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An efficient B(C6F5)3-catalyzed aerobic oxidative C-S cross-coupling reaction of thiophenol with indoles was developed, affording a wide range of diaryl sulfides in good yields. An electron donor-acceptor complex between B(C6F5)3 and indoles was formed, facilitating the photoinduced single-electron transfer (SET) from indole substrates to the B(C6F5)3 catalyst. This protocol demonstrates a new reaction model using B(C6F5)3 as a single-electron oxidant.

A metal-free, photocatalyst-free, photochemical system was developed for the direct alkylation of thiophenols via electron donor-acceptor (EDA) complexes (KEDA = 145 M-1) between two reactants, N-hydroxyphthalimide esters as acceptors and thiophenol anions as donors, in the presence of a tertiary amine. The EDA complexes in the reaction system have a broad range of visible-light absorption (400-650 nm) and can trigger the reaction effectively under sunlight.

We describe a simple and efficient procedure for nucleophilic borylation of imines in the absence of a photoredox catalyst. Visible light irradiation of an acetonitrile solution of an imine, an NHC-borane, and diphenyl disulfide (10 mol %) provides various stable α-amino NHC-boranes in good yields. The reaction proceeds via addition of a nucleophilic boryl radical to an imine, followed by hydrogen abstraction from thiophenol, which is generated from NHC-borane and diphenyl disulfide.

We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 X 10(4) and 4 X 10(5) for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.

Thiophenol as a highly toxic compound can harm the environment and living organisms and thus demands effective detection. In this work, we presented a near-infrared fluorescent probe (DAPH-DNP) for detecting thiophenol according to the ESIPT mechanism using 2,4-dinitrophenyl group as a recognition unit. This probe displayed specificity toward thiophenol over other related analytes. Meanwhile, there was good linearity between the relative fluorescence intensity of DAPH-DNP and the concentration of thiophenol in the range of 0–80 μM. This probe also showed a low detection limit of 3.8 × 10–8 and a marked Stokes shift (192 nm). Further, this probe could be used for monitoring thiophenol in environmental water samples and imaging thiophenol in living cells, which indicated that this probe had a real application in the environment and living organisms.

A complex that was composed of β-cyclodextrin (β-CD) and a flavone derivative (compound 5) was designed as a colorimetric and fluorescence turn-on probe to discriminate thiophenol (PhSH) from bioth...

A new method for synthesizing deoxynucleic guanidine (DNG) oligonucleotides that uses iodine as a mild and inexpensive coupling reagent is reported. This method eliminates the need for the toxic mercury salts and pungent thiophenol historically used in methods aimed at preparing DNG oligonucleotides. This coupling strategy was readily translated to a standard MerMade 12 oligonucleotide synthesizer with coupling yields of 95% and has enabled the synthesis of a 20-mer DNG oligonucleotide, the longest DNG strand to date, in addition to mixed DNA–DNG sequences with 3–9 DNG inserts. Importantly, DNG oligonucleotides exhibit robust unaided cellular uptake as compared to unmodified oligonucleotides without apparent cellular toxicity. Taken together, these findings should greatly increase the accessibility of cationic backbone modifications and assist in the development of oligonucleotide-based drugs.

A novel six-step synthesis of 7,8-difluoro-6,11-dihydrodibenzo[b,e]thiepin-11-ol (1) is described. Starting with 3,4-difloro-2-methylbenzoic acid and using diphenyl disulfide as an ideal sulfur sou...

Molecular reorientation dynamics modulate the physical and chemical properties of molecules at interfaces. This is particularly the case for organic molecules interacting with metallic surfaces-structural motifs of current interest to ultrasensitive chemical/biological detection/imaging. In this context, surface-enhanced Raman scattering (SERS) can be used to gauge the orientation of molecules in the immediate vicinity of plasmonic metals. Herein, we analyze SERS spectra of two aromatic thiols (4-mercaptobenzonitrile and thiophenol) chemisorbed onto silver substrates using ab initio molecular dynamics-based Raman spectral simulations that account for the optical response of molecules in the bulk and oriented molecules at the surface. Through a comparison with prior works aimed at gauging the orientation of our two model systems on metallic substrates, we describe the advantages and discuss the limitations of our described models and approach to gauging the orientation of molecules on metals through time domain simulations of their SERS signatures.

Efforts to elucidate the governing factors in the cation radical Newman–Kwart rearrangement are described. Through a combination of spectroscopic and kinetic analyses, it has been shown that the reactive intermediate is a thione cation radical that has significant thiyl radical character. This intermediate undergoes similar chemistry, such as olefin stereomutation, that has been observed for thiyl radicals generated by other means. Moreover, kinetic studies demonstrate that the electronic dependence observed in the system is the result of rate-limiting intramolecular nucleophilic trapping of the thione cation radical. Importantly, the thiyl radical character of the reactive intermediate can be used to rationalize all reaction observations. This mechanistic model is in line with observed rate enhancement at higher dilutions that decreases the formation of an off-cycle intermediate. A thermochemical cycle was devised to predict which substrates will most easily undergo the cation-radical-mediated rearrangement.

