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Section: Mechanism of action. Molecular photoswitches are utilized in the field of photopharmacology, where the energetics of a molecule can be reversibly controlled with light to achieve spatial and temporal resolution of a particular effect. Photoswitches may function by undergoing photoisomerization through which li... | Wikipedia - Photopharmacology - Mechanism of action | 333 | 1,663 | null |
The structure is two phenyl rings joined with a N=N double bond and is the simplest aryl azo compound. Azobenzene and its derivatives have two accessible absorbance bands: the S1 state from a n-π* transition which can be excited into using blue light, and the S2 state from a π-π* transition that can be excited into usi... | Wikipedia - Photopharmacology - Mechanism of action | 342 | 1,484 | null |
Alternatively, photoswitches may themselves be emissive and exhibit environmental control over their properties. One such example is a class of ruthenium polypyridyl coordination complexes. Typically they contain two bidentate bipyridine or phenanthroline ligands and an extended phenanthroline-phenazine bidentate ligan... | Wikipedia - Photopharmacology - Mechanism of action | 274 | 1,199 | null |
Section: Molecules > Azobenzenes. Azobenzenes are a class of photoswitchable molecules and are used in photopharmalogical applications for their reversible photoisomerization, as described in the previous section. An example of a photoswitchable molecule that uses azobenzene is phototrexate. Phototrexate is an inhibito... | Wikipedia - Photopharmacology - Molecules > Azobenzenes | 180 | 757 | null |
Section: Molecules > Diarylethenes. Diarylethene photoswitches have reversible cyclization and cycloreversion reactions that are photoinduced. They are a class of compounds that have aromatic functional groups bonded to each end of a carbon-carbon double bond. An example of this class of molecule that is used in photop... | Wikipedia - Photopharmacology - Molecules > Diarylethenes | 214 | 930 | null |
Section: Molecules > Photocages. A class of substances known as photocages contain “photosensitive groups, also known as 'photoremovable protecting groups", from which target substances are released upon exposure to specific wavelengths of light”. The photosensitive groups physically and chemically protect the target f... | Wikipedia - Photopharmacology - Molecules > Photocages | 280 | 1,261 | null |
Section: Application. Photopharmacology, the use of light to control the activity of drugs, has emerged as a promising approach to drug delivery and therapy. By harnessing the power of light, researchers can achieve precise control over drug release and activation, offering new possibilities for targeted and personaliz... | Wikipedia - Photopharmacology - Application | 350 | 1,848 | null |
Another application of photopharmacology is developing a luminescent photoCORM grafted on carboxymethyl chitosan, which, when exposed to light, releases carbon monoxide (CO) to induce apoptotic death in colorectal cancer cells, demonstrating precise control over CO release for targeted cancer therapy. Researchers devel... | Wikipedia - Photopharmacology - Application | 327 | 1,687 | null |
This method could potentially modulate the activity of G-quadruplex DNA, crucial in gene expression and telomere maintenance, offering new therapeutic avenues, particularly in cancer treatment. The study underscores photopharmacology's promise in targeting specific DNA structures, suggesting G-quadruplex DNA as a viabl... | Wikipedia - Photopharmacology - Application | 281 | 1,461 | null |
Section: Future directions. The future of photopharmacology holds immense promise. It has the potential to revolutionize conventional drug therapy offering new avenues for precision medicine, treating neurological disorders, and in the field of oncology and ophthalmology. Additionally, it holds promise for the field of... | Wikipedia - Photopharmacology - Future directions | 317 | 1,684 | null |
However, understanding the structural changes during the biological effects induced by photoswitching is limited. This scarcity of knowledge is also a challenge for the growth of this field, as it hampers the optimization of the activity and potency of the isomers to obtain the expected outcomes during applications. Th... | Wikipedia - Photopharmacology - Future directions | 277 | 1,506 | null |
Article: Phytochemistry. Phytochemistry is the study of phytochemicals, which are chemicals derived from plants. Phytochemists strive to describe the structures of the large number of secondary metabolites found in plants, the functions of these compounds in human and plant biology, and the biosynthesis of these compou... | Wikipedia - Phytochemistry - Summary | 254 | 1,112 | null |
Section: Phytochemicals > Alkaloids. Alkaloids are bitter-tasting chemicals, widespread in nature, and often toxic. There are several classes with different modes of action as drugs, both recreational and pharmaceutical. Medicines of different classes include atropine, scopolamine, and hyoscyamine (all from nightshade)... | Wikipedia - Phytochemistry - Phytochemicals > Alkaloids | 176 | 632 | null |
