Sulfur Chemistry Research Articles

Visualizing sulfur with X-rays: From molecules to tissues

Sulfur is sometimes called a spectroscopically silent element because there are so few tools for probing its chemistry. This paper will review how sulfur K-edge X-ray absorption spectroscopy and related methods can be used to overcome this limitation, using examples from the authors’ research. X-rays from synchrotron radiation sources provide the means to study essentially any element in a variety of systems, ranging from pure compounds, to complex mixtures and even structured systems such as biological tissues. We show that sulfur K-edge X-ray absorption spectroscopy provides an important spectroscopic probe of sulfur chemistry in a range of systems, including those containing reactive species. Using a micro-focused X-ray beam, chemically-dependent X-ray fluorescence imaging can be used to image different sulfur species at a variety of spatial resolutions from microscopic to macroscopic. Increased sensitivity and deeper insights into electronic structure will be available in future studies using a suite of methods that are collectively known as advanced X-ray spectroscopy.

New catalytic reactions using sulfur dioxide

The sulfur dioxide surrogate DABSO is employed in a series of metal-catalyzed transformations to access useful sulfonyl-derived functional groups, such as sulfones, sulfonamides and sulfinate salts. Both palladium and copper catalyzed reactions are described. This work was presented at the 28th International Symposium on the Organic Chemistry of Sulfur, held in Tokyo in the summer of 2018.

The role of sulfur and heavier chalcogens in the chemistry of antioxidants

Sulfur chemistry plays a central role in cellular redox homeostasis and cysteine-derived antioxidants like glutathione are the most abundant in biological systems. Inspired by Nature, the insertion of divalent sulfur as a substituent in phenolic antioxidants, e.g in thiatocopherol, seeking for improved antioxidant performance, has been an important strategy for long time. Replacement of sulfur with heavier chalcogens like Selenium and Tellurium has brought to even more performing antioxidants, able to quench peroxyl radical in a catalytic fashion and to express unusually high reactivity. On the other hand, natural bioactive compounds like plant-derived thiosulfinates (R-S(O)S-R) own their exceptional antioxidant properties to the ability of releasing sulfenic acids, whose antioxidant behavior has only recently been clarified. The chemistry and redox properties of unstable sulfenic acids (R-SOH), and analogous selenenic acids (R-SeOH) have also recently been elucidated, to better understand the properties of chalcogen-based natural antioxidants, and to develop novel bio-inspired compounds. This fascinating chemistry will be reviewed and the most significant achievement will be presented.

Total synthesis involving sulfur chemistry

Novel findings during the course of the total synthesis of sulfur-containing natural products are described. These natural products include sporidesmin A, dehydrogliotoxin, tantazole B, and leinamycin.

Structure-Function Analysis Indicates that an Active-Site Water Molecule Participates in Dimethylsulfoniopropionate Cleavage by DddK.

The osmolyte dimethylsulfoniopropionate (DMSP) is produced in petagram quantities in marine environments and has important roles in global sulfur and carbon cycling. Many marine microorganisms catabolize DMSP via DMSP lyases, generating the climate-active gas dimethyl sulfide (DMS). DMS oxidation products participate in forming cloud condensation nuclei and, thus, may influence weather and climate. SAR11 bacteria are the most abundant marine heterotrophic bacteria; many of them contain the DMSP lyase DddK, and their dddK transcripts are relatively abundant in seawater. In a recently described catalytic mechanism for DddK, Tyr64 is predicted to act as the catalytic base initiating the β-elimination reaction of DMSP. Tyr64 was proposed to be deprotonated by coordination to the metal cofactor or its neighboring His96. To further probe this mechanism, we purified and characterized the DddK protein from Pelagibacter ubique strain HTCC1062 and determined the crystal structures of wild-type DddK and its Y64A and Y122A mutants (bearing a change of Y to A at position 64 or 122, respectively), where the Y122A mutant is complexed with DMSP. The structural and mutational analyses largely support the catalytic role of Tyr64, but not the method of its deprotonation. Our data indicate that an active water molecule in the active site of DddK plays an important role in the deprotonation of Tyr64 and that this is far more likely than coordination to the metal or His96. Sequence alignment and phylogenetic analysis suggest that the proposed catalytic mechanism of DddK has universal significance. Our results provide new mechanistic insights into DddK and enrich our understanding of DMS generation by SAR11 bacteria.IMPORTANCE The climate-active gas dimethyl sulfide (DMS) plays an important role in global sulfur cycling and atmospheric chemistry. DMS is mainly produced through the bacterial cleavage of marine dimethylsulfoniopropionate (DMSP). When released into the atmosphere from the oceans, DMS can be photochemically oxidized into DMSO or sulfate aerosols, which form cloud condensation nuclei that influence the reflectivity of clouds and, thereby, global temperature. SAR11 bacteria are the most abundant marine heterotrophic bacteria, and many of them contain DMSP lyase DddK to cleave DMSP, generating DMS. In this study, based on structural analyses and mutational assays, we revealed the catalytic mechanism of DddK, which has universal significance in SAR11 bacteria. This study provides new insights into the catalytic mechanism of DddK, leading to a better understanding of how SAR11 bacteria generate DMS.

