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This investigation demonstrates the excellent photoinitiating properties of novel visible-light absorbing diphenylporphyrins (DPPs) for free-radical (FRP), cationic (CP) and thiol–ene polymerizations under visible LED irradiation (405 and 530 nm) at low intensities, under air or in laminate. Kinetics results on FRP and CP showed that DPPs are much more efficient photoinitiators than common Type II photosensitizers, i.e. camphorquinone or benzophenone. As confirmed by EPR and laser flash photolysis studies, DPPs play a dual role as an electron donor and in the H-abstraction reaction when combined with iodonium salt (Iod), N-methyldiethanol amine (MDEA) or thiol derivative, respectively.

Novel arene RuII complexes containing 2,2'-azobispyridine ligands were synthesized and characterized by using 1 H and 13 C NMR spectroscopy, UV/vis spectroscopy, electrochemistry, DFT calculations and single-crystal X-ray diffraction. Z-configured complexes featuring unprecedented seven-membered chelate rings involving the nitrogen atom of both pyridines were isolated and were shown to undergo irreversible isomerization to the corresponding E-configured five-membered chelate complexes in response to light or electrochemical stimulus.

International audience; Diphosphines displaying azobenzene scaffolds and the corresponding bis-gold chloride complexes have been prepared and fully characterized by photophysical, spectroscopic and X-ray diffraction studies. DFT calculations provide complementary information on their electronic, structural and spectroscopic properties. Comparative investigations have been carried out on compounds featuring phosphorus functions in the meta- and para-positions, respectively, with respect to the azo functions, as well as on diphosphines with an ortho-tetrafluoro substituted azobenzene core. The effects of the substitution patterns on structural and spectroscopic properties are discussed.

Although side-chain polyazobenzenes have been extensively studied, main-chain polyazobenzenes (abbreviated MCPABs) are rarely reported due to the challenges associated with difficulty in synthetic chemistry and photoisomerization of azo bonds in MCPABs. Thus, it is highly demanded to develop new mechanisms other than photoisomerization of azo bonds in MCPABs to extend their applications. In this work, we created a new series of N-linked MCPABs via fast NaBH4-mediated reductive coupling polymerization on N-substituted bis(4-nitrophenyl)amines. The structure of MCPABs has been characterized by comprehensive solid-state NMR experiments such as CPMAS 13C NMR with long and short contact times, cross-polarization polarization-inversion (CPPI), and cross-polarization nonquaternary suppressed (CPNQS). The azo bonds in MCPABs were found to be promising for acid vapor sensing, being acidified to form azonium ion with significant color change from red to green. And the azonium of MCPABs turned from green to red when exposed to base vapor, thus suitable for base vapor sensing.

International audience; Z and E azobenzene isomers are molecular switches which can interconvert both photochemically and thermally. Presently, we studied a ketal-substituted bridged azobenzene in which two stable diastereomeric conformers (Z1 and Z2) photochemically interconvert through transient E isomer. UV-VIS absorption spectroscopy is commonly used to study the relaxation kinetics of azobenzenes, but it does not allow direct quantitation of the process in this case. In the present paper, liquid chromatography coupled to UV detection (LC-UV) and ion mobility-mass spectrometry (IMS-MS) were combined to study the thermal back relaxation kinetics of the E isomer. LC separation of the three isomers was achieved in less than 10 minutes, allowing the characterization of the relatively slow thermal back relaxation kinetics at low temperature through UV detection. In addition, the faster E→Z thermal back relaxation at higher temperature was studied using IMS-MS, which allows shorter time scale separation than LC. Baseline separation of the two Z isomers was achieved in IMS-MS for [Z+Ag]+ ions, and their gas-phase conformations were determined by IRMPD experiments. Both IMS-MS and LC-UV methodologies succeeded to study the E→Z thermal back relaxation kinetics, and appeared to be complementary techniques. We show that the combination of the two techniques allows the characterization of the isomerization processes over a broad temperature range, and the determination of the associated thermodynamic observables.