Article: Pixel Imaging Mass Spectrometry camera. The Pixel Imaging Mass Spectrometry camera (PImMS) is an ultrafast imaging sensor designed for time-of-flight particle imaging. It was invented by professors of chemistry at the University of Oxford, Mark Brouard and Claire Vallance., Renato Turchetta from IMASENIC (form... | Wikipedia - Pixel Imaging Mass Spectrometry camera - Summary | 185 | 861 | null |
Article: Pressure-induced hydration. Pressure-induced hydration (PIH), also known as “super-hydration”, is a special case of pressure-induced insertion whereby water molecules are injected into the pores of microporous materials. In PIH, a microporous material is placed under pressure in the presence of water in the pr... | Wikipedia - Pressure-induced hydration - Summary | 290 | 1,157 | null |
Section: Chemical description > Proanthocyanidin. Proanthocyanidin, a natural compound, particularly Proanthocyanidin B2, is highly impactful on hair and is abundantly found in Annurca apples. Research indicates that Proanthocyanidin influences the mitochondria in hair roots, stimulating them to generate ATP through th... | Wikipedia - Probico - Chemical description > Proanthocyanidin | 213 | 945 | null |
Section: Chemical description > Coenzyme Q10. Coenzyme Q10, also known as ubiquinone, is a non-protein, non-polar molecule. With age, its biosynthesis decreases, necessitating supplementation through diet or supplements. It plays a crucial role in the electron transport chain during cellular respiration, producing ATP ... | Wikipedia - Probico - Chemical description > Coenzyme Q10 | 189 | 795 | null |
Section: History. The field of radioanalytical chemistry was originally developed by Marie Curie with contributions by Ernest Rutherford and Frederick Soddy. They developed chemical separation and radiation measurement techniques on terrestrial radioactive substances. During the twenty years that followed 1897 the conc... | Wikipedia - Radioanalytical chemistry - History | 232 | 1,255 | null |
Section: Radiation decay modes > Beta-particle decay. Beta decay is characterized by the emission of a neutrino and a negatron which is equivalent to an electron. This process occurs when a nucleus has an excess of neutrons with respect to protons, as compared to the stable isobar. This type of transition converts a ne... | Wikipedia - Radioanalytical chemistry - Radiation decay modes > Beta-particle decay | 221 | 649 | null |
Section: Radioanalytical chemistry principles > Sample loss by radiocolloidal behaviour. Samples with very low concentrations are difficult to measure accurately due to the radioactive atoms unexpectedly depositing on surfaces. Sample loss at trace levels may be due to adhesion to container walls and filter surface sit... | Wikipedia - Radioanalytical chemistry - Radioanalytical chemistry principles > Sample loss by radiocolloidal behaviour | 154 | 790 | null |
Section: Radioanalytical chemistry principles > Carrier or tracer addition. Since small amounts of radionuclides are typically being analyzed, the mechanics of manipulating tiny quantities is challenging. This problem is classically addressed by the use of carrier ions. Thus, carrier addition involves the addition of a... | Wikipedia - Radioanalytical chemistry - Radioanalytical chemistry principles > Carrier or tracer addition | 259 | 1,349 | null |
Section: Quality assurance. As this is an analytical chemistry technique quality control is an important factor to maintain. A laboratory must produce trustworthy results. This can be accomplished by a laboratories continual effort to maintain instrument calibration, measurement reproducibility, and applicability of an... | Wikipedia - Radioanalytical chemistry - Quality assurance | 263 | 1,485 | null |
Section: The Rayleigh equation. The original Rayleigh equation was derived by Lord Rayleigh for the case of fractional distillation of mixed liquids. This is an exponential relation that describes the partitioning of isotopes between two reservoirs as one reservoir decreases in size. The equations can be used to descri... | Wikipedia - Rayleigh fractionation - The Rayleigh equation | 322 | 1,251 | null |
Article: Scale (chemistry). The scale of a chemical process refers to the rough ranges in mass or volume of a chemical reaction or process that define the appropriate category of chemical apparatus and equipment required to accomplish it, and the concepts, priorities, and economies that operate at each. While the speci... | Wikipedia - Scale (chemistry) - Summary | 177 | 875 | null |
Use of the term "scale" is unrelated to the concept of weighing; rather it is related to cognate terms in mathematics (e.g., geometric scaling, the linear transformation that enlarges or shrinks objects, and scale parameters in probability theory), and in applied areas (e.g., in the scaling of images in architecture, e... | Wikipedia - Scale (chemistry) - Summary | 318 | 1,703 | null |
