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1.
Yangen Huang Dr. Haixiang Gao Brendan Twamley Dr. Jean'ne M. Shreeve Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(4):917-923
High density energetic salts containing nitrogen‐rich cations and the nitranilic anion were readily synthesized in high yield by metathesis reactions of sodium nitranilate 2 and an appropriate halide. All of the new compounds were fully characterized by elemental, spectral (IR, 1H, 13C NMR), and thermal (DSC) analyses. The structure of hydrazinium nitranilate ( 4 ) was also determined by single‐crystal X‐ray analysis. The high symmetry and oxygen content of the anion give these salts extensive hydrogen bonding capability which further results in the high densities, low water solubilities, and high thermal stabilities (Td> 200 °C) of these compounds. Theoretical performance calculations were carried out by using Gaussian 03 and Cheetah 5.0. The calculated detonation pressures (P) for these new salts fall between 17.5 GPa ( 10 ) and 31.7 GPa ( 4 ), and the detonation velocities (νD) range between 7022 m s?1 ( 13 ) and 8638 m s?1 ( 4 ). 相似文献
2.
Francesca Tessore Dr. Elena Cariati Prof. Franco Cariati Prof. Dominique Roberto Prof. Renato Ugo Prof. Patrizia Mussini Prof. Cristiano Zuccaccia Dr. Alceo Macchioni Prof. 《Chemphyschem》2010,11(2):495-507
A series of 4‐X‐1‐methylpyridinium cationic nonlinear optical (NLO) chromophores (X=(E)‐CH?CHC6H5; (E)‐CH?CHC6H4‐4′‐C(CH3)3; (E)‐CH?CHC6H4‐4′‐N(CH3)2; (E)‐CH?CHC6H4‐4′‐N(C4H9)2; (E,E)‐(CH?CH)2C6H4‐4′‐N(CH3)2) with various organic (CF3SO3?, p‐CH3C6H4SO3?), inorganic (I?, ClO4?, SCN?, [Hg2I6]2?) and organometallic (cis‐[Ir(CO)2I2]?) counter anions are studied with the aim of investigating the role of ion pairing and of ionic dissociation or aggregation of ion pairs in controlling their second‐order NLO response in anhydrous chloroform solution. The combined use of electronic absorption spectra, conductimetric measurements and pulsed field gradient spin echo (PGSE) NMR experiments show that the second‐order NLO response, investigated by the electric‐field‐induced second harmonic generation (EFISH) technique, of the salts of the cationic NLO chromophores strongly depends upon the nature of the counter anion and concentration. The ion pairs are the major species at concentration around 10?3 M , and their dipole moments were determined. Generally, below 5×10?4 M , ion pairs start to dissociate into ions with parallel increase of the second‐order NLO response, due to the increased concentration of purely cationic NLO chromophores with improved NLO response. At concentration higher than 10?3 M , some multipolar aggregates, probably of H type, are formed, with parallel slight decrease of the second‐order NLO response. Ion pairing is dependent upon the nature of the counter anion and on the electronic structure of the cationic NLO chromophore. It is very strong for the thiocyanate anion in particular and, albeit to a lesser extent, for the sulfonated anions. The latter show increased tendency to self‐aggregate. 相似文献
3.
