Li^(+)-ion bound crown ether functionalization enables dual promotion of dynamics and thermodynamics for ambient ammonia synthesis

Electrosynthesis of ammonia from the reduction of nitrogen is still confronted with the limited supply of gas reactant in dynamics as well as high activation barrier in thermodynamics.Unfortunately,despite tremendous efforts devoted to electrocatalysts themselves,they still fail to tackle the above two challenges simultaneously.Herein,we employ a heterogeneous catalyst adlayer-composed of crown ethers associated with Li^(+)ions-to achieve the dual promotion of dynamics and thermodynamics for ambient ammonia synthesis.Dynamically,the bound Li^(+)ions interact with the strong quadrupole moment of nitrogen,and trigger considerable reactant flux toward the catalyst.Thermodynamically,Li^(+)associated with the oxygen of crown ether achieves a higher density of states at the Fermi level for the catalyst,enabling effortless electron transfer from the catalysts to nitrogen and thus greatly reducing the activation barrier.As expected,the proof-of-concept system achieves an ammonia yield rate of 168.5μg h^(-1)mg^(-1)and a Faradaic efficiency of 75.3%at-0.3 V vs.RHE.This system-level approach opens up pathways for tackling the two key challenges that have limited the field of ammonia synthesis.

Synthesis and adsorption properties of chitosan-crown ether resins

Two kinds of novel chitosan-crown ether resins, Schiff base type chitosan-benzo-15-crown-5 （CTS -B15） and chitosan-benzo-18-crown-6 （CTS -B18）, were synthesized through the reaction between -NH2 in chitosan and -CHO in 4′-formyl benzo-crown ethers. Their structures were characterized by elemental analysis and FT-IR spectra analysis. The elemental analysis results show that the mass fractions of nitrogen in CTS -B15 and CTS -B18 are much lower than those of chitosan. The results of FT-IR spectra of CTS -B15 and CTS -B18 reveal that there exist characteristic peak of C=N, N-H and Ar, and characteristic peak of pyr anoside in the chain of chitosan-crown ether resins, showing that the structures of chitosan-crown ethers are as expected. The adsorption properties of CTS -B15 and CTS -B18 for Pd 2+ , Cu 2+ and Hg 2+ were studied and the experimental results show that these adsorbents have both good adsorption characterization and especially high particular adsorption selectivity for Pd 2+ when Cu 2+ and Hg 2+ are in coexistence, and the coefficients of selectivity of CTS -B15 and CTS -B18 for metal ions are K Pd 2+ /Cu 2+ = 7.56, K Pd 2+ /Hg 2+ = 68.00, K Cu 2+ /Hg 2+ = 9.00 and K Pd 2+ /Cu 2+ =6.00, K Pd 2+ /Hg 2+ =19.00, K Cu 2+ /Hg 2+ =3.00, respectively.

Studies on Rare Earth Complexes with Crown Ether (ⅩⅩⅣ)——Synthesis and Characterization of Complexes of Lanthanide Isothiocyanates with Dibenzo-30-crown-10

Introduction The study of metal complexes with the crown ether is a quite interesting research field, but the research has mainly focused on the metal complexes with some crown ethers with a relatively small cavity such as 12-crown-4, 15-crown-5 and 18- crown-6 as well as their derivatives. Crown ethers with a larger cavity contain more oxygen atoms, so they have the ability to form the complexes of a higher co-

SYNTHESIS OF MAIN CHAIN LIQUID CRYSTALLINE COPOLYESTERS WITH X-SHAPED TWO-DIMENSIONAL MESOGENIC UNIT AND CROWN ETHER CYCLE