International audience; In this work, we report on the development of a newly synthesized photoactive reversible azobenzene derived surfactant polymer, which enables active and fast control of the merging of microdroplets in microfluidic chambers, driven by a pulsed UV laser optical stimulus and the well known cis-trans photo-isomerisation of azobenzene groups. We show for the first time that merging of microdroplets can be achieved optically based on a photo-isomerization process with a high spatio-temporal resolution. Our results show that the physical process lying behind the merging of microdroplets is not driven by a change in surface activity of the droplet stabilizing surfactant under UV illumination (as originally expected), and they suggest an original mechanism for the merging of droplets based on the well-known opto-mechanical motion of azobenzene molecules triggered by light irradiation.

Hitherto unknown chromophoric nucleosides are reported. This novel set of visibly coloured dye-labeled 5'-nucleosides, including 1,2,4,5-tetrazine, dicyanomethylene-4H-pyran, benzophenoxazinone, 9,10-anthraquinone and azobenzene chromophores, were prepared mainly under Cu-catalyzed azide-alkyne cycloaddition (CuAAC). The design criteria are outlined. Several derivatives possess in supplement a fluorescence property. The absorption and fluorescence spectra of all coloured nucleosides were recorded to study their potential as visible-range probes. Such nucleodyes are of great interest for future competitive lateral flow test MIP-based strips.

Time-efficient synthetic methods of porous organic polymers are searched in order to extend the applications of these materials. In this work, we show a robust and time-efficient synthetic method of azo-linked porous organic polymers named Azo-POPs based on a NaBH4-mediated reductive coupling polymerization on well-known polynitro monomers. Azo-POPs were found to have a high Brunauer–Emmett–Teller (BET) surface area and potential for aniline adsorption. Interestingly, Azo-POP-1 showed adsorption capacity towards aniline as high as 1059.68 mg g−1 at 293 K, which surpassed that of adsorbent materials reported in the literature.

The first photoswitchable bimetallic gold catalysts based on an azobenzene backbone have been synthesized and their catalytic properties have been investigated. In the intramolecular hydroamination reaction, the reaction rate proved to be dependent on the E- or Z-configuration of the catalyst used, with the Z-isomer being significantly more active. These results suggest that a possible cooperative effect between the two metals operates in this reaction.

Background Nitric-oxide synthases (NOS) catalyze the formation of NO using NADPH as electron donor. We have recently designed and synthesized a new series of two-photon absorbing and photoactivatable NADPH analogues (NT). These compounds bear one or two carboxymethyl group(s) on the 2′- or/and 3′-position(s) of the ribose in the adenosine moiety, instead of a 2′-phosphate group, and differ by the nature of the electron donor in their photoactivatable chromophore (replacing the nicotinamide moiety). Here, we addressed the ability of NTs to photoinduce eNOS-dependent NO production in endothelial cells. Methods The cellular fate of NTs and their photoinduced effects were studied using multiphoton fluorescence imaging, cell viability assays and a BODIPY-derived NO probe for NO measurements. The eNOS dependence of photoinduced NO production was addressed using two NOS inhibitors (NS1 and L-NAME) targeting the reductase and the oxygenase domains, respectively. Results We found that, two compounds, those bearing a single carboxymethyl group on the 3′-position of the ribose, colocalize with the Golgi apparatus (the main intracellular location of eNOS) and display high intracellular two-photon brightness. Furthermore, a eNOS-dependent photooxidation was observed for these two compounds only, which is accompanied by a substantial intracellular NO production accounting for specific photocytotoxic effects. Conclusions We show for the first time that NT photoactivation efficiently triggers electron flow at the eNOS level and increases the basal production of NO by endothelial cells. General significance Efficient photoactivatable NADPH analogues targeting NOS could have important implications for generating apoptosis in tumor cells or modulating NO-dependent physiological processes.

A new series of arene chlorido ruthenium and pentamethylcyclopentadienyl chlorido rhodium complexes containing o -sulfonamide azobenzene ligands with an exocyclic N N bond coordination pattern have been synthesized. These complexes undergo readily E → Z photoisomerization followed by thermal Z → E isomerization (upon resting in the dark). The ruthenium complexes showed low-micromole-ranged cytotoxicity towards a panel of cancer cells. Western blotting and flow cytometric analyses suggest that 1) they are potent apoptotic inducers for cancer cells, probably through a caspase-3 dependent apoptotic pathway, and that 2) they have a much stronger ability to induce HeLa cancer cell apoptosis than cisplatin, a commercial anticancer drug.

