dc.contributor.author | Bucher, G. | en |
dc.contributor.author | Tönshoff, C. | en |
dc.contributor.author | Nicolaïdes, Andrew N. | en |
dc.creator | Bucher, G. | en |
dc.creator | Tönshoff, C. | en |
dc.creator | Nicolaïdes, Andrew N. | en |
dc.date.accessioned | 2019-11-21T06:17:15Z | |
dc.date.available | 2019-11-21T06:17:15Z | |
dc.date.issued | 2005 | |
dc.identifier.uri | http://gnosis.library.ucy.ac.cy/handle/7/55308 | |
dc.description.abstract | Photolysis of the cryptand 1, bearing an intraannular azido substituent, results in a complex photochemistry. Low-temperature photolysis yields the triplet nitrene 32, which has been characterized by EPR spectroscopy. Small differences in ZFS parameters are detected between the uncomplexed nitrene-functionalized ligand (in EtOH: D′ = 0.93 cm-1) and its sodium (NaBr@32 in EtOH: D′ = 0.88 cm-1) and potassium (KBr@32 in MTHF: D′ = 0.89 cm-1) complexes. If the photolysis of the free ligand is conducted at ambient temperature, a derivative of o-aminobenzaldehyde 4 is found to be the main product, which is formed by reaction of the o-iminoquinone methide 9 with water. The latter can be detected by UV/vis spectroscopy. Its lifetime is τ = 254 s in acetonitrile solution at ambient temperature. In the presence of diethylamine, the methyleneazepine derivative 5 is formed, which is indicative of didehydroazepine formation (7). Room-temperature photolysis of acetonitrile solutions of the sodium or potassium complexes also results in formation of the o-aminobenzaldehyde derivative. In the presence of diethylamine, however, no methyleneazepine 5 is found. Formation of the aniline derivative 8 instead points to free radical processes. Laser flash photolysis (LFP) of acetonitrile solutions of 1 leads to the detection of a short-lived (τ = 1.4 μs, λmax = 445 nm plus weak absorption at λ > 500 nm) intermediate A, which decays to transient B (τ = 8 ms, λ max = 295 and ca. 350-400 nm). LFP of acetonitrile solutions of complexes NaBr@1 and KBr@1 gives similar transient spectra. In the presence of sodium and potassium cations, the lifetime of the short-lived transient A is reduced (Na+: A′, τ = 200 ns | en |
dc.description.abstract | K+: A″, τ = 160 ns). Transients A′ and A″ decay to long-lived transients B′ + C′ (B″ + C″). Based on the results of our product studies, a comparison with the low-temperature results, and quantum mechanical calculations, the transients A, A′, and A″ are identified as singlet nitrenes 12, NaBr@12, and KBr@12, while the long-lived transients B, B′, and B″ are assigned to didehydroazepines 7, NaBr@7, and KBr@7. Transients C′ and C″ can be assigned to aminyl radicals NaBr@16 and KBr@16. © 2005 American Chemical Society. | en |
dc.source | Journal of the American Chemical Society | en |
dc.source.uri | https://www.scopus.com/inward/record.uri?eid=2-s2.0-18644378491&doi=10.1021%2fja0447208&partnerID=40&md5=c2ebc84093076dbe122b522d39a842f7 | |
dc.subject | article | en |
dc.subject | unclassified drug | en |
dc.subject | quinone derivative | en |
dc.subject | Quantum theory | en |
dc.subject | Positive ions | en |
dc.subject | Absorption | en |
dc.subject | low temperature | en |
dc.subject | Substitution reactions | en |
dc.subject | Solutions | en |
dc.subject | complex formation | en |
dc.subject | electron spin resonance | en |
dc.subject | ligand | en |
dc.subject | water | en |
dc.subject | potassium derivative | en |
dc.subject | Complexation | en |
dc.subject | Derivatives | en |
dc.subject | quantum mechanics | en |
dc.subject | aniline derivative | en |
dc.subject | Sodium | en |
dc.subject | cation | en |
dc.subject | Ultraviolet spectroscopy | en |
dc.subject | Photolysis | en |
dc.subject | alkali | en |
dc.subject | Nitrogen compounds | en |
dc.subject | sodium derivative | en |
dc.subject | 2 iminoquinone methide | en |
dc.subject | Acetonitrile | en |
dc.subject | acetonitrile derivative | en |
dc.subject | aldehyde derivative | en |
dc.subject | Amines | en |
dc.subject | aminobenzaldehyde | en |
dc.subject | Aryl nitrene | en |
dc.subject | azepine derivative | en |
dc.subject | Azido-functionalized cryptand | en |
dc.subject | didehydroazepine | en |
dc.subject | diethylamine | en |
dc.subject | environmental temperature | en |
dc.subject | laser | en |
dc.subject | Laser applications | en |
dc.subject | Laser flash photolysis (LFP) | en |
dc.subject | methylene azepine | en |
dc.subject | photochemistry | en |
dc.subject | Potassium | en |
dc.subject | Quantum mechanical calculations | en |
dc.title | Photochemistry of an azido-functionalized cryptand: Controlling the reactivity of an extremely long-lived singlet aryl nitrene by complexation to alkali cations | en |
dc.type | info:eu-repo/semantics/article | |
dc.identifier.doi | 10.1021/ja0447208 | |
dc.description.volume | 127 | |
dc.description.issue | 18 | |
dc.description.startingpage | 6883 | |
dc.description.endingpage | 6892 | |
dc.author.faculty | 002 Σχολή Θετικών και Εφαρμοσμένων Επιστημών / Faculty of Pure and Applied Sciences | |
dc.author.department | Τμήμα Χημείας / Department of Chemistry | |
dc.type.uhtype | Article | en |
dc.description.notes | <p>Cited By :12</p> | en |
dc.source.abbreviation | J.Am.Chem.Soc. | en |