Visible light-driven valorization of biomass has recently been a pioneering field for nitrogen-containing heterocyclics syntheses due to its sustainable features.Herein,various aromatic ring-doped g-C_(3)N_(4) nanoshe...Visible light-driven valorization of biomass has recently been a pioneering field for nitrogen-containing heterocyclics syntheses due to its sustainable features.Herein,various aromatic ring-doped g-C_(3)N_(4) nanosheets(Ar-g-C_(3)N_(4);Ar=Py,Pm,Ph)were precisely designed to modulate their intrinsic electronic and band structure,which involves pyridine(Py),pyrimidine(Pm),and benzene(Ph)-doped g-C_(3)N_(4).Photocatalysts(CoPc/Ar-g-C_(3)N_(4)) of cobalt(II)phthalocyanine(CoPc)-fabricated Ar-g-C_(3)N_(4) were then developed for oxidative cyclization of furoin with 1,2-phenylenediamines for syntheses of various biomass-derived quinoxalines under visible-light irradiation.The catalytic activity(in terms of TOFs)of serial CoPc/Ar-g-C_(3)N_(4) samples increased with their transient photocurrents with CoPc/Py-g-C_(3)N_(4) as the most active one.For CoPc/Py-g-C_(3)N_(4),CoPc species functioned as both sensitizer and catalytic sites;while,doped Py led to a narrowed bandgap energy.Mechanism research further demonstrated that O_(2) was activated to superoxide radical(·O_(2)^(-)) by photoexcited high-level-energy electron(HLEE)transfer from Py-g-C_(3)N_(4) to CoPc for the subsequent aerobic oxidation.展开更多
Condensation of D-glucose, o-phenylenediamine and N,N-benzylphenylhydrazine hydrochloride (NNBPHH) in a one-pot reaction, or condensation of 2-(D-arabino-tetritol-1-yl) quinoxaline and NNBPHH, gave 3-(D-erythro-glycer...Condensation of D-glucose, o-phenylenediamine and N,N-benzylphenylhydrazine hydrochloride (NNBPHH) in a one-pot reaction, or condensation of 2-(D-arabino-tetritol-1-yl) quinoxaline and NNBPHH, gave 3-(D-erythro-glycerol-1- yl)-1-phenyl-1H-pyrazolo[3,4-b]quinoxaline. The structure of the latter was determined by 1H NMR spectroscopy and by synthesis using phenylhydrazine hydrochloride instead of NNBPHH. Condensation of D-glucose and 4,5-dichloro-o-phenylenediamine gave 6,7-dichloro-2-(D-arabino-tetritol-1-yl)quinoxaline, which upon condensation with NNBPHH gave the corresponding 6,7-dichloro-3-(D-erythro-glycerol-1-yl)-1-phenyl-1H-pyrazolo[3,4-b]quinoxaline. The structure and mechanism of formation of these compounds are discussed.展开更多
Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in exc...Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water. This method provides a new and efficient protocol in terms of small quantity of catalyst, a wide scope of substrates, and simple work-up procedure.展开更多
Polyethylene glycol(PEG) was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reac...Polyethylene glycol(PEG) was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reaction conditions.展开更多
This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline...This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.展开更多
Two unusual one-dimensional(1-D) compounds,viz.[Co(Medpq)(QUI)·H2O]2n· 2.4nH2O 1 and [Cd(Medpq)(QUI)·H2O]n·nH2O 2,were synthesized by the combination of two different metallic salts and o...Two unusual one-dimensional(1-D) compounds,viz.[Co(Medpq)(QUI)·H2O]2n· 2.4nH2O 1 and [Cd(Medpq)(QUI)·H2O]n·nH2O 2,were synthesized by the combination of two different metallic salts and organic ligands,namely 2,3-pyridinedicarboxylic acid(H2QUI) and 2-methyldipyrido[3,2-f:2',3'-h]quinoxaline(Medpq) ligand.The compounds were characterized by elemental analyses,TG,fluorescent emission and single-crystal X-ray diffraction analyses.展开更多