The reactivity of cationic arene ruthenium complexes bearing a photoswitchable o-tosylamide azobenzene ligand toward various phosphorus nucleophiles was investigated. The resulting phosphine-ruthenium complexes containing an azobenzene ligand were isolated as the Z isomer. Under appropriate reaction conditions, quantitative triphenylphosphine photorelease from the complex was achieved through Z → E isomerization of the ligand. This process was applied to the photoinitiation of the catalytic aza-Morita–Baylis–Hillman reaction.

Ketal-substituted bridged azobenzenes have been synthesized; these display a symmetrical boat conformation with the ketal in pseudo-equatorial positions. These bridged Z-azobenzenes (Z1 ) readily photoisomerize to the E-isomer as well as another Z-conformer (Z2 ) with ketal function on the pseudo-axial position upon irradiation at 406 nm. The two diastereomeric conformers display distinct physicochemical characteristics. Spectroscopic and NMR investigations supported that interconversion of two conformers occurs via the E-isomer, with good photochemical quantum yield (ΦZ1→E =0.45±0.03, ΦE→Z1 =0.33±0.05, ΦE→Z2 =0.37±0.06 and ΦZ2→E =0.36±0.04). The system shows high photostability and no thermal equilibrium between the two stable Z1 and Z2 conformers.

A series of arene ruthenium complexes containing o-sulfonamide azobenzene ligands were synthesized and found to exhibit uncommon coordination pattern with an exocyclic N═N bond. Upon irradiation, these complexes cleanly undergo E → Z photoisomerization followed by thermal Z → E isomerization (upon resting in the dark) whose rate is dependent on the solvent, the nature of the arene group, the sulfonamide moiety, and azobenzene substitution, as revealed by structure–property studies.

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International audience; The spectral features in arrival time distributions (ATDs) recorded by ion mobility spectrometry (IMS) can often be interpretedin terms of the co-existence of different isomers. However, interconversion between co-existing species also participatesto shape the ATD. Overlooking interconversion may then lead to misinterpretation of experimental data. Unfortunately, onlyfew works have addressed this problem so far. We present an analytical model that allows simulating ATDs resulting frominterconverting species. This model is used to reproduce experimental data obtained on a bi-stable system, and to interpret discrepanciesbetween measurements on different types of instruments. We show that the proposed model can be further exploitedto extract kinetic and thermodynamic data from tandem-IMS measurements.

Carbohydrate-based 23- to 28-membered BODIPY-containing macrocycles have been efficiently synthesised from alkyne-functionalised BODIPY acid, C-glucosyl azido amine, and amino acids by employing CuAAC for the macrocyclisation step. BF(OMe) and B(OMe)2 derivatives have also been obtained by treating macrocycle 1 with BCl3 in CH2Cl2 followed by treatment with MeOH. These compounds exhibited similar excellent photophysical properties to those of BODIPY. Investigation of potential receptor properties of the 23- and 27-membered macrocycles 1 and 2 showed that these compounds are sensitive to both anions (F– and CN–) and cations (Cu2+ and Fe3+) in MeCN.

TMS-ethynyl triazolyl benzothiadiazole (BTD) derivatives have been successfully synthesized by mono deprotection of di-TMS-ethynyl BTD followed by click chemistry. The fluorescence intensity of TMS-ethynyl triazolyl BTD–DCM dyad 8 , as well as triazolyl BTD 3, and the DCM derivative 7 could be selectively quenched by Cu 2+ , but almost not affected by different tested anions. Interestingly, the fluorescence emission of DCM-based fluorophores 7 and 8 was highly sensitive to a combination of Cu 2+ , F − , or Br − in a sequence dependent manner. With the dyad 8 , the detection limit as low as 0.13 ppb could be attained for F − in MeCN. The Cu 2+ -promoted aerobic oxidative dimerization of DCM moiety to tetrahydrofuran derivatives has also been demonstrated for the first time.

