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Chemical Reviews

Neha Patel, Radhika Sood, Prasad V Bharatam
Phase-transfer catalysts (PTCs), currently, are one of the most important tools of chemists for performing organic reactions. PTCs accelerate several types of reactions in biphasic systems, giving excellent yields of the desired product. Most of the PTCs belong to the general formula NR4 + X- . In the recent past, several compounds possessing a novel scaffold with the general formula NL2 + X- have been reported as PTCs. In the NL2 + species, a nitrogen atom with a formal positive charge accepts electron density from electron-donating ligands...
August 16, 2018: Chemical Reviews
Jennifer Koviach-Côté, Alyssa L Pirinelli
As an important but underappreciated field, carbohydrate chemistry is a critical topic for undergraduate students to learn. With applications to nutrition, food science, and diabetes, carbohydrates provide real-world relevance to students. This review summarizes the literature of undergraduate laboratory experiments which use carbohydrates since the year 2000. Experiments explore important chemical concepts such as synthesis, kinetics, analysis, and computational chemistry. Experiments designed for general chemistry, organic chemistry, biochemistry, and analytical chemistry at a variety of skill levels are presented...
August 16, 2018: Chemical Reviews
Ashanul Haque, Rayya A Al-Balushi, Idris Juma Al-Busaidi, Muhammad S Khan, Paul R Raithby
Conjugated poly-ynes and poly(metalla-ynes) constitute an important class of new materials with potential application in various domains of science. The key factors responsible for the diverse usage of these materials is their intriguing and tunable chemical and photophysical properties. This review highlights fascinating advances made in the field of conjugated organic poly-ynes and poly(metalla-ynes) incorporating group 4-11 metals. This includes several important aspects of conjugated poly-ynes viz. synthetic protocols, bonding, electronic structure, nature of luminescence, structure-property relationships, diverse applications, and concluding remarks...
August 16, 2018: Chemical Reviews
Adam J Clancy, Mustafa K Bayazit, Stephen A Hodge, Neal T Skipper, Christopher A Howard, Milo S P Shaffer
Since the discovery of buckminsterfullerene over 30 years ago, sp2 -hybridised carbon nanomaterials (including fullerenes, carbon nanotubes, and graphene) have stimulated new science and technology across a huge range of fields. Despite the impressive intrinsic properties, challenges in processing and chemical modification continue to hinder applications. Charged carbon nanomaterials (CCNs), formed via the reduction or oxidation of these carbon nanomaterials, facilitate dissolution, purification, separation, chemical modification, and assembly...
August 15, 2018: Chemical Reviews
Masha G Savelieff, Geewoo Nam, Juhye Kang, Hyuck Jin Lee, Misun Lee, Mi Hee Lim
Neurodegenerative diseases pose a substantial socioeconomic burden on society. Unfortunately, the aging world population and lack of effective cures foreshadow a negative outlook. Although a large amount of research has been dedicated to elucidating the pathologies of neurodegenerative diseases, their principal causes remain elusive. Metal ion dyshomeostasis, proteopathy, oxidative stress, and neurotransmitter deficiencies are pathological features shared across multiple neurodegenerative disorders. In addition, these factors are proposed to be interrelated upon disease progression...
August 10, 2018: Chemical Reviews
Robert J Woods
Complex carbohydrates are ubiquitous in nature, and together with proteins and nucleic acids they comprise the building blocks of life. But unlike proteins and nucleic acids, carbohydrates form nonlinear polymers, and they are not characterized by robust secondary or tertiary structures but rather by distributions of well-defined conformational states. Their molecular flexibility means that oligosaccharides are often refractory to crystallization, and nuclear magnetic resonance (NMR) spectroscopy augmented by molecular dynamics (MD) simulation is the leading method for their characterization in solution...
August 9, 2018: Chemical Reviews
Zhenchuang Xu, Chao Liu, Shujuan Zhao, Si Chen, Yanchuan Zhao
Reliable and precise methods capable of unambiguously identifying target analytes in real-world samples are indispensable in various fields, ranging from biological studies and diagnosis to quality control. Among various analytic techniques, nuclear magnetic resonance (NMR) is uniquely powerful as it provides multidimensional data useful for structural analysis at the atomic level. The rich information obtained from various NMR experiments allows one to access not only molecular structures and interactions but also the dynamics and diffusional properties...