Gram-scale economical synthesis of trans-coniferyl alcohol and its corresponding thiol

AbstractConiferyl alcohol is considered to be a potent antioxidant and a precursor of several bioactive products. In addition, it is a frequently used as a model compound in lignin chemistry. Coniferyl thiol is used analogously to study the sulfur chemistry in technical lignins. Coniferyl alcohol was synthesized in a large scale from commercially available ferulic acid by a mixed anhydride reduction method which affords high yields (84%) under very mild conditions and allows using sodium borohydride. The nucleophilic substitution of 4-O-acetylated coniferyl alcohol (3) with thioacetic acid in the presence of dimethylformamide (DMF) dineopentylacetal afforded 4-O-acetylated coniferyl thioacetate (5) in a 70% yield, which, in a 72% yield, was deprotected to the respective thiol (6). Both coniferyl alcohol and coniferyl thiol were comprehensively analytically characterized [one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy]. The presented approach renders the two model substances readily available on a gram scale and according to low-risk, environmentally compatible protocols.

Chemical ionization quadrupole mass spectrometer with an electrical discharge ion source for atmospheric trace gas measurement

Abstract. We present a chemical ionization quadrupole mass spectrometer (CI-QMS) with a radio-frequency (RF) discharge ion source through N2∕CH3I as a source of primary ions. In addition to the expected detection of PAN, peracetic acid (PAA) and ClNO2 through well-established ion–molecule reactions with I− and its water cluster, the instrument is also sensitive to SO2, HCl and acetic acid (CH3C(O)OH) through additional ion chemistry unique to our ion source. We present ionization schemes for detection of SO2, HCl and acetic acid along with illustrative datasets from three different field campaigns underlining the potential of the CI-QMS with an RF discharge ion source as an alternative to 210Po. The additional sensitivity to SO2 and HCl makes the CI-QMS suitable for investigating the role of sulfur and chlorine chemistry in the polluted marine and coastal boundary layer.

Graphene/RuO2 nanocrystal composites as sulfur host for lithium-sulfur batteries

Abstract An optimized graphene/RuO2/S composite is prepared by hydrothermal growth of RuO2 particles on graphene oxide sheets as the positive electrode for rechargeable lithium-sulfur batteries. The electrode with 6.1 wt% RuO2 nanocrystals and a high sulfur content of 79.0 wt% delivers an optimal electrochemical performance with high residual capacities of 508 mAh g−1 after 200 cycles and 389 mAh g−1 after 800 cycles at 1 C with a low capacity decay of 0.054%. The RuO2 nanocrystals promote the redox reaction kinetics and facilitate the transformation of sulfur chemistry, leading to large improvements in reversibility and rate capability of the composite electrode. The density functional theory calculations signify the formation of Li–O and Ru–S bonds through chemical interactions between RuO2 and Li polysulfides while the adsorption energies between graphene and polysulfide species are much higher in the presence of RuO2 than that of the neat graphene acting alone. These discoveries support the efficient entrapment of polysulfides by the composite electrode to the benefit of enhanced cyclic stability of the battery.

High-level theoretical study of the hydrogen abstraction reaction H2S + O2 = SH + HO2 and prediction of the rate constants

Hydrogen abstraction reaction of hydrogen sulfide (H2S) by molecule oxygen (O2) forming hydroperoxyl radical (HO2) and hydrosulfide radical (SH) is very important for both atmospheric and combustion chemistry. This work reports a systematic theoretical study on this reaction using a combination of high-level quantum chemistry methods and chemical kinetic theory. Geometry optimizations for all species are performed at QCISD/cc-pVQZ level of theory. The energies for minima and transition state are computed using both single- and multi-reference ab initio methods. It is found that the transition state of this reaction exhibits significant multi-reference nature based on 〈S2〉 and T1 diagnostic during CCSD(T) calculations. The predicted reaction barrier from high-level multi-reference CASPT2(20e,13o)/aug-cc-pVTZ method is higher than those from CCSD(T) and W1BD methods by 6–7 kcal mol−1. Reaction energy barriers from a series of DFT methods also show large deviations compared with both single- and multi-reference methods. Thermal rate constants are calculated over a temperature range from 300 to 2500 K by employing canonical transition state theory with Eckart tunneling correction and the treatment of torsional mode. This work provides accurate rate constants for this reaction and fundamental benchmark results for H/O/S reaction systems, which is valuable for theoretical chemistry and kinetic modeling of sulfur chemistry.