Here, we report resonance Raman spectra of CdSe colloidal nanocrystals (NCs) passivated with organic ligands. In addition to the well-known longitudinal optical phonons, we observe ligand vibrations. The ligand vibrations are shown to be resonantly enhanced through electronic mixing with the states of the NC. These measurements were enabled by substituting the native ligands with thiophenol. Thiophenol serves as an ideal probe for exciton–ligand coupling as it is a widely employed Raman molecular tag and quenches background luminescence in CdSe. The ligand vibrations are shown to be resonantly enhanced through exciting NC transitions. We show that vibronic coupling is observable in CdSe with diameters from 2 to 6 nm and for both phosphonic acid and amine native ligands. The coupling is evidenced by both asymmetric and symmetric mode enhancement through Herzberg–Teller or Franck–Condon and Herzberg–Teller mechanisms, repectively. The ligand exchange quenching strategy may be generally applicable to study ...

Thiophenol is the simplest aromatic thiol that is utilized for various applications in industry and agriculture. However, it should be used with care because thiophenol is readily absorbed into the human body by inhalation and ingestion, which leads to serious internal injuries. Thus, there is an urgent need for real-time and accurate monitoring of thiophenol. Despite remarkable advantages of electrogenerated chemiluminescence (ECL) analysis, ECL thiophenol probes have never been reported. Herein, a new strategy for the rapid detection of thiophenol by use of an ECL turn-on chemodosimeter based on a cyclometalated Ir(III) complex is described. This analytical system showed superior sensitivity [limit of detection (LOD) value, 3.8 nM] in comparison to the conventional fluorescence method. In addition, our system exhibited remarkable selectivity and reaction rate toward thiophenol over other analytes. Moreover, it was successfully applied to quantify thiophenol in real water samples, providing a new proof-of-concept for field monitoring based on ECL.

A selective four-electron reduction of CO2 with thiophenol using NaBH4 as a reductant is described to access dithioacetals. This reaction provides a novel synthetic method for the highly selective conversion of CO2 into methylene, and a new access to molecular structures via formation of C–S bonds using CO2 as the C1 source.

CdSe/CdS core/shell quantum dots (QDs) can be used as stable and highly active photoredox catalysts for efficient transfer hydrogenation of imines to amines with thiophenol as a hydrogen atom donor. This reaction proceeds via a proton-coupled electron transfer (PCET) from the QDs conduction band to the protonated imine followed by hydrogen atom transfer from the thiophenol to the α-aminoalkyl radical. This precious metal free transformation is easy to scale up and can be carried out by a one-pot protocol directly from aldehyde, amine, and thiophenol. Additional advantageous features of this protocol include a wide substrate scope, high yield of the amine products, extremely low catalyst loading (0.001 mol %), high turnover number (105), and the mild reaction conditions of using visible light or sun light at room temperature in neutral media.

Molecular couplings at interfaces play important roles in determining the performance of nanophotonics and molecular electronics. In this Letter, using femtosecond sum frequency generation to trace free-induction decay of vibrationally excited aromatic thiol molecules immobilized on metal with and without the bridged methylene group(s), metal surface free electron-coupled and uncoupled phenyl C-H stretching vibrational modes were identified, with dephasing times of ∼0.28 and ∼0.60 ps, respectively. For thiols on Au with the bridged methylene group(s) (benzyl mercaptan and phenylethanethiol), both the coupled and uncoupled modes were observed; for thiol on Au without the bridged methylene group (thiophenol), only the coupled mode was observed. This indicates that the bridged methylene group(s) serving as a spacer can be used to adjust the molecular coupling between the phenyl vibration and surface free electrons. The experimental approach can be used to tune molecular couplings in advanced nanophotonics and molecular electronics.

The advances in boron incorporated organics have captured overwhelming interest on account of their outstanding properties and promising applications in various fields. Mostly, triarylborane compounds (TAB) are exploited as sensors of F– and CN– anions at the expense of the intrinsic Lewis acidic nature of boron. New molecular probes 1 and 2 for detection of toxic thiophenol were designed by conjugating highly fluorescent borylanilines with the luminescent quencher 2,4-dinitrobenzene based sulfonamides (DNBS), wherein the electrophilicity of the DNBS moiety has been modulated by fine-tuning the intrinsic Lewis acidity of boron. The interplay between PET (photoinduced electron transfer) and ICT have been employed for developing the TAB tethered turn-on fluorescent sensor for thiophenol with high selectivity for the first time. The newly developed probes showed very fast response toward thiophenol (within ∼5 min) with limits of detection (LOD) lying in the micromolar range, clearly pointing to their potenti...

