Organic Chemistry

United States

Organic Chemistry

United States
SEARCH FILTERS
Time filter
Source Type

News Article | April 17, 2017
Site: cen.acs.org

Unactivated alkanes are difficult to functionalize, and most catalysts that derivatize them by opening hydrocarbon C–H bonds are based on precious transition metals. Researchers have now developed a class of intermolecular C–H arylation reactions that use catalysts made from more-abundant materials: silicon and boron. The reaction adds aryl groups to C–H bonds of simple hydrocarbons, including to the notoriously inert bonds in methane, at mild temperatures (Science 2017, DOI: 10.1126/science.aam7975). “Alkanes are bulk components of gasoline and as such are supercheap commodities, which, if converted to functionalized compounds, would become much more valuable,” comments Jay Siegel of Tianjin University, who developed a related intramolecular reaction but was not involved in the new study. “This is an area rich in prospects, with a bright future for chemical synthetic methods development.” Hosea M. Nelson and coworkers at the University of California, Los Angeles, prepare the new organosilicon catalyst from an organosilane and a weakly coordinating carborane anion. The catalyst defluorinates an aryl fluoride starting material, likely generating an aryl cation intermediate that inserts electrophilically into a C–H bond of an alkane substrate to yield an arylated alkane. A key trimethylsilyl group on the aryl fluoride aids fluoride abstraction, helps the cation react quickly, and eases catalyst regeneration. At press time, Nelson was scheduled to discuss the findings this week in a Division of Organic Chemistry presentation at the ACS national meeting in San Francisco. “Electrophilic reactions with methane are exceptionally rare, and the C–H functionalization of methane reveals the extraordinary reactivity of this system,” says Douglas Klumpp of Northern Illinois University, an expert on highly reactive electrophilic intermediates. The clever use of a trimethylsilyl group, he says, enabled the researchers “to tame a lion,” the aryl cation intermediate, “and that lion is able to do some very nice tricks.” However, Klumpp notes that one limitation of the chemistry is that “the aryl fluoride starting materials are expensive or difficult to obtain.” “The chemistry isn’t ready for prime-time applications,” Nelson says. “It’s a new strategy that will hopefully fuel further study. We need to find ways to improve the reaction’s efficiency, selectivity, and substrate scope. We have filed a provisional patent and look forward to working with the chemical industry to develop practical applications.”


News Article | April 17, 2017
Site: cen.acs.org

George A. Olah, the Donald P. and Katherine B. Loker Distinguished Professor of Organic Chemistry at the University of Southern California and the recipient of the 1994 Nobel Prize in Chemistry, has died. He was 89. Olah was a towering figure, physically and scientifically, who earned international chemistry fame 40 years ago for his novel use of “magic acid,” a concoction of antimony pentafluoride and fluorosulfonic acid that is billions of times as strong as . . .


The method circumvents the need for dry conditions, and purification steps, which saves time and gives PET radiotracers in very high yields. Fluorine-18, the most commonly used radioisotope in PET imaging, must be attached to vectors in order to diagnose disease. The best example is where fluorine-18 is attached to glucose in order to make [18F]FDG for cancer imaging. This new method has the potential to improve production of PET radiotracers like FDG, but also facilitate development of new radiotracers by allowing previously challenging vectors to be radiolabelled in high yields under mild conditions. Because a radiotracer decays, radio-synthesis needs to be performed quickly, efficiently and in high yield, so there is enough radiotracer to scan all patients at a PET medical centre. "Improving methods for incorporation of fluorine-18 has been a longstanding challenge for the radiotracer community. This research is the first example of a rhenium promoted radio-fluorination, an unprecedented, exciting discovery in the radiochemistry field," said senior author Dr Benjamin Fraser, Radiotracer Method and Organic Chemistry Task leader at ANSTO. Fraser explained that a rhenium complex was selected because of its potential for development as a dual modality PET/optical imaging agent. PET allows diagnosis of tumour location and then optical luminescence guides surgical removal of the tumour. "The choice of rhenium proved fortuitous for the incorporation of F-18 and was good example of 'chance favouring the prepared mind' as the result was not predicted but very significant. It's also important that the reaction can be done in water, as this simplifies subsequent formulation of the radiotracer in saline for injection into a patient in a clinical setting," said Fraser. The study involved the use of microfluidic technologies that had several advantages for the investigation. Dr Giancarlo Pascali, co-senior investigator on the project who is based at the Camperdown cyclotron facility, supervised the radiochemistry work under microfluidic radiolabelling conditions. "Microfluidic technologies allowed us to optimise all the reaction parameters very quickly, such as temperature, time, solvent and additives. We can optimise a given radiolabelling reaction in only three days, which under normal conditions would take one month to complete. Another benefit of microfluidics is that we work with only very small amounts of radioactivity," said Fraser. Fraser points out that at this stage the radiotracer has not been tested for use with PET. "The next step is working on conjugating the tracer to new biological vectors, but also applying the new rhenium method to established radiotracers. We can then also investigate its potential use as a dual modality probe." Explore further: A faster track to the tools that track disease More information: Mitchell A. Klenner et al. A Fluorine-18 Radiolabeling Method Enabled by Rhenium(I) Complexation Circumvents the Requirement of Anhydrous Conditions, Chemistry - A European Journal (2017). DOI: 10.1002/chem.201700440