One complex [Co1.5(C6H5CHCHCOO)3(Medpq)]·H2O(C6H5CHCHCOO = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2,3-h]quinoxaline) 1 has been hydrothermally synthesized and structurally characterized by elemental...One complex [Co1.5(C6H5CHCHCOO)3(Medpq)]·H2O(C6H5CHCHCOO = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2,3-h]quinoxaline) 1 has been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, TG, single-crystal X-ray diffraction and magnetic susceptibility measurements. Complex 1 crystallizes in the triclinic system, space group P1, with a = 10.224(5), b = 14.572(5), c = 15.139(5)A, α = 112.704(5), β = 97.168(5), γ = 109.749(5), V = 1871.8(13) 3 and Z = 2(at 293(2) K). In the crystal structure, the Co(1) ion is hexa-coordinated with six atoms from three different cinnamic acid ligands and the symmetric three different cinnamic acid ligands; the Co(2) center adopts a coordination environment with two nitrogen atoms from Medpq ligand and four oxygen atoms from two different cinnamic ligands, assuming a slightly distorted octahedral geometry, respectively. The negative value of the Weiss constant indicates antiferromagnetic exchange interactions between the Co ions.展开更多
Ga(ClO4)3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%(molar fraction) catalyst u...Ga(ClO4)3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%(molar fraction) catalyst under solvent-free conditions at room temperature.For unsymmetrical o-phenylenediamines bearing electron-withdrawing groups,regio-selective quinoxalines were obtained.展开更多
Quinoxaline 1, 4-dioxides (QdNOs) are quinox-aline derivatives which have been used as an-timicrobial agents and growth promoters in animals widely. They are also assumed to cure human disease such as anticancer, anti...Quinoxaline 1, 4-dioxides (QdNOs) are quinox-aline derivatives which have been used as an-timicrobial agents and growth promoters in animals widely. They are also assumed to cure human disease such as anticancer, antitubercular and inhibiting parasite. QdNOs such as carbadox and their major metabolites induced a special decline of aldosterone production from the swine adrenal in vivo and in vitro, and thus cause hypovolemia, hyponatremia and hyperkalemia. This can also be expected to be the case for human. As a mainly physiological hormone and a novel steroid with potent mineralocorticoid activity, aldosterone plays an important role in the pathophysiological process of brain, renal and heart disease progression and may be a renal and vascular risk factor. Here, we provide evidence to support the hypothesis that QdNOs may lead potential benefits in aldosterone dysmetabolism disease via the synthesis deficiency of aldosterone in adrenal and/or the cardiovascular tissues. If the hypothesis is true, it may provide a new option into the therapy for aldosterone dysmetabolism disease, especially in cardiovascular system, and thus assume a broader application of QdNOs.展开更多
The interaction of metal ions(Hg^2+,Pb^2+,Co^2+,Mn^2+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ) was investigated,and four new complexes ...The interaction of metal ions(Hg^2+,Pb^2+,Co^2+,Mn^2+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ) was investigated,and four new complexes have been synthesized and characterized.Complex 1 exhibits a 0dimensional dual-core structure,2 is a one-dimensional chain structure based on a dual-core Pb unit,while 3 and 4 show a 0 dimensional single-core structural unit.Complex 1 is of monoclinic system,space group C2/c with a = 19.211(4),b = 23.896(5),c = 12.698(3) A°,β= 120.11(3)°,V= 5043.0(17)A°3,Z = 4,S = 1.053,F(000) = 2976,R^a = 0.0637 and wR^b = 0.1068(I 〉 2σ(I)).Complex 2 adopts triclinic system,space group P1 with a = 10.370(2),b = 12.195(2),c = 21.033(4) A°,α = 80.87(3),β= 81.22(3),γ = 82.38(3)°,V= 2579.3(8) A°3,Z = 2,S = 1.099,F(000) = 1328,R^a = 0.0609 and wR^b =0.1365(I 〉 2σ(I)).Complex 3 is of monoclinic system,space group Cllc with a = 14.166(3),b =16.621(3),c = 20.248(4) ?,β = 92.18(3)°,V= 4764.0(16) A°3,Z = 4,S = 1.005,F(000) = 2108,R^a =0.0589 and wR^b = 0.1332(I 〉 2σ(I)).Complex 4 belongs to the monoclinic system,space group C2/c with a = 14.404(3),b = 16.626(3),c = 20.346(4) ?,β = 92.43(3)°,V= 4868.2(17) A°3,Z = 4,S= 1.068,F(000) = 2108,R^a = 0.0833 and wR^b = 0.1591(I 〉 2σ(I)).Furthermore,the behavior of HPDQ with Hg^2+,Pb^2+,Co^2+ and Mn^2+ in the solution was also investigated,and the result shows after the metal ions were added respectively,the emission of all solutions shows fluorescence quenching and has a red shift compared with that of the HPDQ ligand.展开更多
