The structural formula of a chemical compound is a graphic representation of the molecular structure, showing how the atoms are possibly arranged in the real three-dimensional space. The chemical bonding within the molecule is also shown, either explicitly or implicitly. Unlike other chemical formula types, which have a limited number of symbols and are capable of only limited descriptive power, structural formulas provide a more complete geometric representation of the molecular structure. For example, many chemical compounds exist in different isomeric forms, which have different enantiomeric structures but the same molecular formula. There are multiple types of ways to draw these structural formulas such as: Lewis Structures, condensed formulas, skeletal formulas, Newman projections, Cyclohexane conformations, Haworth projections, and Fischer projections.
Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products. Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon.
Cyclohexene is a hydrocarbon with the formula (CH2)4C2H2. It is an example of a cycloalkene. At room temperature, cyclohexene a colorless liquid with a sharp odor. It has few practical applications.
Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. The name is derived from "graphite" and the suffix -ene, reflecting the fact that the graphite allotrope of carbon contains numerous double bonds.
Cyclohexane conformations are any of several three-dimensional shapes adopted by molecules of cyclohexane. Because many compounds feature structurally similar six-membered rings, the structure and dynamics of cyclohexane are important prototypes of a wide range of compounds.
In chemistry, conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about formally single bonds. While any two arrangements of atoms in a molecule that differ by rotation about single bonds can be referred to as different conformations, conformations that correspond to local minima on the potential energy surface are specifically called conformational isomers or conformers. Conformations that correspond to local maxima on the energy surface are the transition states between the local-minimum conformational isomers. Rotations about single bonds involve overcoming a rotational energy barrier to interconvert one conformer to another. If the energy barrier is low, there is free rotation and a sample of the compound exists as a rapidly equilibrating mixture of multiple conformers; if the energy barrier is high enough then there is restricted rotation, a molecule may exist for a relatively long time period as a stable rotational isomer or rotamer. When the time scale for interconversion is long enough for isolation of individual rotamers, the isomers are termed atropisomers. The ring-flip of substituted cyclohexanes constitutes another common form of conformational isomerism.
In chemistry, a molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound. The internal energy of a molecule consists of all the energy stored within it. A strained molecule has an additional amount of internal energy which an unstrained molecule does not. This extra internal energy, or strain energy, can be likened to a compressed spring. Much like a compressed spring must be held in place to prevent release of its potential energy, a molecule can be held in an energetically unfavorable conformation by the bonds within that molecule. Without the bonds holding the conformation in place, the strain energy would be released.
In organic chemistry, a ring flip is the interconversion of cyclic conformers that have equivalent ring shapes that results in the exchange of nonequivalent substituent positions. The overall process generally takes place over several steps, involving coupled rotations about several of the molecule's single bonds, in conjunction with minor deformations of bond angles. Most commonly, the term is used to refer to the interconversion of the two chair conformers of cyclohexane derivatives, which is specifically referred to as a chair flip, although other cycloalkanes and inorganic rings undergo similar processes.
In organic chemistry, pyranose is a collective term for saccharides that have a chemical structure that includes a six-membered ring consisting of five carbon atoms and one oxygen atom. There may be other carbons external to the ring. The name derives from its similarity to the oxygen heterocycle pyran, but the pyranose ring does not have double bonds. A pyranose in which the anomeric −OH at C(l) has been converted into an OR group is called a pyranoside.
In chemistry and molecular physics, fluxionalmolecules are molecules that undergo dynamics such that some or all of their atoms interchange between symmetry-equivalent positions. Because virtually all molecules are fluxional in some respects, e.g. bond rotations in most organic compounds, the term fluxional depends on the context and the method used to assess the dynamics. Often, a molecule is considered fluxional if its spectroscopic signature exhibits line-broadening due to chemical exchange. In some cases, where the rates are slow, fluxionality is not detected spectroscopically, but by isotopic labeling and other methods.
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Diamond and graphite are a familiar example; they are isomers of carbon. Isomerism refers to the existence or possibility of isomers.