Wojciech Nitek Agnieszka Kania Henryk Marona Anna M. Waszkielewicz Ewa esawska 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(7):681-689
Four crystal structures of 2‐amino‐N‐(dimethylphenoxyethyl)propan‐1‐ol derivatives, characterized by X‐ray diffraction analysis, are reported. The free base (R,S)‐2‐amino‐N‐[2‐(2,3‐dimethylphenoxy)ethyl]propan‐1‐ol, C13H21NO2, 1 , crystallizes in the space group P21/n, with two independent molecules in the asymmetric unit. The hydrochloride, (S)‐N‐[2‐(2,6‐dimethylphenoxy)ethyl]‐1‐hydroxypropan‐2‐aminium chloride, C13H22NO2+·Cl?, 2c , crystallizes in the space group P21, with one cation and one chloride anion in the asymmetric unit. The asymmetric unit of two salts of 2‐picolinic acid, namely, (R,S)‐N‐[2‐(2,3‐dimethylphenoxy)ethyl]‐1‐hydroxypropan‐2‐aminium pyridine‐2‐carboxylate, C13H22NO2+·C6H4NO2?, 1p , and (R)‐N‐[2‐(2,6‐dimethylphenoxy)ethyl]‐1‐hydroxypropan‐2‐aminium pyridine‐2‐carboxylate, C13H22NO2+·C6H4NO2?, 2p , consists of one cation and one 2‐picolinate anion. Salt 1p crystallizes in the triclinic centrosymmetric space group P, while salt 2p crystallizes in the space group P41212. The conformations of the amine fragments are contrasted and that of 2p is found to have an unusual antiperiplanar arrangement about the ether group. The crystal packing of 1 and 2c is dominated by hydrogen‐bonded chains, while the structures of the 2‐picolinate salts have hydrogen‐bonded rings as the major features. In both salts with 2‐picolinic acid, the specific R12(5) hydrogen‐bonding motif is observed. Structural studies have been enriched by the generation of fingerprint plots derived from Hirshfeld surfaces. 相似文献
4.
Luca Rocchigiani Prof. Gianfranco Bellachioma Dr. Gianluca Ciancaleoni Dr. Stefano Crocchianti Prof. Antonio Laganà Dr. Cristiano Zuccaccia Dr. Daniele Zuccaccia Prof. Alceo Macchioni 《Chemphyschem》2010,11(15):3243-3254
The self‐aggregation tendency of [N(CH3)2(C18H37)2]X [ 1 X; X?=BF4?, PF6?, OTf?, NTf2?, BPh4?, BTol4?, BArF?, and B(C6F5)4?] salts to form ion quadruples (IQs) and higher aggregates (HAggs) in [D6]benzene is investigated by means of diffusion NMR spectroscopy. The experimental results indicate that salts containing small anions ( 1 BF4, 1 PF6, and 1 OTf) are present in solution as IQs even at the lowest investigated concentration of C=5×10?5 M and show a limited tendency to further self‐aggregate, reaching a maximum average aggregation number (N=VH/${V_{\rm{H}}^{{\rm{0IP}}} }$ , where VH=measured hydrodynamic volume and ${V_{\rm{H}}^{{\rm{0IP}}} }$ =hydrodynamic volume of the ion pair) of about 6–8 (C=0.050–0.100 M ). Salts with larger counterions [ 1 BPh4, 1 BTol4, 1 BArF, and 1 B(C6F5)4] form instead ion pairs at low concentration but steadily self‐aggregate (especially the non‐fluorinated ones) on increasing their concentration up to N values exceeding 50 (C=0.030–0.050 M ). 1 NTf2 behaves in an intermediate fashion. The self‐aggregation tendency of salts is quantified by formulating the dependence of VH on C by means of the equations of indefinitive aggregation models. The following rankings for the formation of IQs and HAggs are obtained: IQs: 1 BF4≈ 1 PF6≈ 1 OTf> 1 NTf2> 1 B(C6F5)4≥ 1 BPh4≥ 1 BTol4≥ 1 BArF; HAggs: 1 BTol4> 1 BPh4> 1 NTf2> 1 B(C6F5)4> 1 BArF> 1 BF4≈ 1 PF6≈ 1 OTf. Interionic NOE NMR studies and DFT calculations were conducted in order to determine the relative anion–cation orientation in the self‐aggregating units. 相似文献
5.