A facile procedure for the synthesis, of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. The reactions were carried out catalyst-free, solvent-free and under microwave irradiation condition...A facile procedure for the synthesis, of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. The reactions were carried out catalyst-free, solvent-free and under microwave irradiation conditions in high yield (84-98%) with short time (3-6 min) and environmental benign, as well as convenient operation. The structures of all the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, mass spectral data.展开更多
A facile and convenient synthesis method has been developed for substituted quinoxalines and 2H-benzo[b][1,4]oxazines from the reactions of a-bromoketones with benzene-1,2-diamine and 2-aminophenol, respectively, whic...A facile and convenient synthesis method has been developed for substituted quinoxalines and 2H-benzo[b][1,4]oxazines from the reactions of a-bromoketones with benzene-1,2-diamine and 2-aminophenol, respectively, which were catalyzed by tetrabutylammonium bromide(TBAB) in aqueous basic media.展开更多
Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine ...Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine and polyamides were characterized by elemental analysis, FTIR and IH-NMR. The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain. They were all soluble in common organic solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF) and N-methylpyrolidone (NMP). The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃ and good thermal stability with the char yields in the range of 65%-82% at 600℃ in nitrogen.展开更多
The interaction of Hg(Ⅱ), Cu(Ⅰ) and Ag(Ⅰ) with dipyridine quinoxaline ligand 2,3-bis(2-pyridyl)quinoxaline(DPQ) were investigated, and three new complexes have been synthesized and characterized. Complex ...The interaction of Hg(Ⅱ), Cu(Ⅰ) and Ag(Ⅰ) with dipyridine quinoxaline ligand 2,3-bis(2-pyridyl)quinoxaline(DPQ) were investigated, and three new complexes have been synthesized and characterized. Complex 1 exhibits a 0D dual-core structure, complex 2 is a 0D tetra nuclear case based on a dual-core Cu unit, and complex 3 shows a one-dimensional pipeline structure. Furthermore, the optical properties of complex and DPQ were also investigated, and the results showed that the fluorescence intensity of complexes was weaker than that of ligand DPQ.展开更多
A new series of quinoxaline 1,4-di-N-oxides were synthesized and evaluated for their antibacterial and antifungal activities. The best result was demonstrated by 3-amino-N-(4-methoxyphenyl)-2-quinoxalinecarboxamide 1,...A new series of quinoxaline 1,4-di-N-oxides were synthesized and evaluated for their antibacterial and antifungal activities. The best result was demonstrated by 3-amino-N-(4-methoxyphenyl)-2-quinoxalinecarboxamide 1,4-di-N-oxide 4e, MIC (0.24 μg/ml) against Aspergillus fumigatus, and (0.12 μg/ml) against Streptococcus pneumonia.展开更多
We have synthesized three bis (thienyl) quinoxalinesilver(I) complexes;however, unlike analogous silver(I) complexes of pyridylquinoxaline that utilize (N, N) bidentate behavior from the quinoxaline and pyridyl ring n...We have synthesized three bis (thienyl) quinoxalinesilver(I) complexes;however, unlike analogous silver(I) complexes of pyridylquinoxaline that utilize (N, N) bidentate behavior from the quinoxaline and pyridyl ring nitrogens, the bis(thienyl) quinoxaline ligands did not utilize the bonding potential of the thienyl rings to give (N, S) bonding modes. PES spectra modeling of these ligands indicates that the preferential metal bonding via only the quinoxaline nitrogen atoms is due to the N-rich, but S-poor, characters of the frontier orbitals.展开更多