Practically speaking, the scale of chemical operations also relates to the training required to carry them out, and can be broken out roughly as follows: procedures performed at the laboratory scale, which involve the sorts of procedures used in academic teaching and research laboratories in the training of chemists an... | Wikipedia - Scale (chemistry) - Summary | 324 | 1,807 | null |
Section: History. Chemistry instruction at ASU can be traced back to the early 1890s. At that time, the educational institution, a Normal School for the Territory of Arizona, “acquired...a supply of chemicals” for instructional purposes. Chemistry classes were held in Old Main during the late 1800s and into the early 1... | Wikipedia - School of Molecular Sciences - History | 337 | 1,676 | null |
Chemistry was the first department to be approved to offer a doctoral degree. In 1960, George Boyd, the university's first coordinator of research, helped secure a portion of Harvey H. Nininger’s meteorites for ASU, making it the largest university-based meteorite collection in the world. In 1961, Geochemist Carleton B... | Wikipedia - School of Molecular Sciences - History | 319 | 1,583 | null |
Section: Scientific Firsts. In 1969 the first measurements of carbon in Apollo Mission lunar-return samples were obtained by Carleton Moore and Charles Lewis. In 1970 the first extraterrestrial amino acids were detected by Carleton Moore in the Murchison meteorite. In 1975 the first quantitative chemical analyses of in... | Wikipedia - School of Molecular Sciences - Scientific Firsts | 249 | 1,211 | null |
Section: Notable alumni. Jesse W. Jones was the first chemistry PhD and earned one of the first four doctorate degrees awarded by Arizona State University in 1963. He is a tenured Professor of Chemistry at Baylor University since 1988 and served seven two-year terms as a State Representative of Texas. In 2012 he was in... | Wikipedia - School of Molecular Sciences - Notable alumni | 306 | 1,487 | null |
Article: Shape of the atomic nucleus. The shape of the atomic nucleus depends on the variety of factors related to the size and shape of its nucleon (proton or neutron) constituents and the nuclear force holding them together. The spatial extent of the prolate spheroid nucleon (and larger nuclides) is determined by roo... | Wikipedia - Shape of the atomic nucleus - Summary | 319 | 1,562 | null |
Section: Origins of nuclear shape. The atomic nucleus is composed of protons and neutrons (collectively called nucleons). In the Standard Model of particle physics, nucleons are in the group called hadrons, the smallest known particles in the universe to have measurable size and shape. Each is in turn composed of three... | Wikipedia - Shape of the atomic nucleus - Origins of nuclear shape | 306 | 1,318 | null |
Section: Simple spherical approximation. The atomic nucleus been depicted as a compact bundle of the two types of nucleons depicted as hard-packed spheres. This depiction of the nucleus only approximates the empirical evidence for the size and shape of the nucleus. The RMS charge radius of most stable (and many unstabl... | Wikipedia - Shape of the atomic nucleus - Simple spherical approximation | 250 | 1,169 | null |
Section: Nucleon shape. The empirical knowledge of nucleon shape originates from the study of the transition from the proton ground state N(938) to the first excited state ∆+(1232). Multiple studies using a variety of models have led to an expectation of non-spherical shape. The proton's RMS charge radius of 0.8414 fm ... | Wikipedia - Shape of the atomic nucleus - Nucleon shape | 350 | 1,519 | null |
The proton's N(938) ground state and ∆+(1232) excited state have different shapes. The transition between the states supports a prolate spheroid deformation for the ground state, and an oblate spheroid deformation for the excited state. The prolate shaped ground state reflects quark-to-quark interactions arising from t... | Wikipedia - Shape of the atomic nucleus - Nucleon shape | 347 | 1,604 | null |
Conversely, when the spins of a pair of unlike fermions align, such as an up-/down-quark pair within a ground-state nucleon, the nuclear force draws the particles close to other each other without violating the Pauli exclusion principle. Within the ground state neutron, this results in a picture of the spin interaction... | Wikipedia - Shape of the atomic nucleus - Nucleon shape | 290 | 1,376 | null |
Section: Space between nucleons. The atomic nucleus is a bound system of protons and neutrons. The spatial extent and shape of the nucleus depend not only on the size and shape of discrete nucleons, but also on the distance between them (the inter-nucleon distance). (Other factors include spin, alignment, orbital motio... | Wikipedia - Shape of the atomic nucleus - Space between nucleons | 344 | 1,485 | null |
Section: Soft core of light nuclides. Electron scattering techniques have yielded clues as to the internal structure of light nuclides. Proton-neutron pairs experience a strongly repulsive component of the nuclear force within ≈ 0.5 fm (see "Space between nucleons" above). As nucleons cannot pack any closer, nearly all... | Wikipedia - Shape of the atomic nucleus - Soft core of light nuclides | 220 | 1,078 | null |