A novel series of main chain liquid crystalline copolyesters with X-shaped two-dimensional mesogenic unit and crown ether cycle of cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 was prepared via solution condensation polymerization from 4,4＇-（a;arhexanedioyloxy） dibenzoyl dichloride （MI）, 2,5-bis（p-octyloxybenzoyloxy） hydro-quinone （M2） and cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 （M3）. Monomer MI was synthesized by esterification and substitution of adipoyl chloride with p-hydroxybenzoic acid, monomer M2 was synthesized by esterfication and reduction reaction of 2,5-dihydroxybenzoquinone and p-octanoxybenzoyl chloride and monomer M3 was synthesized by diazotization and coupling reaction of cis-diaminodibenzo-18-crown-6 with phenol. The molecular weights of copolyesters are not high, and the intrinsic viscosity [η] of copolyesters ranges from 0.25-0.35. The monomers＇ structures were identified by using elemental analysis, IR, UV, ^1H-NMR, MS, etc. All the copolyesters are yellowish powders and insoluble in THF and CHC13 at room temperature except cPg. The properties of copolyesters were investigated by using GPC, [η] , DSC, TG, WAXD and POM. It was found that all the copolyesters entered into liquid crystal phase when they were heated to above their melting temperature （Tin）. The typical smectic and nematic phase texture can be observed on POM. Their mesophase transition temperature and thermal stability change regularly with varying the content of cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 unit in the copolyesters.

SYNTHESIS OF LIQUID CRYSTALLINE COPOLYESTERS WITH T-SHAPED TWO-DIMENSIONAL MESOGENIC UNIT AND CROWN ETHER CYCLE

A novel series of liquid crystalline copolyesters with T-shaped two-dimensional mesogenic unit and crown ether cycle of cis-4,4′-bis(4-hydroxyphenylazo)dibenzo-18-crown-6 was prepared via solution condensation polymerization from 4,4′-(α,ω-hexanedioyloxy)dibenzoyl dichloride(M_1),2-(4′-ethoxyphenyl)hydroquinone(M_2)and cis-4,4′-bis(4- hydroxyphenylazo)dibenzo-18-crown-6(M_3).The molecular weights of copolyesters are not high,and the intrinsic viscosity [η]of copolyesters ranges from 0.29-0.43.The monomers ...

Studies On A Selena-aza-crown Ether: Synthesis and Catalytic Behavior In Hydrosilylation

The synthesis of a new type of selena aza crown ether 6 (4 nitrobenzyl) 1,4,7,10 selenatriazacyclododecane (L) derivated from phenylalanine , and its platinum(Ⅱ) complex was described. The catalytic activity of this complex for the hydrosilylation of olefins by triethoxysilane was investigated.

Studies on Hetero-Macrocyclic Polyether(X VII) the Synthesis of Selena-aza Crown Ethers

A series of selena aza crown ether is condensed by 1,5 bis(p tosylsulphonylamino) 3 selena pentane with ditosylates or dihalides in K 2CO 3/DMF or NaH/DMF. The yields are about 30% 60%.

Synthesis of New Bis-diphenyl-22-and Diphenyl-11-Membered Ring N-pivot lariat Crown Ethers

Bis diphenyl 22 and 11 Membered Ring N pivot lariat Crown Ethers were prepared by one step reaction of 2,2' dihydroxy diphenyl with N tosyl diethanolamine ditoskylate in DMF at refluxing tem perature under N z,Using anhydrous potassium carbonate as condensing agent,respectirely.The tosyl group of(1,2) were removed by treatment with 40%HBr in AcoH in the presence gf a large amount of phenol to give correspondence crown ether compounds(3,4).New N pirot lariat crown thers(5,6)were prepared by one step reaction of(3)with RBr(R=-CH 2CH=CH 2,-CH 2(CH 2) 14 CH 3) in CH 3CN at refluxing temperature under N 2,Using anhydrous K 2CO 3 as condensing agent.New N pivot lariat croon ether(7) were prepared by one step reaction (4)with n bromohexadecane in CH 3CN at refluxing temperature under N 2, Using anhydrous potassium carbonate as condensing agent.New compounds(1,3,5,6,7)were characterized by IR,, 1H NMR,Ms and elemental analysis.

