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Dual water and organic solvent soluble 3-aryl-3-(trifluormethyl) diazirine-functionalized gold nanoparticles (AuNPs) were prepared through a place exchange reaction from triethylene glycol monomethyl ether ([EG.sub.3]-Me) capped AuNPs. These nanoparticles were fully characterized using ¹H and [sup.19]F nuclear magnetic resonance (NMR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). TGA along with ¹H NMR data allowed the determination of 15% incorporation of diazirine (Diaz) ligands onto mixed monolayer AuNPs, while TEM images showed an average diameter of 2.3 ± 0.5 nm. This information led to the estimated molecular formula of [Au.sub.400] [(S-[EG.sub.4]-Diaz).sub.40] [(S-[EG.sub.3]-Me).sub.230] for these AuNPs. It is noteworthy that high-resolution XPS was a powerful tool for quantitative analysis. Irradiation of the diazirine capped AuNPs resulted in nitrogen extrusion and the formation of a highly reactive carbene with evidence of a portion of the reaction proceeding via the diazo intermediate and thus requiring a second photon for activation. The carbene species generated was utilized to tether the attached AuNPs via insertion into C=C or O-H functionality inherent on various substrates. Here, we demonstrated that photolysis of the diazirine modified AuNPs in the presence of a variety of model carbene scavengers led to clean and efficient insertion products while maintaining their solubility in polar solvents. Key words: gold nanoparticles, water soluble, 3-aryl-3-(trifluormethyl) diazirine, carbene, photochemistry, surface modification. Des nanoparticules d'or (AuNPs) fonctionnalisee avec de la 3-aryl-3-(trifluormethyl) diazirine soluble dans un solvant a phases aqueuse et organique ont ete preparees par l'intermediaire d'une reaction d'echange a partir d'AuNP terminees par du monomethyl ether (Me) de triethylene glycol ([EG.sub.3]). Ces nanoparticules ont ete totalement caracterisees a l'aide de la spectroscopie resonance magnetique nucleaire (RMN) ¹H et [sup.19]F, microscope electronique a transmission (MET), analyse thermogravimetrique (ATG) et spectroscopie d'electrons pour analyse chimique (ESCA). Les donnees de l'ATG et de la spectroscopie RMN ¹H NMR ont permis de determiner que le taux d'incorporation des ligands de diazirine (Diaz) sur les AuNP monocouches melangees etait de 15% et les images de MET ont mis en evidence un diametre moyen de 2, 3 ± 0, 5 nm. Ces renseignements ont permis d'obtenir la formule moleculaire estimee d'[Au.sub.400][(S-[EG.sub.4]-Diaz).sub.40] [(S-[EG.sub.3]-Me).sub.230] pour ces AuNP. Il est a noter que l'ESCA a haute resolution a servi d'outil puissant d'analyse quantitative. L'irradiation des AuNP terminees par de la diazirine entraine la liberation d'azote et la formation d'un carbene hautement reactif, une partie de la reaction passant manifestement par un intermediaire diazo et necessitant ainsi un second photon pour l'activation. Les carbenes produits ont ete utilises pour fixer les AuNP en les inserant dans les fonctions C=C ou O-H sur differents substrats. Nous demontrons ici que la photolyse des AuNP modifies par la diazirine en presence de modeles de capteurs de carbene varies conduit a des produits d'insertion propres et efficaces tout en preservant leur solubilite dans des solvants polaires. [Traduit par la Redaction] Mots-cles: nanoparticules d'or, soluble dans l'eau, 3-aryl-3-(trifluormethyl) diazirine, carbene, photochimie, modification de surface., Introduction Gold nanoparticles (AuNPs) possess unique physical and chemical properties that make them outstanding candidates for numerous applications ranging from electronics, catalysis, biology, and sensor science. (1-6) Many of these [...]