Haifeng Huang Prof. Dr. Zhiming Zhou Lixuan Liang Jinhong Song Kai Wang Dan Cao Wenwen Sun Chengming Bian Dr. Min Xue 《化学:亚洲杂志》2012,7(4):707-714
3,4‐Bis(1H‐5‐tetrazolyl)furoxan (H2BTF, 2 ) and its monoanionic salts that contain nitrogen‐rich cations were readily synthesized and fully characterized by multinuclear NMR (1H, 13C) and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analyses. Hydrazinium ( 3 ) and 4‐amino‐1,2,4‐triazolium ( 7 ) salts crystallized in the monoclinic space group P2(1)/n and have calculated densities of 1.820 and 1.764 g cm?3, respectively. The densities of the energetic salts range between 1.63 and 1.79 g cm?3, as measured by a gas pycnometer. Detonation pressures and detonation velocities were calculated to be 23.1–32.5 GPa and 7740–8790 m s?1, respectively. 相似文献
6.
1,1,1‐Trimethylhydrazinium iodide ([(CH3)3N? NH2]I, 1 ) was reacted with a silver salt to form the corresponding nitrate ([(CH3)3N? NH2][NO3], 2 ), perchlorate ([(CH3)3N? NH2][ClO4], 3 ), azide ([(CH3)3N? NH2][N3], 4 ), 5‐amino‐1H‐tetrazolate ([(CH3)3N? NH2][H2N? CN4], 5 ), and sulfate ([(CH3)3N? NH2]2[SO4]?2H2O, 6 ?2H2O) salts. The metathesis reaction of compound 6 ?2H2O with barium salts led to the formation of the corresponding picrate ([(CH3)3N? NH2][(NO2)3Ph ‐ O], 7 ), dinitramide ([(CH3)3N? NH2][N(NO2)2], 8 ), 5‐nitrotetrazolate ([(CH3)3N? NH2][O2N? CN4], 9 ), and nitroformiate ([(CH3)3N? NH2][C(NO2)3], 10 ) salts. Compounds 1 – 10 were characterized by elemental analysis, mass spectrometry, infrared/Raman spectroscopy, and multinuclear NMR spectroscopy (1H, 13C, and 15N). Additionally, compounds 1 , 6 , and 7 were also characterized by low‐temperature X‐ray diffraction techniques (XRD). Ba(NH4)(NT)3 (NT=5‐nitrotetrazole anion) was accidentally obtained during the synthesis of the 5‐nitrotetrazole salt 9 and was also characterized by low‐temperature XRD. Furthermore, the structure of the [(CH3)3N? NH2]+ cation was optimized using the B3LYP method and used to calculate its vibrational frequencies, NBO charges, and electronic energy. Differential scanning calorimetry (DSC) was used to assess the thermal stabilities of salts 2 – 5 and 7 – 10 , and the sensitivities of the materials towards classical stimuli were estimated by submitting the compounds to standard (BAM) tests. Lastly, we computed the performance parameters (detonation pressures/velocities and specific impulses) and the decomposition gases of compounds 2 – 5 and 7 – 10 and those of their oxygen‐balanced mixtures with an oxidizer. 相似文献
7.
Qiao‐Yun Li Gao‐Wen Yang Rong‐Xin Yuan Jia‐Ping Wang Peng‐Fei Cui 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):m26-m29
The CoII atom in bis(5‐aminotetrazole‐1‐acetato)tetraaquacobalt(II), [Co(C3H4N5O2)2(H2O)4], (I), is octahedrally coordinated by six O atoms from two 5‐aminotetrazole‐1‐acetate (atza) ligands and four water molecules. The molecule has a crystallographic centre of symmetry located at the CoII atom. The molecules of (I) are interlinked by hydrogen‐bond interactions, forming a two‐dimensional supramolecular network structure in the ac plane. The CdII atom in catena‐poly[[cadmium(II)]‐bis(μ‐5‐aminotetrazole‐1‐acetato], [Cd(C3H4N5O2)2]n, (II), lies on a twofold axis and is coordinated by two N atoms and four O atoms from four atza ligands to form a distorted octahedral coordination environment. The CdII centres are connected through tridentate atza bridging ligands to form a two‐dimensional layered structure extending along the ab plane, which is further linked into a three‐dimensional structure through hydrogen‐bond interactions. 相似文献
8.
