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1.
Glassy carbon electrodes are modified with a thin film of a cellulose‐chitosan nanocomposite. Cellulose nanofibrils (of ca. 4 nm diameter and 250 nm length) are employed as an inert backbone and chitosan (poly‐D ‐glucosamine, low molecular weight, 75–85% deacetylated) is introduced as a structural binder and “receptor” or molecular binding site. The composite films are formed in a solvent evaporation method and prepared in approximately 0.8 μm thickness. The adsorption of three molecular systems into the cellulose‐chitosan films is investigated and approximate Langmuirian binding constants are evaluated: i) Fe(CN)64? (KFerrocyanide=2.2×103 mol?1 dm3 in 0.1 M phosphate buffer at pH 6) is observed to bind to ammonium chitosan functionalities (present at pH<7), ii) triclosan (KTriclosan=2.6×103 mol?1 dm3 in 0.1 M phosphate buffer pH 9.5) is shown to bind only weakly and under alkaline conditions, and iii) the anionic surfactant dodecylsulfate (KSDS=3.3×104 mol?1 dm3 in 0.1 M phosphate buffer pH 6) is shown to bind relatively more strongly in acidic media. The competitive binding of Fe(CN)64? and dodecylsulfate anions is proposed as a way to accumulate and indirectly determine the anionic surfactant.  相似文献   

2.
袁爱华  沈小平  周虎  陆路德 《化学学报》2005,63(19):1795-1801
将Ni(teta)(ClO4)2 (teta=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)的DMF溶液和K3[Fe(CN)6]的水溶液在填充了琼脂冻胶的U型管中通过扩散反应, 得到了标题化合物(H2teta)2{[Ni(teta)][Fe(CN)6]2}•17H2O, 该化合物晶体属三斜晶系, 空间群P1, 晶胞参数为a=0.9998(2) nm, b=1.5514(3) nm, c=1.6647(4) nm, α=114.15(2)°, β=100.91(2)°, γ=93.42(2)°, V=2.2863(10) nm3, z=1, Dc=1.196 g•cm-3, F(000)=890, μ=5.84 cm-1, GOF=0.894, R1=0.0582, wR2=0.1446 [I>2σ(I)]. 该化合物的基本单元由2个[H2teta]2+阳离子、1个{[Ni(teta)][Fe(CN)6]2}4-阴离子和17个水分子组成, 它们之间通过N—H…N氢键而形成具有二维平面结构的超分子化合物. 1.8~300 K变温磁化率研究表明, 化合物中三核体系Fe (s=1/2)-Ni (s=1)-Fe (s=1/2)中心原子间通过氰基桥联而发生强的铁磁相互作用, 磁参数J=4.33 cm-1, g=2.6, θ=60 K. 通过TG-DTG测定了配合物的热稳定性.  相似文献   

3.
A new cyano‐bridged binuclear 4f‐3d complex Sm(DMSO)4‐(H2O)3Cr(CN)6 was synthesized and characterized by single crystal structure analysis. It crystallizes in monoclinic, space group P21 with a=0.9367(2) nm, b = 1.3917(3) nm, c = 1.1212(2) run, β = 99.88(3)° and Z = 2. In this binuclear complex, Sm atom is eight coordinated and linked to the Cr atom by a cyano bridge. The molecules packs to form 3D structure due to the hydrogen bonds among them. [K3(18‐C‐6)3(H2O)4]Cr(CN)6·3H2O (18‐C‐6 represents 18‐crown‐6‐ether) that was synthesized as a byproduct in the preparation of a Gd—Cr complex is also structurally characterized. Crystal data: triclinic, space group P‐l with a = 1.0496(7) nm, b= 1.1567(14) nm, c = 1.3530(13) nm, a = 94.15(9)°, β = 96.04(8)°, γ = 95.25(9)° and Z = l. [K3(18‐C‐6)3(H2O)4]‐Cr(CN)6·3H2O consists of ionic [K3(18‐C‐6)3(H2O)4]3+ and [Cr(CN)6]3‐ pairs, of which the [K3(18‐C‐6)3(H2O)4]3+ ion is a trinuclear duster connected by water, and K atoms are eight coordinated by eight oxygen atoms of one 18‐C‐6 and two water molecules.  相似文献   