Evaluation of Operating and Design Parameters of Pressurized Flue Gas Systems with Integrated Removal of NOx and SOx

This study investigates the operating and design parameters of product gas compression and integrated control of nitrogen oxides (NO x ) and sulfur oxides (SO x ) in large-scale oxy-fuel and chemical looping combustion processes. A process model that includes a comprehensive description of nitrogen and sulfur chemistry and mass transfer is developed. The results show that the fraction of NO oxidation into NO 2 will be 10-50% in a multistage compressor to 30 bars (1-4% O 2 in the gas) depending on the residence times in intercoolers and pressure levels. At lower O 2 concentrations (>0.1% O 2 in the gas), the oxidation is limited but still active. Nitric acid formation in the compressor condensate is, thus, inevitable, although limited, as most water is condensed in the early stages, whereas the acid gases are formed in the later stages. The NO 2 /NO x ratio has an important effect on the total amount of NO x absorbed and extra residence time should be added after the compressor to increase this ratio. Evaluation of the process behavior in relation to simultaneous absorption of SO 2 and NO x revealed that increased SO 2 /NO x ratio and bottom liquid recycling enhanced the total NO x absorption. In addition, maintaining the pH in the absorbing solution above 5 improves the removal efficiencies of NO x and SO 2 . NO x removal rates of up to around 95% can be achieved for SO 2 /NO x > 1 in the flue gas with appropriate design of the absorber. For SO 2 /NO x < 1, increasing the packing height or addition of S(IV) solutions could enhance the NO x removal rates to 95% or more. The model predictions are compared with the experimental data from a laboratory-scale absorber. The process model developed in this work enables design studies and techno-economic evaluation of absorption-based NO x and SO x removal concepts.

Microbial Biomarker Transition in High-Altitude Sinter Mounds From El Tatio (Chile) Through Different Stages of Hydrothermal Activity.

Geothermal springs support microbial communities at elevated temperatures in an ecosystem with high preservation potential that makes them interesting analogs for early evolution of the biogeosphere. The El Tatio geysers field in the Atacama Desert has astrobiological relevance due to the unique occurrence of geothermal features with steep hydrothermal gradients in an otherwise high altitude, hyper-arid environment. We present here results of our multidisciplinary field and molecular study of biogeochemical evidence for habitability and preservation in silica sinter at El Tatio. We sampled three morphologically similar geyser mounds characterized by differences in water activity (i.e., episodic liquid water, steam, and inactive geyser lacking hydrothermal activity). Multiple approaches were employed to determine (past and present) biological signatures and dominant metabolism. Lipid biomarkers indicated relative abundance of thermophiles (dicarboxylic acids) and sulfate reducing bacteria (branched carboxylic acids) in the sinter collected from the liquid water mound; photosynthetic microorganisms such as cyanobacteria (alkanes and isoprenoids) in the steam sinter mound; and archaea (squalane and crocetane) as well as purple sulfur bacteria (cyclopropyl acids) in the dry sinter from the inactive geyser. The three sinter structures preserved biosignatures representative of primary (thermophilic) and secondary (including endoliths and environmental contaminants) microbial communities. Sequencing of environmental 16S rRNA genes and immuno-assays generally corroborated the lipid-based microbial identification. The multiplex immunoassays and the compound-specific isotopic analysis of carboxylic acids, alkanols, and alkanes indicated that the principal microbial pathway for carbon fixation in the three sinter mounds was through the Calvin cycle, with a relative larger contribution of the reductive acetyl-CoA pathway in the dry system. Other inferred metabolic traits varied from the liquid mound (iron and sulfur chemistry), to the steam mound (nitrogen cycle), to the dry mound (perchlorate reduction). The combined results revealed different stages of colonization that reflect differences in the lifetime of the mounds, where primary communities dominated the biosignatures preserved in sinters from the still active geysers (liquid and steam mounds), in contrast to the surviving metabolisms and microbial communities at the end of lifetime of the inactive geothermal mound.