Nonadiabatic photodissociation dynamics of thiophenol (PhSH) and deuterated thiophenol (PhSD) via the 1ππ* state was investigated by a reduced three-dimensional (3D) quantum model based on the associated 3D diabatic potential energy surfaces constructed at the explicitly correlated multireference configuration interaction (MRCI-F12) level with the cc-pVTZ-F12 basis. The lifetimes of the low-lying vibronic S1 states for PhSH and PhSD were calculated using a low-storage filter diagonalization method and were in reasonably good agreement with the available experimental results. The nonadiabatic effect was further examined in the photodissociation process by comparing the results in diabatic and adiabatic models. It was found that the adiabatic lifetimes were about 2–4 times shorter than the exact ones in the diabatic model for both PhSH and PhSD. More importantly, the exact ground wave function including the geometric phase (GP) possessed a node along the C–C–S–H/C–C–S–D torsional coordinate, while the node ...

We report a cinchona alkaloid catalyzed addition of thiophenol into rapidly interconverting aryl-naphthoquinones, resulting in stable biaryl atropisomers upon reductive methylation. An array of thiophenols and naphthoquinone substrates were evaluated, and we observed selectivities up to 98.5:1.5 e.r. Control of the quinone redox properties allowed us to study the stereochemical stabilities of each oxidation state of the substrates. The resulting enantioenriched products can also be moved on via an S(N)Ar-like reaction sequence to arrive at stable derivatives with excellent enantioretention.

Adsorption of analytes on surface enhanced Raman scattering (SERS) active nanometallic substrates is influenced by a variety of factors, including analyte–metal interactions, analyte–solvent interactions, and competition for the limited number of available sites on the surface. In this article, we present a study of the effects of solubility on the binding of analytes to metallic substrates as well as an equation to describe the effect of these interactions on the observed SERS signal. A variety of solvents are used to demonstrate the effect on binding of 1,2-bis(4-pyridyl)-ethylene and thiophenol to nanostructured gold SERS substrates. These solvents include mixtures of ethanol/water and acetonitrile/water with different ratios of organic/water fractions. In our previous work, two types of sites were observed on nanostructured gold substrates—nucleophilic and electrophilic—which tend to bind with analytes that are either electron poor or electron rich, respectively. The present study shows that the compo...

The plasmonic electron oscillations in optically excited metallic nanoparticles result in surface confinement of photon energy over much longer time scales in comparison to the unconfined photons t...

In recent years, a large number of monolayer-protected clusters (MPCs) have been studied by means of single crystal structure characterization. A central aspect of research on MPCs is the correlation of their interesting optical properties with structural features and the formulation of a theoretical framework that allows interpretation of their unique properties. For this, superatom and jellium models have been proven successful. Little attention, however, has been paid to the influence of the protecting ligands. Here, we investigate the effect of changes in [Au25(SR)18-x(SR′)x]−, where SR′ represents a para-substituted thiophenolate derivative (SPh-4-X). We computed the first hyperpolarizabilities, screening a broad range of substituents X. For [Au25(SR)17(SR′)1]− clusters, significant first hyperpolarizabilities were calculated, spanning 2 orders of magnitude depending on X. A strong dependence on the electron-donating/withdrawing properties of the substituent was found for para-substituted thiophenol ...

The catalytic cycle of a new derivative of ebselen, 1, was elucidated via three steps by the density functional theory and solvent-assisted proton exchange procedure involving indirect proton exchange through a hydrogen-bonded transfer network. Different behaviors of the aromatic and aliphatic thiols were investigated in the reduction of selenoxide (step 2 → 3) and selenurane (step 3 → 1) based on their nucleophilicity. The reduction of selenoxide in the presence of thiophenol (ΔG‡ = 15.9 kcal·mol–1) is faster than that of methanethiol (ΔG‡ = 29.3 kcal·mol–1), and methanethiol makes the reduction of selenoxide unspontaneous and kinetically unfavorable (ΔG = 2.8 kcal·mol–1). The nucleophilic attack may be enhanced by using the thiophenol backbone at the selenium center to lower the energy barrier of the selenoxide reduction (ΔG‡ = 15.9 kcal·mol–1). On the basis of the turnover frequency calculations, during the catalytic cycle, the rate of the reaction was analyzed and discussed. Low values of the electron...

