5097-92-7Relevant academic research and scientific papers
Photoresponsive coordination of stilbazoles to metalloporphyrins
Iseki, Y?ki,Watanabe, Eishun,Mori, Atsunori,Inoue, Shohei
, p. 7313 - 7317 (1993)
The coordination of stilbazole derivatives to metalloporphyrins was investigated. Among the stilbazoles examined, a stilbazole with a bulky group such as 4-phenyl-3-stilbazole (4) showed considerable difference between the trans and cis isomers in its ability to coordinate to aluminum and zinc porphyrins with bulky peripheral substituents. The extent of coordination of 4 to metalloporphyrins could be changed by the trans → cis isomerization of 4 upon UV irradiation.
Magnetic properties of iron(III) complexes with photoisomerizable ligands
Hirose,Hayami,Maeda
, p. 2059 - 2066 (2000)
New spin-crossover Iron(III) complexes [Fe(salten)(trans-stpy)]BPh4·(CH3)2CO·0.5H2O 1 and [Fe(salten)(cis-stpy)]BPh4 2 with cis-trans photoisomerizable ligands have been synthesized and characterized, where trans-stpy is trans-4-styrylpyridine and cis-stpy cis-4-styrylpyridine, and salten denotes bis(3-salicylideneaminopropyl)amine, which is a quinquedentate Schiff base derived from the condensation of salicylaldehyde and di(3-aminopropyl)amine. The data of the variable-temperature magnetic susceptibility measurements for the complexes show that 1 and 2 exhibit spin-crossover phenomena in a solid. The spin-state transition temperature of 1 is lower than that of 2. The temperature dependencies of the Mossbauer spectra for the complexes also provide evidence that spin-state transitions between the high- and low-spin states take place, and that the rates of the spin interexchange at 298 K are faster than the inverse of the lifetime (1 x 10-7 s) of the Mossbauer nucleus. A temperature dependence of the UV-visible spectra suggesting spin-equilibrium in acetonitrile solution was obtained. The X-ray diffraction structures of single crystals of 1 and 2 were determined. Crystal data for 1: C60H61N4O3.5FeB, space group P1 (2), Z = 2, a = 14.83(1), b = 17.98(1), c = 11.31(2) A, α = 103.71(8), β = 110.60(8), γ = 94.31(7)°, V = 2702(5) A3, R = 14.0%, RW = 17.2%. Crystal data for 2: C57H54N4O2FeB, space group P21/n (14), Z = 4, a = 14.823(9), b = 17.417(7), c = 18.37(1) A, β = 95.331(8)°, V = 4722(3) A3. The coordination cores of both complexes have trans coordination in oxygen atoms. Although light irradiation to 1 in acetonitrile brings about isomerization from trans- to cis- of styrylpyridine, the change in the spin-state of the complexes is not clear.
Highly conjugated molecules from dibromonaphthyl derivatives and 4- vinylpyridine or 4-acetoxystyrene by the Heck reaction
Chang,Chen,Yu
, p. 5603 - 5610 (1999)
Palladium-catalyzed coupling of 1,6- and 2,6-dibromonaphthyl derivatives with 4-vinylpyridine or 4-acetoxystyrene resulted in mono- and bis- arylvinylation depending on the choice of reaction conditions. For the 1,6- dibromoarenes, the mono-arylvinylated derivative at position-6 was the sole product in the presence of (o-tol)3P/Et3N. The bis-arylvinylated derivative was the major product, accompanied by a minor product, arylvinylated at position-6 and reduced at position-1, in the presence of (o- tol)3P/Et3N/MeCN. For the 2,6-dibromoarenes, the bis-arylvinylated derivative was the sole product in the presence of either Ph3P or (o- tol)3P, if provided with a small volume of Et3N/MeCN solvent, and the mono- arylvinylated derivative was the major product with larger solvent volume and higher haloarene ratio. Fluorescence intensities of 2,6-bis-arylvinylated products were 2 to 3 orders of magnitude higher than that of stilbene. Nematic phases, at relatively high temperatures, were observed for some of the rodlike molecules. Shown by 1H NMR study, at the photostationary state of isomerization, smaller fractions of cis-form were obtained for molecules that exhibited larger fluorescence quantum yields. The results presented here are beneficial to the pursuit of nonlinear optical materials, fluorescent mesogens, photo- and electroactive materials.
