54773-16-9Relevant academic research and scientific papers
Photosensitive and Photoswitchable TRPA1 Agonists Optically Control Pain through Channel Desensitization
Luo, Jiajie,Qi, Hang,Qiao, Zhen,Tang, Xiaowen,Tang, Yi-Quan,Wang, KeWei,Wei, Ningning,Yin, Zhengji,Zhang, Yanru,Zhou, Qiqi,Zhu, Wei
supporting information, p. 16282 - 16292 (2021/11/12)
Transient receptor potential ankyrin 1 (TRPA1) channel, as a nonselective ligand-gated cation channel robustly in dorsal root ganglion sensory neurons, is implicated in sensing noxious stimuli and nociceptive signaling. However, small-molecule tools targeting TRPA1 lack temporal and spatial resolution, limiting their use for validation of TRPA1 as a therapeutic target for pain. In our previous work, we found that 4,4′-(diazene-1,2-diyl)dianiline (AB1) is a photoswitchable TRPA1 agonist, but the poor water solubility and activity hinder its further development. Here, we report a series of specific and potent azobenzene-derived photoswitchable TRPA1 agonists (series 1 and 2) that enable optical control of the TRPA1 channel. Two representative compounds 1g and 2c can alleviate capsaicin-induced pain in the cheek model of mice through channel desensitization but not in TRPA1 knockout mice. Taken together, our findings demonstrate that photoswitchable TRPA1 agonists can be used as pharmacological tools for study of pain signaling.
Azobenzene-based ruthenium(ii) catalysts for light-controlled hydrogen generation
Telleria,Van Leeuwen,Freixa
supporting information, p. 3569 - 3578 (2017/03/22)
Eight new ruthenium(ii) half-sandwich complexes containing azobenzene-appended pyridine (1), bipyridine (2-5) and phosphine (6 and 7) ligands have been synthesized and fully characterized. UV-vis spectroscopic studies showed that the trans-to-cis photoisomerization was strongly inhibited upon coordination to the metal centre in azopyridine-derived ligands 1 and 2, but it remained efficient in azobenzene-appended bipyridine (3-5) and phosphine (6 and 7) ligands. The complexes were tested as precatalysts for photo-controlled hydrogen generation by hydrolytic decomposition of ammonia-borane (AB). In situ irradiation of the reaction mixtures of compounds [Ru(p-Cym)(6)Cl]Cl and [Ru(p-Cym)(7)Cl]Cl induced a clear change in the catalytic reaction rate, serving as a proof of concept for light-controlled hydrogen generation.
Azobenzene-Appended Bis-Cyclometalated Iridium(III) Bipyridyl Complexes
Telleria, Ainara,Pérez-Miqueo, Jorge,Altube, Ainhoa,García-Lecina, Eva,De Cózar, Abel,Freixa, Zoraida
, p. 5513 - 5529 (2015/12/23)
A new synthetic route toward photochromic azobenzene-appended bipyridyl ligands has been developed, and 20 new cationic iridium(III) bis-cyclometalated complexes containing up to four azobenzene fragments on their structure have been synthesized and characterized electronically and spectroscopically. These compounds incorporate photochromic azobenzene units in their neutral pyridyl ligands 1-5, and in four of them azobenzenes have been also introduced a posteriori on their phenylpyridyl ligands by palladium-catalyzed cross-coupling. UV-vis-monitored light-triggered trans-to-cis isomerization of the azobenzene-appended ligands revealed a strong inhibition of this process upon coordination to the d6-metal ion. TD-DTF calculations revealed that this inhibition could be a consequence of a metal to ligand charge transfer relaxation process.
Thermal spin crossover behaviour of two-dimensional hofmann-type coordination polymers incorporating photoactive ligands
Ragon, Florence,Yaksi, Korcan,Sciortino, Natasha F.,Chastanet, Guillaume,Ltard, Jean-Francois,D'Alessandro, Deanna M.,Kepert, Cameron J.,Neville, Suzanne M.