Dr. Jie Sun Dr. Di Sun Shuai Yuan Dr. Dongxu Tian Liangliang Zhang Prof. Xingpo Wang Prof. Dr. Daofeng Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(51):16525-16530
A series of C3i‐symmetric bicapped trigonal antiprismatic Cd8 cages [2X@Cd8L6(H2O)6] ? n Y ? solvents (X=Cl?, Y=NO3?, n=2: MOCC‐4 ; X=Br?, Y=NO3?, n=2: MOCC‐5 ; X=NO3?, Y=NO3?, n=2: MOCC‐6 ; X=NO3?, Y=BF4?, n=2: MOCC‐7 ; X=NO3?, Y=ClO4?, n=2: MOCC‐8 ; X=CO32?, n=0: MOCC‐9 ), doubly anion templated by different anions, were solvothermally synthesized by means of a flexible ligand. Interestingly, the CO32? template for MOCC‐9 was generated in situ by two‐step decomposition of DMF solvent. For other MOCCs, spherical or trigonal monovalent anions could also play the role of template in their formation. The template abilities of these anions in the formation of the cages were experimentally studied and are discussed for the first time. Anion exchange of MOCC‐8 was carried out and showed anion‐size selectivity. All of the cage‐like compounds emit strong luminescence at room temperature. 相似文献
9.
Solvent‐Mediated Functionalization of Benzofuroxan on Electron‐Rich Ruthenium Complex Platform
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Dr. Prabir Ghosh Sanchaita Dey Sanjib Panda Prof. Goutam Kumar Lahiri 《化学:亚洲杂志》2018,13(12):1582-1593
An unprecedented reactivity profile of biochemically relevant R‐benzofuroxan (R=H, Me, Cl), with high structural diversity and molecular complexity on a selective {Ru(acac)2} (acac=acetylacetonate) platform, in conjugation with EtOH solvent mediation, is revealed. This led to the development of monomeric [RuIII(acac)2(L1R)] ( 1 a – 1 c ; L1R=2‐nitrosoanilido derivatives) and dimeric [{RuII(acac)2}2(L2R)] ( 2 a – 2 b ; L2R=(1E,2E)‐N1,N2‐bis(2‐nitrosophenyl)ethane‐1,2‐diimine derivatives) complexes in one pot with a change in the metal redox conditions. The functionalization of benzofuroxan in 1 and 2 implied in situ reduction of N=O to NH? in the former and solvent‐assisted multiple N?C coupling in the latter. The aforesaid transformation processes were authenticated through structural elucidation of representative complexes, and evaluated by their spectroscopic/electrochemical features, along with C2D5OD labeling and monitoring of the impact of substituents (R) in the benzofuroxan framework on the product distribution process. The noninnocent potential of newly developed L1 and L2 in 1 and 2 , respectively, was also probed by spectroelectrochemistry in combination with DFT calculations. 相似文献
10.
《Physics and Chemistry of Liquids》2012,50(5):617-629
Densities (ρ), viscosities (η) and surface tension (γ) as function of the molarity of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 for LiNO3, NaNO3, KNO3, Sr(NO3)2, Ba(NO3)2 and Pb(NO3)2 electrolytes are reported at 32°C. Data were regressed for limiting values for solute–solvent interactions and effects of shell numbers and electronic configurations. A confidence variance of 95.5% at Gaussian distribution was noted. Densities explained ionic forces and sizes, and viscosities defined frictional forces while the surface tension focused surface energies of hydrated ions. Slopes of densities, viscosities and surface tensions explained the concentration effects on ionic interactions. Limiting densities from Li+ to Ba2+ increased with increase in sizes. Pb2+ smaller in size than the Ba2+ had lower limiting densities. The ρ 0 are Ba2+?>?Sr2+?>?Pb2+?>?K+?>?Na+?>?Li+ with 3.24, 2.98, 4.53, 2.109, 2.257 and 2.38?×?103?kg?m?3 densities of nitrate salts, respectively, in the solid state. 相似文献
11.