Bundles of single-walled carbon nanotubes (SWCNTs) prepared by plasma torch method and further purified, are deposited over a glass coverslip to estimate the spatial resolution of tip-enhanced Raman spectroscopy measurements. For this purpose, near-field Raman maps and spectra of isolated bundles of carbon nanotubes are collected using optimized experimental conditions such as a tightly focused beam using a 1.4 numerical aperture oil immersion microscope objective and a gold coated atomic force microscope probe illuminated by a radially polarized 632.8 nm wavelength to selectively excite the localized surface plasmon confined at the extremity of the tip. The near-field nature of the collected Raman signals is evaluated through measuring the decay of the Raman signal with respect to the tip-sample separation. Key words: tip-enhanced Raman spectroscopy, localized surface plasmon resonance, near-field spectroscopy, radial polarization, atomic force microscopy, spatial resolution, enhancement factor, single-walled carbon nanotubes. Des fagots de nanofils de carbone simple-paroi, prepares par torche plasma puis purifies sont deposes sur des lamelles de microscope dans la perspective de mesurer la resolution spatiale de mesures Raman locales exaltees par effet de pointe. A cette fin, des cartographies ainsi que des spectres Raman sont collectes dans des conditions experimentales optimisees basees sur l'utilisation d'un objectif de microscope a forte ouverture numerique (O.N. 1.4) et d'une excitation avec une polarisation radiale a 632, 8 nm afin d'exciter selectivement le plasmon de surface localise et de confiner ce dernier a l'extremite de la pointe en or. Le champ proche Raman est evalue en analysant la decroissance du signal collecte en fonction de la distance entre la pointe et l'echantillon. Mots-cles: spectroscopie Raman exaltee par effet de pointe, plasmon de surface localise, microscopie en champ proche, polarisation radiale, microscopie a force atomique, resolution spatiale, facteur d'exaltation, nanofils de carbone a simple paroi., Introduction The discovery of surface-enhanced Raman spectroscopy (SERS) in the early 1970's was a milestone in improving the inherent low efficiency of inelastic Raman scattering. (1, 2) The improved sensitivity [...]

The name Juan Cesar Scaiano, of course, better known to most as Tito Scaiano, is synonymous with photochemistry and indeed chemistry in Canada. Since settling in Canada in 1979, Tito [...]

Irradiation of saturated monolayers of 3- and 4-substituted pyridyl diazoacetates on single-crystal Pt surfaces leads to either the corresponding reactive carbene or stable ketene intermediate with the chemoselectivity determined by the position of the photoreactive substituent on the pyridyl ring, which ultimately directs the available interactions with neighboring substrates. Key words: ketene, carbene, diazoester, saturated monolayer, photochemistry, Pt surfaces. L'irradiation de monocouches saturees de diazoacetates de pyridyles substitues dans les positions 3 et 4 sur des surfaces de monocristaux de platine conduit a la formation soit du carbene reactif correspondant ou de l'intermeediaire ceetene stable dans lesquels la chimioselectivite est deetermineee par la position du substituant photoreactif sur le noyau pyridyle qui en fin de compte dirige les interactions disponibles avec les substrats avoisinants. Mots-cles: cetene, carbene, diazoester, monocouche saturee, photochimie, surfaces de platine. [Traduit par la Redaction], Introduction The ability to precisely control the reactivity of organic molecules as saturated monolayers on metal surfaces is a significant challenge. Results of such studies remain of interest because of [...]