, p. 1563 - 1573 (2015/01/09)
Two spin crossover (SCO)-active 2D Hofmann-type framework materials, [Fe(3-PAP)2Pd(CN)4] (A) and [Fe(4-PAP)2 Pd(CN)4] (B) containing the photoactive azo-benzene-type ligands 3-phenylazo-pyridine (3-PAP) and 4-phenylazopyridine (4-PAP) were prepared. These materials form non-porous Hofmann-type structures whereby 2D [FeIIPd(CN)4] grids are separated by 3- or 4-PAP ligands. The iron(II) sites of both materials (A and B) undergo abrupt and hysteretic spin transitions with characteristic transition temperatures T1/2↓,↑: 178, 190K (ΔT: 12K) and T1/2↓,↑: 233, 250K (ΔT: 17 K), respectively. Photo-magnetic characterisations reveal light-induced excited spin state trapping (LIESST) activity in both A and B with characteristic T(LIESST) values of 45 and 40 K. Although both free ligands show trans- to-cis isomerisation in solution under UV-irradiation, as evidenced via absorption spectroscopy, such photo-activity was not observed in the ligands or complexes A and B in the solid state. Structural analysis of a further non-SCO active isomer to B, [Fe(4-PAP)2 Pd(CN)4]·1/2(4-PAP) (B·(4-PAP)), which contains free ligand in the pore space is reported.
Modulation of magnetic properties at room temperature: Coordination-induced valence tautomerism in a cobalt dioxolene complex
Witt, Alexander,Heinemann, Frank W.,Khusniyarov, Marat M.,Sproules, Stephen
, p. 11149 - 11162,14 (2015/02/02)
The valence-tautomeric six-coordinate complex [Co(tbdiox) 2(4-papy)2] (1; tbdiox=redox-active 3,5-di-tert-butyl-o- dioxolene, 4-papy=4-phenylazopyridine) was synthesized and its electronic structure examined. Whereas 1 shows regular thermally driven valence tautomerism in the solid state, it partially dissociates in solution to form the five-coordinate species [Co(tbdiox)2(4-papy)] (2) and free 4-papy. Species 1 and 2 exhibit different electronic structures - low-spin (ls) Co III and high-spin (hs) CoII, respectively - in solution at room temperature and therefore different magnetic properties. Since 1 and 2 are in an equilibrium that is 4-papy-dependent, the magnetic moment of the solution species can be tuned by means of the ligand content. Thus, the concept of coordination-induced valence tautomerism (CIVT) has been introduced. The electronic structures of 1 and 2 as well as their CIVT were elucidated by X-ray crystallography, electrochemistry, titration experiments, and all variable-temperature SQUID susceptometry, NMR, EPR, and electronic absorption spectroscopy. The experimental findings are strongly supported by broken-symmetry DFT calculations. The magnetic exchange interactions in different types of valence-tautomeric cobalt complexes were explored computationally.
FeIII spin-crossover complexes with photoisomerizable ligands: Experimental and theoretical studies on the ligand-driven light-induced spin change effect
Bannwarth, Alexander,Schmidt, Sven Olaf,Peters, Gerhard,Soennichsen, Frank D.,Thimm, Wulf,Herges, Rainer,Tuczek, Felix
experimental part, p. 2776 - 2783 (2012/08/14)
Conflicting results have been reported with respect to the photoinduced switching of the magnetic properties of [FeIII(salten)]+ complexes [salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate)] coordinated by photoisomerizable ligands. In order to address this problem, two FeIII complexes [Fe(salten)(3-azpy)]BPh4 (1) and [Fe(salten)(4-azpy)]BPh4 (2) have been synthesized and characterized by various physicochemical methods (azpy = phenylazopyridine). Both 1 and 2 exhibit a low spin (S = 1/2) to high spin (HS, S = 5/2) transition in the solid state. In solution at room temperature both complexes are predominantly HS. Upon exposure to 310 (trans → cis) and 440 nm radiation (cis → trans) the free and coordinated 3- and 4-azpy ligands undergo a reversible cis-trans isomerization. For 2 a corresponding reduction of the HS fraction 2% is observed, whereas in 1 no effect is observed. Extensive DFT calculations, which employ different functionals and basis sets, explain this experimental result. The consequences of these findings with respect to the design of spin-switchable iron(III) complexes with photoactive ligands are discussed.