Andreas Lemmerer 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(8):746-752
A series of five binary complexes, i.e. three cocrystals and two molecular salts, using 2‐chloro‐4‐nitrobenzoic acid as a coformer have been produced with five commonly available compounds, some of pharmaceutical relevance, namely, 2‐chloro‐4‐nitrobenzoic acid–isonicotinamide (1/1), C7H4ClNO4·C6H6N2O, 2‐chloro‐4‐nitrobenzoic acid–3,3‐diethylpyridine‐2,4(1H,3H)‐dione (2/1), 2C7H4ClNO4·C9H13NO2, 2‐chloro‐4‐nitrobenzoic acid–pyrrolidin‐2‐one (1/1), C7H4ClNO4·C4H7NO, 2‐carboxypiperidinium 2‐chloro‐4‐nitrobenzoate, C6H12NO2?·C7H3ClNO4?, and (2‐hydroxyethyl)ammonium 2‐chloro‐4‐nitrobenzoate, C2H8NO+·C7H3ClNO4?. The coformer falls under the classification of a `generally regarded as safe' compound. All five complexes make use of a number of different heteromeric hydrogen‐bonded interactions. Intermolecular potentials were evaluated using the CSD‐Materials module. 相似文献
12.
Matthias Weil 《无机化学与普通化学杂志》2005,631(8):1346-1348
Light‐yellow single crystals of the mixed‐valent mercury‐rich basic nitrate Hg8O4(OH)(NO3)5 were obtained as a by‐product at 85 °C from a melt consisting of stoichiometric amounts of (HgI2)(NO3)2·2H2O and HgII(OH)(NO3). The title compound, represented by the more detailed formula HgI2(NO3)2·HgII(OH)(NO3)·HgII(NO3)2·4HgIIO, exhibits a new structure type (monoclinic, C2/c, Z = 4, a = 6.7708(7), b = 11.6692(11), c = 24.492(2) Å, β = 96.851(2)°, 2920 structure factors, 178 parameters, R1[F2 > 2σ(F2)] = 0.0316) and is made up of almost linear [O‐HgII‐O] and [O‐HgI‐HgI‐O] building blocks with typical HgII‐O distances around 2.06Å and a HgI‐O distance of 2.13Å. The Hg22+ dumbbell exhibits a characteristic Hg‐Hg distance of 2.5079(7) Å. The different types of mercury‐oxygen units form a complex three‐dimensional network exhibiting large cavities which are occupied by the nitrate groups. The NO3? anions show only weak interactions between the nitrate oxygen atoms and the mercury atoms which are at distances > 2.6Å from one another. One of the three crystallographically independent nitrate groups is disordered. 相似文献
13.
Methyl (2E,4R)‐4‐hydroxydec‐2‐enoate, methyl (2E,4S)‐4‐hydroxydec‐2‐enoate, and ethyl (±)‐(2E)‐4‐hydroxy[4‐2H]dec‐2‐enoate were chemically synthesized and incubated in the yeast Saccharomyces cerevisiae. Initial C‐chain elongation of these substrates to C12 and, to a lesser extent, C14 fatty acids was observed, followed by γ‐decanolactone formation. Metabolic conversion of methyl (2E,4R)‐4‐hydroxydec‐2‐enoate and methyl (2E,4S)‐4‐hydroxydec‐2‐enoate both led to (4R)‐γ‐decanolactone with >99% ee and 80% ee, respectively. Biotransformation of ethyl (±)‐(2E)‐4‐hydroxy(4‐2H)dec‐2‐enoate yielded (4R)‐γ‐[2H]decanolactone with 61% of the 2H label maintained and in 90% ee indicating a stereoinversion pathway. Electron‐impact mass spectrometry analysis (Fig. 4) of 4‐hydroxydecanoic acid indicated a partial C(4)→C(2) 2H shift. The formation of erythro‐3,4‐dihydroxydecanoic acid and erythro‐3‐hydroxy‐γ‐decanolactone from methyl (2E,4S)‐4‐hydroxydec‐2‐enoate supports a net inversion to (4R)‐γ‐decanolactone via 4‐oxodecanoic acid. As postulated in a previous work, (2E,4S)‐4‐hydroxydec‐2‐enoic acid was shown to be a key intermediate during (4R)‐γ‐decanolactone formation via degradation of (3S,4S)‐dihydroxy fatty acids and precursors by Saccharomyces cerevisiae. 相似文献
14.