Azide-terminated alkyl thiolate monolayer-protected gold nanoparticles (1-[C.sub.12]MPN) with a core size of 1.8 ± 0.2 nm were prepared. 1-[C.sub.12]MPN was modified in high yields via an uncatalyzed 1,3-dipolar cycloaddition (click-type reaction) with a variety of terminal acyl-alkynes under hyperbaric conditions at 11000 atm. The resulting 1,2,3- triazole modified MPNs (2-[C.sub.12]MPN) were characterized using ¹H NMR spectroscopy and were verified by comparison of the spectra to those obtained for the products of the model reactions of 1-azidododecane with the same alkynes. TEM analysis showed that the high-pressure conditions did not affect the size of the gold core, suggesting that the only effect is to facilitate the chemical reaction on the particles. Key words: nanoparticles, hyperbaric chemistry, 1,3-dipolar cycloaddition, monolayers. On a prepare des nanoparticules d'or protegees par une monocouche d'alkylthiol (1-[C.sub.12]MPN) portant une fonction azide en position terminale et dont le diametre principal est egal a 1,8 ± 0,2 nm. Le produit 1-[C.sub.12]MPN a ete modifie avec des rendements eleves par le biais d'une cycloaddition 1,3-dipolaire non catalysee (reaction de type par un clic) avec une variete d'acyl-alcynes terminales, dans des conditions hyperbariques, a 11,000 atmospheres. Les nanoparticules d'or modifiees, protegees par une monocouche d'alkylthiol (2-[C.sub.12]MPN) et portant un cycle 1,2,3-triazole ont ete caracterisees par spectroscopie RMN du 111 et ont ete verifiees par comparaison avec les spectres obtenus pour les produits des reaction' modeles du 1-azidodecane avec les memes alcynes. Une analyse par microscopie electronique a transmission (MET) a permis de montrer que les conditions de haute pression n'ont pas affecte la taille du diametre principal de l'or suggerant que le seul effet est de faciliter la reaction chimique sur les particules. Mots-cles : nanoparticules, chimie hyperbarique, cycloaddition 1, 3-dipolaire, monocouches. [Traduit par la Redaction], Introduction The Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of azides to terminal alkynes to produce a triazole ring, the 'click' reaction, is a popular and powerful tool in organic synthesis and combinatorial [...]

To fine‐tune structure–property correlations of thiolate‐protected gold nanoclusters through post‐assembly surface modifications, we report the synthesis of the o, m, and p regioisomeric forms of the anionic azide‐functionalized [Au25(SCH2CH2‐C6H4‐N3)18]1− platform. They can undergo cluster–surface strain‐promoted alkyne–azide cycloaddition (CS‐SPAAC) chemistry with complementary strained‐alkynes. Although their optical properties are similar, the electrochemical properties appear to correlate with the position of the azido group. The ability to conduct CS‐SPAAC chemistry without altering the parent nanocluster structure is different as the isomeric form of the surface ligand is changed, with the [Au25(SCH2CH2‐p‐C6H4‐N3)18]1− isomer having the highest reaction rates, while the [Au25(SCH2CH2‐o‐C6H4‐N3)18]1− isomer is not stable following CS‐SPAAC. Single‐crystal X‐ray diffraction provide the molecular structure of the neutral forms of the three regioisomeric clusters, [Au25(SCH2CH2‐o/m/p‐C6H4‐N3]0, which illustrates correlated structural features of the central core as the position of the azido moiety is changed. [ABSTRACT FROM AUTHOR]

A maleimide-modified mixed monolayer protected gold nanoparticle (MPGN) containing maleimide-terminated dodecanethiolate/dodecanethiolate ligands is synthesized. The cycloaddition reaction has occurred more readily with N-dodecylmaleimide than with mixed monolayer MPGN with all nitrones, which has shown that the environment of the latter has affected the cycloaddition reaction.

