Synthesis and Optical Properties of 2,13‐Dibenzothiazol‐2′‐yldibenzo[b,k]‐18‐crown‐6

A new crown ether of 2,13‐dibenzothiazol‐2′‐yldibenzo[b,k]‐18‐crown‐6 was synthesized from 2,13‐diformyl‐ dibenzo[b,k]‐18‐crown‐6 with 2‐aminothiophenol. The binding behavior and the optical properties of the crown ether were examined through UV‐visible spectroscopy and fluorescence spectroscopy. When complexed with Na⁺, K⁺, Rb⁺ and Cs⁺ ions, it led to intramolecular charge transfer and caused the changes of the fluorescence spectra. The protonation of the crown ether was also studied.     

Study of solvent effects on the stability constant and ionic mobility of the dibenzo‐18‐crown‐6 complex with potassium ion by affinity capillary electrophoresis

The effect of solvent on the strength of noncovalent interactions and ionic mobility of the dibenzo‐18‐crown‐6 complex with K⁺ in water/organic solvents was investigated by using affinity capillary electrophoresis. The proportion of organic solvent (methanol, ethanol, propan‐2‐ol, and acetonitrile) in the mixtures ranged from 0 to 100 vol.%. The stability constant, K_KL, and actual ionic mobility of the dibenzo‐18‐crown‐6‐K⁺ complex were determined by the nonlinear regression analysis of the dependence of the effective electrophoretic mobility of dibenzo‐18‐crown‐6 on the concentration of K⁺ (added as KCl) in the background electrolyte (25 mM lithium acetate, pH 5.5, in the above mixed hydro–organic solvents). Competitive interaction of the dibenzo‐18‐crown‐6 with Li⁺ was observed and quantified in mixtures containing more than 60 vol.% of the organic solvent. However, the stability constant of the dibenzo‐18‐crown‐6‐Li⁺ complex was in all cases lower than 0.5 % of K_KL. The log K_KL increased approximately linearly in the range 1.62–4.98 with the increasing molar fraction of organic solvent in the above mixed solvents and with similar slopes for all four organic solvents used in this study. The ionic mobilities of the dibenzo‐18‐crown‐6‐K⁺ complex were in the range (6.1–43.4) × 10^?9 m² V^?1 s^?1.     

碱金属碘化物与冠醚或穴醚的配合物中I3-和I-的氧化还原行为及其在染料敏化纳米薄膜太阳电池中的应用研究

本文利用超微铂电极和循环伏安法研究了在碱金属碘化物与冠醚或穴醚配合物的3-甲氧基丙腈(MePN)溶液中I₃^-和I^-的氧化还原行为。发现I₃^-和I^-在其中的表观扩散系数与阳离子有关，且I₃^-的表观扩散系数符合以下规律：1,2-二甲基-3-丙基咪唑阳离子(DMPI⁺)> [Na(¯¯15-C-5]⁺ > [K(¯¯18-C-6]⁺ > [Na(¯¯2.2.1-cryptand]⁺，I^-的表观扩散系数则为：[Na(¯¯2.2.1-cryptand]⁺> [Na(¯¯15-C-5]⁺ ≈[K(¯¯18-C-6]⁺> DMPI⁺。比较了由上述配合物和1,2-二甲基-3-丙基咪唑碘(DMPII)组成的染料敏化纳米薄膜太阳电池(DSC)的光伏性能，结果表明由上述配合物组成的DSC，其短路电流略高于DMPII，填充因子略低于DMPII，这与I^-和I₃^-在其中的表观扩散系数的大小是相一致的。此外，电解质溶液中的溶剂对DSC的光电转换效率也有较大影响，以MePN为溶剂，含DMPII的DSC的光电转换效率要高于[K(¯¯18-C-6]I，而以乙腈为溶剂，两者的光电转换效率并没有明显的差别。     

Extraction chromatography of thorium ion by solid phase impregnated resins containing bi-functional organic extractants</p> </p>

Summary Macroporous methyl methacrylate polymeric resin (XAD-7) was investigated incorporating both acidic organophosphorous extractant (cyanex-301) and one neutral extractant from the followings: dibenzo 18 crown 6 (DB18C6), 18 crown 6 (18C6) and 15 crown 5 (15C5). The sorption behavior of the solvent impregnated resin (SIR) towards thorium ion, including batch equilibrium, and kinetic operation are described. Different factors affecting the uptake of metal ions and hence, the separation efficiency of the impregnated resins were investigated. The maximum uptakes of Th⁴⁺ were found to be 62.9, 66.7 and 92.6% for DB18C6, 18C6 and 15C5, respectively. Synergistic extraction of various CE towards thorium ion was tested with cyanex-301 to enhance the sorption capacity as well as the selective separation efficiency. A relatively high capacity of the chelating resin towards tetravalent thorium was found. The capacities of the co-impregnated resins were found to be 2.11, 2.42 and 3.85 mmol/g for DB18C6, 18C6 and 15C5, respectively. The impregnated resin containing cyanex-301 and 15C5 can be utilized for selective separation and pre-concentration of thorium ion from nitrate medium in the presence of several interfering metal ions.</p> </p>     