Section: Alpha particle as possible building block. Although the proton and the neutron are the building blocks of the atomic nucleus, the unusual natural abundance of alpha nuclides has prompted investigations of the role of the alpha particle, or helium-4 nucleus, as a potential building block of matter. Alpha cluste... | Wikipedia - Shape of the atomic nucleus - Alpha particle as possible building block | 339 | 1,135 | null |
Section: Heavier nuclides. For many medium-to-heavy nuclides, in particular those far from the magic numbers of protons and neutrons, a spherical model of the atomic nucleus is incompatible with observed large quadrupole moments, indicating that lower potential energy is obtained for an ellipsoidal shape than for a sph... | Wikipedia - Shape of the atomic nucleus - Heavier nuclides | 245 | 1,120 | null |
Section: Aims. The aim of the soft chemistry is to synthesize materials, drawing capacity of living beings - more or less basic - such as diatoms capable of producing glass from silicates dissolved. It is a new branch of materials science that differs from conventional solid-state chemistry and its application to the i... | Wikipedia - Soft chemistry - Aims | 310 | 1,667 | null |
Article: Solid-state electrolyte. A solid-state electrolyte (SSE) is a solid ionic conductor and electron-insulating material and it is the characteristic component of the solid-state battery. It is useful for applications in electrical energy storage in substitution of the liquid electrolytes found in particular in th... | Wikipedia - Solid-state electrolyte - Summary | 344 | 1,655 | null |
Section: History. The first inorganic solid-state electrolytes were discovered by Michael Faraday in the nineteenth century, these being silver sulfide (Ag2S) and lead(II) fluoride (PbF2). The first polymeric material able to conduct ions at the solid-state was PEO, discovered in the 1970s by V. Wright. The importance ... | Wikipedia - Solid-state electrolyte - History | 253 | 1,169 | null |
Section: Properties. For Solid State Batteries (SSBs) / Solid Electrolytes (SEs) to become a major market challenger it must meet some key performance measurements. The major criteria that an SSB/SE should have are: Ionic conductivity: Historically, SSBs have suffered from low ionic conductivities due to poor interfaci... | Wikipedia - Solid-state electrolyte - Properties | 346 | 1,719 | null |
Hence, it is important that their mechanical, thermal, and electrochemical stability are considered. High mechanical strength (at least tens of MPa) can be measured through a traditional tensile test. Wide electrochemical stability windows (ESW) (at least 4-5 V) can be measured through linear sweep voltammetry (LSV) or... | Wikipedia - Solid-state electrolyte - Properties | 262 | 1,346 | null |
Section: Categories. SSEs have the same role of a traditional liquid electrolyte and they are classified into all-solid-state electrolyte and quasi-solid-state electrolyte (QSSE). All-solid-state electrolytes are furthermore divided into inorganic solid electrolyte (ISE), solid polymer electrolyte (SPE) and composite p... | Wikipedia - Solid-state electrolyte - Categories | 184 | 824 | null |
Section: Categories > All-solid-state electrolyte > Inorganic solid electrolyte (ISE). Inorganic solid electrolyte (ISE) are a particular type of all-solid-state electrolyte that is constituted by an inorganic material in the crystalline or glassy state, that conducts ions by diffusion through the lattice. The main adv... | Wikipedia - Solid-state electrolyte - Categories > All-solid-state electrolyte > Inorganic solid electrolyte (ISE) | 348 | 1,233 | null |
Section: Categories > All-solid-state electrolyte > Advances in Interface Engineering and Composite Solid Electrolytes. In recent years, advancements in interface engineering have significantly improved the compatibility of inorganic solid electrolytes (ISEs) with lithium metal anodes. To overcome these issues, researc... | Wikipedia - Solid-state electrolyte - Categories > All-solid-state electrolyte > Advances in Interface Engineering and Composite Solid Electrolytes | 312 | 1,504 | null |
• Chemical Doping: Elemental doping, such as fluoride (F⁻) and chloride (Cl⁻) incorporation, has been explored to enhance the electrochemical stability of sulfide-based electrolytes, reducing their reactivity with lithium metal while maintaining high ionic conductivity. • Mechanical Compression and Sintering: High-pres... | Wikipedia - Solid-state electrolyte - Categories > All-solid-state electrolyte > Advances in Interface Engineering and Composite Solid Electrolytes | 328 | 1,717 | null |
Section: Categories > All-solid-state electrolyte > Solid polymer electrolyte (SPE). Solid polymer electrolyte (SPE) are defined as a solvent-free salt solution in a polymer host material that conducts ions through the polymer chains. Compared to ISEs, SPEs are much easier to process, generally by solution casting, mak... | Wikipedia - Solid-state electrolyte - Categories > All-solid-state electrolyte > Solid polymer electrolyte (SPE) | 346 | 1,552 | null |