August 6, 2018: Chemical Reviews
Sandeep Ghosh, Liberato Manna
Over the years, scientists have identified various synthetic "handles" while developing wet chemical protocols for achieving a high level of shape and compositional complexity in colloidal nanomaterials. Halide ions have emerged as one such handle which serve as important surface active species that regulate nanocrystal (NC) growth and concomitant physicochemical properties. Halide ions affect the NC growth kinetics through several means, including selective binding on crystal facets, complexation with the precursors, and oxidative etching...
July 31, 2018: Chemical Reviews
Martin P Stewart, Robert Langer, Klavs F Jensen
Intracellular delivery is a key step in biological research and has enabled decades of biomedical discoveries. It is also becoming increasingly important in industrial and medical applications ranging from biomanufacture to cell-based therapies. Here, we review techniques for membrane disruption-based intracellular delivery from 1911 until the present. These methods achieve rapid, direct, and universal delivery of almost any cargo molecule or material that can be dispersed in solution. We start by covering the motivations for intracellular delivery and the challenges associated with the different cargo types-small molecules, proteins/peptides, nucleic acids, synthetic nanomaterials, and large cargo...
July 27, 2018: Chemical Reviews
Changshui Huang, Yongjun Li, Ning Wang, Yurui Xue, Zicheng Zuo, Huibiao Liu, Yuliang Li
Graphynes (GYs) are carbon allotropes with single-atom thickness that feature layered 2D structure assembled by carbon atoms with sp - and sp2 - hybridization form. Various functional theories have predicted GYs to have natural band gap with Dirac cones structure, presumably originating from inhomogeneous π-bonding between those carbon atoms with different hybridization and overlap of the carbon 2p z orbitals. Among all the GYs, graphdiyne (GDY) was the first reported to be prepared practically and, hence, attracted the attention of many researchers toward this new planar, layered material, as well as other GYs...
July 26, 2018: Chemical Reviews
Ke Zheng, Xiaohua Liu, Xiaoming Feng
The metal-catalyzed asymmetric conjugate addition (ACA) reaction has emerged as a general and powerful approach for the construction of optically active compounds and is among the most significant and useful reactions in synthetic organic chemistry. In recent years, great progress has been made in this area with the use of various chiral metal complexes based on different chiral ligands. This review provides comprehensive and critical information on the enantioselective 1,4-conjugate addition of nonorganometallic (soft) nucleophiles and their importance in synthetic applications...
July 26, 2018: Chemical Reviews
Christopher D Spicer, E Thomas Pashuck, Molly M Stevens
The conjugation of biomolecules can impart materials with the bioactivity necessary to modulate specific cell behaviors. While the biological roles of particular polypeptide, oligonucleotide, and glycan structures have been extensively reviewed, along with the influence of attachment on material structure and function, the key role played by the conjugation strategy in determining activity is often overlooked. In this review, we focus on the chemistry of biomolecule conjugation and provide a comprehensive overview of the key strategies for achieving controlled biomaterial functionalization...
July 24, 2018: Chemical Reviews
Agostino Cilibrizzi, Vincenzo Abbate, Yu-Lin Chen, Yongmin Ma, Tao Zhou, Robert C Hider
Hydroxypyridinones (HOPOs) form outstanding building blocks for the development of a variety of agents in the field of metal chelation. The pyridinone ring is easily synthesized and readily converted into tetradentate, hexadentate, and octadentate chelators. There is considerable potential for the control of the stereochemistry of the resulting metal complex and hence the properties of these multidentate molecules. Their ability to rapidly bind hard metals in aqueous media has facilitated the development of efficient applications in both biological and medical contexts...
July 23, 2018: Chemical Reviews
Ángela Vivancos, Candela Segarra, Martin Albrecht
Mesoionic carbenes are a subclass of the family of N-heterocyclic carbenes that generally feature less heteroatom stabilization of the carbenic carbon and hence impart specific donor properties and reactivity schemes when coordinated to a transition metal. Therefore, mesoionic carbenes and their complexes have attracted considerable attention both from a fundamental point of view as well as for application in catalysis and beyond. As a follow-up of an earlier Chemical Reviews overview from 2009, the organometallic chemistry of N-heterocyclic carbenes with reduced heteroatom stabilization is compiled for the 2008-2017 period, including specifically the chemistry of complexes containing 1,2,3-triazolylidenes, 4-imidazolylidenes, and related 5-membered N-heterocyclic carbenes with reduced heteratom stabilization such as (is)oxazolylidenes, pyrrazolylidenes, and thiazolylidenes, as well as pyridylidenes as 6-membered N-heterocyclic carbenes with reduced heteroatom stabilization...