Thiophenol is extensively used in the manufacture of industry and agriculture. However, the high concentration of thiophenol will cause damage to living organisms and environment pollution. Herein, a BODIPY-based fluorescent probe has been designed and synthesized for probing thiophenol pollutant in solutions and cells. It shows high selectivity and a turn-on effect. Cell experiments demonstrate that the probe has low cell toxicity, good and rapid cell membrane penetrability, and excellent imaging properties in living cells. The real water samples can be detected directly by fluorescent assay or test strips made from the probe. Therefore, the probe has important value on the detection of thiophenol in the environment and industrial production.

The surface characterization of branched and spherical gold nanoparticles was done by two complementary techniques: scattering correlation spectroscopy (SCS) and surface-enhanced Raman spectroscopy (SERS). Thiophenol was used as a surface marker to probe the surface area and the gold–thiophenol interaction in gold nanourchins (GNUs) and gold nanospheres (GNSs). We observed that, for GNU, the thiophenol is first grafted on the core, with a saturation concentration of about 10–3 M as observed for GNSs. Afterward, the saturation of the branches occurs at a higher thiophenol concentration (∼1 M). A numerical calculation of the surface areas of GNSs of different sizes allowed for the estimation of the GNU surface area. The hydrodynamic radius was measured at different steps of thiophenol–GNP functionalization. By comparing spherical and nonspherical nanoparticles, we demonstrate that the molecule–GNP interaction is highly dependent on the nanoparticle morphology (size and shape).

Ultrasmall nanomolecules (

To improve selectivity of electrocatalytic degradation of toxic, odorous mercaptans, the fractal-structured dendritic Au/BDD (boron-doped diamond) anode with molecular recognition is fabricated through a facile replacement method. SEM and TEM characterizations show that the gold dendrites are single crystals and have high population of the Au (111) facet. The distinctive structure endows the electrode with advantages of low resistivity, high active surface area, and prominent electrocatalytic activity. To evaluate selectivity, the dendritic Au/BDD is applied in degrading two groups of synthetic wastewater containing thiophenol/2-mercaptobenzimidazole (targets) and phenol/2-hydroxybenzimidazole (interferences), respectively. Results show that targets removals reach 91%/94%, while interferences removals are only 58%/48% in a short time. The corresponding degradation kinetic constants of targets are 3.25 times and 4.1 times that of interferences in the same group, demonstrating modification of dendritic gold on BDD could effectively enhance electrocatalytic target-selectivity. XPS and EXAFS further reveal that the selective electrocatalytic degradation derives from preferential recognition and fast adsorption to thiophenol depending on strong Au-S bond. The efficient, selective degradation is attributed to the synergetic effects between accumulative behavior and outstanding electrochemical performances. This work provides a new strategy for selective electrochemical degradation of contaminants for actual wastewater treatment.

Au-38(SCH2CH2Ph)(24) nanomolecules upon etching with tert-butylthiol undergo core-size conversion to green-gold Au-30(S-tBu)(18) via Au-36(SCH2CH2Ph)(24-x)(S-tBu)(x) intermediate. The structural transformation from Au38 to Au30 indicates a strong steric effect due to the tert-butyl group of the exchanging ligand in contrast to electronic effect by ligands such as thiophenol, which transforms the Au-38(SCH2CH2Ph)(24) to Au-36(S-tBu)(24). In this work, fast reaction kinetics were observed and thermodynamically stable Au-30(S-tBu)(18) was obtained in molecular purity.

Aerobic oxidation of thiols to disulfides was achieved photocatalytically using a tellurorhodamine chromophore (9-mesityl-3,6-bis(dimethylamino)telluroxanthylium hexafluorophosphate) as both the sensitizer and catalyst. The proposed mechanism, supported experimentally and computationally with DFT, involves the formation of a tellurorhodamine telluroxide from reaction with water and singlet oxygen generated by irradiation of the tellurorhodamine. The oxidation to the telluroxide is accompanied by the formation of hydrogen peroxide. The telluroxide oxidizes thiols to regenerate the tellurorhodamine and the disulfide plus water. Mechanistically, DFT suggests adding two thiols to the telluroxide with the loss of H2O to give a trigonal-bipyramidal Te(IV), which undergoes concerted loss of disulfide to regenerate 1. Oxidation of thiophenol and 2-naphthalenethiol was complete after 2 h of irradiation with visible light under atmospheric conditions. Oxidation of the electron-poor 2,6-dichlorothiophenol, the steri...

A squaraine-based far-red/near-infrared fluorescent probe (SQ-DNBS) was exploited for thiophenol detection. SQ-DNBS is a colorimetric and "off-on" fluorometric dual-channel "naked-eye" chemosensor showing high selectivity, high sensitivity (detection limit: 9.9 nM), and rapid response to thiophenol in aqueous solution. SQ-DNBS also can be used in practical applications for the detection of thiophenol in water samples. Photophysical and spectral characterization results revealed that the probing mechanism of SQ-DNBS toward thiophenol lies in the thiolate-mediated cleavage reaction. Our discovery demonstrates the potential of the arylmethylene-squaraine skeleton as a promising fluorophore unit to construct high-performance far-red/near-infrared chemosensors.