The interaction of Hg^2+ with polyphenyl quinoxaline ligand 2,3,6,7,10,11-hexaphenyldipyrazino[2,3-f:2',3'-h]quinoxaline(HPQ) was investigated, and a new complex(C(49)H(32)N6Br2Cl2Hg) has been synthesized ...The interaction of Hg^2+ with polyphenyl quinoxaline ligand 2,3,6,7,10,11-hexaphenyldipyrazino[2,3-f:2',3'-h]quinoxaline(HPQ) was investigated, and a new complex(C(49)H(32)N6Br2Cl2Hg) has been synthesized and characterized. It exhibits a 0D single-core structure,and adopts triclinic P 1 space group with a = 11.139(2), b = 13.429(3), c = 14.488(3)A, α =76.10(3), β = 83.16(3), γ = 87.36(3)o, V = 2088.4(7) A^3, Z = 2, S = 1.056, F(000) = 1104, R = 0.0417 and w R = 0.0931(I 〉 2σ(I)). Furthermore, the behavior of HPQ with Hg^2+ in the solution was also investigated, and the result shows that HPQ was found to have excellent fluorescent selectivity for Hg^2+ over many other metal ions(Li^+, K^+, Na^+, Sr^+, Ca^2+, Mg^2+, Mn^2+, Fe^3+, Ni^2+, Co^2+, Cu^2+, Zn^2+,Cd^2+, Pb^2+, Al^3+ and Cr^3+) based on the intermolecular charge-transfer mechanism, which makes HPQ a potential fluorescence sensor or probe for Hg^2+.展开更多
Two high coordination crystals were obtained by the interaction of Ce^(3+) and Nd^(3+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ), and the...Two high coordination crystals were obtained by the interaction of Ce^(3+) and Nd^(3+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ), and they were characterized. Complex 1 exhibits a 0 dimensional three-nuclear structure, with the three Ce(Ⅲ) atoms being ten-, eleven- and twelve-coordinated. Complex 2 is a 0 dimensional dual-core structure and the Nd(Ⅲ) atom is ten-coordinated. Complex 1 is of monoclinic system, space group P2/c with a = 16.850(3), b = 16.617(3), c = 24.017(5) ?, β = 100.94(3)o, V = 6602(2) ?~3, Z = 4, S = 1.062, F(000) = 3372, R = 0.0504 and wR = 0.1463(I 〉 2σ(I)). Complex 2 adopts a monoclinic system, space group C2/c with a = 25.795(5), b = 20.166(4), c = 13.059(3) ?, β = 112.29(3)°, V = 6286(2) ?~3, Z = 4, S = 1.004, F(000) = 2664, R = 0.0663 and wR = 0.1821(I 〉 2σ(I)). Furthermore, the behaviors of HPDQ with Ce^(3+) and Nd^(3+) in the solution are also investigated. After the Ce^(3+) is added, the ultraviolet absorption of the solution is enhanced with a red shift compared with that of the HPDQ ligand. While after adding Nd^(3+), the ultraviolet absorption of the solution is weakened, and it has a red shift which is the same as Ce^(3+). However, after the respective addition of metal ions, the emission of all solutions is quenched and has a red shift compared with that of the HPDQ ligand.展开更多
Simple inorganic base cesium hydroxide is found to be the best catalyst for aerobic annulation reaction of o-phenylenediamine andα-hydroxy-2-phenylacetophenone in constructing the quinoxaline skeleton,i.e.,catalytic ...Simple inorganic base cesium hydroxide is found to be the best catalyst for aerobic annulation reaction of o-phenylenediamine andα-hydroxy-2-phenylacetophenone in constructing the quinoxaline skeleton,i.e.,catalytic amount of cesium hydroxide can catalyze the reaction efficiently under mild conditions of room temperature in air atmosphere.This method is extendable to a series of vicinal diamines andα-hydroxyl ketones,thus having a relatively broad substrate scope.As no transition metal catalyst is required and cesium hydroxide highly water-soluble,cesiume can be effectively removed by washing with water,the prodcuts can be obtained without cesium and transition metal residue contamination.This reaction requires no other stoichiometric oxidants but the readily available and convenient air as the oxidant,and the only byproduct is water,hence a transition metal-free,mild and efficient,green and practical approach for efficient construction of the quinoxaline derivatives is provided.展开更多
