|
Neocuproine
Neocuproine is a heterocyclic organic compound and chelating agent. Phenanthroline ligands were first published in the late 19th century, and the derivatives substituted at the 2 and 9 positions are among the most studied of the modified phenanthrolines. Synthesis and structure Neocuproine can be prepared by sequential Skraup reactions ( Doebner-Miller reaction/condensation) of o-nitroaniline ( 2-Nitroaniline) with crotonaldehyde diacetate. An alternate synthesis involves the condensation of o-phenylenediamine, m-nitrobenzenesulphonate, and crotonaldehyde diacetate. This method gives higher yields but is less economical. Neocuproine crystallizes as a dihydrate and a hemihydrate. Coordination chemistry In the early 1930s, phenanthroline derivatives became known for their use as colorimetric indicators for many transition metals. Neocuproine proved to be highly selective for copper(I). The resulting complex, u(neocuproine)2sup>+ has a deep orange-red color. The properties of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocyclic
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these heterocycles. Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles. 59% of US FDA-approved drugs contain nitrogen heterocycles. Classification The study of heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are quinol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotaxane
In chemistry, a rotaxane () is a mechanically interlocked molecular architecture consisting of a dumbbell-shaped molecule which is threaded through a macrocycle (see graphical representation). The two components of a rotaxane are kinetically trapped since the ends of the dumbbell (often called ''stoppers'') are larger than the internal diameter of the ring and prevent dissociation (unthreading) of the components since this would require significant distortion of the covalent bonds. Much of the research concerning rotaxanes and other mechanically interlocked molecular architectures, such as catenanes, has been focused on their efficient synthesis or their utilization as artificial molecular machines. However, examples of rotaxane substructure have been found in naturally occurring peptides, including: cystine knot peptides, cyclotides or lasso-peptides such as microcin J25. Synthesis The earliest reported synthesis of a rotaxane in 1967 relied on the statistical probabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, vacu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocytes
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system. Function Through a process called melanogenesis, melanocytes produce melanin, which is a pigment found in the skin, eyes, hair, nasal cavity, and inner ear. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from oxidation of already-existing melanin. There are both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zebrafish
The zebrafish (''Danio rerio'') is a freshwater fish belonging to the minnow family ( Cyprinidae) of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often called a "tropical fish" although both tropical and subtropical). It is also found in private ponds. The zebrafish is an important and widely used vertebrate model organism in scientific research, for example in drug development, in particular pre-clinical development. It is also notable for its regenerative abilities, and has been modified by researchers to produce many transgenic strains. Taxonomy The zebrafish is a derived member of the genus '' Brachydanio'', of the family Cyprinidae. It has a sister-group relationship with ''Danio aesculapii''. Zebrafish are also closely related to the genus ''Devario'', as demonstrated by a phylogenetic tree of close species. Distribution Range The zebrafish is native to fresh water h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanin
Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against Ultraviolet, UV radiation. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathocuproine
Bathocuproine is a derivative of 1,10-phenanthroline with two methyl groups and two phenyl groups in the 2,9 and 4,7 positions, respectively. Like 1,10-phenanthroline, bathocuproine is a bidentate chelating ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec .... The two methyl groups flank the nitrogen centers, such that bathocuproine is a bulky ligand. It is a pale yellow solid that is soluble in polar organic solvents.{{cite encyclopedia, author=Guosheng Liu, Yichen, Wu, year=2012, title = Encyclopedia of Reagents for Organic Synthesis, doi=10.1002/047084289X.rn01392, encyclopedia=eEROS, chapter=Bathocuproine, isbn=978-0471936237 References Chelating agents Phenanthrolines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Journal Of Pharmacology
The ''British Journal of Pharmacology'' is a biweekly peer-reviewed medical journal covering all aspects of experimental pharmacology. It is published for the British Pharmacological Society by Wiley-Blackwell. It was established in 1946 as the ''British Journal of Pharmacology and Chemotherapy''. The journal obtained its current title in 1968. The current editor-in-chief is Amrita Ahluwalia. Previous editors-in-chief include Ian McGrath, Humphrey Rang, Alan North, Phil Moore, Bill Large, and Tony Birmingham. A sister journal, also published for the British Pharmacological Society by Wiley-Blackwell is the '' British Journal of Clinical Pharmacology''. The journal publishes research papers, review articles, commentaries and correspondence in all fields of pharmacology. It also publishes themed issues, as well as supplements. ''The Concise Guide to PHARMACOLOGY'' The ''Concise Guide to PHARMACOLOGY'' is a supplement of the ''British Journal of Pharmacology'', replacing the "Guide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S-Nitrosothiol
In organic chemistry, ''S''-nitrosothiols, also known as thionitrites, are organic compounds or functional groups containing a nitroso group attached to the sulfur atom of a thiol. ''S''-Nitrosothiols have the general formula , where ''R'' denotes an organic group. Originally suggested by Ignarro to serve as intermediates in the action of organic nitrates, endogenous S-nitrosothiols were discovered by Stamler and colleagues (S-nitrosoalbumin in plasma and S-nitrosoglutathione in airway lining fluid) and shown to represent a main source of NO bioactivity ''in vivo''. More recently, S-nitrosothiols have been implicated as primary mediators of protein S-nitrosylation, the oxidative modification of cysteine thiol that provides ubiquitous regulation of protein function. S-Nitrosothiols have received much attention in biochemistry because they serve as donors of both the nitrosonium ion and of nitric oxide and thus best rationalize the chemistry of NO-based signaling in livin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrosonium
The nitrosonium ion is , in which the nitrogen atom is bonded to an oxygen atom with a bond order of 3, and the overall diatomic species bears a positive charge. It can be viewed as nitric oxide with one electron removed. This ion is usually obtained as the following salts: , (nitrosylsulfuric acid, more descriptively written ) and . The and salts are slightly soluble in acetonitrile . NOBF4 can be purified by sublimation at 200–250 °C and . is isoelectronic with CO, and . It arises via protonation of nitrous acid: :HONO + H+ NO+ + H2O Chemical properties Hydrolysis reacts readily with water to form nitrous acid: : For this reason, nitrosonium compounds must be protected from water or even moist air. With base, the reaction generates nitrite: : As a diazotizing agent reacts with aryl amines, , to give diazonium salts, . The resulting diazonium group is easily displaced (unlike the amino group) by a variety of nucleophiles. As an oxidizing agent , e.g. as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catenane
In macromolecular chemistry, a catenane () is a mechanically interlocked molecular architecture consisting of two or more interlocked macrocycles, i.e. a molecule containing two or more intertwined rings. The interlocked rings cannot be separated without breaking the covalent bonds of the macrocycles. They are conceptually related to other mechanically interlocked molecular architectures, such as rotaxanes, molecular knots or molecular Borromean rings. Recently the terminology "mechanical bond" has been coined that describes the connection between the macrocycles of a catenane. Catenanes have been synthesised in two different ways: statistical synthesis and template-directed synthesis. Synthesis There are two primary approaches to the organic synthesis of catenanes. The first is to simply perform a ring-closing reaction with the hope that some of the rings will form around other rings giving the desired catenane product. This so-called "statistical approach" led to the fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