News Article | April 17, 2017
Site: phys.org

Correlation between cryo-transmission electron microscope (TEM) images and the crystal structure. a) TEM image showing three colliding clusters. The scale bar is 10 nm. b) Relative positions of molecules derived from the X-ray diffraction crystal structure are overlaid (brown) on the TEM image. A twinning plane is shown (green line) Credit: Weizmann Institute of Science Crystallization is a very basic chemical process: School children can witness it with their own eyes. But scientists had not, until now, been able to observe this process on the molecular level - that is, the instant in which molecules overcome their tendencies to float individually in a liquid solution and take their place in the rigid lattice of a solid crystal structure. Researchers at the Weizmann Institute of Science have, for the first time, directly observed the process of crystallization on the molecular level, validating some recent theories about crystallization, as well as showing that if one knows how the crystal starts growing, one can predict the end structure. The research took place in the lab of Prof. Ronny Neumann of the Weizmann Institute's Organic Chemistry Department. Neumann explains that in order to bond to one another, the molecules must overcome an energy barrier: "The prevalent theory had been that chance contacts between molecules leads to bonding, eventually creating small clusters that become nuclei for larger crystals to grow. But the molecules, which move randomly in solution, must be aligned properly to crystalize. In recent years researchers have begun to think that this process might present too high an energy barrier." Theories proposed in the past few decades suggest that if the molecules were to congregate together in a so-called dense phase, in which they aggregate into a sardine-like state - close together but unorganized - and then crystallize from this state, the energy barrier would be lower.To test the theories, Neumann and PhD student Roy Schreiber created large, rigid molecules and froze them in place in solution. They then placed the frozen solution under an electron microscope beam that warmed up the mixture just enough to allow some movement, and thus interactions between the molecules. Adjusting the makeup of the solution by adding different ions enabled the scientists to produce crystallization with and without dense phases; for the first time, aided by Drs. Lothar Houben and Sharon Wolf of the Electron Microscopy Unit, they were able to observe dense phases forming and subsequently transforming into crystal nuclei. While both states yielded crystals, the experimental results showed that when dense phases form, the energy barrier to formation of an orderly, crystalline arrangement of molecules is, as the theory predicted, lower. The scientists also found that the growth arising from dense phases results in larger, more stable crystal nuclei. In addition they discovered that the arrangement of molecules in fully grown crystals, which they determined by X-ray crystallography with the aid of Dr. Gregory Leitus of Chemical Research Support, was in good agreement with that in the small clusters of just a few molecules in the original nuclei. "This means that the forces and factors that determine the process are constant throughout the growth of the crystal," says Neumann. "We have really observed an elementary event in the world of chemistry," says Neumann. "The findings are also leading us into new inquiries in this area, looking at the effects and significance of dense-phases on chemical reactivity." More information: Roy E. Schreiber et al. Real-time molecular scale observation of crystal formation, Nature Chemistry (2016). DOI: 10.1038/nchem.2675