Highly enantioselective sulfa-Michael additions(SMA)between 2-alkenyl quinoxalines and aromatic thiols are accomplished using a low loading of chiral phosphoric acid catalyst(1 mol%).It was confirmed by an investigati...Highly enantioselective sulfa-Michael additions(SMA)between 2-alkenyl quinoxalines and aromatic thiols are accomplished using a low loading of chiral phosphoric acid catalyst(1 mol%).It was confirmed by an investigation of a lot of azaarenes that the two C-N units of quinoxalines are indispensable for controlling the reaction enantioselectivities.A series of non-terminal 2-alkenes substituted with aryls or alkyls,even other electro-withdrawing groups such as ketones,esters,or amides,selectively reacted and afforded the desired SMA products(48 examples)in good regioselectivities with high yields(up to 99%)and good ee values(up to 97%).展开更多
基金supported by the National Natural Science Foundation of China(22075104)the Youth Science and Technology Innovation Talent of Guangdong TeZhi Plan,China(2019TQ05L111)+1 种基金Innovation Team Project in Guangdong Colleges and Universities,China(2021KCXTD009)Educational Commission of Guangdong Province of China(2021ZDZX4037)。
文摘Visible light-driven valorization of biomass has recently been a pioneering field for nitrogen-containing heterocyclics syntheses due to its sustainable features.Herein,various aromatic ring-doped g-C_(3)N_(4) nanosheets(Ar-g-C_(3)N_(4);Ar=Py,Pm,Ph)were precisely designed to modulate their intrinsic electronic and band structure,which involves pyridine(Py),pyrimidine(Pm),and benzene(Ph)-doped g-C_(3)N_(4).Photocatalysts(CoPc/Ar-g-C_(3)N_(4)) of cobalt(II)phthalocyanine(CoPc)-fabricated Ar-g-C_(3)N_(4) were then developed for oxidative cyclization of furoin with 1,2-phenylenediamines for syntheses of various biomass-derived quinoxalines under visible-light irradiation.The catalytic activity(in terms of TOFs)of serial CoPc/Ar-g-C_(3)N_(4) samples increased with their transient photocurrents with CoPc/Py-g-C_(3)N_(4) as the most active one.For CoPc/Py-g-C_(3)N_(4),CoPc species functioned as both sensitizer and catalytic sites;while,doped Py led to a narrowed bandgap energy.Mechanism research further demonstrated that O_(2) was activated to superoxide radical(·O_(2)^(-)) by photoexcited high-level-energy electron(HLEE)transfer from Py-g-C_(3)N_(4) to CoPc for the subsequent aerobic oxidation.
文摘Condensation of D-glucose, o-phenylenediamine and N,N-benzylphenylhydrazine hydrochloride (NNBPHH) in a one-pot reaction, or condensation of 2-(D-arabino-tetritol-1-yl) quinoxaline and NNBPHH, gave 3-(D-erythro-glycerol-1- yl)-1-phenyl-1H-pyrazolo[3,4-b]quinoxaline. The structure of the latter was determined by 1H NMR spectroscopy and by synthesis using phenylhydrazine hydrochloride instead of NNBPHH. Condensation of D-glucose and 4,5-dichloro-o-phenylenediamine gave 6,7-dichloro-2-(D-arabino-tetritol-1-yl)quinoxaline, which upon condensation with NNBPHH gave the corresponding 6,7-dichloro-3-(D-erythro-glycerol-1-yl)-1-phenyl-1H-pyrazolo[3,4-b]quinoxaline. The structure and mechanism of formation of these compounds are discussed.
文摘Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water. This method provides a new and efficient protocol in terms of small quantity of catalyst, a wide scope of substrates, and simple work-up procedure.
基金supported by the Natural Science Foundation of China(No.20272047,20572086)the Gansu Natural Science Foundation of China(No.0308RJZA-100)Key Laboratory of Eco-Environment-Related Polymer Material(Northwest Normal University),Ministry of the Education of China
文摘Polyethylene glycol(PEG) was found to be an effective catalyst for the condensation of 1,2-diamines with 1,2-dicarbonyl compounds to afford the corresponding quinoxaline derivatives in excellent yields under mild reaction conditions.
文摘This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.