PDMS) and fluoropolymers (e.g. PVDF, PVDF-HFP). Bio-polymers like lignin, chitosan and cellulose are also gaining a lot of interest as standalone SPEs or blended with other polymers, on one side for their environmentally friendliness and on the other for their high complexation capability on the salts. Furthermore, dif... | Wikipedia - Solid-state electrolyte - Categories > All-solid-state electrolyte > Solid polymer electrolyte (SPE) | 298 | 1,226 | null |
Section: Categories > Quasi-solid-state electrolyte. Quasi solid-state electrolytes (QSSEs) are a wide class of composite compounds consisting of a liquid electrolyte and a solid matrix. This liquid electrolyte serves as a percolating pathway of ion conduction while the solid matrix adds mechanical stability to the mat... | Wikipedia - Solid-state electrolyte - Categories > Quasi-solid-state electrolyte | 322 | 1,406 | null |
A number of polymer hosts have been used in GPEs, including PEO, PAN, PMMA, PVDF-HFP, etc. The polymers are synthesized with increased porosity to incorporate solvents such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and dimethyl carbonate (DMC). Low molecular weight poly(ethylene gly... | Wikipedia - Solid-state electrolyte - Categories > Quasi-solid-state electrolyte | 345 | 1,448 | null |
"soggy sand" electrolytes) can achieve liquid-like ionic conductivities (~ 10 mS cm−1) while being in the solid state. Matrix materials such as SiO2 nanoparticles are typically paired with low viscosity solvents (e.g., ethylene carbonate (EC)) to create a gel, whose properties can be modified based on the matrix loadin... | Wikipedia - Solid-state electrolyte - Categories > Quasi-solid-state electrolyte | 184 | 862 | null |
Section: Opportunities. The versatility and properties of the solid-state electrolyte widen the possible applications towards high energy density and cheaper battery chemistries that are otherwise prevented by the current state-of-the-art of Li-ion batteries. Indeed, by introducing a SSE in the battery architecture the... | Wikipedia - Solid-state electrolyte - Opportunities | 259 | 1,260 | null |
Section: History. The influence of sonic waves travelling through liquids was first reported by Robert Williams Wood (1868–1955) and Alfred Lee Loomis (1887–1975) in 1927. The experiment was about the frequency of the energy that it took for sonic waves to "penetrate" the barrier of water. He came to the conclusion tha... | Wikipedia - Sonochemistry - History | 302 | 1,499 | null |
Section: Physical principles. Sound waves propagating through a liquid at ultrasonic frequencies have wavelengths many times longer than the molecular dimensions or the bond length between atoms in the molecule. Therefore, the sound wave cannot directly affect the vibrational energy of the bond, and can therefore not d... | Wikipedia - Sonochemistry - Physical principles | 347 | 1,848 | null |
Bubble collapse in liquids produces enormous amounts of energy from the conversion of kinetic energy of the liquid motion into heating the contents of the bubble. The compression of the bubbles during cavitation is more rapid than thermal transport, which generates a short-lived localized hot-spot. Experimental results... | Wikipedia - Sonochemistry - Physical principles | 187 | 1,021 | null |
Section: Sonochemical reactions. Three classes of sonochemical reactions exist: homogeneous sonochemistry of liquids, heterogeneous sonochemistry of liquid-liquid or solid–liquid systems, and, overlapping with the aforementioned, sonocatalysis (the catalysis or increasing the rate of a chemical reaction with ultrasound... | Wikipedia - Sonochemistry - Sonochemical reactions | 340 | 1,701 | null |
Atul Kumar has reported multicomponent reaction Hantzsch ester synthesis in Aqueous Micelles using ultrasound. Some water pollutants, especially chlorinated organic compounds, can be destroyed sonochemically. Sonochemistry can be performed by using a bath (usually used for ultrasonic cleaning) or with a high power prob... | Wikipedia - Sonochemistry - Sonochemical reactions | 255 | 1,179 | null |
Article: Stable phosphorus radicals. Stable and persistent phosphorus radicals are phosphorus-centred radicals that are isolable and can exist for at least short periods of time. Radicals consisting of main group elements are often very reactive and undergo uncontrollable reactions, notably dimerization and polymerizat... | Wikipedia - Stable phosphorus radicals - Summary | 185 | 987 | null |
Section: Neutral phosphorus radicals > Monoradicals > Synthesis. Synthetic methods for obtaining neutral phosphorus mondoradicals include photolytic reduction of trivalent phosphorus chlorides, P-P homolytic cleavage, single electron oxidation of phosphines, and cleavage of P-S or P-Se bonds. The first persistent two-c... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Monoradicals > Synthesis | 332 | 1,224 | null |