July 17, 2018: Chemical Reviews
Liuqing Wen, Garrett Edmunds, Christopher Gibbons, Jiabin Zhang, Madhusudhan Reddy Gadi, Hailiang Zhu, Junqiang Fang, Xianwei Liu, Yun Kong, Peng George Wang
Oligosaccharides together with oligonucleotides and oligopeptides comprise the three major classes of natural biopolymers. Automated systems for oligonucleotide and oligopeptide synthesis have significantly advanced developments in biological science by allowing nonspecialists to rapidly and easily access these biopolymers. Researchers have endeavored for decades to develop a comparable general automated system to synthesize oligosaccharides. Such a system would have a revolutionary impact on the understanding of the roles of glycans in biological systems...
July 16, 2018: Chemical Reviews
Chang-Sheng Wang, Pierre H Dixneuf, Jean-François Soulé
Transition metal-catalyzed C-H bond functionalizations have been the focus of intensive research over the last decades for the formation of C-C bonds from unfunctionalized arenes, heteroarenes, alkenes. These direct transformations provide new approaches in synthesis with high atom- and step-economy compared to the traditional catalytic cross-coupling reactions. However, such methods still suffer from several limitations including functional group tolerance and the lack of regioselectivity. In addition, they often require harsh reaction conditions and some of them need the use of strong oxidant, in a stoichiometric amount, avoiding these processes to be truly eco-friendly...
July 16, 2018: Chemical Reviews
Jun Cheng, Lijun Wang, Peng Wang, Liang Deng
High-oxidation-state 3d metal species have found a wide range of applications in modern synthetic chemistry and materials science. They are also implicated as key reactive species in biological reactions. These applications have thus prompted explorations of their formation, structure, and properties. While the traditional wisdom regarding these species was gained mainly from complexes supported by nitrogen- and oxygen-donor ligands, recent studies with N-heterocyclic carbenes (NHCs), which are widely used for the preparation of low-oxidation-state transition metal complexes in organometallic chemistry, have led to the preparation of a large variety of isolable high-oxidation-state 3d metal complexes with NHC ligation...
July 16, 2018: Chemical Reviews
Katharina Hüll, Johannes Morstein, Dirk Trauner
Synthetic photoswitches have been known for many years, but their usefulness in biology, pharmacology, and medicine has only recently been systematically explored. Over the past decade photopharmacology has grown into a vibrant field. As the photophysical, pharmacodynamic, and pharmacokinetic properties of photoswitches, such as azobenzenes, have become established, they have been applied to a wide range of biological targets. These include transmembrane proteins (ion channels, transporters, G protein-coupled receptors, receptor-linked enzymes), soluble proteins (kinases, proteases, factors involved in epigenetic regulation), lipid membranes, and nucleic acids...
July 9, 2018: Chemical Reviews
Aba Losi, Kevin H Gardner, Andreas Möglich
Sensory photoreceptors underpin light-dependent adaptations of organismal physiology, development, and behavior in nature. Adapted for optogenetics, sensory photoreceptors become genetically encoded actuators and reporters to enable the noninvasive, spatiotemporally accurate and reversible control by light of cellular processes. Rooted in a mechanistic understanding of natural photoreceptors, artificial photoreceptors with customized light-gated function have been engineered that greatly expand the scope of optogenetics beyond the original application of light-controlled ion flow...
July 9, 2018: Chemical Reviews
Carmanah D Hunter, Tianlin Guo, Gour Daskhan, Michele R Richards, Christopher W Cairo
The plasma membrane of cells contains a diverse array of lipids that provide important structural and biological features. Glycolipids are typically a minor component of the cell membrane and consist primarily of glycosphingolipids (GSLs). GSLs in vertebrates contain a multifarious assortment of glycan headgroups, which can be important to biological functions based on lipid-lipid and lipid-protein interactions. The design of probes to study these complex targets requires advanced synthetic methodologies. In this Review, we will discuss recent advances in chemical and chemoenzymatic synthesis of GSLs in conjunction with the use of these approaches to design new probes...
July 6, 2018: Chemical Reviews
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