Role of cation - π interactions in the photodimerization of trans-4-styrylpyridines
Yamada, Shinji,Uematsu, Naoko,Yamashita, Kaori
, p. 12100 - 12101 (2007)
In order to explore the contribution of the cation-π interaction in the photocyclodimerization of styrylpyridines, the effects of the acid concentration and the substituent on the aryl ring on the product distribution were investigated. The structures of
Visible-Light-Sensitized Cis-Trans Isomerization of N-Methyl-4-(β-styryl)pyridinium Ions
Takagi, Katsuhiko,Ogata, Yoshiro
, p. 1409 - 1412 (1982)
Cis-trans isomerization of N-methyl-4-(β-styryl)pyridinium ions (1) is sensitized by visible-light absorbers such as tris(2,2'-bipyridine)ruthenium 2+> and tetraphenylporphyrin complexes (MTPP).The predominance of the trans isomer at t
Copper(0) nanoparticle catalyzed Z-Selective Transfer Semihydrogenation of Internal Alkynes
Moran, Maria Jesus,Martina, Katia,Bieliunas, Vidmantas,Baricco, Francesca,Tagliapietra, Silvia,Berlier, Gloria,De Borggraeve, Wim M.,Cravotto, Giancarlo
supporting information, p. 2850 - 2860 (2021/05/06)
The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead-free alternative to Lindlar catalysts. A stereo-selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)-alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non-noble copper nanoparticles for reduction of both electron-rich and electron-deficient, aliphatic-substituted and aromatic- substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo- and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes. (Figure presented.).
A Solid-Phase Assisted Flow Approach to In Situ Wittig-Type Olefination Coupling
Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Polyzos, Anastasios,Tadros, Joseph
supporting information, p. 4184 - 4194 (2021/08/24)
Described herein is the development of a continuous flow, solid-phase triphenylphosphine (PS-PPh3) assisted protocol to facilitate the in situ coupling of reciprocal pairs of halogen and carbonyl functionalised molecular pairs by a Wittig olefination within 15 mins. The protocol entails injecting a single solution (1 : 1 CHCl3 : EtOH) containing the halogenated and carbonyl-based substrates into a continuously flowing stream of CHCl3 : EtOH (1 : 1), passed through a fixed bed of K2CO3 and PS-PPh3. With advancement to the previous PS-PPh3 coupling procedures, the method employs a traditional polystyrene-based immobilisation matrix, the substrate scope of the protocol extended to substituted ketones, secondary alkyl chlorides, and an unprotected maleimide scaffold.
HIGHLY SELECTIVE ELECTROCHEMICAL HYDROGENATION OF ALKYNES
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Page/Page column 7; 12, (2020/10/20)
Disclosed are electrochemical methods to prepare an alkane or an alkene, such as a cis- alkene, from an alkyne, or an alkane from an alkene. The method utilizes an electrochemical cell having a cathode and an anode and a reactor.
Chemoselective Hydrogenation of Alkynes to (Z) -Alkenes Using an Air-Stable Base Metal Catalyst
Zubar, Viktoriia,Sklyaruk, Jan,Brzozowska, Aleksandra,Rueping, Magnus
supporting information, p. 5423 - 5428 (2020/07/24)
A highly selective hydrogenation of alkynes using an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperativity.
Methanol as the Hydrogen Source in the Selective Transfer Hydrogenation of Alkynes Enabled by a Manganese Pincer Complex
Sklyaruk, Jan,Zubar, Viktoriia,Borghs, Jannik C.,Rueping, Magnus
supporting information, p. 6067 - 6071 (2020/08/28)
The first base metal-catalyzed transfer hydrogenation of alkynes with methanol is described. An air and moisture stable manganese pincer complex catalyzes the reduction of a variety of different alkynes to the corresponding (Z)-olefins in high yields. The