At room temperature the species decomposes in solution and in the solid state with a half life of 30 minutes at 3 x 10−2 M. The first structurally characterised phosphorus radical [Me3SiNP(μ3-NtBu)3{μ3-Li(thf)}3X]• (X = Br, I) was synthesised by Armstrong et al. in 2004 by the oxidation of the starting material with ha... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Monoradicals > Synthesis | 288 | 994 | null |
Section: Neutral phosphorus radicals > Monoradicals > Synthesis > Metal stabilised radicals. In 2007, Cummins et al. synthsised a phosphorus radical using nitridovanadium trisanilide metallo-ligands with similar form to Lappert, Power and co-workers' "jack-in-the-box" diphosphines. This is made by the synthesis of the ... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Monoradicals > Synthesis > Metal stabilised radicals | 257 | 1,095 | null |
Section: Neutral phosphorus radicals > Monoradicals > Structure and properties. As previously mentioned, kinetic stabilisation through bulky ligands has been an effective strategy for producing persisting phosphorus radicals. Delocalisation of the electron has also shown a stabilising effect on phosphorus radical speci... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Monoradicals > Structure and properties | 275 | 1,306 | null |
This stability was assigned to the steric bulk of the substituents and the absence of beta-hydrogen atoms. A structural study of this species conducted using X-ray crystallography, gas-phase electron diffraction, and ab initio molecular orbital calculations found that the source of this stability was not the bulkiness ... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Monoradicals > Structure and properties | 341 | 1,425 | null |
Section: Neutral phosphorus radicals > Biradicals > Synthesis. The first phosphorus biradical was reported in 2011 by T. Breweies and co-workers. The biradicaloid [P(μ-NR)]2 (R=Hyp, Ter) was synthesised by the reduction of cyclo-1,3-diphospha (III)-2,4-diazanes using [(Cp2TiCl}2] as the reducing agent. The bulky Ter (t... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Biradicals > Synthesis | 329 | 1,074 | null |
Section: Neutral phosphorus radicals > Characterisation. Phosphorus radicals are commonly characterized by EPR/ESR to elucidate the spin localisation of the radical across the radical species. Higher coupling constants are indicative of higher localisation on phosphorus nuclei. Quantum chemical calculations on these sy... | Wikipedia - Stable phosphorus radicals - Neutral phosphorus radicals > Characterisation | 200 | 910 | null |
Section: Phosphorus radical cations > Synthesis. Phosphorus radical cations are often obtained from the one-electron oxidation of diphosphinidenes and phosphalkenes. In 2010, the Bertrand group found that carbene-stabilised diphosphinidenes can undergo one-electron oxidation in toluene with Ph3C+B(C6F5)4− at room tempe... | Wikipedia - Stable phosphorus radicals - Phosphorus radical cations > Synthesis | 279 | 982 | null |
Other diradicals synthesised by the Bertrand group involved species single phosphorus atoms. These included [(TMP)P(cAAC)]•+ where spin is localised on phosphorus (67%) and [bis(carbene)-PN]•+ with spin density distributed over phosphorus (0.40e), central nitrogen atom (0.18e), and N atom of cAAC (0.19e). Treatment wit... | Wikipedia - Stable phosphorus radicals - Phosphorus radical cations > Synthesis | 323 | 1,137 | null |
This was supported by DFT calculations where 80.9% of spin density was found to be localised on phosphorus atom. Weakly coordinating anions were also used to stabilise cyclic biradical cations synthesised by Schulz and colleagues where the spin density was found to reside exclusively on the phosphorus atoms (0.46e each... | Wikipedia - Stable phosphorus radicals - Phosphorus radical cations > Synthesis | 281 | 1,020 | null |
Section: Phosphorus radical anions > Synthesis. The most common method for accessing radical anions is through the use of reducing agents. In 2014 the Wang group reported the synthesis of a phosphorus-centred radical anion through the reduction of a phosphaalkene using either Li in DME or K in THF yielding purple cryst... | Wikipedia - Stable phosphorus radicals - Phosphorus radical anions > Synthesis | 323 | 1,430 | null |
Article: Stereochemistry. Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and seque... | Wikipedia - Stereochemistry - Summary | 156 | 777 | null |
Section: History. In 1815, Jean-Baptiste Biot's observation of optical activity marked the beginning of organic stereochemistry history. He observed that organic molecules were able to rotate the plane of polarized light in a solution or in the gaseous phase. Despite Biot's discoveries, Louis Pasteur is commonly descri... | Wikipedia - Stereochemistry - History | 344 | 1,521 | null |
Section: Significance > Thalidomide example. Stereochemistry has important applications in the field of medicine, particularly pharmaceuticals. An often cited example of the importance of stereochemistry relates to the thalidomide disaster. Thalidomide is a pharmaceutical drug, first prepared in 1957 in Germany, prescr... | Wikipedia - Stereochemistry - Significance > Thalidomide example | 307 | 1,439 | null |