The electron transfer (ET) reduction of benzyl benzenesulfenate ester (1) and tert-butyl benzenesulfenate ester (2) was investigated using electrochemical techniques. Analysis of the cyclic voltammetry of each compound suggests that the ET reduction proceeds via a stepwise dissociative mechanism. The voltammograms of 1 are similar to those of diaryl disulfides and it was found through controlled potential electrolysis (CPE) product studies that ET reduction leads to S--O bond cleavage. The voltammograms of 2 are dramatically different with a sharper dissociative wave occurring ata more negative peak potential. CPE experiments indicate products that result from ET leading to C--O bond cleavage in this case. DFT calculations of the singly occupied molecular orbitals (SOMOs) of 1 and 2 were performed and offer a rationale for the different reactivity of the two radical anions. Key words: sulfenate esters, dissociative electron transfer, electrochemistry, radical anions. On a etudie la reaction de reduction par transfert d'electron (TE) du benzenesulfenate de benzyle (1) et du benzenesulfenate de tert-butyle (2) en faisant appel a des techniques electrochimiques. L'analyse de la voltamperometrie cyclique de chaque compos, suggere que la reduction par TE se produit par un mecanisme par dissociations successives. Le voltamperogramme du compose 1 est semblable a celui des disulfures de diaryles et, sur la base d'etudes des produits par electrolyse a potentiel controle (EPC), on a trouve que la reduction par TE conduit a une coupure de la liaison S--O. Le voltamperogramme du compose 2 est dramatiquement different et il presente une vague dissociative qui se presente a un pic de potentiel beaucoup plus negatif. Les etudes d'EPC indiquent que, dans ce cas, les produits qui resultent d'un TE proviennent d'une coupure d'une liaison C--O. Des calculs effectues sur la base de la theorie de la densite fonctionnelle des orbitales moleculaires a occupation singulet (SOMO) des composes 1 et 2 et ils permettent de presenter une rationalisation pour les reactivites differentes des deux radicaux anions. Mots cles : esters de l'acide sulfenique, transfert d'electron avec dissociation, electrochimie, radicaux anions. [Traduit par la Redaction], Introduction A major focus of our group has been the study of dissociative electron transfer (ET) reactions through electrochemical methods. The work provides an opportunity to investigate many aspects of [...]

The reductive desorption of a self-assembled monolayer (SAM) of a fluorescent thiol molecule (BodipyC10SH) from Au was characterized and monitored for the first time with electrochemistry and epi-fluorescence microscopy. The observations reveal that the selective desorption might have profound application in the creation of a thiol-modified surface with a desired pattern and multifunction, and in the electrofluorescence technique in the detection strategy used for SAM array sensors.

A series of monolayer-protected clusters (MPCs) modified with a photoreactive [4-(11-mercaptoundecyl)phenyl](2-methylphenyl)methanone (1) moiety have been prepared where 1 is co-absorbed to the MPC surface with dodecanethiol, octadecanethiol, or 11-mercaptoundecanoic acid methyl ester. Upon irradiation the MPC-anchored 1 reacts efficiently through its triplet excited states, yielding 1,4-biradicals that collapse to synthetically useful, long-lived photodienol intermediates, which can be efficiently trapped in Diels-Alder type chemistry by dienophiles--namely, dimethyl acetylenediearboxylate (DMAD). In all cases the Diels-Alder trapping of the dienol occurred efficiently resulting in > 60% conversion to the Diels-Alder adduct. This indicates that the local environment surrounding 1 did not influence its ability to react via the Diels-Alder reaction; however, the reaction could not be taken to completion. The inability to react completely is attributed to 1 binding to distinct sites on the MPC core; there are edge, vertice, and terrace sites. Selective population of these specific sites and the subsequent irradiations show that MPCs with 1 anchored predominantly at edge and verfice sites results in an extent of reaction of 85 [+ or -]3%, whereas selectively populating the terrace sites results in an extent of reaction of 36 [+ or -] 2%. These results suggest that 1 anchored to edge and vertice sites is more reactive to the Diels-Alder reaction than that involving terrace sites. Key words: monolayer protected cluster, site selective reactivity, Diels-Alder, photochemistry.