Akin solid–solid biphasic conversion of a Li–S battery achieved by coordinated carbonate electrolytes

The sulfur chemistry is transited from the conventional dissolution–precipitation category to solid–solid biphasic conversion by tuning the coordinating structure of the carbonate based electrolyte, paving the way for achieving Li–S batteries with lower E/S ratios.

Sulfur-substituted perylene diimides: efficient tuning of LUMO levels and visible-light absorption via sulfur redox.

A series of sulfide and sulfone substituted perylene diimides (PDIs) with different LUMO levels covering a range of 0.72 eV were synthesized through simple sulfur redox chemistry. The LUMO level of phenylsulfone substituted PDI reached a record-breaking -4.75 eV. In addition, the maximum emission ranged from 540 to 692 nm.

Tailorable surface sulfur chemistry of mesoporous Ni3S2 particles for efficient oxygen evolution

Tailoring the surface sulfur chemistry of Ni3S2 can enrich Ni3+ and regulate Ni binding energy, thus intrinsically boosting the OER performance.

In My Element: Sulfur

The In My Element series celebrates the personal accounts from Chemistry – A European Journal Editorial Board members for the 2019 International Year of the Periodic Table. In this contribution, Tien-Yau Luh gives his story on sulfur. I never “loved” smelly sulfur compounds, but have always admired the versatility of sulfur chemistry. In the 1980s, we worked on organometallics to mimic desulfurization by Raney nickel and oil refining hydrotreatment. My first Ph.D. student, Zhi-Jie Ni, joined the Chinese University of Hong Kong in 1986. He was more synthetically oriented and had just learned cross-coupling from Kumada's seminar in Shanghai. Quite quickly, he discovered the nickel-catalyzed olefination of benzylic and allylic dithioacetals under Kumada conditions. Silyl-substituted styrenes and dienes could be obtained conveniently using this method. Meanwhile, Lam Lung Yeung unearthed Mo(CO)6-promoted desulfurdimerization of dithiolanes. These discoveries led us to work systematically on the conversion of two C−S bonds in dithioacetals into two C−C bonds. Ping-Fan Yang furnished geminal dimethylation using a bidendate phosphine ligand. After I moved back to Taiwan in 1988, Ken-Tsung Wong invented chelation-assisted, nickel-catalyzed olefination of aliphatic dithioacetals. Sulfur and carbon have similar electronegativities, and thus, Hsian-Rong Tseng and Chi-Fa Lee found that the propargylic dithioacetal serves as a propyne-1,3-zwitterion sython. This strategy offers a one-pot annulation of substituted furans and pyrroles. Chi-Wei Chen used the Mitsunobu reagent to eliminate β-thioalkoxyalcohols (obtained from dithioacetals). The reaction could then be extended for the selective synthesis of oligodiacetylenes. Our group members’ endeavor have shaped the dithioacetal group as a “pet” functionality in our laboratory. Position Professor Emeritus and Distinguished Chair Professor E-mail [email protected] Homepage https://www.ch.ntu.edu.tw/english/faculty/?id=tyluh&lang=en Education B.Sc. National Taiwan University (1967 and Taipei) Ph.D. University of Chicago (1974, Leon M. Stock, Chemistry of Cubane, Chicago) Postdoctoral positions (1974-76, Paul G. Gassman, Minneapolis) Notable awards Academic Award, Chemical Society Located in Taipei, 2012, JSPS Fellow, 2010, National Chair Award, Ministry of Education, 1999-2002, Ministry of Education Award for the Outstanding Research in Science, 1998, Outstanding Scholar Award, Foundation for the Advancement of Outstanding Scholarship, 1995-2000, Executive Yuan′s Outstanding Award on Science and Technology, 1994 Research interests Organometallics in organic and polymer synthesis, and chemistry of materials Hobbies Hiking, museums, calligraphy The Luh research group.

Systemic swings in end-Permian climate from Siberian Traps carbon and sulfur outgassing

Siberian Traps flood basalt magmatism coincided with the end-Permian mass extinction approximately 252 million years ago. Proposed links between magmatism and ecological catastrophe include global warming, global cooling, ozone depletion and changes in ocean chemistry. However, the critical combinations of environmental changes responsible for global mass extinction are undetermined. In particular, the combined and competing climate effects of sulfur and carbon outgassing remain to be quantified. Here we present results from global climate model simulations of flood basalt outgassing that account for sulfur chemistry and aerosol microphysics with coupled atmosphere and ocean circulation. We consider the effects of sulfur and carbon in isolation and in tandem. We find that coupling with the ocean strongly influences the climate response to prolonged flood basalt-scale outgassing. We suggest that sulfur and carbon emissions from the Siberian Traps combined to generate systemic swings in temperature, ocean circulation and hydrology within a longer-term trend towards a greenhouse world in the early Triassic. Carbon and sulfur release from the Siberian Traps igneous province caused climate swings during the end-Permian mass extinction, according to coupled global climate simulations.