Section: Future directions. Combining various experimental and computational techniques can provide comprehensive insights into complex structures. Integrating data from X-ray crystallography, NMR spectroscopy, and computational modeling enhances accuracy and reliability. Continued progress in computational simulations... | Wikipedia - Structural chemistry - Future directions | 181 | 1,158 | null |
Section: Overview. Anions are negatively charged ions and therefore usually exhibit nucleophilic reaction behavior. However, it has been shown that there are anions which behave in a strongly electrophilic manner despite their negative charge. This means that they form bonds with reaction partners in chemical reactions... | Wikipedia - Superelectrophilic anion - Overview | 341 | 1,570 | null |
Section: Origin of the concept. Originally, the term superelectrophilic was used exclusively for dications. It was introduced by George A. Olah when he discovered that certain electrophilic monocations can be activated in the condensed phase by the presence of particularly strong acids - the so-called superacids. This ... | Wikipedia - Superelectrophilic anion - Origin of the concept | 330 | 1,578 | null |
Since anions are negatively charged and formally have an electron excess, they generally exhibit nucleophilic reaction behavior and should therefore not be able to form stable bonds to noble gas atoms. However, in direct contrast to this intuitive concept, it was shown in 2017 that the negatively charged gas-phase frag... | Wikipedia - Superelectrophilic anion - Origin of the concept | 253 | 1,118 | null |
Section: Precursors. The superelectrophilic anions [B12X11]– can be generated from the very stable closo-dodecaborate dianions [B12X12]2– by fragmentation in the gas phase. The closo-dodecaborate dianions, which serve as precursors, consist of twelve boron atoms arranged in a highly symmetrical, cage-like closo structu... | Wikipedia - Superelectrophilic anion - Precursors | 226 | 800 | null |
Section: Generation. To generate the superelectrophilic anions from the closo-dodecaborate dianions [B12X12]2–, fragmentation is carried out in the mass spectrometer using collision-induced dissociation (CID). In this process, a substituent (X–) is cleaved from the dianion precursor. As a result, only eleven of the twe... | Wikipedia - Superelectrophilic anion - Generation | 278 | 1,016 | null |
Section: Reactivity and bond formation > Reactions with noble gases > Favored formation and stabilization of the collision complex. The strongly electrophilic (positive) binding site within the overall anionic framework generates an unusual electric field near the reactive boron atom. Polar nucleophiles approaching the... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with noble gases > Favored formation and stabilization of the collision complex | 187 | 931 | null |
Section: Reactivity and bond formation > Reactions with noble gases > Favorable electrostatics and dispersion forces. In addition to the coordinative noble gas-boron bond, dispersion interactions and electrostatics contribute to the stabilization of the noble gas complex. The electrophilic bonding site is located withi... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with noble gases > Favorable electrostatics and dispersion forces | 172 | 871 | null |
Section: Reactivity and bond formation > Reactions with diatomic molecules: CO, N2. The binding of the diatomic molecules CO and N2 to superelectrophilic anions was studied using mass spectrometry, infrared photodissociation (IRPD) spectroscopy, and theoretical calculations. CO binds to the vacant boron atom of the ele... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with diatomic molecules: CO, N2 | 189 | 780 | null |
Section: Reactivity and bond formation > Reactions with saturated hydrocarbons. The high reactivity of the [B12X11]– anions allows not only reactions with noble gases, but also direct functionalization of saturated hydrocarbons. To elucidate the reaction mechanism, detailed investigations were carried out on the reacti... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with saturated hydrocarbons | 319 | 1,167 | null |
Figs. 8 and 9). In addition, the fragment ions [B12Br11]– and [B12Cl11]– were deposited on surfaces by the ion soft-landing method, where they reacted with the alkyl chains of organic compounds. The attachment to the nonpolar alkyl chains occurred selectively in the presence of much more reactive functional groups such... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with saturated hydrocarbons | 160 | 699 | null |
Section: Reactivity and bond formation > Reactions with anions. In the gas phase, ion-ion reactions can usually only take place between ions of opposite polarity - i.e. between anion and cation. The reaction partners attract each other by long-range Coulomb force, and the complementary reactivities of the nucleophilic ... | Wikipedia - Superelectrophilic anion - Reactivity and bond formation > Reactions with anions | 322 | 1,343 | null |