International audience; A new series of photoactivable NADPH mimics bearing one or two O-carboxymethyl groups on the adenosine moiety have been readily synthesized using click chemistry. These compounds display interesting one- or two-photon absorption properties. Their fluorescence emission wavelength and quantum yields (Phi) are dependent on the solvent polarity, with a red-shift in a more polar environment (lambda(max,em) = 460-467 nm, Phi > 0.53 in DMSO, and lambda(max,em) = 475-491 nm, Phi < 0.17 in Tris). These compounds show good binding affinity towards the constitutive nNOS and eNOS, confirming for the first time that the carboxymethyl group can be used as a surrogate of phosphate. Two-photon fluorescence imaging of nanotriggers in living cells showed that the presence of one carboxymethyl group (especially on the 3' position of the ribose) strongly favors the addressing of nanotriggers to eNOS in the cell context.

We have investigated the most efficient way of preparing biocompatible gold nanorods (GNR) used as tool for cancer imaging and therapy. The surface of cetyltrimethylammonium bromide-stabilized gold nanorods (GNR-CTAB) was functionalized with various thio-polyethylene glycols of the general formula HS-PEG mX ( m = 356–10,000; X = −OMe, −NH 2 ). The influence of several parameters such as PEG chain length, reaction conditions and purification method on long-term stability, morphology and optical properties of the produced GNR-S-PEG mX was studied, demonstrating the existence of a threshold HS-PEG mX chain length (with molecular weight m ⩾ 2000) for efficient steric stabilization of GNR. Several purification techniques were compared: dialysis, centrifugation and a rarely used technique in this field, size exclusion chromatography. While a very weak efficiency of dialysis was evidenced, both centrifugation and size exclusion chromatography were found to provide pure GNRs, though the latter method yielded nanoparticles with a significantly higher stability. Finally, the long-term stability of the produced GNRs was investigated in various media: water, PBS buffer and serum.

The ability of A*[s]U dinucleosides to gel organic solvents and water is modulated by changing the nature of the substituents at OC(2′) and OC(3′), as evidenced by comparing the gelation of the dinucleosides 7–9 and the properties of the gels. A mere extension of the hydrophobic moiety, by replacing the isopropylidene groups of 2 by cyclohexylidene groups, as in 7, has a small effect, while changing the conformation of the ribose ring and reducing the size of the hydrophobic moiety, as in 8, has a strong effect on the scope of gelation, the minimum gelation concentration, as low as 0.07% for pentanol and decanol, and the properties of the gel. The fully deprotected dinucleoside 9 gels water at a minimal gelation concentration of 0.6%. A TEM of the corresponding xerogel shows the formation of fibers with a diameter of ca. 30 to 90 nm.

The sulfone 2, and the sulfoxides (S)-3 and (R)-3 were obtained by oxidation of the thiomethylene-linked A*[s]U dinucleoside 1. Conformational analysis and association studies of 2, (S)-3, and (R)-3 reveal a strong influence of the configuration on the conformation of the linking unit and on the self-association of the dinucleosides.

Chemical cross-linking of proteins permits the stabilization of noncovalent complexes through introduction of covalent bonds. A crucial challenge is to find the fastest and most efficient cross-linkers in order to minimize reaction times and to handle delicate complexes. New cross-linkers were synthesized by introducing N-hydroxyphthalimide, hydroxybenzotriazole, and 1-hydroxy-7-azabenzotriazole as leaving groups instead of the commonly used N-hydroxysuccimidyl moiety. With the use of matrix-assisted laser desorption ionization (MALDI) mass spectrometry, these new cross-linkers were then compared with the commercially available disuccinimidyl suberate (DSS) for covalent stabilization of the gluthatione-S-transferase (GST) dimer and of an antibody-antigen complex. They showed a better efficiency, generated about 30% more cross-linked complex, and reacted about 10 times faster than DSS. The reaction with the GST dimer was utilized to get information about their reaction efficiency and kinetics. Their ability to stabilize only specific protein complexes was verified by incubating them with a mixture of the proteins GST and ubiquitin. Finally, the cross-linkers were incubated with synthetic peptides to study the selectivity of the binding with various amino acid side chains. Not only lysine but also tyrosine was found to react with the newly synthesized cross-linker containing 1-hydroxy-7-azabenzotriazole as the reactive group.