Sulfur Chemistry in Polymer and Materials Science.

Sulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented. In particular, many important references in the primary literature of sulfur chemistry are referred to, including thiol-ene, thiol-yne, thiol-Michael addition, disulfide cross-linking, and thiol-disulfide exchange, among others, by explaining and illustrating the important principles. Last but not least, the grand aim to underpin the importance of sulfur in modern polymer and materials science is achieved by presenting selected examples in diverse fields and postulating the respective potential for real-world applications.

High-resolution SOFIA/EXES Spectroscopy of SO2 Gas in the Massive Young Stellar Object MonR2 IRS3: Implications for the Sulfur Budget.

Sulfur has been observed to be severely depleted in dense clouds leading to uncertainty in the molecules that contain it and the chemistry behind their evolution. Here, we aim to shed light on the sulfur chemistry in young stellar objects (YSOs) by using high-resolution infrared spectroscopy of absorption by the ν 3 rovibrational band of SO2 obtained with the Echelon-Cross-Echelle Spectrograph on the Stratospheric Observatory for Infrared Astronomy. Using local thermodynamic equilibrium models we derive physical parameters for the SO2 gas in the massive YSO MonR2 IRS3. This yields a SO2/H abundance lower limit of 5.6 ± 0.5 × 10-7, or >4% of the cosmic sulfur budget, and an intrinsic line width (Doppler parameter) of b < 3.20 km s-1. The small line widths and high temperature (T ex = 234 ± 15 K) locate the gas in a relatively quiescent region near the YSO, presumably in the hot core where ices have evaporated. This sublimation unlocks a volatile sulfur reservoir (e.g., sulfur allotropes as detected abundantly in comet 67P/Churyumov-Gerasimenko), which is followed by SO2 formation by warm, dense gas-phase chemistry. The narrowness of the lines makes formation of SO2 from sulfur sputtered off grains in shocks less likely toward MonR2 IRS3.

SO2 Donors and Prodrugs, and Their Possible Applications: A Review.

SO2 is widely recognized as an air pollutant and is a known cause of acid rain. At a sufficiently high level, it also causes respiratory diseases. A much lesser known side of SO2 is its endogenous nature and possible physiological roles. There is mounting evidence that SO2 is produced during normal cellular metabolism and may possibly function as a signaling molecule in normal physiology. The latter aspect is still at the stage of being carefully examined as to the validity of classifying SO2 as a gasotransmitter with endogenous signaling roles. One difficulty in studying the biological and pharmacological roles of SO2 is the lack of adequate tools for its controllable and precise delivery. Traditional methods of using SO2 gas or mixed sulfite salts do not meet research need for several reasons. Therefore, there has been increasing attention on the need of developing SO2 donors or prodrugs that can be used as tools for the elucidation of SO2's physiological roles, pharmacological effects, and possible mechanism(s) of action. In this review, we aim to review basic sulfur chemistry in the context of sulfur signaling and various chemical strategies used for designing SO2 donors. We will also discuss potential pharmacological applications of SO2 donors, lay out desirable features for such donors and possibly prodrugs, analyze existing problems, and give our thoughts on research needs.

“Shuttle” in Polysulfide Shuttle: Friend or Foe?

The polysulfide shuttle effect, where sulfur species reach the negative electrode surface and undergo chemical reduction, is believed to be a major bottleneck in lithium–sulfur chemistry. The importance of this phenomenon is often judged based on phenomenological arguments, which do not account for mesoscale complexations. This work presents a comprehensive investigation of the coupled interactions arising from speciation, concentrated electrolyte solution, and reaction time scales. Polysulfide transport consists of diffusion and migration, which determines the net flux. This study demonstrates that the polysulfide shuttle effect can be bounded between reaction-limited and shuttle-limited regimes, depending on the operational extremes. At high sulfur to electrolyte ratio (i.e. lean electrolyte condition), the polysulfide shuttle effect may not necessarily attribute to the cell performance limitation, believed contrarily otherwise.