News Article | May 18, 2017
Site: phys.org

The ability to assemble electronic building blocks consisting of individual molecules is an important objective in nanotechnology. An interdisciplinary research group at Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) is now significantly closer to achieving this goal. The team of researchers headed by Prof. Dr. Sabine Maier, Prof. Dr. Milan Kivala and Prof. Dr. Andreas Görling has successfully assembled and tested conductors and networks made up of individual, newly developed building block molecules. These could in future serve as the basis of components for optoelectronic systems, such as flexible flat screens or sensors. The FAU researchers have published their results in the journal Nature Communications. Lithographic techniques in which the required structures are cut from existing blocks are mainly employed at present to produce micro- and nano-electronic components. 'This is not unlike how a sculptor creates an object from existing material by cutting away what they do not need. How small we can make these structures is determined by the quality of the material and our mechanical skills,' explains Prof. Dr. Sabine Maier from the Chair of Experimental Physics. "We now have something like a set of Lego bricks for use in the nanoelectronic field; this enables us to fabricate the required objects 'bottom-up', in other words, we start from the base and place the tiny units one on top of the other." The researchers can now use these building blocks to produce the smallest one-dimensional structures -conductors - and two-dimensional structures -networks - under precision-controlled conditions. The structures are characterised by their extreme regularity with no structural flaws. Flawless structures of this kind are essential for producing minuscule nanoelectronic components with various properties. The basis of these synthetic organic semiconductors - the Lego bricks as it were - was synthesised at the Institute for Organic Chemistry at FAU. 'Our basic building block is a triangle consisting of 21 carbon atoms with one nitrogen atom at its centre, with either hydrogen, iodine or bromine deposited at the corners depending on the desired structure' clarifies Prof. Dr. Milan Kivala from the Chair of Organic Chemistry I. The FAU researchers attach the corresponding molecules to a carrier surface made of gold and this is then heated to 150 - 270°C. This process initially forms hexagons or chains. When the samples reach a temperature of 270°C, the molecular building blocks form chemically bound, flat and honeycomb-like meshes that are similar in structure to that of the Nobel Prize-winning material graphene. The research group has already managed to determine one of the major electrical properties - the so-called 'band gap'. 'We have established that the band gap of two-dimensional structures is smaller than that of one-dimensional arrangements of the same molecular building blocks,' adds Prof. Dr. Andreas Görling from the Chair of Theoretical Chemistry. 'These insights will help us in the future to predict the properties of these structures and adjust them to the desired values for specific optoelectronic applications.' This research has opened up the possibility of fabricating ever-smaller nanoelectronic components. The current lithographic techniques used in the commercial production of microchips can only create structures larger than 14 nanometres. The conductors generated in Erlangen are only a little wider than one nanometre and therefore around fifty thousand times thinner than a human hair. However, a number of additional developments are necessary before they can be used in technological applications. For example, it is still necessary to find a suitable electrically non-conductive carrier material. More information: Christian Steiner et al, Hierarchical on-surface synthesis and electronic structure of carbonyl-functionalized one- and two-dimensional covalent nanoarchitectures, Nature Communications (2017). DOI: 10.1038/ncomms14765


News Article | May 22, 2017
Site: www.cemag.us

Separation technology is at the heart of water purification, sewage treatment and reclaiming materials, as well as numerous basic industrial processes. Membranes are used to separate out the smallest, nanoscale particles and even molecules and metal ions. Professor Boris Rybtchinski and his group of the Weizmann Institute of Science’s Organic Chemistry Department have developed a new type of membrane that could extend the life of a separation system, lower its cost and, in some cases, increase its efficiency as well. The membranes he and his group have created may be produced in different ways, with different materials, and they come together in water and contain water as a major component (the membranes are akin to hydrogels). The first-generation membranes the group developed were made of unique molecules that organize themselves into the membrane material. This property also enables the membrane to be easily recycled and the particles trapped in the separation process to be reclaimed. The membranes can separate particles based on size, from one to several nanometers. The second-generation membranes also contain a second self-assembled polymer layer, thus broadening the range of applications for this technology. These new membranes can sustain high pressures and are capable of purifying water from poisonous heavy metals and organic molecules, showing for the first time that self-assembled “aqua materials” can be used for demanding industrial application.  Unlike conventional materials, the self-assembled membranes can be easily disassembled; this is critical for fighting membrane fouling, which is the biggest challenge in membrane applications. The membrane fabrication process is simple, and their performance is excellent, making the technology inherently worthwhile, even before the ability to recycle and reuse them is taken into consideration. The latter, of course, is of enormous importance, as it renders the membranes sustainable. Indeed, the goal of creating sustainable nanomaterials is at the core of the research performed by Rybtchinski and his group. Yeda Research and Development, which advances the industrial application of Weizmann Institute of Science research findings, is working on bringing this innovative technology to market.