Quantification of Ion‐Pairing Effects on the Nucleophilic Reactivities of Benzoyl‐ and Phenyl‐Substituted Carbanions in Dimethylsulfoxide
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Dr. Francisco Corral‐Bautista Dr. Roland Appel Johanna S. Frickel Prof. Dr. Herbert Mayr 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):875-884
Second‐order rate constants for the reactions of acceptor‐substituted phenacyl (PhCO?CH??Acc) and benzyl anions (Ph?CH??Acc) with diarylcarbenium ions and quinone methides (reference electrophiles) have been determined in dimethylsulfoxide (DMSO) solution at 20 °C. By studying the kinetics in the presence of variable concentrations of potassium, sodium and lithium salts (up to 10?2 mol L?1), the influence of ion‐pairing on the reaction rates was examined. As the concentration of K+ did not have any influence on the rate constants at carbanion concentrations in the range of 10?4–10?3 mol L?1, the acquired rate constants could be assigned to the reactivities of the free carbanions. The counter ion effects increase, however, in the series K+<Na+<Li+, and the sensitivity of the carbanion reactivities toward variation of the counter ion strongly depends on the structure of the carbanions. The reactivity parameters N and sN of the free carbanions were derived from the linear plots of log k2 against the electrophilicity parameters E of the reference electrophiles, according to the linear‐free energy relationship log k2(20 °C)=sN(N+E). These reactivity parameters can be used to predict absolute rate constants for the reactions of these carbanions with other electrophiles of known E parameters. 相似文献
15.
Vinicius Oliveira Araujo Brbara Tirloni Lívia Streit Vnia Denise Schwade 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(1):1-7
Semicarbazones can exist in two tautomeric forms. In the solid state, they are found in the keto form. This work presents the synthesis, structures and spectroscopic characterization (IR and NMR spectroscopy) of four such compounds, namely the neutral molecule 4‐phenyl‐1‐[phenyl(pyridin‐2‐yl)methylidene]semicarbazide, C19H16N4O, (I), abbreviated as HBzPyS, and three different hydrated salts, namely the chloride dihydrate, C19H17N4O+·Cl?·2H2O, (II), the nitrate dihydrate, C19H17N4O+·NO3?·2H2O, (III), and the thiocyanate 2.5‐hydrate, C19H17N4O+·SCN?·2.5H2O, (IV), of 2‐[phenyl({[(phenylcarbamoyl)amino]imino})methyl]pyridinium, abbreviated as [H2BzPyS]+·X?·nH2O, with X = Cl? and n = 2 for (II), X = NO3? and n = 2 for (III), and X = SCN? and n = 2.5 for (IV), showing the influence of the anionic form in the intermolecular interactions. Water molecules and counter‐ions (chloride or nitrate) are involved in the formation of a two‐dimensional arrangement by the establishment of hydrogen bonds with the N—H groups of the cation, stabilizing the E isomers in the solid state. The neutral HBzPyS molecule crystallized as the E isomer due to the existence of weak π–π interactions between pairs of molecules. The calculated IR spectrum of the hydrated [H2BzPyS]+ cation is in good agreement with the experimental results. 相似文献
16.