4.
Using spectrophotometric methods, the protopysis constant of the 5.ClDMPAP reagent (pKa1 = −0.19; pKa2 = 1.97; pKa3 = 11.98) and the stability constant of its vanadic complex (6.0 ± 0.11) × 1014 were determined. A high-sensitivity spectrophotometric method was developed to determine V(V) using 0.1–1.2 ppm and pH = 3.8. ε586 = 55,300 ± 400 liters · mol−1 · cm−1. A study on the most important interferences and the way to eliminate them was carried out. The method can be applied to the determination of the element in steels and ferrovanadiums.  相似文献   

5.
Crystals of K2Pt(CN)6 doped with Pt(CN)2?4 show an absorption band at 337 nm which is assigned as a mixed-valence (MV) transition from Pt (II) to Pt(IV). From a Hush model analysis, the absorption band is interpreted to be class II in the Day—Robin scheme. When the MV band is laser excited at 337 nm, emmision is observed from Pt(CN)2?4 clusters.  相似文献   

6.
The iron(III) dimeric complex [Fe2(CN)10]4− is reduced to the iron(III)iron(II) species [Fe2(CN)10]5− by iodide ion, the equilibrium constant being strongly dependent upon the nature of the alkali metal cation, reduction being favoured in the sequence: Cs+>NH 4 + ≥K+>Na+>Li+. The reaction kinetics are autocatalytic in character, the catalytic species being the mixed valence dimer. The rates of reactions are also strongly catalysed by alkali metal cations, in the same sequence as for the equilibrium constants. The reaction mechanism involves the formation of I 2 as a reactive intermediate which can be oxidised by both [Fe2(CN)10]4− and [Fe2(CN)10]5−.  相似文献   

7.
Two novel one‐ and two‐dimensional network structure bismuth(III) complexes with N, N‐di(2‐hydroxylethyl)‐aminodithiocarboxylate, {Bi[S2CN(C2H4OH)2]2[1, 10‐Phen]2(NO3)}·3H2O (1) and (Bi[S2CN(C2H4OH)2]3)2 (2) were synthesized. Their crystal and molecular structures were determined by X‐ray single crystal diffraction analysis. The crystal 1 belongs to monoclinic system with space group C2/c, a=1.6431(7) nm, b=2.4323(10) nm, c= 1.2646(5) nm, β=126. 237(5), Z=4, V=4.076(3) nm3, Dc=1.757 Mg/m3, μ=4.598 mm?1, F(000)=2156, R= 0.0211, wR=0.0369. The structure shows a distorted square antiprism configuration with eight‐coordination for the central Bi atom. The one‐dimensional chain structure was formed by H‐bonding interaction between hydroxyl group of N, N‐di(2‐hydroxylethyl)aminodithiocarboxylate ligands and crystal water. The crystal 2 belongs to monoclinic system with space group p2(1)/c, a= 1.1149(4) nm, b=2.1274(8) nrn, c=2.2107(8) nm, β=98.325(8)°, 2=4, V=5. 188(3) nm3, Dc=1.920 Mg/m3, μ=7.315 mm?1, F(000)=2944, R=0.0565, wR=0.0772. The structure shows a distorted square antiprism configuration with eight‐coordination for the central Bi atoms. The two‐dimensional network structure was formed by H‐bonding interaction between adjacent molecules.  相似文献   

8.
Synthesis, Crystal Structure, and Solid State MAS-NMR Spectroscopic Investigation of K5H(CN2)3 Single phase K5H(CN2)3 was synthesized by reaction of KHCN2 with metallic potassium in liquid ammonia or by reaction of KNH2 with melamine C3N3(NH2)3 at 320 °C, respectively. The crystal structure was determined from X-ray powder and single crystal data: K5H(CN)3, space group Im3m, a = 795.68(7) pm, Z = 2, R1 = 0.025, wR2 = 0.0438. In the solid K5H(CN2)3 contains K+ and CN22–, the anions exhibit D∞h symmetry. According to 1H and 13C solid state MAS-NMR investigations, temperature dependent impedance spectroscopy, and FTIR spectroscopy the protons are only loosely bound to the CN22– ions. The proton conductivity shows a sharp increase above 70 °C.  相似文献   