文摘Two unusual one-dimensional(1-D) compounds,viz.[Co(Medpq)(QUI)·H2O]2n· 2.4nH2O 1 and [Cd(Medpq)(QUI)·H2O]n·nH2O 2,were synthesized by the combination of two different metallic salts and organic ligands,namely 2,3-pyridinedicarboxylic acid(H2QUI) and 2-methyldipyrido[3,2-f:2',3'-h]quinoxaline(Medpq) ligand.The compounds were characterized by elemental analyses,TG,fluorescent emission and single-crystal X-ray diffraction analyses.
基金supported by Tonghua Normal University field project(No.201402)
文摘One complex [Co1.5(C6H5CHCHCOO)3(Medpq)]·H2O(C6H5CHCHCOO = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2,3-h]quinoxaline) 1 has been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, TG, single-crystal X-ray diffraction and magnetic susceptibility measurements. Complex 1 crystallizes in the triclinic system, space group P1, with a = 10.224(5), b = 14.572(5), c = 15.139(5)A, α = 112.704(5), β = 97.168(5), γ = 109.749(5), V = 1871.8(13) 3 and Z = 2(at 293(2) K). In the crystal structure, the Co(1) ion is hexa-coordinated with six atoms from three different cinnamic acid ligands and the symmetric three different cinnamic acid ligands; the Co(2) center adopts a coordination environment with two nitrogen atoms from Medpq ligand and four oxygen atoms from two different cinnamic ligands, assuming a slightly distorted octahedral geometry, respectively. The negative value of the Weiss constant indicates antiferromagnetic exchange interactions between the Co ions.
基金Supported by the National Natural Science Foundation of China(Nos.20772088,21172163)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(No.JSSYSXK2010007)
文摘Ga(ClO4)3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%(molar fraction) catalyst under solvent-free conditions at room temperature.For unsymmetrical o-phenylenediamines bearing electron-withdrawing groups,regio-selective quinoxalines were obtained.
文摘Quinoxaline 1, 4-dioxides (QdNOs) are quinox-aline derivatives which have been used as an-timicrobial agents and growth promoters in animals widely. They are also assumed to cure human disease such as anticancer, antitubercular and inhibiting parasite. QdNOs such as carbadox and their major metabolites induced a special decline of aldosterone production from the swine adrenal in vivo and in vitro, and thus cause hypovolemia, hyponatremia and hyperkalemia. This can also be expected to be the case for human. As a mainly physiological hormone and a novel steroid with potent mineralocorticoid activity, aldosterone plays an important role in the pathophysiological process of brain, renal and heart disease progression and may be a renal and vascular risk factor. Here, we provide evidence to support the hypothesis that QdNOs may lead potential benefits in aldosterone dysmetabolism disease via the synthesis deficiency of aldosterone in adrenal and/or the cardiovascular tissues. If the hypothesis is true, it may provide a new option into the therapy for aldosterone dysmetabolism disease, especially in cardiovascular system, and thus assume a broader application of QdNOs.
基金supported by the NNSFC(21301100)the Education Department Fund of Henan(13A150819)Special fund of Nanyang Normal University(ZX2013029)
文摘The interaction of metal ions(Hg^2+,Pb^2+,Co^2+,Mn^2+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ) was investigated,and four new complexes have been synthesized and characterized.Complex 1 exhibits a 0dimensional dual-core structure,2 is a one-dimensional chain structure based on a dual-core Pb unit,while 3 and 4 show a 0 dimensional single-core structural unit.Complex 1 is of monoclinic system,space group C2/c with a = 19.211(4),b = 23.896(5),c = 12.698(3) A°,β= 120.11(3)°,V= 5043.0(17)A°3,Z = 4,S = 1.053,F(000) = 2976,R^a = 0.0637 and wR^b = 0.1068(I 〉 2σ(I)).Complex 2 adopts triclinic system,space group P1 with a = 10.370(2),b = 12.195(2),c = 21.033(4) A°,α = 80.87(3),β= 81.22(3),γ = 82.38(3)°,V= 2579.3(8) A°3,Z = 2,S = 1.099,F(000) = 1328,R^a = 0.0609 and wR^b =0.1365(I 〉 2σ(I)).Complex 3 is of monoclinic system,space group Cllc with a = 14.166(3),b =16.621(3),c = 20.248(4) ?,β = 92.18(3)°,V= 4764.0(16) A°3,Z = 4,S = 1.005,F(000) = 2108,R^a =0.0589 and wR^b = 0.1332(I 〉 2σ(I)).Complex 4 belongs to the monoclinic system,space group C2/c with a = 14.404(3),b = 16.626(3),c = 20.346(4) ?,β = 92.43(3)°,V= 4868.2(17) A°3,Z = 4,S= 1.068,F(000) = 2108,R^a = 0.0833 and wR^b = 0.1591(I 〉 2σ(I)).Furthermore,the behavior of HPDQ with Hg^2+,Pb^2+,Co^2+ and Mn^2+ in the solution was also investigated,and the result shows after the metal ions were added respectively,the emission of all solutions shows fluorescence quenching and has a red shift compared with that of the HPDQ ligand.
