Publications by authors named "Jean Rouillon"

8 Publications

  • Page 1 of 1

Metal-Free Visible-Light Synthesis of Arylsulfonyl Fluorides: Scope and Mechanism.

Chemistry 2021 Jun 11;27(34):8704-8708. Epub 2021 May 11.

Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, Université Lyon 1, CNRS, CPE-Lyon, INSA 43 Bd du 11 Novembre 1918, 69622, Villeurbanne, France.

The first metal-free procedure for the synthesis of arylsulfonyl fluorides is reported. Under organo-photoredox conditions, aryl diazonium salts react with a readily available SO source (DABSO) to afford the desired product through simple nucleophilic fluorination. The reaction tolerates the presence of both electron-rich and -poor aryls and demonstrated a broad functional group tolerance. To shed the light on the reaction mechanism, several experimental techniques were combined, including fluorescence, NMR, and EPR spectroscopy as well as DFT calculations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.202101056DOI Listing
June 2021

Reevaluating the Solution Photophysics of Tetraphenylethylene at the Origin of their Aggregation-Induced Emission Properties.

Chemistry 2021 May 22;27(30):8003-8007. Epub 2021 Apr 22.

UMR 5182, Laboratoire de Chimie, Univ Lyon, ENS Lyon, CNRS, Université Claude Bernard Lyon 1, 69342, Lyon, France.

Although tetraphenylethylene (TPE) and its derivatives have been the most commonly used building blocks in the construction of molecules with aggregation-induced emission (AIE) properties, no absolute consensus exists regarding the mechanisms at the origin of the phenomenon. Restriction of intramolecular rotations (RIR) of peripheral phenyls has historically been a dominant paradigm, which has served as a valuable guideline in the molecular engineering of AIEgens. Yet, an increasing number of recent works have established that photoisomerization or photocyclization may actively participate in the nonradiative dissipation of the excitation energy. In this paper, the first experimental evaluation of the quantum efficiencies of these different processes is reported, and photoisomerization is shown to be by far the dominant photophysical pathway in solution, accounting for virtually all nonradiative decay of the molecule's excited state in degassed solution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.202100926DOI Listing
May 2021

Determination of Photoinduced Radical Generation Quantum Efficiencies by Combining Chemical Actinometry and F NMR Spectroscopy.

Anal Chem 2021 02 21;93(5):2926-2932. Epub 2021 Jan 21.

Laboratoire de Chimie, Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, UMR 5182, 46 Allée d'Italie, 69364 Lyon, France.

We introduce a general and relatively straightforward protocol aimed at determining the absolute photoinduced radical generation efficiency via NMR monitoring. This approach relies on the use of a radical scavenger probe that combines a nitroxide moiety that specifically reacts with radicals and a trifluoromethyl group used as a F NMR signaling unit. Using an LED source, whose fluence is precisely determined by a chemical actinometry procedure also described herein, the method is used to determine the radical photogeneration quantum yields of three well-known polymerization initiators: azobisisobutyronitrile (AIBN), 4,4'-bis(,-diethylamino)benzophenone (BDEBP, a derivative of Michler's ethyl ketone), and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (MAPO). The overall good agreement with values previously reported in the literature proves the robustness of this new method. We then extended the study to the precise measurement of the quantum yield of free-radical photogeneration on a newly synthesized photoinitiator used for two-photon direct laser writing. This study highlights the potential of this methodology for the quantitative determination of photoinduced radical generation efficiency used in many fields of applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.0c04540DOI Listing
February 2021

Two-Photon Absorbing AIEgens: Influence of Stereoconfiguration on Their Crystallinity and Spectroscopic Properties and Applications in Bioimaging.

ACS Appl Mater Interfaces 2020 Dec 20;12(49):55157-55168. Epub 2020 Nov 20.

Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie, UMR 5182, 46 Allée d'Italie, 69364 Lyon, France.