Zsolt Baranyai Ern Brücher Tímea Ivnyi Rbert Kirly Istvn Lzr Lszl Zkny 《Helvetica chimica acta》2005,88(3):604-617
Eu3+, Dy3+, and Yb3+ complexes of the dota‐derived tetramide N,N′,N″,N′′′‐[1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(1‐oxoethane‐2,1‐diyl)]tetrakis[glycine] (H4dotagl) are potential CEST contrast agents in MRI. In the [Ln(dotagl)] complexes, the Ln3+ ion is in the cage formed by the four ring N‐atoms and the amide O‐atom donor atoms, and a H2O molecule occupies the ninth coordination site. The stability constants of the [Ln(dotagl)] complexes are ca. 10 orders of magnitude lower than those of the [Ln(dota)] analogues (H4dota=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The free carboxylate groups in [Ln(dotagl)] are protonated in the pH range 1–5, resulting in mono‐, di‐, tri‐, and tetraprotonated species. Complexes with divalent metals (Mg2+, Ca2+, and Cu2+) are also of relatively low stability. At pH>8, Cu2+ forms a hydroxo complex; however, the amide H‐atom(s) does not dissociate due to the absence of anchor N‐atom(s), which is the result of the rigid structure of the ring. The relaxivities of [Gd(dotagl)] decrease from 10 to 25°, then increase between 30–50°. This unusual trend is interpreted with the low H2O‐exchange rate. The [Ln(dotagl)] complexes form slowly, via the equilibrium formation of a monoprotonated intermediate, which deprotonates and rearranges to the product in a slow, OH?‐catalyzed reaction. The formation rates are lower than those for the corresponding Ln(dota) complexes. The dissociation rate of [Eu(dotagl)] is directly proportional to [H+] (0.1–1.0M HClO4); the proton‐assisted dissociation rate is lower for [Eu(H4dotagl)] (k1=8.1?10?6 M ?1 s?1) than for [Eu(dota)] (k1=1.4?10?5 M ?1 s?1). 相似文献
17.
Juraj ernk Anna Pavlov Michal Duek Karla Fejfarov 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):m260-m262
<!?tpct=26.8pt>In the ionic title compound, [Ni(NO3)(C10H9N3)2]NO3, the central NiII atom exhibits cis‐NiN4O2 octahedral coordination with three chelating ligands, viz. one nitrate anion and two di‐2‐pyridylamine (dpya) molecules. A second nitrate group acts as a counter‐ion. The complex cations and the nitrate anions are also linked by N—H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO3)2 and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO3)2/dpya/maleic acid/NaOH system. 相似文献
18.
Purnandhu Bose Dr. Iyyamperumal Ravikumar Bidyut Akhuli Prof. Pradyut Ghosh 《化学:亚洲杂志》2012,7(10):2373-2380
A new series of tris(2‐aminoethyl)amine (tren)‐based L ‐alanine amino acid backboned tripodal hexaamide receptors (L1–L5) with various attached moieties based on electron‐withdrawing fluoro groups and lipophilicity have been synthesized and characterized. Detailed binding studies of L1–L5 with different anions, such as halides (F?, Cl?, Br?, and I?) and oxyanions (AcO?, BzO? (Bz=benzoyl), NO3?, H2PO4?, and HSO4?), have been carried out by isothermal titration calorimetric (ITC) experiments in acetonitrile/dimethylsulfoxide (99.5:0.5 v/v) at 298 K. ITC titration experiments have clearly shown that receptors L1–L4 invariably form 1:1 complexes with Cl?, AcO?, BzO?, and HSO4?, whereas L5 forms a 1:1 complex only with AcO?. In the case of Br?, I?, and NO3?, no appreciable heat change is observed owing to weak interactions between these anions and receptors; this is further confirmed by 1H NMR spectroscopy. The ITC binding studies of F? and H2PO4? do not fit well for a 1:1 binding model. Furthermore, ITC binding studies also revealed slightly higher selectivity of this series of receptors towards AcO? over Cl?, BzO?, and HSO4?. Solid‐state structural evidence for the recognition of Cl? by this new category of receptor was confirmed by single‐crystal X‐ray structural analysis of the complex of tetrabutylammonium chloride (TBACl) and L1. Single‐crystal X‐ray diffraction clearly showed that the pentafluorophenyl‐functionalized amide receptor (L1) encapsulated Cl? in its cavity by hydrogen bonds from amides, and the cavity of L1 was capped with a TBA cation through hydrogen bonding and ion‐pair interactions to form a capped‐cleft orientation. To understand the role of the cationic counterpart in solution‐state Cl? binding processes with this series of receptors (L1–L4), a detailed Cl? binding study was carried out with three different tetraalkylammonium (Me4N+, Et4N+, and Bu4N+) salts of Cl?. The binding affinities of these receptors with different tetralkylammonium salts of Cl? gave binding constants with the TBA cation in the following order: butyl>ethyl>methyl. This study further supports the role of the TBA countercation in ion‐pair recognition by this series of receptors. 相似文献
19.