9.
Zusammenfassung Die relativen Basizitätskonstanten von 5H-Dibenzo(a,h)phenoxazon-(5) (I) (K=3,2 · 10–2), 5H-Dibenzo(a,j)phenoxazon-(5) (II) (K=6,5 · 10–2), 9-(N-1-Naphthylamino)-5H-dibenzo(a,j)phenoxazon-(5) (III) (K=1,12), 9-(N-2-Naphthylamino)-5H-dibenzo(a, j)phenoxazon-(S) (IV) (K=1,22), 9-Anilino-5H-dibenzo(a,j) phenoxazon-(5) (V) (K=1,28) und 9-(p-Tolylamino)-5H-dibenzo(a,j)phenoxazon-(5) (VI) (K=1,45) wurden für das Puffersystem Acetat-Antipyrinperchlorat in wasserfreier Essigsäure bestimmt. Die Verbindungen II, V und VI wurden zur visuellen Indikation von Titrationen schwacher Basen mit Perchlorsäure in wasserfreier Essigsäure benutzt. Mit Indicator II können Basen mit pKa(H2O)-Werten von 2–4 und mit den Indicatoren V und VI stärkere Basen mit pKa(H2O)-Werten von 4–7 bestimmt werden.
Dibenzophenoxazone-(5)-derivatives as neutralisation indicators in non-aqueous acetic acid
The relative basicity constants of 5H-dibenzo(a,h)phenoxazone-(5) (I) (K=3.2×10–2), 5H-dibenzo(a,j)phenoxazone-(5) (II) (K=6.5×10–2), 9-(N-1-naphthylamino)-5H-dibenzo(a,j)phenoxazone-(5) (III) (K=1.12), 9-(N-2-naphthylamino)-5H-dibenzo(a,j)phenoxazone-(5) (IV) (K=1.22), 9-anilino-5H-dibenzo(a,j)phenoxazone-(5) (V) (K=1.28) and 9-(p-tolylamino)-5H-dibenzo(a,j)phenoxazone-(5) (VI) (K=1.45) have been determined with respect to the buffer system antipyrine acetate-antipyrine perchlorate in non-aqueous acetic acid. The compounds II, V and VI were employed for visual indication of titrations of weak bases with perchloric acid in non-aqueous acetic acid. Indicator II is convenient for the titration of bases with pK a (H2O) values 2–4 and indicators V and VI for bases with pKa(H2O) values 4–7.
  相似文献   

10.
Abstract

2-(2′-Pyridyl)benzimidazole (pybzim = LH) coordinates to iron(II) as a bidentate and forms the tris-ligated complex, [Fe(pybzim)3]2+ as isolated in the solid. Titration of [Fe(pybzim)3]2+ with base demonstrates the successive deprotonation of the imino hydrogens of the coordinated ligands. Protonation constants for the free ligand, pybzim (Iog10 K H = 11.33) and the complex, [Fe(pybzim)3]2+ (log10 K H 1 = 9.58, log10 K H 2 = 8.13 and log10 K H 3 = 6.97) were measured in 30% (v/v) H2O/EtOH. Results show that coordination to iron(II) increases the acidity of the imino hydrogen of the ligand. Spin-crossover behaviour of the complex were studied in different solvents ME, AC, AN, NM, NB, DMF, DMSO and ANL. The complex shows strong spin-crossover behaviour which is solvent dependent. Values of the spin-equilibrium constant (K sc) and the associated thermodynamic parameters (ΔH sc = 18.1–21.3 kJ mol?1 and δS sc = 69.6–84.4JK?1 mol?1) were calculated. An increase of the enthalpy is observed with increasing donor number (DN) of the solvent.  相似文献   

11.
From the 1:1 system of [Cu(dien)2](NO3)2 and K[Ag(CN)2] in water (dien is diethyl­enetri­amine, C4H13N3), the novel compound catena‐poly­[bis­[[μ‐cyano‐1:2κ2C:N‐diethyl­enetri­amine‐2κ3N‐copper(II)silver(I)]‐μ‐cyano‐1:2′κ2C:N] di­cyano­silver(I) tri­cyanodisilver(I)], [CuAg(CN)2(dien)]2[Ag(CN)2][Ag2(CN)3], has been isolated. The structure is formed from positively charged [–Cu(dien)–NC–Ag–CN–]nn+ chains and two isolated centrosymmetric [Ag(CN)2]? and [Ag2(CN)3]? anions. In the cationic chains, the Cu atoms are linked by bridging di­cyano­argentate groups, and the deformed square‐pyramidal coordination polyhedron of the CuII cation is formed from a tridentate chelate‐like bonded dien ligand and two N‐bonded bridging cyano groups. One of the bridging cyano groups occupies the apical (ap) position [mean Cu—­Neq = 2.02 (2) Å, and Cu—Nap = 2.170 (3) Å; eq is equatorial]. Short argentophilic interactions in the range 3.16–­3.30 Å are present in the crystal structure.  相似文献   

