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Accounts of Chemical Research

Brian P Chaplin
Growing worldwide population, climate change, and decaying water infrastructure have all contributed to a need for a better water treatment and conveyance model. Distributed water treatment is one possible solution, which relies on the local treatment of water from various sources to a degree dependent on its intended use and, finally, distribution to local consumers. This distributed, fit-for-purpose water treatment strategy requires the development of new modular point-of-use and point-of-entry technologies to bring this idea to fruition...
February 15, 2019: Accounts of Chemical Research
Wei Gao, Hiroki Ota, Daisuke Kiriya, Kuniharu Takei, Ali Javey
Wearable sensors play a crucial role in realizing personalized medicine, as they can continuously collect data from the human body to capture meaningful health status changes in time for preventive intervention. However, motion artifacts and mechanical mismatches between conventional rigid electronic materials and soft skin often lead to substantial sensor errors during epidermal measurement. Because of its unique properties such as high flexibility and conformability, flexible electronics enables a natural interaction between electronics and the human body...
February 15, 2019: Accounts of Chemical Research
Kelly M Craft, Steven D Townsend
This Account describes the risky proposition of organizing a multidisciplinary team to interrogate a challenging problem in chemical biology: characterizing how human milk, at the molecular level, protects infants from infectious diseases. At the outset, our initial hypothesis was that human milk oligosaccharides (HMOs) possess antimicrobial and antivirulence activities. Early on, we discovered that HMOs do indeed modulate bacterial growth and biofilm production for numerous bacterial pathogens. In light of this discovery, three priorities emerged for our program moving forward...
February 14, 2019: Accounts of Chemical Research
Amandeep Kaur, Elizabeth J New
The availability of electrons to biological systems underpins the mitochondrial electron transport chain (ETC) that powers living cells. It is little wonder, therefore, that the sufficiency of electron supply is critical to cellular health. Considering mitochondrial redox activity alone, a lack of oxygen (hypoxia) leads to impaired production of adenosine triphosphate (ATP), the major energy currency of the cell, whereas excess oxygen (hyperoxia) is associated with elevated production of reactive oxygen species (ROS) from the interaction of oxygen with electrons that have leaked from the ETC...
February 12, 2019: Accounts of Chemical Research
Haoyi Li, Xun Wang
Crystalline polymorphs have been considered a prevailing phenomenon in inorganic nanocrystals and provide approaches to modulate fundamental properties and innovative advanced applications. As a basic demand for phase engineering, accessible and controllable synthetic methodologies are indispensable for acquisition of high-quality products in expected phases. Phase stability is also a non-negligible issue that determines continuous gains of functionality and long-term sustainability of characteristic features...
February 12, 2019: Accounts of Chemical Research
Scott E Crawford, Michael J Hartmann, Jill E Millstone
From size-dependent luminescence to localized surface plasmon resonances, the optical properties that emerge from common materials with nanoscale dimensions have been revolutionary. As nanomaterials get smaller, they approach molecular electronic structures, and this transition from bulk to molecular electronic properties is a subject of far-reaching impact. One class of nanomaterials that exhibit particularly interesting optoelectronic features at this size transition are coinage metal (i.e., group 11 elements copper, silver, and gold) nanoparticles with core diameters between approximately 1 to 3 nm (∼25-200 atoms)...
February 11, 2019: Accounts of Chemical Research
Jiani Ma, Xiting Zhang, David Lee Phillips
In recent years, unusual and efficient self-photoredox reactions were detected for selected benzophenone derivatives (BPs) and anthraquinone derivatives (AQs) in aqueous environments by Wan and co-workers, where the carbonyl undergoes reduction to the corresponding alcohol and a side-chain alcohol group undergoes oxidation to the corresponding carbonyl. To unravel the photoredox reaction mechanisms of these types of BPs and AQs in aqueous environments, we have utilized a combination of time-resolved spectroscopy techniques such as femtosecond transient absorption, nanosecond transient absorption, and nanosecond time-resolved resonance Raman spectroscopy to detect and characterize the electronic absorption and vibrational spectra of the intermediates and transient species from the femtosecond to microsecond time region after they are generated in the photoredox reactions...