A series of ferrocenyl substituted azines (1-Fc/Ar, where Ar = 4-N[O.sub.2][C.sub.6][H.sub.4], 4-CN[C.sub.6][H.sub.4], 4-OC[H.sub.3][C.sub.6][H.sub.4], [C.sub.5][H.sub.4]N, ferrocene, anthracene, and pyrene) were investigated by electrochemical ad photochemical techniques. All the 1-Fc/Ar exhibited oxidation waves within 60 mV of each other, consistent with the expected oxidation of the ferrocene moiety. The reduction properties of 1-Fc/Ar is governed by the nature of the Ar substituent. The standard reduction potentials suggest that ferrocene has comparable electron donating abilities as a 4-methoxyphenyl and 4-dimethyl-aminopbenyl group. The anthracenyl azines exhibit one-electron reversible reduction followed by dimerization of the radical anion resulting in dimerization rate constants (k.sub.d) between 5.1 x [10.sup.4] and 1.5 x [10.sup.5] [M.sup.-1] [s.sup.-1]. 1-Fc/Anth and related azines undergo photochemical E/Z isomerization of the C=N bonds to produce E/Z and Z/Z isomers from the thermodynamically most stable E/E form. Fluorescence at 77 K, was observed for these compounds only after long-wavelength irradiation to produce a mixture of E/E, E/Z, and Z/Z isomers. Fluorescence quantum yields of 0.042, 0.090, and 0.176 were determined for 2-Anth/H, 2-Anth/Anth, and 1-Fc /Anth, respectively. The electrochemical, photochemical, and X-ray data suggest that the azine unit is a conjugation "limiter" and may be a general characteristic of azine molecules. Key words: azines, electrochemistry, cyclic voltammetry, reduction, electron transfer.

Research has been conducted on the reactions of CuCl with Te(Ph)SiMe (sub)3 and solublizing trialkylphosphine ligands. Results indicate that these reactions produce structurally characterized polynuclear copper-phenyltellurolate complexes and that the complex formation depend on the ancillary phosphine ligand.

The chemistry of azines is probed in terms of their stability and reactivity as influenced by the conjugation through the C=N-N=C. Results describe the electrochemical redox properties of substituted acetophenone azines in aprotic solvents. Both symmetrical and asymmetrical aryl azines are examined to determine the influence of the conjugation on the solution-phase redox properties.

On 19 September 2017, Canadian chemistry lost one of our foremost physical organic chemists, James Peter Guthrie, to Guillain-Barre Syndrome in his 76th year. Peter Guthrie was born in rural [...]

Time-resolved UV-vis and infrared laser flash photolysis methods help examine the reactivity of the azidyl radical, N(sub 3)(super .), with olefins, using the pseudohalogen azidyl radical anion N(sub 6)(super.-). The reaction of N(sub 3)(super .) with alkyl olefins does not involve hydrogen atom transfer, suggesting that the reaction proceeds through addition. These addition reactions are controlled by polar effects and are free of steric factors.

Nanosecond laser flash photolysis helps determine rate constants for reactions of the 9-phenylanthracene (PA) and 9,10-diphenylanthracene (DPA) radical cations with acyclic amines in acetonitrile. Primary amines exhibit a nucleophilic addition reaction with PA(+) and DPA(.+), while tertiary amines show an electron-transfer reaction. Secondary amines show both nucleophilic addition and electron-exchange reactions. Electronic and steric factors influence kinetics of nucleophilic substitution and electron exchange processes.

Cyclic voltammetry and electromechanical methods were used to study the reduction of the antimalarial agent Artemisinin (ART) in N,N-dimethylformamide (DMF). The standard potential of the dissociative reduction of ART is found to be -0.89 V versus SCE in DMF, which is ca. 0.8 V more positive than the irreversible direct reduction resulting from cyclic voltammetric measurements. Moreover, the value of the dissociative reduction of ART can be used to estimate the O-O bond dissociation energy.

The photoelectrochemical behavior of two polymers of the polythiophene series containing electron-acceptor groups in the main chain is studied and compared to that of the nonmodified polymer, poly(2,2'-bithiophene), PBT. The values of external quantum efficiency are estimated in a liquid-cell arrangement to be 0.27 and 0.19% for modified and nonmodified polymers, respectively.

The homogeneous and heterogeneous reductions of the endoperoxides 9,10-epidioxyanthracene (DPA-O2) and 9,10-dimethyl-9,10-epidioxyanthracene (DMA-O2) are investigated. The initial electron transfer (ET) reduction DPA-O2 and DMA-O2 follows a dissociative mechanism with fragmentation of the O-O bond to yield a distonic radical anion.