We have developed visible-light photoredox decarboxylative couplings of N-(acetoxy)phthalimides without an added photocatalyst in which simple and commercially available thiophenols are used as the effective organocatalysts, and 4-(trifluoromethyl)thiophenol shows optimal catalytic activity. Three representative decarboxylative examples were chosen including one amination and two C-C bond couplings to confirm efficacy of the visible-light photoredox reactions, and the results exhibited that they performed very well at room temperature. The interesting discovery should provide a novel and environmentally friendly strategy for visible-light photoredox transformation of organic molecules.

We report herein a highly selective and sensitive turn-on fluorescent probe (compound 1) with a fast response time (less than 2 min) for thiophenol detection based on an enhanced SNAr reaction between thiophenols and a sulfonyl-ester moiety covalently attach to curcumin. Reaction of 1 in Hepes-MeOH (1:1, v/v, pH 7.4) in the presence of 4-methylthiophenol (MTP) resulted in a remarkable enhancement of the fluorescence. A linear response in the presence of MTP of the relative fluorescent intensity (F - F0) of 1 at 536 nm in the 0-40 mu M MTP concentration range was found. A limit of detection (LOD) for the detection of MTP of 26 nM, based on the definition by IUPAC (C-DL = 3 Sb/m), was calculated. Probe 1 was applied to monitor and imaging exogenous MTP in live cells and to the detection of MTP in real water samples., The work was supported by the National Natural Science Foundation of China (Grant No. 21472118, 21672131), the Program for the Top Young and Middle-Aged Innovative Talents of Higher Learning Institutions of Shanxi (TYMIT, Grant No. 2013802), Talents Support Program of Shanxi Province (Grant No. 2014401), Shanxi Province Outstanding Youth Fund (Grant No. 2014021002), Scientific Instrument Center, Shanxi University and Shanxi University funds for study aboard 2014. The Generalitat Valenciana (Project PROMETEOII/2014/047) and the Spanish Government (Projects MAT2012-38429-C04 and MAT2015-64139-C4-1 MINECO/FEDER)) are also gratefully acknowledged.

Sulfur and nitrogen are two common constituents of natural and synthetic organic molecules, especially in systems where organisms play a role. There is evidence in the literature that nitrogen and sulfur containing functional groups have an influence on adsorption of organic molecules to calcite surfaces. The purpose of this work was to investigate the interaction of these functional groups with CaCO3 and to explore how adsorption is affected by various side groups and the H atom. First, we used density functional theory with semiempirical dispersion corrections (DFT-D2) to determine the energy of adsorption on the dominant calcite face, {10.4} for molecules containing nitrogen (ammonia, methylamine, ethylamine, aniline, hydrogen cyanide, acetonitrile, propionitrile, benzonitrile, dimethylamine, pyrrole, trimethylamine, and pyridine) and sulfur (hydrogen sulfide, methanethiol, ethanethiol, thiophenol, dimethyl sulfide, and thiophene). Second, based on the determined adsorption energies, we predicted desor...

In situ characterization of surfaces with tip-enhanced Raman spectroscopy (TERS) provides chemical and topographic information with high spatial resolution and submonolayer chemical sensitivity. To further the versatility of the TERS approach toward more complex systems such as biological membranes or energy conversion devices, adaptation of the technique to solid/liquid working conditions is essential. Here, we present a home-built side-illumination TERS setup design based on a commercial scanning tunneling microscope (STM) as a versatile, cost-efficient solution for TERS at solid/liquid interfaces. Interestingly, the results obtained from showcase resonant dye and nonresonant thiophenol monolayers adsorbed on Au single crystals suggest that excitation beam aberrations due to the presence of the aqueous phase are small enough not to limit TER signal detection. The STM parameters are found to play a crucial role for solid/liquid TERS sensitivity. Raman enhancement factors of 10(5) at μW laser power demonstrate the great potential the presented experimental configuration holds for solid/liquid interfacial spectroscopic studies.

We describe a general method to synthesize the iminium tetrahydrothiophene embedded in the dimeric Nuphar alkaloids. In contrast to prior studies, the sulfur atom of the thiaspirane pharmacophore is shown to be electrophilic. This α-thioether reacts with thiophenol or glutathione at ambient temperature to cleave the C–S bond and form a disulfide. Rates of conversion are proportional to the corresponding ammonium ion pKa and exhibit half-lives less than 5 h at a 5 mM concentration of thiol. A simple thiophane analogue of the Nuphar dimers causes apoptosis at single-digit micromolar concentration and labels reactive cysteines at similar levels as the unsaturated iminium “warhead”. Our experiments combined with prior observations suggest the sulfur of the Nuphar dimers can react as an electrophile in cellular environments and that sulfur-triggered retrodimerization can occur in the cell., We describe a new method for the synthesis of the Nuphar iminium thiophane pharmacophore and disclose its previously unidentified sulfur electrophilicity.