February 11, 2019: Accounts of Chemical Research
Buddhinie S Jayathilake, Supriyo Bhattacharya, Nagarajan Vaidehi, S R Narayanan
Increasing levels of carbon dioxide in the atmosphere and the growing need for energy necessitate a shift toward reliance on renewable energy sources and the utilization of carbon dioxide. Thus, producing carbonaceous fuel by the electrochemical reduction of carbon dioxide has been very appealing. We have focused on addressing the principal challenges of poor selectivity and poor energy efficiency in the electrochemical reduction of carbon dioxide. We have demonstrated here a viable pathway for the efficient and continuous electrochemical reduction of CO2 to formate using the metal-independent enzyme type of formate dehydrogenase (FDH) derived from C andida boidinii yeast...
February 11, 2019: Accounts of Chemical Research
Alexandria Deliz Liang, Joan Serrano-Plana, Ryan L Peterson, Thomas R Ward
Artificial metalloenzymes (ArMs) result from anchoring a metal-containing moiety within a macromolecular scaffold (protein or oligonucleotide). The resulting hybrid catalyst combines attractive features of both homogeneous catalysts and enzymes. This strategy includes the possibility of optimizing the reaction by both chemical (catalyst design) and genetic means leading to achievement of a novel degree of (enantio)selectivity, broadening of the substrate scope, or increased activity, among others. In the past 20 years, the Ward group has exploited, among others, the biotin-(strept)avidin technology to localize a catalytic moiety within a well-defined protein environment...
February 8, 2019: Accounts of Chemical Research
Arthur Hirsch, Laurent Dejace, Hadrien O Michaud, Stéphanie P Lacour
Emerging applications of the Internet of Things in healthcare, wellness, and gaming require continuous monitoring of the body and its environment, fueling the need for wearable devices able to maintain intimate, reliable, and unobtrusive contact with the human body. This translates in the necessity to develop soft and deformable electronics that match the body's mechanics and dynamics. In recent years, various strategies have been proposed to form stretchable circuits and more specifically elastic electrical conductors embedded in elastomeric substrate using either geometrical structuring of solid conductors or intrinsically stretchable materials...
February 4, 2019: Accounts of Chemical Research
Junnian Wei, Paula L Diaconescu
Switchable catalysts incorporate stimuli-responsive features and allow synthetic tasks that are difficult or impossible to accomplish in other ways. They mimic biological processes in that they can provide both spatial and temporal control, unlike most reactions promoted by human-made catalysts that usually occur according to carefully optimized conditions. In the area of switchable catalysis, redox-switchable ring-opening polymerization (ROP) has attracted much attention, emerging as a powerful strategy for the development of environmentally friendly biodegradable copolymers, especially those containing blocks with complementary properties...
February 1, 2019: Accounts of Chemical Research
Changjian Xie, Christopher L Malbon, Hua Guo, David R Yarkony
It is now well established that conical intersections play an essential role in nonadiabatic radiationless decay where their double-cone topography causes them to act as efficient funnels channeling wave packets from the upper to the lower adiabatic state. Until recently, little attention was paid to the effect of conical intersections on dynamics on the lower state, particularly when the total energy involved is significantly below that of the conical intersection seam. This energetic deficiency is routinely used as a sufficient condition to exclude consideration of excited states in ground state dynamics...
February 1, 2019: Accounts of Chemical Research
Mysore S Shashidhar, Shobhana Krishnaswamy
It is far more difficult to recognize and predict the chemical reactions that a molecule of an organic compound can undergo in crystalline (solid) state as compared to the solution state (the "organic functional group" approach), since the published data on solid-state structure-reactivity investigations and correlations are scant. The discovery of the first intermolecular acyl-transfer reaction in molecular crystals of racemic 2,4-di- O-benzoyl- myo-inositol-1,3,5-orthoformate (DiBz) during our attempts to develop methods for the synthesis of phosphoinositols, motivated us to find other molecular crystals capable of supporting similar reactions...