12.
The reactions of MnII(O2CCH3)2 with NEt3Me+CN and NEt2Me2+CN form (NEt3Me)2MnII5(CN)12 ( 1 ) and (NEt2Me2)2MnII5(CN)12 ( 2 ), respectively. Structure model-building and Rietveld refinement of high-resolution synchrotron powder diffraction data revealed a cubic [a=24.0093 Å ( 1 ), 23.8804 Å ( 2 )] 3D extended structural motif with adjacent tetrahedral and octahedral MnII sites in a 3:2 ratio. Each tetrahedral MnII site is surrounded by four low-spin octahedral MnII sites, and each octahedral MnII site is surrounded by six high-spin tetrahedral MnII sites; adjacent sites are antiferromagnetically coupled in 3D. Compensation does not occur, and magnetic ordering as a ferrimagnet is observed at Tc=13 K for 2 based on the temperature at which remnant magnetization, Mr(T)→0. The hysteresis has an unusual constricted shape with inflection points around 50 and 1.2 kOe with a 5 K coercivity of 16 Oe and remnant magnetization, Mr, of 2050 emuOe mol−1. The unusual structure and stoichiometry are attributed to the very ionic nature of the high-spin N-bonded MnII ion, which enables the maximization of the attractive van der Waals interactions through minimization of void space via a reduced ∠ MnNC. This results in an additional example of the AxMnIIy(CN)x+2y (x=0, y=1; x=1, y=3; x=2, y=1; x=2, y=2; x=2, y=3; x=3, y=5; and x=4, y=1) family of compounds possessing an unprecedented stoichiometry and lattice motif that are cation adaptive structured materials.  相似文献   

13.
A high‐yield, mmolar‐scale synthesis of pure guanidinium nitroprusside, (CN3H6)2[(57)Fe(CN)5NO] (GNP) from iron metal is described. The iron metal contained pieces of 95.3% 57Fe together with normal iron so that an isotope enrichment in 57Fe of 25% was achieved. Single‐crystals of GNP could be grown in cubic shape and dimensions of about 3 × 4 × 4 mm3. The purity of the GNP product and the intermediates K4[(57)Fe(CN)6] · 3 H2O and Na2[(57)Fe(CN)5NO] · 2 H2O was ascertained by 57Fe Mössbauer spectroscopy as well as 13C, 14N and 57Fe NMR spectroscopy. The 57Fe NMR chemical shift for [(57)Fe(CN)5NO]2– in GNP was detected at +2004.0 ppm [vs Fe(CO)5].  相似文献   

14.
Using X-ray analysis, we have determined the crystal structure of di(1-n-dodecylpyridine) decahydrocloso-decaborate(2-), (py-C12H25)2[B10H10] (I), a yellow salt-like substance obtained by reaction of (py-C12H25)Br and K2[B10H10] in an aqueous solution. Compound I melts at 1250 without decomposition and luminesces under ultraviolet radiation (λmax=555 nm at 298 K). In I, quaternary pyridine bases, containing a hydrocarbon radical with the C12 chain, are combined with the closo-cluster hydroborate anion [B10H10]2-. This results in a charge transfer structure having shortened nonvalent (equatorial B) H.…H(C of pyridine) contacts of 2.41(8) Å. Crystals I are orthorhombic with a=8.584 (1), b=7.739(1), c=31.183(5) Å, Vcell=2071.4(5) Å3, space group Pnmm, Z=2, dcalc=0.986 g/cm3 (a Syntex P21 automatic diffractometer, λCUKα, Nmsd/used=1654/711, Raniso=0.076, Rw=0.080, w=1/(σ(Fobs)2+0.0007·F obs 2 ). Substantial changes are observed in the vibration range of the valent B?H bonds in the IR spectrum of I as compared to that of pure ionic K2[B10H10], confirming the interaction.  相似文献   