The A*[s]U(*) dinucleosides 1 and 2 form thermoreversible gels in organic solvents. The basis of the gelation is the formation of linear aggregates by base pairing following desolvation of the nucleobases. This is evidenced by the absence of gel formation by the C(6)-deaminated analogue 3 of 1, the correlation of gelation with the anti-conformation, as preferred for 1, and the temperature-, concentration-, and time-dependent CD spectra. The gels were also characterized by the minimum gelation concentration, the gel–sol transition (melting) temperature, and rheological properties.

Two approaches allowing access to the tricyclic stemona backbone are presented. Both approaches rely on a free-radical cyclization reaction as the key step. In the formal synthesis of (+/-)-stemoamide, the construction of the A ring of the natural product was achieved via a 5-exo-trig radical cyclization with atom transfer. The two diastereoisomers issuing from this cyclization showed different reactivity while forming the seven-membered ring of the final product. In the second part of this study, a 7-exo-trig free radical cyclization was realized allowing access to the (+/-)-9,10-bis-epi-stemoamide. This reaction was highly stereoselective and allowed the control of three of the four contiguous stereocenters present in the molecule.

A reductive desymmetrization of a γ-1,3-diketoester was used as the key step to control the C8, C9 and C9a stereocenters of (+)-stemoamide.

A rapid synthesis of (′)-9,10-bis-epi-stemoamide is presented. Three of the four contiguous stereocenters of this compound were set in a diastereoselective radical 7-exo-trig cyclization, which also allowed the construction of the tricyclic core of the molecule.

S,S-[346440-54-8] C15H22N2O (MW 246.35) R,R-[390766-89-9] InChI = 1S/C15H22N2O/c1-15(2,3)14-16-12(13(18)17(14)4)10-11-8-6-5-7-9-11/h5-9,12,14,16H,10H2,1-4H3/t12-,14-/m0/s1 InChIKey = SKHPYKHVYFTIOI-JSGCOSHPSA-N InChI = 1S/C15H22N2O/c1-15(2,3)14-16-12(13(18)17(14)4)10-11-8-6-5-7-9-11/h5-9,12,14,16H,10H2,1-4H3/t12-,14-/m1/s1 InChIKey = SKHPYKHVYFTIOI-TZMCWYRMSA-N (catalyst used for asymmetric iminium- and enamine-type organocatalytic transformations) Alternative Names: MacMillan OrganoCatalyst™. Physical Data: mp 92–94 °C. Solubility: soluble in most organic solvents, partially soluble in pentane and hexane. Form Supplied in: crystalline solid. Preparative Methods: the title compound can be prepared in multigram scale from (S)-phenylalanine methyl ester using a modified Seebach protocol (eq 1): the ester of the amino acid, or the corresponding HCl salt, is converted to N-methylamide with excess of ethanolic MeNH2, which, in turn, is condensed with pivalaldehyde in the presence of a catalytic amount of FeCl3 (20 mol %) and molecular sieves. Under these conditions the Schiff base intermediate undergoes cyclization and forms a mixture of cis- and trans-imidazolidinone•HCl. The undesired trans-isomer•HCl can be filtered off and the residue recrystallized to provide the cis-(2S,5S)-isomer as a crystalline solid. The trans-isomer can be converted to the cis-isomer by partial epimerization in THF solution in the presence of FeCl3. (1) Purification: recrystallization from pentane/CH2Cl2 9/1.

Propargyl ketones can be directly transformed to enantio-enriched saturated secondary alcohols in a one-pot reaction using chiral RuCl[ N -(tosyl)-1,2-diphenylethylenediamine)( p -cymene) and Pd/BaSO 4 as catalysts, under transfer hydrogenation conditions.