January 30, 2019: Accounts of Chemical Research
Lewis A Churchfield, F Akif Tezcan
Nature puts to use only a small fraction of metal ions in the periodic table. Yet, when incorporated into protein scaffolds, this limited set of metal ions carry out innumerable cellular functions and execute essential biochemical transformations such as photochemical H2 O oxidation, O2 or CO2 reduction, and N2 fixation, highlighting the outsized importance of metalloproteins in biology. Not surprisingly, elucidating the intricate interplay between metal ions and protein structures has been the focus of extensive structural and mechanistic scrutiny over the last several decades...
January 30, 2019: Accounts of Chemical Research
Xiaoming Tao
Fiber-based electronic and photonic devices have the most desired human-friendly features, such as being soft, ubiquitous, flexible, stretchable, light, and permeable, and thus are ideal to be employed as the interface platform between humans, the environment, and machines. Today, these smart wearable devices are normally powered by rechargeable batteries. It is extremely desirable to have an undisrupted power supply for us to go anywhere at any time. Harvesting energy from the ambient environment or our body can potentially fulfill such a goal...
January 30, 2019: Accounts of Chemical Research
Yu Qiu, Elric Zhang, Roshan Plamthottam, Qibing Pei
Creating an artificial muscle has been one of the grand challenges of science and engineering. The invention of such a flexible, versatile, and power efficient actuator opens the gate for a new generation of lightweight, highly efficient, and multifunctional robotics. Many current artificial muscle technologies enable low-power mobile actuators, robots that mimic efficient and natural forms of motion, autonomous robots and sensors, and lightweight wearable technologies. They also have serious applications in biomedical devices, where biocompatibility, from a chemical, flexibility, and force perspective, is crucial...
January 30, 2019: Accounts of Chemical Research
Sean N Natoli, John F Hartwig
Enzymes have evolved to catalyze a range of biochemical transformations with high efficiencies and unparalleled selectivities, including stereoselectivities, regioselectivities, chemoselectivities, and substrate selectivities, while typically operating under mild aqueous conditions. These properties have motivated extensive research to identify or create enzymes with reactivity that complements or even surpasses the reactivity of small-molecule catalysts for chemical reactions. One of the limitations preventing the wider use of enzymes in chemical synthesis, however, is the narrow range of bond constructions catalyzed by native enzymes...
January 29, 2019: Accounts of Chemical Research
Abu Asaduzzaman, Demian Riccardi, Akef T Afaneh, Sarah J Cooper, Jeremy C Smith, Feiyue Wang, Jerry M Parks, Georg Schreckenbach
Mercury (Hg) is a global environmental contaminant. Major anthropogenic sources of Hg emission include gold mining and the burning of fossil fuels. Once deposited in aquatic environments, Hg can undergo redox reactions, form complexes with ligands, and adsorb onto particles. It can also be methylated by microorganisms. Mercury, especially its methylated form methylmercury, can be taken up by organisms, where it bioaccumulates and biomagnifies in the food chain, leading to detrimental effects on ecosystem and human health...
January 28, 2019: Accounts of Chemical Research
Gregory I Peterson, Sanghee Yang, Tae-Lim Choi
Metathesis cyclopolymerization (CP) of α,ω-diynes is a powerful method to prepare functional polyacetylenes (PAs). PAs have long been studied due to their interesting electrical, optical, photonic, and magnetic properties which make them candidates for use in various advanced applications. Grubbs catalysts are widely used throughout synthetic chemistry, largely due to their accessibility, high reactivity, and tolerance to air, moisture, and many functional groups. Prior to our entrance into this field, only a few examples of CP using modified Grubbs catalysts existed...
January 28, 2019: Accounts of Chemical Research
Manfred T Reetz
Transition metal catalysts mediate a wide variety of chemo-, stereo-, and regioselective transformations, and therefore play a pivotal role in modern synthetic organic chemistry. Steric and electronic effects of ligands provide organic chemists with an exceedingly useful tool. More than four decades ago, chemists began to think about a different approach, namely, embedding achiral ligand/metal moieties covalently or noncovalently in protein hosts with formation of artificial metalloenzymes. While structurally fascinating, this approach led in each case only to a single (bio)catalyst, with its selectivity and activity being a matter of chance...
January 28, 2019: Accounts of Chemical Research
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