Toshifumi Satoh Tomoko Imai Norihiko Sugie Ryuji Nonokawa Kazuaki Yokota Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):965-970
The bulk cyclopolymerization of diepisulfide, 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐1,2:5,6‐tetradeoxy‐D ‐mannitol ( 1 ), was studied using R4N+Br? (R = ? CH3, C2H5, C3H7, C4H9, and C7H15) and (C4H9)4N+X? (X = Cl, I, NO3, and ClO4) as the initiators. All the bulk polymerizations of 1 using quaternary tetraalkylammonium salts at 90 °C proceeded without gelation even at high conversion to produce gel‐free polymers consisting of 2,5‐anhydro‐1,5‐dithio‐D ‐glucitol (I) as the major cyclic repeating unit along with 1,5‐anhydro‐2,5‐dithio‐D ‐mannitol (II) and the desulfurized acyclic unit (III) as the minor units. The polymerization rate and molar fraction of the I unit increased with the increasing alkyl chain length of the tetraalkylammonium cation and the increasing nucleophilicity of the counteranion. Tetrabutylammonium chloride exhibited the highest catalytic activity and the highest stereoselectivity, that is, the thiosugar polymer with I:II:III = 81:15:4 and a number‐average molecular weight of 31.9 × 103 was obtained in 85% yield for a polymerization time of 0.5 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 965–970, 2002 相似文献
20.
Raman Spectroscopic Study on Alkyl Chain Conformation in 1‐Butyl‐3‐methylimidazolium Ionic Liquids and their Aqueous Mixtures
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Dr. Dheeraj K. Singh Dr. Seoncheol Cha Dr. Dahyun Nam Prof. Dr. Hyeonsik Cheong Prof. Dr. Sang‐Woo Joo Prof. Dr. Doseok Kim 《Chemphyschem》2016,17(19):3040-3046
Ionic liquids of 1‐butyl‐3‐methylimidazolium ([BMIM]) cation with different anions (Cl?, Br?, I?, and BF4?), and their aqueous mixtures were investigated by using Raman spectroscopy and dispersion‐included density functional theory (DFT). The characteristic Raman bands at 600 and 624 cm?1 for two isomers of the butyl chain in the imidazolium cation showed significant changes in intensity for different anions as well as in aqueous solutions. The area ratio of these two bands followed the order I?>Br?>Cl?>BF4? (in terms of the anion X in [BMIM]X), indicating that the butyl chain of [BMIM]I tends to adopt the trans conformation. The butyl chain was found to adopt the gauche conformation upon dilution, irrespective of the anion type. The Raman bands in the butyl C?H stretch region for [BMIM]X (X=Cl?, Br?, and I?) blueshifted significantly with the increase in the water concentration, whereas that for [BMIM]BF4 changed very little upon dilution. The blueshift in the C?H stretch region upon dilution also followed the order: [BMIM]I>[BMIM]Br>[BMIM]Cl>[BMIM]BF4, the same order as the above trans conformation preference of the butyl chain in pure imidazolium ionic liquids, which suggested that the cation‐anion interaction plays a role in determining the conformation of the chain. 相似文献