Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Chemical compound
Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as 1 [O 2] or 1 O 2), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, but the rate of decay is slow.
The lowest excited state of the diatomic oxygen molecule is a singlet state.
It is a gas with physical properties differing only subtly from those of the more prevalent triplet ground state of O2. In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds. It is responsible for the photodegradation of many materials but can be put to constructive use in preparative organic chemistry and photodynamic therapy. Trace amounts of singlet oxygen are found in the upper atmosphere and in polluted urban atmospheres where it contributes to the formation of lung-damaging nitrogen dioxide.[1]: 355–68 It often appears and coexists confounded in environments that also generate ozone, such as pine forests with photodegradation of turpentine.[citation needed]
The terms 'singlet oxygen' and 'triplet oxygen' derive from each form's number of electron spins. The singlet has only one possible arrangement of electron spins with a total quantum spin of 0, while the triplet has three possible arrangements of electron spins with a total quantum spin of 1, corresponding to three degenerate states.
In spectroscopic notation, the lowest singlet and triplet forms of O2 are labeled 1Δg and 3Σ− g, respectively.[2][3][4]
^Wayne RP (1969). "Singlet Molecular Oxygen". In Pitts JN, Hammond GS, Noyes WA (eds.). Advances in Photochemistry. Vol. 7. pp. 311–71. doi:10.1002/9780470133378.ch4. ISBN 9780470133378.
^Klán P, Wirz J (2009). Photochemistry of Organic Compounds: From Concepts to Practice (Repr. 2010 ed.). Chichester, West Sussex, U.K.: Wiley. ISBN 978-1405190886.
^Atkins P, de Paula J (2006). Atkins' Physical Chemistry (8th ed.). W.H.Freeman. pp. 482–3. ISBN 978-0-7167-8759-4.
^Hill C. "Molecular Term Symbols" (PDF). Archived from the original (PDF) on 5 September 2017. Retrieved 10 October 2016.
Singletoxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as 1 [O 2] or...
(O3). Others are: Atomic oxygen (O1), a free radical. Singletoxygen (O* 2), one of two metastable states of molecular oxygen. Tetraoxygen (O4), another...
peroxide and sulfur dioxide. DABCO and related amines are quenchers of singletoxygen and effective antioxidants, and can be used to improve the lifetime...
shirt or vest wrestling singlet, a one-piece garment specific to wrestling BID/60, a British encryption machine Singletoxygen, the common name used for...
hydroperoxide (O2H), superoxide (O2-), hydroxyl radical (OH.), and singletoxygen. ROS are pervasive because they are readily produced from O2, which...
making triplet oxygen an unusual example of a stable and commonly encountered diradical: it is more stable as a triplet than a singlet. According to molecular...
common organic molecules than is normal (triplet) molecular oxygen. In nature, singletoxygen is commonly formed from water during photosynthesis, using...
transfer from a substrate molecule and highly reactive state of oxygen known as singletoxygen (Type II). PDT is a multi-stage process. First a photosensitiser...
have been suggested. Reactive oxygen species, especially singletoxygen, have a role in the acceptor-side, singletoxygen and low-light mechanisms. In...
heat, potassium chloride, and oxygen in excited state, singlet delta oxygen. Spontaneous transition of excited oxygen to the triplet sigma ground state...
radicals and oxidizing radicals. Oxidizing species include singletoxygen, hydroxyl, monatomic oxygen, and hydroperoxyl. Such intermediates are short-lived...
states are often called metastable. Long-lived nuclear isomers and singletoxygen are two examples of this. Atoms can be excited by heat, electricity...
wavelength of 689 nm in the presence of oxygen, produces highly reactive short-lived singletoxygen and other reactive oxygen radicals, resulting in local damage...
arachidonic acid and linoleic acid, are primary targets for free radical and singletoxygen oxidations. For example, in tissues and cells, the free radical oxidation...
appear to be additive. Ozone, along with reactive forms of oxygen such as superoxide, singletoxygen, hydrogen peroxide, and hypochlorite ions, is produced...
plant tissues by helping to absorb the energy from singletoxygen, an excited form of the oxygen molecule O2 which is formed during photosynthesis. β-Carotene...
molecules have a central carbon atom that is connected by a double bond to oxygen, a single bond to hydrogen and another single bond to a third substituent...
the analyte concentration. The luminescent oxygen channeling immunoassay (LOCI) generates singletoxygen species in microbeads coupled to the analyte...
The reaction is affected by the presence of oxygen. Anthracene also reacts with dienophile singletoxygen in a [4+2]-cycloaddition (Diels–Alder reaction):...
the antibonding orbitals occupy a degenerate π* orbital, and oxygen is now in a singlet state (indicated as 1O2). 1O2 is very reactive with a lifetime...
ultraviolet light, such as in sunlight, alpha-terthienyl generates the toxic singletoxygen. Alpha-terthienyl results in damage to the respiratory, digestive and...
excited state. This can then react with ambient oxygen, converting it into highly reactive singletoxygen. Quenchers are able to absorb energy from excited...
also capable of preventing oxidative damage by directly scavenging singletoxygen (1O2). OCP was first described in 1981 by Holt and Krogmann who isolated...
however, create peroxide, superoxide, and singletoxygen to destroy invading microbes. Recently, singletoxygen has been found to be a source of biologically-produced...
Global Information
