12596-60-0Relevant academic research and scientific papers
308 nm laser photodissociation of HN3 adsorbed on Si(111)-7×7
Bu, Y.,Lin, M. C.
, p. 118 - 128 (1994)
The photodissociation of HN3 adsorbed on Si(111)-7×7 at 308 nm was investigated using HREELS and XPS. Species such as NHx N2, and N3 were identified on the surface with comparable concentrations after the irradiation with 1×1020 photons of a 10 L HN3 dosed Si(111) surface. The N3 species showed two stretching modes at 178 and 255 meV, while that of the N2 appeared at 206 meV in HREELS. The formation of these products was also corroborated by the corresponding XPS results. Further laser irradiation caused the dissociation and partial desorption of the adsorbates with NHx left on the surface. Annealing the post-irradiated sample to 500 and 800 K resulted in the breaking of the NH bond and the desorption of the H-species, while the atomic N remained on the surface forming silicon nitride. The possibility of using HN3 for laser-induced chemical vapor deposition of Si3 N4 and group-III nitrides at low temperatures is suggested.
Photodecomposition of cis-azidoamminebis(2,4-pentanedionato)cobalt(III). The photoactive state
Reed, James L.
, p. 2590 - 2595 (1981)
The photodecomposition of cis-Co(acac)2N3NH3 (acac = 2,4-pentanedionate) occurs with the formation of Co(acac)2 and azide radicals. This reaction has been effected with the use of exciting radiations throughout the 250-580-nm region, and in the 250-470-nm region the quantum efficiency for this reaction is surprisingly wavelength independent. Examination of the optical spectra of Co(acac)2N3NH3 and Co(acac)3 and the respective optical electronegativities of the azide and 2,4-pentanedionate ligands suggests that photooxidation of the 2,4-pentanedionato group should be favored over that of the azido group. Yet photooxidation of the azido group is the only observed reaction. This observation, the relative constancy of the quantum efficiency, and the energy of the threshold for the onset of redox photodecomposition ((21.3-17.2) × 103 cm-1) suggest that the photoactive state is a triplet charge-transfer state involving the azido group. The photoreaction has an apparent activation energy of 11.7 kcal/mol, and solvent assistance in the loss of the azide radical is implicated.
Role of Azide Concentration in Pulse Radiolysis Studies of Oxidation: 3,4-Dihydroxyphenylalanine
Lambert, Chris,Truscott, T. George,Land, Edward J.,Riley, Patrick A.
, p. 2939 - 2942 (1991)
The radiolysis of aqueous solutions of 3,4-dihydroxyphenylalanine (dopa) using N3 as a one-electron oxidant leads to the formation of dopasemiquinone and, successively, dopaquinone and dopachrome.It is now shown that under pH conditions where significant protonation of N3(1-) to HN3 occurs, dopachrome formation is supressed, probably due predominantly to addition of HN3 to dopaquinone.The possibility of such nucleophilic reactions occuring needs to be considered in studies of quinone intermediates generated using N3 as oxidant.
Design and characterization of a synthetic electron-transfer protein
Kornilova, Anna Y.,Wishart, James F.,Xiao, Wenzhong,Lasey, Robin C.,Fedorova, Anna,Shin, Yeon-Kyun,Ogawa, Michael Y.
, p. 7999 - 8006 (2000)
A 30-residue polypeptide [H21(30-mer)] with the sequence Ac-K(IEALEGK)2(IEALEHK)-(IEALEGK)G-NH2 was synthesized. The circular dichroism (CD) spectrum of the peptide shows minima at 208 and 222 nm and θ222/θ208 = 1.06, which indicates the formation of a self-assembled coiled-coil when dissolved in aqueous solution. The concentration dependence of the CD data can be fit to an expression that describes a two-state monomer - dimer equilibrium for the apopeptide(K(d) = 1.5 ± 0.4 μM and θ(max) = -23 800 ± 130 deg cm2 dmol-1), showing that it has a maximum helicity of 69%. A [MTSL-C21(30-mer)] dimer was also prepared in which MTSL is the thiol-specific nitroxide spin label 1-oxyl-2,2,5,5-tetramethyl-Δ3-pyrroline-3-methyl-methanethiosulfonate attached to C21 of the 30-mer. Fourier deconvolution analysis of the dipolar line broadening of the electron paramagnetic resonance (EPR) spectrum yields a measure of the interchain Cα - Cα distance of 13.5 ± 0.9 A at position 21 of the coiled-coil, which is nearly identical to those distances observed for the isostructural family of bZip proteins. Two metallohomodimers, [Ru(trpy)(bpy)-H21(30-mer)]2 and [Ru(NH3)5-H21(30-mer)]2, in which the ruthenium complexes were coordinated with the H21 site of the 30-mer, were prepared. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS - PAGE), chemical cross-linking studies, and analytical ultracentrifugation show that the peptides exist as a dimeric coiled-coil with a molecular weight of ~ 7.5 kDa. The electron transfer (ET) heterodimer, [Ru(trpy)(bpy)-H21 (30-mer)]/ [Ru(NH3)5-H21(30-mer)], was prepared, and molecular modeling shows that the two metal complexes are separated by a metal-to-metal distance of ~ 24 A across the noncovalent peptide interface. Pulse radiolysis was used to measure an ET rate constant of k(et) = 380 ± 80 s-1 for the intracomplex electron transfer (ΔG°= -1.11 eV) from the Ru(II)(NH3)5-H21 donor to the Ru(III)(trpy)(bpy)-H21 acceptor. The value for k(et) falls within the range reported for modified proteins over comparable distances and supersedes the one reported in an earlier communication.