Separation technology is at the heart of water purification, sewage treatment and reclaiming materials, as well as numerous basic industrial processes. Membranes are used to separate out the smallest nanoscale particles and even molecules and metal ions. Prof. Boris Rybtchinski and his group of the Weizmann Institute of Science's Organic Chemistry Department have developed a new type of membrane that could extend the life of a separation system, lower its cost and, in some cases, increase its efficiency as well. The membranes he and his group have created may be produced in different ways, with different materials, and they come together in water and contain water as a major component (the membranes are akin to hydrogels). The first-generation membranes the group developed were made of unique molecules that organize themselves into the membrane material. This property also enables the membrane to be easily recycled and the particles trapped in the separation process to be reclaimed. The membranes can separate particles based on size, from one to several nanometers. The second-generation membranes also contain a second self-assembled polymer layer, thus broadening the range of applications for this technology. These new membranes can sustain high pressures and are capable of purifying water from poisonous heavy metals and organic molecules, showing for the first time that self-assembled "aqua materials" can be used for demanding industrial application. Unlike conventional materials, the self-assembled membranes can be easily disassembled; this is critical for fighting membrane fouling, which is the biggest challenge in membrane applications. The membrane fabrication process is simple, and their performance is excellent, making the technology inherently worthwhile, even before the ability to recycle and reuse them is taken into consideration. The latter, of course, is of enormous importance, as it renders the membranes sustainable. Indeed, the goal of creating sustainable nanomaterials is at the core of the research performed by Rybtchinski and his group. Explore further: Decontamination of water with a robust and sustainable membrane


News Article | May 29, 2017
Site: www.sciencedaily.com

Chemists at the University of Amsterdam's Van 't Hoff Institute for Molecular Sciences have discovered a new class of molecules. This week they report in Nature Communications on their synthesis method leading to 'quasi[1]catenanes': pretzel-like molecules consisting of two molecular rings 'oppositely' coupled at a central carbon atom. The discovery is an important step towards synthesis of lasso peptides; new molecules with a potential use as medicines. The Nature Communication article is the crowning achievement of a five-year research effort at the Synthetic Organic Chemistry research group of professor Jan van Maarseveen, with PhD student Luuk Stemers in the lead. He has developed a method that paves the way for synthesis of so-called lasso peptides. Lasso peptides are small proteins that, as their name indicates, consist of a molecular 'loop' around a molecular 'rope'. They were first isolated from bacteria at the turn of the current century. Recently, DNA analysis has revealed that lasso peptides are quite common in the realm of bacteria. Their biological function is to act as an antibiotic against other micro-organisms, which makes them a potential new class of antibiotics. The fact that 15 years after the discovery of lasso-peptides synthetic chemists have not yet been able to develop a strategy leading to their unique molecular architecture underpins the complexity of these molecules. The bottleneck here is that the rope is usually tightly bound within the loop. This distinguishes lasso peptides from rotaxanes for which Scottish chemist Sir Fraser Stoddart shared the Nobel prize for chemistry last year. During rotaxane synthesis the rope is 'pulled' through the loop. Since this is impossible for lasso peptide synthesis, the Amsterdam chemists used a different approach, forcing the loop to close in the right place around the rope. This turned out to be quite an undertaking. Eventually Luuk Stemers managed to create a molecular scaffold assisting the synthesis in such a way that the loop correctly forms around the rope. The new synthesis method is a major step forward in the synthetic route towards functional lasso peptides. To demonstrate the power of the method Stemers applied his scaffold to also force both ends of the rope to form a second loop. This resulted in the synthesis of a whole new class of pretzel-like molecules that the Amsterdam researchers coined quasi[1]catenanes. ('Real' catenanes consist of two loosely intertwined molecular ring-like structures. The French chemist Jean-Pierre Sauvage developed catenanes and shared the Nobel prize with Stoddard, and Dutch chemist Ben Feringa.) The next step in the research effort of the Amsterdam researchers towards lasso peptide synthesis will be to introduce easily breakable bonds in the quasi[1]catenane, so that the rings can be unlocked.