A simple strategy for the syntheses of 2-alkyl indoles via regioselective ring-opening of 2-(2-haloaryl)-3-alkyl-N-tosylaziridines with thiophenol, followed by copper powder-mediated intramolecular C-N cyclization and subsequent aromatization by the elimination of thiophenol, with good yields is described. Utilizing this protocol, 2-carboxyindole has been synthesized easily.

Surface crossing of bound (S1, ππ*) and continuum (S2, πσ*) states has been observed in the ultrafast S–D bond dissociation reaction of thiophenol-d1. It is manifested by an unanticipated variation of fragment angular distribution as a function of the excitation energy. The anisotropy parameter (β) of +0.25 at the S1 origin decreases to −0.60 at ∼600 cm–1 above the S1 zero-point level, giving a broad peak in β with a bandwidth of ∼200 cm–1. The peak in β is ascribed to the in-plane S-D bending mode excitation by which the nuclear configuration in the proximity of the S1/S2 conical intersection seam is directly accessed, showing a mixed character of parallel (S1–S0) and perpendicular (S2–S0) transition dipole moments at the same time. As a result, the dynamic aspect of the conical intersection is experimentally revealed here through direct access to the nuclear configuration on the multidimensional conical intersection seam.

A new aromatic thiolate protected gold nanomolecule Au99(SPh)42 has been synthesized by reacting the highly stable Au144(SCH2CH2Ph)60 with thiophenol, HSPh. The ubiquitous Au144(SR)60 is known for its high stability even at elevated temperature and in the presence of excess thiol. This report demonstrates for the first time the reactivity of the Au144(SCH2CH2Ph)60 with thiophenol to form a different 99-Au atom species. The resulting Au99(SPh)42 compound, however, is unreactive and highly stable in the presence of excess aromatic thiol. The molecular formula of the title compound is determined by high resolution electrospray mass spectrometry (ESI-MS) and confirmed by the preparation of the 99-atom nanomolecule using two ligands, namely, Au99(SPh)42 and Au99(SPh-OMe)42. This mass spectrometry study is an unprecedented advance in nanoparticle reaction monitoring, in studying the 144-atom to 99-atom size evolution at such high m/z (∼12k) and resolution. The optical and electrochemical properties of Au99(SPh)42 are reported. Other substituents on the phenyl group, HS-Ph-X, where X = -F, -CH3, -OCH3, also show the Au144 to Au99 core size conversion, suggesting minimal electronic effects for these substituents. Control experiments were conducted by reacting Au144(SCH2CH2Ph)60 with HS-(CH2)n-Ph (where n = 1 and 2), bulky ligands like adamantanethiol and cyclohexanethiol. It was observed that conversion of Au144 to Au99 occurs only when the phenyl group is directly attached to the thiol, suggesting that the formation of a 99-atom species is largely influenced by aromaticity of the ligand and less so on the bulkiness of the ligand.

Surface-enhanced Raman spectroscopy (SERS) is generally performed on planar surfaces, which can be difficult to prepare and may limit the interaction of the sensing surface with targets in large volume samples. We propose that nanocomposite materials can be configured that both include SERS probes and provide a high surface area-to-volume format, i.e., fibers. Thiol-yne nanocomposite films and fibers were fabricated using exposure to long-wave ultraviolet light after the inclusion of gold nanoparticles (AuNPs) functionalized with thiophenol. A SERS response was observed that was proportional to the aggregation of the AuNPs within the polymers and the amount of thiophenol present. Overall, this proof-of-concept fabrication of SERS active polymers indicated that thiol-yne nanocomposites may be useful as durable film or fiber SERS probes. Properties of the nanocomposites were evaluated using various techniques including UV-vis spectroscopy, μ-Raman spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, and transmission electron microscopy.

Thiophenol is commonly used as a model system for surface-enhanced Raman scattering (SERS) of molecules due to the strong affinity of the −SH group toward noble metal surfaces. By performing time-, temperature-, and pH-dependent measurements of thiophenol adsorption on commercial nanostructured gold SERS substrates, we have observed both physisorption and chemisorption processes. These two distinct adsorption regimes were found dependent on the pH which controlled the ionization state of thiophenol in an aqueous medium. At low pH the sulfhydryl proton remains bound, and the kinetic adsorption profile obtained from the SERS intensity follows a sigmoid-shaped curve with an initially slow adsorption rate that deviates from a Langmuir profile. In addition, from temperature-dependent measurements, a near zero value for the activation energy is obtained, indicating that physisorption is the rate-limiting step. At high pH, where the sulfhydryl proton becomes detached, the kinetic adsorption profile follows a cla...