Engineered Regulon to Enable Autonomous Azide Ion Biosensing, Recombinant Protein Production, and in Vivo Glycoengineering
Bandi, Chandra Kanth,Skalenko, Kyle S.,Agrawal, Ayushi,Sivaneri, Neelan,Thiry, Margaux,Chundawat, Shishir P. S.
, p. 682 - 689 (2021)
Detection of azide-tagged biomolecules (e.g., azido sugars) inside living cells using "click"chemistry has been revolutionary to the field of chemical biology. However, we currently still lack suitable synthetic biology tools to autonomously and rapidly d
The Redox Potential of the Azide/Azidyl Couple
Alfassi, Zeev B.,Harriman, Anthony,Huie, Robert E.,Mosseri, S.,Neta, P.
, p. 2120 - 2122 (1987)
Pulse radiolysis experiments were carried out with neutral aqueous solutions containing azide with iodide, bromide, or thiocyanate to examine possible one-electron transfer rates and equilibria involving the N3 radical/N3(1-) couple.The N3 radical was found to oxidize I(1-) with a rate constant of 4.5E8/M*s.No reaction was observed between I2(1-) radical and N3(1-).With Br(1-), however, the system reached equilibrium, Br2(1-) radical + N3(1-)->f = 4.0E8/M*s and kr = 7.3E3/M2*s.From the equilibrium constant K = 5.5E4 M and the redox potential E(Br2(1-) radical/2Br(1-)) = 1.63 V we calculated E(N3 radical/N3(1-)) = 1.35 +/- 0.02 V vs.NHE.Cyclic voltammetry experiments with N3(1-) showed a single peak on the anodic scan and no peak on the cathodic scan due to the rapid decay of the N3 radicals.From the dependence of peak potential on scan rate we derived E1/2 for the N3 radical/N3(1-) couple, 1.32 /- 0.03 V vs.NHE.
Time resolved resonance Raman observation of the extreme protonation forms of a radical zwitterion in water
Tripathi
, (2005)
The reactions of the aqueous proton with the zwitterionic p-aminophenoxyl radical in strongly basic to extremely acidic aqueous solutions have been investigated using time-resolved resonance Raman spectroscopy. The dynamic stability of the different protonation forms of the radical, observed on the microsecond time scale in this work, has been achieved by controlling the proton exchange rate in water. In strongly acidic solutions we observe a rare ring-H+ bonded dication species, a key intermediate in the amine hydrolysis. The neutral p-aminophenoxyl radical undergoes NH2- deprotonation in strongly basic aqueous solutions, which has no analogues in closed-shell amines.
Observation of N3 by Laser-Induced Fluorescence
Beaman, R. A.,Nelson, T.,Richards, D. S.,Setser, D. W.
, p. 6090 - 6092 (1987)
Gas-phase N3 was generated by the F + NH3 reaction and detected by using laser-induced fluorescence in a flow reactor.The and the excitations were investigated.Evidence was obtained for an upper-state lifetime of level or the smaller spin-orbit splitting in the level can be utilized for monitoring of N3 by the LIF technique using a monochromator to disperse the fluorescence.Very weak transitions were identified, and these could be useful for monitoring the laser-induced fluorescence of N3 with an interference filter.
Photodissociation of HN3 at 248 nm and Longer Wavelength: A CASSCF Study
Fang, Wei-Hai
, p. 4045 - 4050 (2000)
In the present work, photodissociation of HN3 at 248 nm and longer wavelength is investigated with the complete active space SCF (CASSCF) molecular orbital method. The stationary points on the ground- and excited-state potential energy surfaces are fully optimized at the CASSCF level with cc-pVDZ and cc-pVTZ basis sets. The potential energy profiles, governing HN3 dissociation to NH + N2 and H + N3, are characterized with the multireference MP2 (CASPT2) algorithm. The pathways leading to different products are determined on the basis of the obtained potential energy surfaces of dissociation and their crossing points. A comparison is made among the present and previous theoretical results and experimental findings. The present study provides an insight into the mechanism of the UV photodissociation of HN3 at a wavelength range from 355 to 248 nm.
Ultraviolet photodissociation dynamics of HN3: The H+N3 channel
Zhang, Jingsong,Xu, Kesheng,Amaral, Gabriel
, p. 285 - 290 (1999)
The H+N3(X 2Πg) channel in the ultraviolet photodissociation of HN3 has been studied at 248.3 and 193.3 nm using the high-n Rydberg H-atom time-of-flight technique. In 248.3 nm photodissociation, center-of-mass translational energy distribution reveals a propensity toward product translation (〈ftrans〉=0.71) and N3 bending and symmetric stretching excitation. An anisotropic product angular distribution (β≈-0.8) indicates a perpendicular electronic transition and rapid dissociation on the excited-state surface. H-N bond energy is estimated: D0(H-N3)≤88.7±0.5 kcal/mol. At 193.3 nm, 〈ftrans〉 is smaller and product angular distribution is energy-dependent, suggesting multiple dissociation pathways via different electronic states.
