Borospherene (B 40 ) is an electron-deficient cluster molecule containing 40 boron atoms. It bears similarities to other homoatomic cluster structures such as buckminsterfullerene (C 60 ), stannaspherene, and plumbaspherene, but with a different symmetry. The first experimental evidence for borospherene was reported in July 2014, and is described in the journal Nature Chemistry . The molecule includes unusual hexagonal and heptagonal faces. Despite many calculation-based investigations into its structure and properties, a viable route for the synthesis and isolation of borospherene has yet to be established, and as a consequence it is still relatively poorly understood.
27-476: B40 , B-40 , or B.40 may refer to: Roads [ edit ] Autovia B-40 , a Spanish motorway in Catalonia Bundesstraße 40 , a German road In Science [ edit ] Borospherene , B 40 , an allotropic cage-like molecule of pure boron HLA-B40 , an HLA-B serotype Military [ edit ] Vietnamese designation of
54-413: A standard circuit breaker current rating B40 Balkan Cities Network , an intercity organization between Balkans cities Sicilian Defence , Encyclopaedia of Chess Openings code [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change
81-418: A combination of simulated spectra of a sheet-like, quasi-planar global minimum of the B 40 anion (C s symmetry) and its nearly degenerate fullerene-like structural isomer (D 2d symmetry). Many theoretical papers have been published on the structure, properties, and potential applications of borospherene. Neutral borospherene has a large HOMO-LUMO gap of 3.13 eV (which destabilises its anion, making
108-407: A fractional B-B bond order respectively. This encapsulates well the large degree of both sigma- and pi-delocalisation of electrons across the electron-deficient cluster as opposed to buckminsterfullerene, which has more localised bonds and features only two bond lengths corresponding to a C-C single bond and a C-C double bond respectively. The HOMO of borospherene is quadruply degenerate, computed to be
135-406: A homoelemental fullerene -like B 40 cluster was reported by Zhai et al ., after decades of theoretical investigations into boron cage structures following the discovery of buckminsterfullerene. Anionic B 40 clusters were transiently produced by laser vaporisation of a B-enriched boron disc target, and studied with photoelectron spectroscopy . Their experimental spectrum corresponded well to
162-409: A pi-bond delocalised over 5 boron atoms. Lai-Sheng Wang , professor of chemistry at Brown University , modeled possible B 40 and B 40 anion structures. The simulated spectra of two energetically lowest-lying isomers of the anion - a sheet-like structure and a closed cage - were found to fit experimental data well. Photoelectron spectroscopy revealed that the substance formed in the laboratory
189-432: A potential sensor for sulfur -containing gases, and found that it behaved as an electronic sensor for sulfur dioxide and carbon disulfide (their adsorption to the boron cluster significantly stabilises its LUMO, increasing its population of conducting electrons), and additionally as a Φ-type sensor for the former (due to significant change to its work function Φ upon the adsorption of SO 2 ), but behaved as neither for
216-420: A role in strain reduction contributing to the stability of the cluster. 16 boron atoms of borospherene are four-coordinate, and 24 are five-coordinate. It has four sets of eight equivalent boron atoms, and two sets of four equivalent atoms. Neutral borospherene has a diameter of 6.2 Å. It comprises eleven unique bond lengths ranging from 1.60 Å to 1.85 Å, corresponding to a B-B bond order of slightly below 2 to
243-422: Is "a reaction for which the overall standard enthalpy change Δ H ⚬ is negative". Some examples of exothermic process are fuel combustion , condensation and nuclear fission , which is used in nuclear power plants to release large amounts of energy. In an endothermic reaction or system, energy is taken from the surroundings in the course of the reaction, usually driven by a favorable entropy increase in
270-408: Is equal to the enthalpy change, i.e. while at constant volume , according to the first law of thermodynamics it equals internal energy ( U ) change, i.e. In an adiabatic system (i.e. a system that does not exchange heat with the surroundings), an otherwise exothermic process results in an increase in temperature of the system. In exothermic chemical reactions, the heat that is released by
297-651: The RPG-2 , the first rocket-propelled grenade launcher designed in the Soviet Union BSA B40, a 350cc British motorcycle Blackburn B.40 , an experimental Blackburn flying boat Rolls-Royce B40 Engine , an inline-four petrol engine primarily used in the Austin Champ Unterseeboot B-40 , World War I Imperial Germany Navy submarine U-boat YB-40 Flying Fortress , an aircraft Other [ edit ] 40 amp, type B –
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#1732776838288324-494: The cage-like structure of borospherene, as well as borospherene's coordinatively unsaturated hexagonal and heptagonal faces, allows for the possibility of its endohedral or exohedral doping. With metal dopants, significant charge transfer is calculated to occur from the metals to the B 40 cage - resulting in a positive charge forming on the metal, ostensibly making it capable of polarising small molecules. Such complexes formed are theorised to have applications in catalysis, and
351-414: The classical understanding of heat. In an exothermic reaction, the activation energy (energy needed to start the reaction) is less than the energy that is subsequently released, so there is a net release of energy. Some examples of exothermic processes are: Chemical exothermic reactions are generally more spontaneous than their counterparts, endothermic reactions . In a thermochemical reaction that
