Thulium

"Thulium is a chemical element that has the symbol Tm and atomic number 69. Thulium is the second least abundant of the lanthanides (promethium is only found in trace quantities on Earth). It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices and in solid-state lasers."

"Pure thulium metal has a bright, silvery luster. It is reasonably stable in air, but should be protected from moisture. The metal is soft, malleable, and ductile.^[1] Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K and paramagnetic above 56 K.^[2] Liquid thulium is very volatile."

"Naturally occurring thulium is composed of one stable isotope, ¹⁶⁹Tm (100% natural abundance). Thirty one radioisotopes have been characterized, with the most stable being ¹⁷¹Tm with a half-life of 1.92 years, ¹⁷⁰Tm with a half-life of 128.6 days, ¹⁶⁸Tm with a half-life of 93.1 days, and ¹⁶⁷Tm with a half-life of 9.25 days. All of the remaining radioactive isotopes have half-lives that are less than 64 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 14 meta states, with the most stable being ^164mTm (t_½ 5.1 minutes), ^160mTm (t_½ 74.5 seconds) and ^155mTm (t_½ 45 seconds)."

Phospholipid

Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from sphingosine instead of glycerol. The first phospholipid identified as such in biological tissues was lecithin, or phosphatidylcholine, in the egg yolk, by Theodore Nicolas Gobley, a French chemist and pharmacist, in 1847. The structure of the phospholipid molecule generally consists of hydrophobic tails and a hydrophilic head. It is usually found with cholesterol molecules which are found in-between the spaces of the phospholipid. Purified Phospholipids are produced commercially by companies like NOF Corporation, VAV Life Sciences, Avanti Polar etc.

The 'head' is hydrophilic (attracted to water), while the hydrophobic 'tails' are repelled by water and are forced to aggregate. The hydrophilic head contains the negatively charged phosphate group, and may contain other polar groups. The hydrophobic tail usually consists of long fatty acid hydrocarbon chains. When placed in water, phospholipids form a variety of structures depending on the specific properties of the phospholipid. These specific properties allow phospholipids to play an important role in the phospholipid bilayer. In biological systems, the phospholipids often occur with other molecules (e.g., proteins, glycolipids, cholesterol) in a bilayer such as a cell membrane.^[1] Lipid bilayers occur when hydrophobic tails line up against one another, forming a membrane hydrophilic heads on both sides facing the water.

Organolithium Reagents

"An organolithium reagent is an organometallic compound with a direct bond between a carbon and a lithium atom. As the electropositive nature of lithium puts most of the charge density of the bond on the carbon atom, effectively creating a carbanion, organolithium compounds are extremely powerful bases and nucleophiles. For use as bases, butyllithiums are often used and are commercially available."

"Organolithium reagents can be aggregated, with lithium coordinating to more than one carbon atom and carbon coordinating to more than one lithium atom. Three general factors affect aggregation: the electrostatic interaction between opposite charges, the coordination sphere of lithium which can be either solvent molecules or Lewis base and the steric hindrance of the hydrocarbon part.^[2] The lithium atoms tend to form triangles and higher aggregates."

"In the solid state of methyllithium, 4 lithium atoms form a tetrahedron with each face capped by a methyl group which bonds simultaneously to three Li atoms (η³ hapticity). Long-range interactions between (MeLi)₄ units are based on η³-Li-CH₃-η¹-Li bonding. Butyllithium forms a hexameric Li₆ octahedron without any long-range interactions."

Penicillin

"Penicillin (sometimes abbreviated PCN or pen) is a group of antibiotics derived from Penicillium fungi.^[1] They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V. Penicillin antibiotics are historically significant because they are the first drugs that were effective against many previously serious diseases, such as syphilis, and infections caused by staphylococci and streptococci. Penicillins are still widely used today, though many types of bacteria are now resistant. All penicillins are β-lactam antibiotics and are used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms."

"The term 'penam' is used to describe the core skeleton of a member of the penicillin antibiotics. This skeleton has the molecular formula R-C₉H₁₁N₂O₄S, where R is a variable side chain."

"Normal penicillin has a molecular weight of 313^[6] to 334^[7][8] g/mol (latter for penicillin G). Penicillin types with additional molecular groups attached may have a molar mass around 500 g/mol. For example, cloxacillin has a molar mass of 476 g/mol and dicloxacillin has a molar mass of 492 g/mol."

Dichloromethane

"Dichloromethane (DCM)—or methylene chloride—is an organic compound with the formula CH₂Cl₂. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents."

"DCM was first prepared in 1840 by the French chemist Henri Victor Regnault (1810–1878), who isolated it from a mixture of chloromethane and chlorine that had been exposed to sunlight."

"DCM's volatility and ability to dissolve a wide range of organic compounds makes it a useful solvent for many chemical processes. Concerns about its health effects have led to a search for alternatives in many of these applications."

"It is widely used as a paint stripper and a degreaser. In the food industry, it has been used to decaffeinate coffee and tea as well as to prepare extracts of hops and other flavorings.^[2] Its volatility has led to its use as an aerosol spray propellant and as a blowing agent for polyurethane foams."

Rhodium

"Rhodium is a chemical element that is a rare, silvery-white, hard, and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one naturally-occurring isotope, ¹⁰³Rh. Naturally occurring rhodium is usually found as the free metal, alloyed with similar metals, and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest precious metals."