This paper aims at designing chromophores with efficient aggregation-induced emission (AIE) properties for two-photon fluorescence microscopy (2PFM), which is one of the best-suited types of microscopy for the imaging of living organisms or thick biological tissues. Tetraphenylethylene (TPE) derivatives are common building blocks in the design of chromophores with efficient AIE properties. Therefore, in this study, extended TPE AIEgens specifically optimized for two-photon absorption (2PA) are synthesized and the resulting (/) isomers are separated using chromatography on chiral supports. Comparative characterization of the AIE properties is performed on the pure () and () isomers and the mixture, allowing us, in combination with powder X-ray diffraction and solid-state NMR, to document a profound impact of crystallinity on solid-state fluorescence properties. In particular, we show that stereopure AIEgens form aggregates of superior crystallinity, which in turn exhibit a higher fluorescence quantum yield compared to diastereoisomers mixtures. Preparation of stereopure organic nanoparticles affords very bright fluorescent contrast agents, which are then used for cellular and intravital two-photon microscopy on human breast cancer cells and on zebrafish embryos.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c15810DOI Listing
December 2020

Cardiovascular autonomic control during short-term thermoneutral and cool head-out immersion.

Aviat Space Environ Med 2008 Jan;79(1):14-20

Université de Franche Comté, Physiologie, Faculté de Médecine, Besançon, France.

Background: Moderately cold head-out water immersion stimulates both baro- and cold-receptors, and triggers complex and contradictory effects on the cardiovascular system and its autonomic nervous control.

Objectives: To assess the effects of water immersion and cold on cardiovascular status and related autonomic nervous activity.

Methods: Hemodynamic variables and indexes of autonomic nervous activity (analysis of heart rate and blood pressure variability) were evaluated in 12 healthy subjects during 3 exposures of 20 min each in the upright position, i.e., in air (AIR, 24-25 degrees C), and during head-out water immersion at 35-36 degrees C (WIn) and 26-27 degrees C (WIc).

Results: Plasma noradrenaline, systolic and diastolic blood pressure, and total peripheral resistances were reduced during WIn compared to AIR (263.9 +/- 39.4 vs. 492.5 +/- 35.7 pg x ml(-1), 116.5 +/- 3.7 and 65.4 +/- 1.7 mmHg vs. 140.8 +/- 4.7 and 89.8 +/- 2.8 mmHg, 14.1 +/- 1.0 vs. 16.3 +/- 0.9 mmHg x L(-1) x min, respectively) while they were increased during WIc (530.8 +/- 84.7 pg ml(-1), 148.0 +/- 7.0 mmHg, 80.8 +/- 3.0 mmHg, and 25.8 +/- 1.9 mmHg x L(-1) x min, respectively). The blood pressure variability was reduced to the same extent during WIc and Win compared to AIR. Heart rate decreased during WIn (67.8 +/- 2.7 vs. 81.2 +/- 2.7 bpm during AIR), in parallel with an increased cardiac parasympathetic activity. This pattern was strengthened during WIc (55.3 +/- 2.2 bpm).

Conclusions: Thermoneutral WI lowered sympathetic activity and arterial tone, while moderate whole-body skin cooling triggered vascular sympathetic activation. Conversely, both WI and cold triggered cardiac parasympathetic activation, highlighting a complex autonomic control of the cardiovascular system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3357/asem.2147.2008DOI Listing
January 2008

Conditions of autonomic reciprocal interplay versus autonomic co-activation: effects on non-linear heart rate dynamics.

Auton Neurosci 2007 Dec 26;137(1-2):27-36. Epub 2007 Jul 26.

Université de Franche Comté, EA 3920 and IFR133, Physiologie, Faculté de Médecine, Besançon, France.