基金Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials for financial support(No.JSKC07041)
文摘A facile procedure for the synthesis, of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. The reactions were carried out catalyst-free, solvent-free and under microwave irradiation conditions in high yield (84-98%) with short time (3-6 min) and environmental benign, as well as convenient operation. The structures of all the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, mass spectral data.
基金Supported by the National Natural Science Foundation of China(Nos.20572013 and 20711130229)the Department of Science and Technology of Jilin Province, China(No.20050309-2).
文摘A facile and convenient synthesis method has been developed for substituted quinoxalines and 2H-benzo[b][1,4]oxazines from the reactions of a-bromoketones with benzene-1,2-diamine and 2-aminophenol, respectively, which were catalyzed by tetrabutylammonium bromide(TBAB) in aqueous basic media.
文摘Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine and polyamides were characterized by elemental analysis, FTIR and IH-NMR. The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain. They were all soluble in common organic solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF) and N-methylpyrolidone (NMP). The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃ and good thermal stability with the char yields in the range of 65%-82% at 600℃ in nitrogen.
基金supported by the NSFC(21301100)the Education Department Fund of Henan(13A150819)Special fund of Nanyang Normal University(ZX2013029)
文摘The interaction of Hg(Ⅱ), Cu(Ⅰ) and Ag(Ⅰ) with dipyridine quinoxaline ligand 2,3-bis(2-pyridyl)quinoxaline(DPQ) were investigated, and three new complexes have been synthesized and characterized. Complex 1 exhibits a 0D dual-core structure, complex 2 is a 0D tetra nuclear case based on a dual-core Cu unit, and complex 3 shows a one-dimensional pipeline structure. Furthermore, the optical properties of complex and DPQ were also investigated, and the results showed that the fluorescence intensity of complexes was weaker than that of ligand DPQ.
文摘A new series of quinoxaline 1,4-di-N-oxides were synthesized and evaluated for their antibacterial and antifungal activities. The best result was demonstrated by 3-amino-N-(4-methoxyphenyl)-2-quinoxalinecarboxamide 1,4-di-N-oxide 4e, MIC (0.24 μg/ml) against Aspergillus fumigatus, and (0.12 μg/ml) against Streptococcus pneumonia.
文摘We have synthesized three bis (thienyl) quinoxalinesilver(I) complexes;however, unlike analogous silver(I) complexes of pyridylquinoxaline that utilize (N, N) bidentate behavior from the quinoxaline and pyridyl ring nitrogens, the bis(thienyl) quinoxaline ligands did not utilize the bonding potential of the thienyl rings to give (N, S) bonding modes. PES spectra modeling of these ligands indicates that the preferential metal bonding via only the quinoxaline nitrogen atoms is due to the N-rich, but S-poor, characters of the frontier orbitals.