Section: Variants. By exchanging the substituents (X), different variants of the closo-dodecaborate precursors and thus also of the fragment anions can be generated. So far, five variants have been produced experimentally in the gas phase and their reactivity investigated: The fragment anions [B12X11]– with substituent... | Wikipedia - Superelectrophilic anion - Variants | 325 | 1,443 | null |
It can be seen that the reactivities of [B12Cl11]– and [B12Br11]– can be classified as similar, while [B12F11]– and [B12I11]– are less reactive. The reduced noble gas binding strength can be attributed to a less electrophilic vacant boron atom in the case of X = F, because the atomic charge of the vacant boron calculat... | Wikipedia - Superelectrophilic anion - Variants | 330 | 1,330 | null |
The latter depends significantly on the size of the substituents X, since these contribute to a spatial shielding of the vacant boron atom. It should be noted, however, that the reactivities depend to a large extent on the type of reaction partner used. Expressed in a simplified way, the variants have different prefere... | Wikipedia - Superelectrophilic anion - Variants | 310 | 1,421 | null |
Section: Theoretical studies / computer simulations. Complementary to the described experimental studies, the reactivity of superelectrophilic anions has also been extensively investigated by theoretical "computational chemistry" methods. The noble gas-boron bond has been analyzed both in combined experimental-theoreti... | Wikipedia - Superelectrophilic anion - Theoretical studies / computer simulations | 194 | 932 | null |
Section: Scientific relevance and potential applications. The extraordinary reactivity of superelectrophilic anions enables them to form bonds to very unreactive atoms or molecules. Such reactions between superelectrophilic anions and unreactive substances are of interest in many respects: Exploring new reaction mechan... | Wikipedia - Superelectrophilic anion - Scientific relevance and potential applications | 333 | 1,675 | null |
Moreover, they are comparatively robust against attack by nucleophiles such as water. At room temperature, small amounts of nucleophiles such as water can hardly be avoided in vacuum instruments and tend to decompose noble gas-containing reaction products by substitution reactions. However, this problem does not play a... | Wikipedia - Superelectrophilic anion - Scientific relevance and potential applications | 275 | 1,302 | null |
Section: Research locations. Research on superelectrophilic anions in the gas phase has its origin at the University of Bremen and at the Wilhelm Ostwald Institute (WOI) of the University of Leipzig (Germany). The main focus is currently at WOI, where most of the experimental studies take place. U.S. research groups fr... | Wikipedia - Superelectrophilic anion - Research locations | 180 | 844 | null |
Article: Superplasticizer. Superplasticizers (SPs), also known as high range water reducers, are additives used for making high strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers all... | Wikipedia - Superplasticizer - Summary | 327 | 1,513 | null |
Section: Working mechanism. Traditional plasticizers are lignosulfonates as their sodium salts. Superplasticizers are synthetic polymers. Compounds used as superplasticizers include (1) sulfonated naphthalene formaldehyde condensate, sulfonated melamine formaldehyde condensate, acetone formaldehyde condensate and (2) p... | Wikipedia - Superplasticizer - Working mechanism | 296 | 1,204 | null |
The negatively charged polymer backbone adsorbs onto the positively charged colloidal particles of unreacted cement, especially onto the tricalcium aluminate (C3A) mineral phase of cement. Melaminesulfonate (PMS) and naphthalenesulfonate (PNS) mainly act by electrostatic interactions with cement particles favoring thei... | Wikipedia - Superplasticizer - Working mechanism | 162 | 706 | null |
Article: Supramolecular chemistry. Supramolecular chemistry refers to the branch of chemistry concerning chemical systems composed of a discrete number of molecules. The strength of the forces responsible for spatial organization of the system range from weak intermolecular forces, electrostatic charge, or hydrogen bon... | Wikipedia - Supramolecular chemistry - Summary | 224 | 1,236 | null |
Section: History. The existence of intermolecular forces was first postulated by Johannes Diderik van der Waals in 1873. However, Nobel laureate Hermann Emil Fischer developed supramolecular chemistry's philosophical roots. In 1894, Fischer suggested that enzyme–substrate interactions take the form of a "lock and key",... | Wikipedia - Supramolecular chemistry - History | 331 | 1,570 | null |
The term supermolecule (or supramolecule) was introduced by Karl Lothar Wolf et al. (Übermoleküle) in 1937 to describe hydrogen-bonded acetic acid dimers. The term supermolecule is also used in biochemistry to describe complexes of biomolecules, such as peptides and oligonucleotides composed of multiple strands. Eventu... | Wikipedia - Supramolecular chemistry - History | 252 | 1,172 | null |
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