Fluorographene (or perfluorographane, graphene fluoride) is a fluorocarbon derivative of graphene. It is a two dimensional carbon sheet of sp3 hybridized carbons, with each carbon atom bound to one fluorine. The chemical formula is (CF)n. In comparison, Teflon (polytetrafluoroethylene), -(CF2)n-, consists of carbon "chains" with each carbon bound to two fluorines.
Bilayer graphene is a material consisting of two layers of graphene. One of the first reports of bilayer graphene was in the seminal 2004 Science paper by Geim and colleagues, in which they described devices "which contained just one, two, or three atomic layers"
For inorganic compounds of carbon, chlorographene is fully chlorinated graphene with the chemical formula of (CCl)n. Upon reaction with chlorine, graphene's sp2 planar lattice structure is transformed to sp3 hybridized buckled structure, this structure is similar to hydrogenated graphene (graphane) and fluorinated graphene (fluorographene).
Germanane is a single-layer crystal composed of germanium with one hydrogen bonded in the z-direction for each atom, in contrast to germanene which contains no hydrogen. In material science, great interest is shown in related single layered materials, such as graphene, composed of carbon, and silicene, composed of silicon. Such materials represent a new generation of semiconductors with potential applications in computer chips and solar cells. Germanane's structure is similar to graphane, and therefore graphene. Bulk germanium does not adopt this structure. Germanane has been produced in a two-step route starting with calcium germanide. From this material, the calcium is removed by de-intercalation with HCl to give a layered solid with the empirical formula GeH. The Ca sites in Zintl phase CaGe2 interchange with the H atoms in the HCl solution, which leaves GeH and CaCl2.
In materials science, the term single-layer materials or 2D materials refers to crystalline solids consisting of a single layer of atoms. These materials are promising for some applications but remain the focus of research. Single-layer materials derived from single elements generally carry the -ene suffix in their names, e.g. graphene. Single-layer materials that are compounds of two or more elements have -ane or -ide suffixes. 2D materials can generally be categorized as either 2D allotropes of various elements or as compounds.
Penta-graphene is a hypothetical carbon allotrope composed entirely of carbon pentagons and resembling the Cairo pentagonal tiling. Penta-graphene was proposed in 2014 on the basis of analyses and simulations. Further calculations predicted that it is unstable in its pure form, but can be stabilized by hydrogenation. Due to its atomic configuration, penta-graphene has an unusually negative Poisson’s ratio and very high ideal strength believed to exceed that of a similar material, graphene.
Graphene is a semimetal whose conduction and valence bands meet at the Dirac points, which are six locations in momentum space, the vertices of its hexagonal Brillouin zone, divided into two non-equivalent sets of three points. The two sets are labeled K and K'. The sets give graphene a valley degeneracy of gv = 2. By contrast, for traditional semiconductors the primary point of interest is generally Γ, where momentum is zero. Four electronic properties separate it from other condensed matter systems.
Graphene is the only form of carbon in which every atom is available for chemical reaction from two sides. Atoms at the edges of a graphene sheet have special chemical reactivity. Graphene has the highest ratio of edge atoms of any allotrope. Defects within a sheet increase its chemical reactivity. The onset temperature of reaction between the basal plane of single-layer graphene and oxygen gas is below 260 °C (530 K). Graphene combusts at 350 °C (620 K). Graphene is commonly modified with oxygen- and nitrogen-containing functional groups and analyzed by infrared spectroscopy and X-ray photoelectron spectroscopy. However, determination of structures of graphene with oxygen- and nitrogen- functional groups requires the structures to be well controlled.
Twistronics is the study of how the angle between layers of two-dimensional materials can change their electrical properties. Materials such as bilayer graphene have been shown to have vastly different electronic behavior, ranging from non-conductive to superconductive, that depends sensitively on the angle between the layers. The term was first introduced by the research group of Efthimios Kaxiras at Harvard University in their theoretical treatment of graphene superlattices.