The present study was aimed at investigating the autonomic nervous system influences on the fractal organization of human heart rate during sympathovagal interactions, with special emphasize on the short-term fractal organization in heart rate variability (HRV), as assessed by the scaling exponent (alpha(1)) of the detrended fluctuation analysis. Linear and non-linear HRV analyses were used to study the sympathetic and vagal modulation of heart rate in ten healthy men (mean +/- SEM; age 26 +/- 1 years) during conditions of 1) increased sympathetic activity and vagal withdrawal (head-up tilt), 2) decreased sympathetic activity and increased vagal outflow (thermoneutral upright head-out water immersion, WIn), and 3) simultaneous activation of the two arms of the autonomic nervous activity (upright head-out immersion in cold water, WIc). Hemodynamic and linear HRV results were consistent with previous reports during similar physiological conditions. alpha(1) increased significantly during head-up tilt (from 0.71 +/- 0.13 supine to 0.90 +/- 0.15 upright) and WIn (0.86 +/- 0.10) and was significantly decreased during WIc (0.61 +/- 0.15). Thus, alpha(1) increased when the cardiac autonomic interplay was altered in a reciprocal fashion, whatever the direction of the balance change. Conversely, alpha(1) decreased during the concomitant activation of both vagal and sympathetic activities. The results of linear analysis were necessary to precisely define the direction of change in autonomic control revealed by an increase in alpha(1), while the direction of change in alpha(1) indicated whether an increased vagal activity is coupled with a decreased or increased sympathetic activation. Using both linear and non-linear analysis of HRV may increase the understanding of changes in cardiac autonomic status.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.autneu.2007.06.284DOI Listing
December 2007

Effects of Aging on Perceived Exertion and Pain During Arm Cranking in Women 70 to 80 YEARS OLD.

J Sports Sci Med 2006 1;5(2):208-14. Epub 2006 Jun 1.

The aim of this study was to examine the effects of aging on perceived exertion (PE) and perceived arm pain (PaP) at the end of a maximal graded arm test in 70- to 80-year -old women. Twelve healthy young (mean age 22.9 ± 3.3 years), and 12 healthy elderly (mean age 74.6 ± 3.7 years) women performed a maximal graded test (GXT) on an arm crank ergometer until exhaustion. The results revealed no significant difference between both groups concerning PE (p > 0.05; Effect Size = 0.62) and when heart rate (HR) was expressed as a theoretical maximal heart rate (THRmax) (p > 0.05; Effect Size = 0.17). Nevertheless, PaP was significantly lower (p < 0.05; Effect Size = 2.95) in the elderly compared to the young group. In conclusion, these results suggest that, at the end of GXT, PE is not influenced, whereas PaP may be altered by aging of the women tested in the present study. Therefore, it appears difficult to use PaP in these elderly women to regulate exercise intensity during a training program. Key PointsAt the end of a maximal graded arm test, perceived exertion is not influenced, whereas perceived arm pain may be altered by aging.It appears difficult to use perceived arm pain in elderly women to regulate exercise intensity during a training program.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827562PMC
November 2013

Effects on the crank torque profile when changing pedalling cadence in level ground and uphill road cycling.

J Biomech 2005 May;38(5):1003-10

Laboratoire de Mécanique Appliquée, Université de Franche Comté, U.M.R. C.N.R.S. 6604, 24 chemin de l'Epitaphe, 25000 Besançon, France.

Despite the importance of uphill cycling performance during cycling competitions, there is very little research investigating uphill cycling, particularly concerning field studies. The lack of research is partly due to the difficulties in obtaining data in the field. The aim of this study was to analyse the crank torque in road cycling on level and uphill using different pedalling cadences in the seated position. Seven male cyclists performed four tests in the seated position (1) on level ground at 80 and 100 rpm, and (2) on uphill road cycling (9.25% grade) at 60 and 80 rpm.The cyclists exercised for 1 min at their maximal aerobic power. The bicycle was equipped with the SRM Training System (Schoberer, Germany) for the measurement of power output (W), torque (Nm), pedalling cadence (rpm), and cycling velocity (km h(-1)). The most important finding of this study indicated that at maximal aerobic power the crank torque profile (relationship between torque and crank angle) varied substantially according to the pedalling cadence and with a minor effect according to the terrain. At the same power output and pedalling cadence (80 rpm) the torque at a 45 degrees crank angle tended (p < 0.06) to be higher (+26%) during uphill cycling compared to level cycling. During uphill cycling at 60 rpm the peak torque was increased by 42% compared with level ground cycling at 100 rpm. When the pedalling cadence was modified, most of the variations in the crank torque profile were localised in the power output sector (45 degrees to 135 degrees).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jbiomech.2004.05.037DOI Listing
May 2005
-->