, simple to implement, but suffering fro the classical "missing cone" problem, or sample rotation, delivering images with quasi-isotropic, but lower resolution. We have developed an original-, combined tomographic diffractive microscope setup, making use of specimen rotation as well as illumination rotation, which is able to deliver images with an almost isotropic resolution better than 200 nm.
Macromolecular Chemistry and Physics, 2021
In order to respond to the growing demand for radiation‐curable waterborne products like hydrogel... more In order to respond to the growing demand for radiation‐curable waterborne products like hydrogels or inks, there is a need for water‐soluble radical photoinitiators exhibiting absorption in the near UV to visible range. Herein the synthesis of a novel type‐I diphenylphosphine oxide photoinitiator bearing a 2,6‐dimethyl‐4‐dimethylaminobenzoyl group is described. The presence of a tertiary amino group in the para position of the benzoyl group results in an increased absorption in the visible range and its facile conversion into water‐soluble derivatives after a subsequent protonation or quaternization reaction. Quaternization with methyl triflate (MeOTf) yields a water‐soluble monoacylphosphine oxide compound displaying a quaternary ammonium group N(CH3)3+ OTf−. The main characteristics are water‐solubility, shelf‐stability, absorption in near‐UV range, low cytotoxicity, and efficient α‐scission as evidenced by steady‐state photolysis experiments. Its photopolymerization efficiency ...
ChemPhysChem, 2020
The photophysical properties and the photoinitiating reactivity of a ditopic alkoxynitrostilbene ... more The photophysical properties and the photoinitiating reactivity of a ditopic alkoxynitrostilbene were compared to those of its single branch chromophore used as a reference. Whereas a trivial additive effect is observed when considering the one‐ and two‐photon absorption properties, a clear and very significant amplification has been highlighted for the photoreactivity of this free radical photoinitiator which was used as a hydrogen abstractor in presence of an aliphatic amine co‐reactant. We indeed demonstrate that the proximity of two nitroaromatics moieties within the same molecular architecture gives rise to an original cycling mechanism based on a stepwise photo triggering of each photoredox center followed by a subsequent regenerative process. The combination of a high two‐photon absorption cross‐section (δ780nm≈330 GM) with a strong enhancement in photoreactivity makes this nitrostilbene bichromophore a very suitable candidate for two‐photon polymerization applications.
Physical Chemistry Chemical Physics, 2020
The branching effect on the photophysical properties of styrylpyrimidines is studied experimental... more The branching effect on the photophysical properties of styrylpyrimidines is studied experimentally and theoretically.
Highly Virulent Bactericidal Effects of Curcumin-Based μ-Cages Fabricated by Two-Photon Polymerization
ACS Applied Materials & Interfaces, 2020
A new antibacterial strategy is reported based on the two-photon fabrication of three-dimensional... more A new antibacterial strategy is reported based on the two-photon fabrication of three-dimensional curcumin-embedded µ-cages. Such devices were designed to entrap and kill S. aureus bacteria upon visible light irradiation. The proposed concept mainly relies on the pivotal role of cur-cumin which is sequentially used as two-photon active free radical initiator and as photogenerator of reactive oxygen species within the cages µ-volumes. We show that these µ-cages exhibit extremely high antimicrobial properties lead-ing to 95 % bacteria mortality after only 10 min visible irra-diation. A pre-concentration mechanism of photogenerated oxygen species is proposed to account for this highly per-forming bactericidal effect whose virulence can be strikingly switched-on by increasing the light exposure time from 5 to 10 min.
Uploads
Papers by Arnaud Spangenberg