STUDIES ON CROWN ETHER CYANINE DYES(XI)THE SYNTHESIS OF BENZOTELLURAZOLE CROWN ETHER CYANINE DYES

Three methods for synthesis of benzotellurazole crown ether(6)are described.The cyanine dye(8)can be easily obtained by treating(6) with CH_3I and CH(OEt)_3.

The Synthesis and Film Forming Properties of Unsymmetrical Phthalocyanine Bearing One Crown Ether Void

The synthesis of phthalocyanines bearing one crown ether macrocycle and three alkoxyl chains is described. They form stable monolayers and can be employed for the preparation of multilayer films by the Langmuir-Blogett technique. The orientations of the molecules in the film were affected by alkali metal ions in the subphase. lt is suggested that a kind of 'sandwich' dimer was formed in the film induced by potassium ions

STUDIES ON COMPLEXES OF RARE EARTHS WITH CROWN ETHERS(V)-SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF RARE EARTH NITRATES WITH 2,2'-DINITRO-4,5,4',5'-BIS-(15-CROWN-5)-DIBENZO DISULFIDE

Three new solid complexes of macrocyclic polyether ligand 2, 2'-dinitro-4, 5, 4', 5'bis-(15- crown-5)-dihenzo disulfide(L) with trivalent rare earth nitrates having composition of RE(NO_3)_3·L ·6H_2O(RE=Ce, Pr, Nd) have been synthesized in acetonitrile. All the isolated complexes have been characterized by elementary analysis, IR and UV spectra, differential thermal and thermogravimetric analysis, X-ray powder diffraction analysis, molar conductance and measurements of solubility in some general solvents.

Synthesis of A New Group of Flavones Containing Crown Ether Moiety

Flavones are main components of natural occurring flavonoils. It is well documented in the literatures that flavones are known to exhibit a wide variety of biological and pharmaceutical activities. Many of them have been used therapentically for the treatments of symptoms of chronic venous insufficiency, of varicose veins, of conditions and of diabetic retinopathy, etc.. Some flavones have

STUDIES ON COMPLEXES OF RARE EARTHS WITH CROWN ETHERS(Ⅳ)SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF RARE EARTH NITRATES WITH 4'-BROMO-5'-NITROBENZO-15-CROWN-5

Six new solid complexes of macrocyclic polyether ligand 4′-bromo-5′-nitrobenzo-15-crown-5(L)with Uivalent rare earth nitrates having composition of RE(NO_3)_3·L·mCH_3CN·nH_2O(RE=L_a--Nd,m=n=0, RE=Sm,Bu,m=0.1,n=1,4)have been synthesized in acetonitrile or acetone.All the isolated complexes have been char- acterized by elementary analysis,IR and UV spectra,differential thermal and thermogravimetric analysis,X-ray powder diffraction analysis,molar conductance and measurementa of solubility in some general solventa.It shows that coordination number of the rare earth cation in the complexes of La,Ce,Pr and Nd nitrate is eleven.

A CONVENIENT SYNTHESIS OF PERFLUOROALRYLBENZO CROWN ETHERS

Perfluoroalkylbenzo crown ethers were readily prepared from the reaction of benzo crown ethers with sodium perfluoroalkanesulfinates in the presence of an oxidizing agent such as Ce(SO_4)_2 or Mn(OAC)_3.2H_2O in good yields through a radical process.

Synthesis and Crystal Structure of 3,3'-Dimethyl-dibenzo-18-crown-6

3,3′-Dimethyl-dibenzo-18-crown-6 was synthesized and characterized by elemental analysis, FT-IR, ^1H NMR, UV, MS spectra and X-ray single-crystal diffraction. It belongs to orthorhombic, space group Pna21 with a = 8.0790（18）, b = 16.780（4）, c = 15.222（3） .A, Z= 4, V= 2063.6（8） A3 Dc = 1.250 g/cm^3,μ = 0.090 mm^-1, F（000） = 832, R = 0.0474 and wR = 0.1103. According to structural analysis, the title compound possesses a boat-like configuration.