"Rhodium is a so-called noble metal, resistant to corrosion, found in platinum- or nickel ores together with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds, produced after it reacted with the powerful acid mixture aqua regia."

"The element's major use (more that 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium is usually alloyed with platinum or palladium and applied in high-temperature and corrosion-resistive coatings. White gold is often plated with a thin rhodium layer to improve its optical impression while sterling silver is often rhodium plated for tarnish resistance."

"Rhodium detectors are used in nuclear reactors to measure the neutron flux level."

Organotin Compounds

"Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry.^[1] The first organotin compound was diethyltin diiodide, discovered by Edward Frankland in 1849. An organotin compound is commercially applied as a hydrochloric acid scavenger (or heat stabilizer) in polyvinyl chloride and as a biocide. Tributyltin oxide has been extensively used as a wood preservative. Tributyltin compounds are used as marine anti-biofouling agents. Concerns over toxicity^[2] of these compounds (some reports describe biological effects to marine life at a concentration of 1 nanogram per liter) have led to a worldwide ban by the International Maritime Organization. n-Butyltin trichloride is used in the production of tin dioxide layers on glass bottles by chemical vapor deposition."

"Organotin compounds are generally classified according to their oxidation states. Tin(IV) compounds are much more common and more useful."

"Compounds of Sn(I) are rare and only observed with very bulky ligands. One prominent family of cages is accessed by pyrolysis of the 2,6-diethylphenyl-substituted tristannylene [Sn(C₆H₃-2,6-Et₂)₂]₃, which affords the cubane and a prismane. These cages contain Sn(I) and have the formula [Sn(C₆H₃-2,6-Et₂)]_n where n = 8, 10.^[9] A stannyne contains a carbon to tin triple bond and a distannyne a triple bond between two tin atoms (RSnSnR). Distannynes only exist for extremely bulky substituents. Unlike alkynes, the C-Sn-Sn-C core of these distannynes are nonlinear, although they are planar. The Sn-Sn distance is 3.066(1) Å, and the Sn-Sn-C angles are 99.25(14)°. Such compounds are prepared by reduction of bulky aryltin(II) halides."

Organophosphorus Compounds

"Organophosphorus compounds are degradable organic compounds containing carbon–phosphorus bonds (thus excluding phosphate and phosphite esters, which lack this kind of bonding), used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Organophosphorus chemistry is the corresponding science of the properties and reactivity of organophosphorus compounds. Phosphorus shares group 5 in the periodic table with nitrogen and phosphorus compounds and nitrogen compounds are somewhat related."

"The definition of organophosphorus compounds is variable, which can lead to confusion. In industrial and environmental chemistry, an organophosphorus compound need contain only an organic substituent, but need not have a direct P-C bond. Thus most pesticides, e.g., malathion, are often included in this class of compounds."

"Phosphorus can adopt a variety of oxidation states, and it is general to classify organophosphorus compounds based on their being derivatives of phosphorus(V) vs phosphorus(III), which are the predominant classes of compounds. In a descriptive but only intermittently used nomenclature, phosphorus compounds are identified by their coordination number δ and their valency λ. In this system, a phosphine is a δ³λ³ compound."

Organoboron Compounds

"Organoborane or organoboron compounds are chemical compounds that are organic derivatives of BH₃, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds.^[1][2] Organoboron compounds are important reagents in organic chemistry enabling many chemical transformations, the most important one called hydroboration."

"The C-B bond has low polarity (the difference in electronegativity 2.55 for carbon and 2.04 for boron) and therefore alkyl boron compounds are in general stable though easily oxidized. Vinyl groups and aryl groups donate electrons and make boron less electrophilic and the C-B bond gains some double bond character. Like the parent borane, diborane, organoboranes are classified in organic chemistry as strong electrophiles because boron is unable to gain a full octet of electrons. Unlike diborane however, organoboranes do not form dimers."

"Other boranes of interest are carboranes, which are cluster compounds of carbon and boron and borabenzene, the boron equivalent of benzene. The cyclic compound borole, a structural analog of pyrrole, has not been isolated, but substituted derivatives known as boroles are known."

Graphene

"Graphene is a substance made of pure carbon, with atoms arranged in a regular hexagonal pattern similar to graphite, but in a one-atom thick sheet. It is very light, with a 1 square meter sheet weighing only .77 milligrams. It is an allotrope of carbon whose structure is a single planar sheet of sp²-bonded carbon atoms that are densely packed in a honeycomb crystal lattice.^[1] The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm,^[2] who described single-layer carbon foils in 1962.^[3] Graphene is most easily visualized as an atomic-scale chicken wire made of carbon atoms and their bonds. The crystalline or "flake" form of graphite consists of many graphene sheets stacked together."

"The carbon-carbon bond length in graphene is about 0.142 nanometers.^[4] Graphene sheets stack to form graphite with an interplanar spacing of 0.335 nm. Graphene is the basic structural element of some carbon allotropes including graphite, charcoal, carbon nanotubes and fullerenes. It can also be considered as an indefinitely large aromatic molecule, the limiting case of the family of flat polycyclic aromatic hydrocarbons."

"The Nobel Prize in Physics for 2010 was awarded to Andre Geim and Konstantin Novoselov at the University of Manchester 'for groundbreaking experiments regarding the two-dimensional material graphene'".