News Article | May 26, 2017
Site: phys.org

The Nature Communication article is the crowning achievement of a five-year research effort at the Synthetic Organic Chemistry research group of professor Jan van Maarseveen, with PhD student Luuk Stemers in the lead. He has developed a method that paves the way for synthesis of so-called lasso peptides. Lasso peptides are small proteins that, as their name indicates, consist of a molecular 'loop' around a molecular 'rope'. They were first isolated from bacteria at the turn of the current century. Recently, DNA analysis has revealed that lasso peptides are quite common in the realm of bacteria. Their biological function is to act as an antibiotic against other micro-organisms, which makes them a potential new class of antibiotics. The fact that 15 years after the discovery of lasso-peptides synthetic chemists have not yet been able to develop a strategy leading to their unique molecular architecture underpins the complexity of these molecules. The bottleneck here is that the rope is usually tightly bound within the loop. This distinguishes lasso peptides from rotaxanes for which Scottish chemist Sir Fraser Stoddart shared the Nobel prize for chemistry last year. During rotaxane synthesis the rope is 'pulled' through the loop. Since this is impossible for lasso peptide synthesis, the Amsterdam chemists used a different approach, forcing the loop to close in the right place around the rope. This turned out to be quite an undertaking. Eventually Luuk Stemers managed to create a molecular scaffold assisting the synthesis in such a way that the loop correctly forms around the rope. The new synthesis method is a major step forward in the synthetic route towards functional lasso peptides. To demonstrate the power of the method Stemers applied his scaffold to also force both ends of the rope to form a second loop. This resulted in the synthesis of a whole new class of pretzel-like molecules that the Amsterdam researchers coined quasi[1]catenanes. ('Real' catenanes consist of two loosely intertwined molecular ring-like structures. The French chemist Jean-Pierre Sauvage developed catenanes and shared the Nobel prize with Stoddard, and Dutch chemist Ben Feringa.) The next step in the research effort of the Amsterdam researchers towards lasso peptide synthesis will be to introduce easily breakable bonds in the quasi[1]catenane, so that the rings can be unlocked. Explore further: New tool, RODEO, promises to capture the breadth of microbial biosynthetic potential More information: Luuk Steemers et al. Synthesis of spiro quasi[1]catenanes and quasi[1]rotaxanes via a templated backfolding strategy, Nature Communications (2017). DOI: 10.1038/ncomms15392