Studies on Heteromacrocyclic Polyether （X） Synthesis and Structural Ch

Dibenzo-1 , 4 , 10 , 13-tetraselena-7 , 16-dioxacyclo-octadeca-2 , 11-diene was synthesized by the condensation of poly (o-diselenobenzene) with bis (2-chloroethyl) ether in the presence of potassium borohydride. The molecular structure was examined by IR, MS and ￣1H NMR spectra, and confirmed by an X-ray diffraction study. The molecule in the crystal has a centrosymmetry and shows a chair conformation. The dihedral angle between the plane containing the four Se atoms and the benzene ring is 104. 1 (2)°. All geometrical parameters of the molecule are unexceptional. Crystal data : C_20H_24O_2Se_4, M_r= 612. 26, monoclinic, space group P2_1/c, a=8. 866(2) , b=5. 349(1). c=22. 315(3) A, β=96. 04(2)°, V=1052. 3 A￣3, Z=2,D_c=1.932 g/cm￣-3 , μ(MoKα) = 69. 15 cm￣-1, F(000) = 592, T= 297K, R= 0. 038for 1270 observed reflections and 154 refined parameters.

Synthesis and Crystal Structure of 13-Phenyl-1,10-dithia-4,7-dioxa-13-aza-15-Crown-5

Crystal structure of the title compound C 16 H 25 O 2NS 2 has been determined by X-ray diffraction method. Its crystallographic data were as follows: M r=327.51, triclinic, space group P1, a=8.864(3), b=10.127(4), c=10.390(3) , α=105.94(3), β=103.10(2), γ=90.96(3)°, V=870.3(7) 3, Z=2, D c=1.250g.cm -3 , μ(MoKα)=2.966cm -1 , F(000)=176, a total of 3275 reflections measured (2θ max =50°), 2246[I5σ(I)] used in the refinement, R=0.067, R w=0.082. The result shows that the distances of N(1)-C(2) and N(1)-C(3) are longer than that of N(1)-C(11), which indicates that the interaction of C Ar -N sp 2 is stronger than that of C sp 3 -N sp 2 . Oxygen, nitrogen and sulfur atoms of the ring in the same plane was deduced from the least\|squares planes and the dihedral angles.

Synthesis and Crystal Structure of ［Na（DB18C6）（CH_3OH）］_2Mo_6O_（19）·（DB18C6）·（CH_3OH）

The preparation method of [Na ( DB18C6) (CH_3OH )]_2Mo_6O_(19)·(DB18C6)·(CH_3OH) , where DB18C6 is dibenzo-18-crown-6, is described. Thecrystal and molecular structure of the title complex has been determined crystallographically. The title complex crystallizes in the monoclinic system,space group P2_1/c ,a=18. 727(6) ,b=19. 555(6) , c=22. 827(7) ,β=112. 84(3)°, V=7704(4) ￣3 ,M_r = 2102. 9 , Z = 4 , F (000 ) = 4224 , μ= 1 . 028 mm ￣(-1), D_c = 1.813 g/cm￣3 . final R =0. 075 and R_w= 0. 078 based on 4463 observed reflections with F>6. 0σ(F) . The complex consists of [Mo_6O_(19)]￣(2-) ,[Na(DB18C6)]￣+ and CH_3OH, which are linked by long distance interaction through O-Na-O bond.

Synthesis of (S,S)-1,5-bis(4-alkyl-5-hydroxy-2-oxo-3-azapentyl)-1,5-diazacyclooctane

Synthesis of a series of chiral aza crown ethers ((S,S)-1, 5-bis (4-alkyl-5-hydroxy- 2-oxo-3-azapentyl)-1, 5-diazacyclooctane) are described.