378-435: The detection or storage of small molecules such as H 2 . Exploiting the thermal stability of B 40 (calculated to be stable up to 1000 K), Liu et al . investigated, with Van der Waals -corrected density functional theory calculations, the feasibility of using alkali metal-decorated B 40 for the reversible storage and optical detection of hydrogen. Optimisation of (AM) 6 B 40 structures (AM = Li, Na, K) revealed
405-459: The form of heat. The concept is frequently applied in the physical sciences to chemical reactions where chemical bond energy is converted to thermal energy (heat). Exothermic and endothermic describe two types of chemical reactions or systems found in nature, as follows: An exothermic reaction occurs when heat is released to the surroundings. According to the IUPAC , an exothermic reaction
432-462: The gases carbonyl sulfide and hydrogen sulfide . Modelling an exohedral Ca 6 B 40 , Esrafili et al . simulated carbon dioxide adsorption to the complex and found the upper bound of adsorption to be four CO 2 molecules per Ca, with an average binding energy of -0.54 eV each - falling within the optimal range of binding energies for a CO 2 adsorbent (0.40 - 0.80 eV), allowing facile desorption at elevated temperatures. Undecorated B 40
459-440: The ground state of B 40 the quasi-planar isomer). However, it has been calculated to be prone to exothermic dimerisation, with a low activation barrier of 63 meV, followed by trimerisation with a lower energy barrier, and runaway aggregation. As a result, borospherene has yet to be isolated and is poorly experimentally-characterised, unlike buckminsterfullerene. Borospherene has a unique C 2 axis of symmetry, and belongs to
486-427: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=B40&oldid=1202831955 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Borospherene In 2014, the first experimental evidence of
513-449: The metal atoms to be distributed above the centres of each hexagon and heptagon of B 40 , with a large binding energy in each case suggesting these complexes should be stable. H 2 adsorption to these complexes induced a red-shift in their simulated TDDFT optical spectra in the case of Li 6 B 40 , and a blue-shift in the cases of Na 6 B 40 and K 6 B 40 . Li et al . computationally investigated undecorated borospherene as
540-454: The optimal range for reversible hydrogen storage. Subsequent H 2 molecules are physisorbed to the cluster instead of chemisorbed , and have a much weaker binding energy. Exothermic process In thermodynamics , an exothermic process (from Ancient Greek έξω ( éxō ) 'outward' and θερμικός ( thermikós ) 'thermal') is a thermodynamic process or reaction that releases energy from
567-477: The reaction takes the form of electromagnetic energy or kinetic energy of molecules. The transition of electrons from one quantum energy level to another causes light to be released. This light is equivalent in energy to some of the stabilization energy of the energy for the chemical reaction, i.e. the bond energy . This light that is released can be absorbed by other molecules in solution to give rise to molecular translations and rotations, which gives rise to
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#1732776838288594-464: The sun and use it in an endothermic, otherwise non-spontaneous process. The chemical energy stored can be freed by the inverse (spontaneous) process: combustion of sugar, which gives carbon dioxide, water and heat (radiant energy). Exothermic refers to a transformation in which a closed system releases energy (heat) to the surroundings, expressed by When the transformation occurs at constant pressure and without exchange of electrical energy , heat Q
621-444: The symmetry group is D 2d ( antiprismatic symmetry , like a baseball ) - in contrast to buckminsterfullerene, which has icosahedral symmetry . It features eight close-packed B 6 triangles, two staggered hexagonal holes at its top and bottom, as well as four heptagonal holes along its sides. Unusually, the heptagons induce positive Gaussian curvature (as opposed to negative Gaussian curvature in carbon nanotubes), which may play
648-473: The system to its surroundings , usually in the form of heat , but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen). The term exothermic was first coined by 19th-century French chemist Marcellin Berthelot . The opposite of an exothermic process is an endothermic process, one that absorbs energy, usually in
675-441: The system. An example of an endothermic reaction is a first aid cold pack, in which the reaction of two chemicals, or dissolving of one in another, requires calories from the surroundings, and the reaction cools the pouch and surroundings by absorbing heat from them. Photosynthesis , the process that allows plants to convert carbon dioxide and water to sugar and oxygen, is an endothermic process: plants absorb radiant energy from
702-425: Was calculated to be a poor candidate for reversible hydrogen storage, being capable of the irreversible sequestration of only one hydrogen molecule per B 40 within its cage. Li 6 B 40 , however, is calculated to be capable of adsorbing up to 18 H 2 molecules (3 H 2 molecules at each Li site) - corresponding to a gravimetric density of 7.1 wt% - with a moderate average binding energy of 0.11 eV/H 2 , within
729-412: Was this cage. Both neutral borospherene and the cage-like isomer of its anion have the same D 2d symmetry, the additional electron in the anion being housed within the B 40 cage structure. The structure of the cage is not perfectly uniform – "Several atoms stick out a bit from the others, making the surface of borospherene somewhat less smooth than a buckyball" according to Wang. The cavity within
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