News Article | May 9, 2017
Site: www.businesswire.com

VICTORIA, British Columbia--(BUSINESS WIRE)--Aurinia Pharmaceuticals Inc. (NASDAQ:AUPH / TSX:AUP) (“Aurinia” or the “Company”), a clinical stage biopharmaceutical company focused on the global immunology market, today announced the appointment of George M. Milne, Jr., Ph.D. to its board of directors. Prior to his retirement, Dr. Milne served as Executive Vice President of Global Research and Development and President of Worldwide Strategic and Operations Management at Pfizer. Dr. Milne serves on multiple corporate boards including Charles River Laboratories where he is the lead director and Amylyx Pharmaceuticals and is Venture Partner at Radius Ventures. “George has made significant contributions to the pharmaceutical sector during his successful career. His experience in the board room will prove extremely valuable as we approach the next crucial stage of development as a company working to advance voclosporin to market while exploring potential additional indications for the compound,” said Richard M. Glickman, Chief Executive Officer of Aurinia. Dr. Milne has over 30 years of experience in pharmaceutical research and product development. He joined Pfizer in 1970 and held a variety of positions conducting both chemistry and pharmacology research. Dr. Milne became director of the department of immunology and infectious diseases at Pfizer in 1981, was its executive director from 1984 to 1985, and was vice president of research and development from 1985 to 1988. He was appointed senior vice president in 1988. In 1993 he was appointed President of Pfizer Central Research and a senior vice president of Pfizer with global responsibility for human and veterinary medicine R&D. Dr. Milne has served on multiple corporate boards including Mettler-Toledo, Inc., MedImmune, Athersys, Biostorage Technologies, Aspreva, and Conor Medsystems. Dr. Milne received his B.Sc. in Chemistry from Yale University and his Ph.D. in Organic Chemistry from MIT. "Aurinia has demonstrated its leadership in advancing a viable treatment option for patients suffering from lupus nephritis,” added George Milne. “I look forward to working alongside this exceptional team and sharing my expertise as we pursue a successful future for the company.” Additionally, the company announced that Dr. Greg Ayers has resigned from Aurinia’s board of directors, effective immediately. “On behalf of the board of directors, I thank Greg for his service and contributions and wish him well in future endeavors," added Dr. Glickman. Voclosporin, an investigational drug, is a novel and potentially best-in-class calcineurin inhibitor (“CNI”) with clinical trial data in over 2,200 patients across indications. Voclosporin is an immunosuppressant, with a synergistic and dual mechanism of action that has the potential to improve near- and long-term outcomes in LN when added to standard of care (MMF). By inhibiting calcineurin, voclosporin blocks IL-2 expression and T-cell mediated immune responses. Voclosporin is made by a modification of a single amino acid of the cyclosporine molecule which results in a more predictable pharmacokinetic and pharmacodynamic relationship with potential for flat dosing. In addition, Voclosporin is more potent than and has an improved metabolic profile versus cyclosporine. Aurinia anticipates that upon regulatory approval, patent protection for voclosporin will be extended in the United States and certain other major markets, including Europe and Japan, until at least October 2027 under the Hatch-Waxman Act and comparable laws in other countries. LN, an inflammation of the kidney caused by Systemic Lupus Erythematosus (“SLE”), represents a serious progression of SLE. SLE is a chronic, complex and often disabling disorder that affects more than 500,000 people in the United States (mostly women). The disease is highly heterogeneous, affecting a wide range of organs & tissue systems. It is estimated that as many as 60% of all SLE patients have clinical LN requiring treatment. Unlike SLE, LN has a strong surrogate marker, proteinuria, which correlates with meaningful longer term clinical outcome. In patients with LN, renal damage results in proteinuria and/or hematuria and a decrease in renal function as evidenced by reduced estimated glomerular filtration rate (eGFR), and increased serum creatinine levels. LN is debilitating and costly and if poorly controlled, LN can lead to permanent and irreversible tissue damage within the kidney, resulting in end-stage renal disease (ESRD), thus making LN a serious and potentially life-threatening condition. Aurinia is a clinical stage biopharmaceutical company focused on developing and commercializing therapies to treat targeted patient populations that are suffering from serious diseases with a high unmet medical need. Aurinia is currently developing voclosporin, an investigational drug, for the treatment of LN. Aurinia is headquartered in Victoria, BC and focuses its development efforts globally. www.auriniapharma.com. This press release contains forward-looking statements, including statements related to Aurinia’s plans to advance voclosporin to market and explore additional indications for the compound, Dr. Milne’s expected impact on Aurinia’s progress, the belief that voclosporin is a potentially best-in-class CNI and a viable treatment option for patients suffering from LN with potential to improve near- and long-term outcomes in LN, and the belief that upon regulatory approval, patent protection for voclosporin will be extended in the United States and certain other major markets, including Europe and Japan, until at least October 2027. It is possible that such results or conclusions may change based on further analyses of these data. Words such as "plans," "intends," “may,” "will," "believe," and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon Aurinia’s current expectations. Forward-looking statements involve risks and uncertainties. Aurinia’s actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, the risk that Aurinia’s analyses, assessment and conclusions of the results of its clinical studies may change based on further analyses, the risk that Aurinia will not successfully complete its clinical programs and the risk that Aurinia’s clinical studies for voclosporin may not lead to regulatory approval. These and other risk factors are discussed under "Risk Factors" and elsewhere in Aurinia’s Annual Information Form for the year ended December 31, 2016 filed with Canadian securities authorities and available at www.sedar.com and on Form 40-F with the U.S. Securities Exchange Commission and available at www.sec.gov, each as updated by subsequent filings, including filings on Form 6-K. Aurinia expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in Aurinia's expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based, except as required by law.

Loading Organic Chemistry collaborators
Loading Organic Chemistry collaborators