15.
The new carbodiimide compounds Li2RE2Sr(CN2)5 (RE = Sm, Gd, Eu, Tb) were prepared by a straight forward solid state metathesis reaction of REF3, SrF2, and Li2(CN2) at around 600 °C. The crystal structure of Li2Gd2Sr(CN2)5 was solved based on X‐ray single‐crystal diffraction data. Corresponding Li2RE2Sr(CN2)5 compounds were analyzed by isotypic indexing of their powder patterns. The crystal structure of Li2Gd2Sr(CN2)5 can be well related to that of Gd2(CN2)3, because both structures are based on layered structures composed of close packed layers of [N=C=N]2– sticks, alternating with layers of metal ions. The crystal structure of Li2Gd2Sr(CN2)5 can be considered to contain an ABC layer sequence of [N = C=N]2– layers with the interlayer voids being occupied by (three) distinct types of cations.  相似文献   

16.
蒋治良  彭忠利  刘绍璞 《中国化学》2002,20(12):1566-1572
Proteindeterminationisveryimportanttobiochem istryandbioanalyticalchemistry ,andananalyticalitemofqualitycontrolsintheseparationorpurificationofbio logicalandchemicalpharmaceuticalsandthatoffoodex amination .Comparedwithcommonspectrophotometricmethodsuc…  相似文献   

17.
The spectral features of the squarylium near-infrared (NIR) dye NN525 in different solutions and its complexation with several metal ions were investigated. The absorbance maximum of the dye is λ=663 nm in methanol. This value matches the output of a commercially available laser diode (650 nm), thus making use of such a source practical for excitation. The emission wavelength of the dye in methanol is λem=670 nm. The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye. The Stern–Volmer quenching constant, KSV, was calculated from the Stern–Volmer plot to be KSV=2.70×107 M−1 for Co(II) ion. The KSV value for Fe(III) ion could not be established due to the non-linearity of the Stern–Volmer plot and the modified Stern–Volmer plot for this ion. The detection limit is 6.24×10−8 M for Fe(III) ion and 1.55×10−5 M for Co(III) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant, KS, of the metal–dye complex was calculated to be 3.14×106 M−1 for the Fe–dye complex and 2.64×105 M−1 for the Co–dye complex.  相似文献   

18.
The title compound {Cs2[Zn(S2C=C(CN)2)2]}n(2),Catena-poly {dicesium [bis(l,l-dicyanoethene-2,2-dithiolato-S,S':N)-Zinc(Ⅱ)]},is the second example of bridging [S2C=C(CN)2] (hereafter referred to as i-mnt) for metal-containing polymer.It crystallizes in the non-centrosymmetric space group Ia (alt.Cc,No.9).There are two coordination modes of i-mnt in this compound:μ-η1-η1-i-mnt,bridging two Zn moieties with two S atoms and terminal i-mnt.A characteristic feature of the structure is the infinite-Zn(η2-i-mnt)(η1-η1-i-mnt)-Zn(η1-η1-i-mnt)(η2-i-mnt)-wave-like chain.Cs atoms are located between the chains to form three-dimensional network-like packing.An efficient second harmonic generation from the crystal has been observed on the irradiation with the 1064 nm output of a Nd:YAG laser.  相似文献   

19.
Nine new polynuclear 2-(5-tetrazolyl)ethyl podands have been obtained by the azidation of the corresponding nitriles. Using Bjerrum distribution functions, the values of pK a 1, pK a 2, pK a 3, and pK a 4 have been determined by a potentiometric method for 14 polynuclear tetrazoles in aqueous and aqueous methanolic solution. The found values lie in the range from 3.5 to 7.5 pH units. The overall rules and the sequence of the ionization of the spatially separated tetrazole fragments in these podand systems are discussed.  相似文献   

20.
Discovering new functional genes and developing high-performance materials are the goals being pursued by scientists. In this work, we successfully obtained a second-order nonlinear optical (NLO) material via the aqueous solution method, Y[N(CN)2]4[NH(C2H5)3] ⋅ 3H2O, which is the first NLO material with the anionic group N(CN)2. Remarkably, this material is not only strongly NLO-active at 1064 nm with a response of about 2.8 × KH2PO4, but also possesses a short UV absorption edge of 250 nm. In-depth first-principles calculations illustrate well that the optical properties are mainly from the strong interaction of N, C and Y atoms. This result indicates that the N(CN)2 anion may be a new NLO functional gene. This work enriches the diversity of NLO functional genes and materials.  相似文献   

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