基金supported by the NSFC(21301100)the Education Department Fund of Henan(13A150819)Special Fund of Nanyang Normal University(ZX2013029)
文摘The interaction of Hg^2+ with polyphenyl quinoxaline ligand 2,3,6,7,10,11-hexaphenyldipyrazino[2,3-f:2',3'-h]quinoxaline(HPQ) was investigated, and a new complex(C(49)H(32)N6Br2Cl2Hg) has been synthesized and characterized. It exhibits a 0D single-core structure,and adopts triclinic P 1 space group with a = 11.139(2), b = 13.429(3), c = 14.488(3)A, α =76.10(3), β = 83.16(3), γ = 87.36(3)o, V = 2088.4(7) A^3, Z = 2, S = 1.056, F(000) = 1104, R = 0.0417 and w R = 0.0931(I 〉 2σ(I)). Furthermore, the behavior of HPQ with Hg^2+ in the solution was also investigated, and the result shows that HPQ was found to have excellent fluorescent selectivity for Hg^2+ over many other metal ions(Li^+, K^+, Na^+, Sr^+, Ca^2+, Mg^2+, Mn^2+, Fe^3+, Ni^2+, Co^2+, Cu^2+, Zn^2+,Cd^2+, Pb^2+, Al^3+ and Cr^3+) based on the intermolecular charge-transfer mechanism, which makes HPQ a potential fluorescence sensor or probe for Hg^2+.
基金supported by the NNSFC(21301100)the Education Department Fund of Henan(13A150819)Special fund of Nanyang Normal University(ZX2013029)
文摘Two high coordination crystals were obtained by the interaction of Ce^(3+) and Nd^(3+) with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline(HPDQ), and they were characterized. Complex 1 exhibits a 0 dimensional three-nuclear structure, with the three Ce(Ⅲ) atoms being ten-, eleven- and twelve-coordinated. Complex 2 is a 0 dimensional dual-core structure and the Nd(Ⅲ) atom is ten-coordinated. Complex 1 is of monoclinic system, space group P2/c with a = 16.850(3), b = 16.617(3), c = 24.017(5) ?, β = 100.94(3)o, V = 6602(2) ?~3, Z = 4, S = 1.062, F(000) = 3372, R = 0.0504 and wR = 0.1463(I 〉 2σ(I)). Complex 2 adopts a monoclinic system, space group C2/c with a = 25.795(5), b = 20.166(4), c = 13.059(3) ?, β = 112.29(3)°, V = 6286(2) ?~3, Z = 4, S = 1.004, F(000) = 2664, R = 0.0663 and wR = 0.1821(I 〉 2σ(I)). Furthermore, the behaviors of HPDQ with Ce^(3+) and Nd^(3+) in the solution are also investigated. After the Ce^(3+) is added, the ultraviolet absorption of the solution is enhanced with a red shift compared with that of the HPDQ ligand. While after adding Nd^(3+), the ultraviolet absorption of the solution is weakened, and it has a red shift which is the same as Ce^(3+). However, after the respective addition of metal ions, the emission of all solutions is quenched and has a red shift compared with that of the HPDQ ligand.
文摘Simple inorganic base cesium hydroxide is found to be the best catalyst for aerobic annulation reaction of o-phenylenediamine andα-hydroxy-2-phenylacetophenone in constructing the quinoxaline skeleton,i.e.,catalytic amount of cesium hydroxide can catalyze the reaction efficiently under mild conditions of room temperature in air atmosphere.This method is extendable to a series of vicinal diamines andα-hydroxyl ketones,thus having a relatively broad substrate scope.As no transition metal catalyst is required and cesium hydroxide highly water-soluble,cesiume can be effectively removed by washing with water,the prodcuts can be obtained without cesium and transition metal residue contamination.This reaction requires no other stoichiometric oxidants but the readily available and convenient air as the oxidant,and the only byproduct is water,hence a transition metal-free,mild and efficient,green and practical approach for efficient construction of the quinoxaline derivatives is provided.
基金supported by the West Light Foundation of the Chinese Academy of Sciences(No.25E0C304)the Sichuan Science and Technology Program(No.2021ZYD0061).
文摘Highly enantioselective sulfa-Michael additions(SMA)between 2-alkenyl quinoxalines and aromatic thiols are accomplished using a low loading of chiral phosphoric acid catalyst(1 mol%).It was confirmed by an investigation of a lot of azaarenes that the two C-N units of quinoxalines are indispensable for controlling the reaction enantioselectivities.A series of non-terminal 2-alkenes substituted with aryls or alkyls,even other electro-withdrawing groups such as ketones,esters,or amides,selectively reacted and afforded the desired SMA products(48 examples)in good regioselectivities with high yields(up to 99%)and good ee values(up to 97%).