Acid-catalysed disproportionation and benzidine rearrangement of phenylhydrazinopyridines: Reaction pathways, kinetics and mechanism
Buncel, Erwin,Cheon, Kap-Soo
, p. 1241 - 1247 (2007/10/03)
A kinetic and product analysis study of the reaction of 4-[N′-(4-hydroxyphenylhydrazino)]pyridine (1) and 4-(N′-phenylhydrazino)pyridine (2) in 10-55 wt% aqueous sulfuric acid media is reported. The final products obtained from 1 are the oxidation product, 4-(4-hydroxyphenylazo)pyridine (3), and the two reduction products 4-aminophenol and 4-aminopyridine. This product pattern resembles that of the disproportionation products observed in some cases of the benzidine rearrangement. The reaction of 2 gives a complex product mixture including the disproportionation products 4-(phenylazo)pyridine (4), aniline and 4-aminopyridine, and other benzidine-type products including a p-semidine. Complicating the situation is the concurrent hydroxylation and disproportionation of 4 which take place in these media, giving 3, 4-aminopyridine and 4-aminophenol. The observed pseudo-first-order rate constants for the disproportionations increase steeply with acid concentration without showing any downturn at higher acidities. The disproportionation rate constants for 1 and 2 are much larger than those for the hydroxylation of 4. A reasonable mechanism which explains the observations is a benzidine-type rearrangement with accompanying disproportionation. To our knowledge this work is the first description of this type of reaction in substrates containing pyridinium rings.
Acid-catalysed aryl hydroxylation of phenylazopyridines: Reaction intermediates, kinetics and mechanism
Cheon, Kap-Soo,Cox, Robin A.,Keum, Sam-Rok,Buncel, Erwin
, p. 1231 - 1239 (2007/10/03)
A kinetic and product analysis study of the reactions of the three isomeric phenylazopyridines (PAPys) in aqueous sulfuric acid media (30-97 wt% H2SO4) is reported. The final products obtained from the reaction of 4-(phenylazo)pyridine (4-PAPy) are the hydroxylated product 4-(4-hydroxyphenylazo)pyridine, the reduction products 4-aminophenol and 4-aminopyridine, and a small amount of a dimerized product. 3-(Phenylazo)pyridine is unreactive, but 2-(phenylazo)pyridine gives the equivalent 2-(4-hydroxyphenylazo)pyridine, 4-aminophenol and 2-aminopyridine products. This product pattern, an oxidized azo-compound and two reduced amines, is similar to that found in the disproportionation of di-p-substituted hydrazinobenzenes observed in benzidine rearrangement studies. Consequently it has been proposed that the corresponding [N′-(4-hydroxyphenylhydrazino)]pyridines were formed as reaction intermediates in the present system; this is confirmed by showing that [N′-4-(4-hydroxyphenylhydrazino)-pyridine synthesized independently gave the same products as 4-PAPy under the same conditions. The kinetic study shows that the 4-isomer reacted faster than the 2-isomer at all the acid concentrations investigated (the 3-isomer being inert). Rate maxima are observed, at ～72 wt% H2SO4 for 4-PAPy and ～86 wt% H2SO4 for 2-PAPy. To facilitate the kinetic analysis, values of pKBH22+ for the protonation of the substrates and the possible hydroxy products at the azo-group were determined, using the excess acidity method; the first protonation occurs on the pyridine nitrogen in the pH region. An excess acidity analysis of the observed pseudo-first-order rate constants as a function of acidity indicate an A2 mechanism, with the diprotonated substrate and either one HSO4- ion or one H2O molecule in the activated complex. The proposed mechanism thus involves nucleophilic attack of HSO4- or H2O at an aryl carbon of the diprotonated substrate in the slow step, resulting in an intermediate hydrazo species which gives the observed products in a subsequent fast step (cf. benzidine rearrangement).
A novel synthesis of unsymmetrical azo aromatics inaccessible by diazo-coupling reaction
Ayyangar,Naik,Srinivasan
, p. 7253 - 7256 (2007/10/02)
A novel synthesis of unsymmetrical azo aromatics inaccessible by diazo-coupling reaction is reported. The synthesis involved the reaction of acetanilides with nitroarenes under moderate reaction conditions. A reaction pathway via a nitrosoarene intermediate involving elimination of the elements of the acetate anion, is proposed.
THERMAL AND PHOTOCHEMICAL DECOMPOSITION OF 3- AND 4-AZIDOPYRIDINE 1-OXIDES IN NUCLEOPHILIC SOLVENTS
Abramovitch, Rudolph A.,Bachowska, Barbara,Tomasik, Piotr
, p. 805 - 815 (2007/10/02)
The thermolysis and photolysis of the title compounds in aniline, N-methylaniline, N,N-dimethylaniline, morpholine and dioxane containing methoxide ion in methanol afforded complex mixtures from which only major products were isolated.No ring-expansion products were detected.In aniline, many of its known oxidation products were found, the N-oxide acting as an oxidizing agent.Hydrogen-abstraction products were the main ones formed from pyridine 1-oxides.