This work explores the electronic energy of CdSe nanoparticles as a function of nanoparticle (NP) size and capping ligand. Differential pulse voltammetry was used to determine the valence band edge of CdSe NPs that are capped with three different ligands (aniline, thiophenol, and phenylphosphonic acid), and the experimental values are compared with DFT calculations. These results show how the energy position and the size-dependent behavior of the energy bands of CdSe can be modulated by the chemical nature of the capping ligand. The computations underscore how the nature of the highest lying filled states of the nanoparticle can change with ligand type and how this can explain differences between previously reported size-dependent data on similar systems. The findings show that both the ligand and quantum confinement effects should be accounted for in modeling size-dependent effects for different NP–ligand systems.

Proton-coupled electron transfer (PCET) with phenols has been investigated in considerable detail in recent years while at the same time analogous mechanistic studies of PCET with thiophenols have remained scarce. We report on PCET between a series of thiophenols and a photoexcited Ru(II) complex, which acts as a combined electron/proton acceptor. Depending on the exact nature of the thiophenol, PCET occurs through different reaction mechanisms. The results are discussed in the context of recent studies of PCET between phenols and photoexcited d6 metal complexes.

Through the reaction of the aminotroponiminatogermylene monochloride complex [(Bui2ATI)GeCl] (1) with sodium pyrrolide, the stable N-germylene pyrrole complex [(Bui2ATI)GeNC4H4] (2) has been isolated. The reaction of compound 2 with thiophenol and selenophenol afforded the first germylene thio- and selenophenoxide complexes [(Bui2ATI)GeSPh] (3) and [(Bui2ATI)GeSePh] (4) through the substitution of the pyrrole moiety (NC4H4) with an EPh moiety (E = S (3), Se (4)), respectively. Interestingly, the chalcogenide derivatives of compound 2, such as the N-germathioacylpyrrole complex [(Bui2ATI)Ge(S)NC4H4] (5) and N-germaselenoacylpyrrole complex [(Bui2ATI)Ge(Se)NC4H4] (6), also underwent the aforementioned substitution reaction with thiophenol and selenophenol, resulting in the first examples of germa thioester complexes ([(Bui2ATI)Ge(S)SPh] (7) and [(Bui2ATI)Ge(Se)SPh] (8)) and germa selenoester complexes ([(Bui2ATI)Ge(S)SePh] (9) and [(Bui2ATI)Ge(Se)SePh] (10)), respectively. All the novel germanium compounds ...

Herein we report a metal-free method for the direct anti-Markovnikov hydroamination of unsaturated amines. Irradiation of the amine substrates with visible light in the presence of catalytic quantities of easily synthesized 9-mesityl-10-methylacridinium tetrafluoroborate and thiophenol as a hydrogen atom donor furnished the nitrogen containing heterocycles with complete regio-control. Two examples of in termolecular anti-Markovnikov alkene hydroamination are also disclosed.

The activation and ring-opening of methyl furanosides in the four natural sugar scaffolds (ribo, lyxo, arabino, and xylo) efficiently afforded acyclic thioacetals with high S(N)2-like selectivity at the acetal center in the presence of Me2BBr and thiophenol. The stereochemical outcome of these reactions provides important mechanistic insights into the activation pathway of five-membered semicyclic acetals. The thioacetal products should find applications in oligosaccharides synthesis and allow further development of acyclic strategies for the synthesis of novel nucleoside analogues.

Model systems of organic self-assembled monolayers are important in achieving full atomic-scale understanding of molecular-electronic interfaces as well as the details of their charge transfer physics. Here we use two-photon photoemission to measure the evolving unoccupied and occupied interfacial electronic structure of two thiolate species, thiophenol and p-fluorothiophenol, adsorbed on Cu(111) as a function of molecular coverage. Our measurements focus on the role of adsorbates in shifting surface polarization and effecting surface electron confinement. As the coverage of each molecule increases, their photoemission-measured work functions exhibit nearly identical behavior up to 0.4-0.5 ML, at which point their behavior diverges; this behavior can be fit to an interfacial bond model for the surface dipole. In addition, our results show the emergence of an interfacial electronic state 0.1-0.2 eV below the Fermi level. This electronic state is attributed to quantum-mechanical-confinement shifting of the Cu(111) surface state by the molecular adsorbates.

Density functional theory calculations were used to examine the effects of intrinsic surface defects of Au(111) on nondissociative thiophenol (PhSH) adsorption and the follow-up reaction pathways toward the dissociation of PhSH to form phenyl-thiolate (PhS) and then stable PhS adsorption structures. The calculations yielded the surface geometry of the most probable adsorption products, on Au(111) with and without the presence of adatoms (Auad) and vacancies, including the adsorption geometry of stable PhS−Auad−PhS surface complexes formed as the optimal products of dissociative adsorption toward the growth of a self-assembled monolayer of phenyl-thiolates. The validity of the computational adsorption geometries and our analysis of them are supported by the agreement between our simulated scanning tunneling microscopic images derived from these adsorption structures and the experimental images available in the literature. To elucidate further the adsorption reaction dynamics, we calculated the relevant reaction pathways and activation barriers and found that whereas the lowest energy barrier for the formation of the most stable PhS−PhS pair with the closest separation on clean Au(111) with no intrinsic defects is 0.68 eV, the counterpart with Auad is only 0.32 eV. This and our other calculated results highlight the facilitating role of intrinsic defects of Au(111) in driving the dissociative adsorption of thiophenol and articulate the reaction mechanism of the formation of the trans-PhS−Auad−PhS surface complex, which is the precursor to the final completion of a self-assembled monolayer of phenyl-thiols: the end product of thiophenol adsorption.

The interaction of two sets of structurally related molecules, thiophenol/thioanisole, and thiophene/tetrahydrothiophene, with vacuum-annealed and ion-bombarded TiO(2)(110) surfaces has been studied using a combination of temperature-programmed reaction spectroscopy (TPRS) and X-ray photoelectron spectroscopy (XPS). All thioethers studied were observed to adsorb and desorb from both surfaces without producing reaction products, while thiophenol, the only species studied containing a S-H bond, reacted with both surfaces. Approximately 25% of surface bound thiophenol decomposed over the vacuum-annealed surface. On the bombarded surface, thiophenol both decomposed into surface-bound C(x)H(y)/S fragments, and reacted to form benzene, which desorbed from the surface at 400 K. We propose that phenylthiolate formation on the bombarded surface leads to the observed production of benzene. These results highlight the importance of defects in the reactivity of titania, and lay the foundation for the study of larger, refractory sulfur compounds present in fuel.

Thermochemical parameters of the complete series of congeners of chlorinated thiophenols are derived based on the accurate chemistry model of CBS-QB3. The effect of the change in pattern and degree of chlorination has been thoroughly investigated. Optimized geometries of chlorinated thiophenol molecules exhibit to a large extent very similar geometrical features. Standard enthalpies of formation of chlorinated thiophenol and thiophenoxy radicals are calculated using isodesmic work reactions. Thermodynamic scales of H and G enable the highlighting of the most stable isomer in each homologue group. Standard entropies and heat capacities are calculated with the treatment of internal rotations of the S-H group as hindered rotors. It is found that there is a rather minor effect of changes in pattern and degree of chlorination on the calculated bond dissociation enthalpies (BDH) of the S-H bond in chlorinated thiophenols. Values of solvation energies designate that the interaction of chlorinated congeners of thiophenols with water molecules decreases with the degree of chlorination; however, no apparent dependency can be deduced with regard to the pattern of chlorination. A thermodynamic cycle was constructed to estimate pK a values based on gas phase deprotonation free energies and calculated solvation energies for chlorinated thiophenol molecules and chlorinated thiophenolate anions. Calculated pK a values are in good agreement with limited available experimental measurements.

Otherwise sluggish or completely ineffective radical reductions of alkyl and aryl halides by N-heterocyclic carbene boranes (NHC-boranes) are catalyzed by thiols. Reductions and reductive cyclizations with readily available 1,3-dimethylimidazol-2-ylidene borane and a water-soluble triazole relative are catalyzed by thiophenol and tert-dodecanethiol [C(9)H(19)C(CH(3))(2)SH]. Rate constants for reaction of the phenylthiyl (PhS•) radical with two NHC-boranes have been measured to be ~10(8) M(-1) s(-1) by laser flash photolysis experiments. An analysis of the available evidence suggests the operation of polarity reversal catalysis.

Polymers bearing the dibromomaleimide (DBM) group as a functional chain end have been synthesized by RAFT polymerization. A DBM functional chain transfer agent (CTA) was utilized to afford well-defined PtBA, PMA, and PTEGA, without the requirement of protecting group chemistry. It was found that RAFT polymerization of NIPAM and styrene with this CTA was severely retarded/inhibited which is ascribed to their relatively low propagation rate constants compared to acrylates. This observation is accounted for by a reversible trapping of propagating radicals by the DBM group in RAFT polymerizations using a monomer with low kp. However, further attempts to synthesize DBM-terminated PtBA and PMA by ATRP using an analogous initiator were unsuccessful, and broad PDI were observed. Furthermore, highly efficient postpolymerization functionalization of DBM-terminated PMA produced by RAFT, with the model compound thiophenol was also demonstrated.