[Na(DB18-C-6)(H2O)2][Na(DB18-C-6)(SCN)2]：Two-Di-mensional Network Complex Assembled by π-π Stacking Interactios,Hydrogen Bonds and Electrostatic Interactions

A novel two‐dimensional network dibenzo‐18‐crown‐6 (DB18‐C6) complex: [Na (DB18‐C‐6) (H₂O)₂] [Na (DB18‐C‐6) (SCN)₂] has been isolated and characterized by elemental, IR and X‐ray diffraction analysis. The crystal structure belongs to monoclinic, space group P2₁/c with cell dimensions a = 1.06178(7), b = 1.40243(8), c = 3.03496(19) nm, β = 90.4220(10)°, V = 4.5292(5) nm³, Z=4, D_calcd =1.351 g/ cm³, F(000) = 1936, R₁ = 0.0369, wR₂ = 0.0821. The most interesting feature in this structure is that complex cation and complex anion form a two‐dimensional network via τ‐τ stacking interactions, hydrogen bonds and electrostatic interactions.     

Conductance and Thermodynamic Study of the Complexation of Ammonium Ion with Different Crown Ethers in Binary Nonaqueous Solvents

A conductance study of the interaction between ammonium ion and 18‐Crown‐6 (18C6), dicyclohexano‐18‐crown‐6 (DC18C6), ditertbutyl‐dicyclohexano‐18‐crown‐6 (t‐bu)₂DC18C6, diaza‐15‐crown‐5 (DA15C5), dibenzo‐21‐crown‐7 (DB21C7) and N‐Phenylaza‐15‐crown‐5 (NPA15C5) in acetonitril‐di‐methylsulfoxide mixture was carried out at various temperatures. The formation constants of the resultant 1:1 complexes were determined from the molar conductance‐mole ratio data and found to vary in the order of DA15C5 > DC18C6 > 18C6 > (t‐bu)₂DC18C6 > DB21C7 > NPA15C5. The enthalpy and entropy of the complexation reactions were determined from the temperature dependence of the formation constants.     

Ion-pair extraction of uranyl ion from aqueous medium using crown ethers

Ion-pair extraction behaviour of uranyl ion from aqueous solutions was studied at pH 3.0 employing crown ethers viz. benzo 15 crown 5 (B15C5), 18 crown 6 (18C6), dibenzo 18 crown 6 (DB18C6), and dibenzo 24 crown 8 (DB24C8) in chloroform as the organic phase and picric acid as the organophilic counter anion. The stoichiometry of the extracted species corresponded to [UO₂(crown ether)_n]²⁺·[pic⁻]₂ where n=1.5 for benzo 15 crown 5 and 1 for 18 crown 6 as well as dibenzo 18 crown 6. Adducts of DB24C8 could not be observed as practically no extraction was possible using this reagent. The separation behaviour of fission products from an irradiated uranium target was also studied. An interesting observation on the separation of trivalent lanthanides from uranyl ion is reported.     

Membrane Composition Effects on the Analytical Behavior of Solid Contact Potentiometric Pb2+ Selective Electrodes Based on Diazadibenzo‐18‐crown‐6 Ionophores

The effect of component contents and membrane thickness on the detection limit (DL), slope (m), linear range (LR) and response time (RT) of Pb²⁺ solid contact potentiometric ion selective electrodes (SCISE) based on 4,10‐diaza‐2,3,11,12‐dibenzo‐18‐crown‐6 (1), 4,10‐diaza‐2,3,11,12‐di(4‐tert‐butylbenzo)‐18‐crown‐6 (2) and 4,10‐diaza‐2,3,11,12‐dibenzo‐18‐crown‐6‐N,N′‐di(carboxymethyl) (3) as ionophores was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The use of an intermediate layer of poly(3‐octyl)thiophene between the gold substrate and the selective membrane was explored. SCISE prepared showing the best responses had typical DL, m, LR and RT values of 10^?6 M, 29 mV/dec, 10^?5 to 10^?3 M and 2 minutes.     

Synthesis and Cation Recognition Study of Novel Benzo Crown Ether Functionalized Enamine Derivatives

A novel series of benzo crown ether (dibenzo 18-crown-6 ether, benzo 18-crown-6 ether, and benzo 15-crown-5 ether) functionalized enamines derivatives from amino benzo crown ether (4-amino dibenzo 18-crown-6 ether, 4-amino benzo 18-crown-6 ether, 4-amino benzo 15-crown-5 ether) and substituted 3-(dimethylamino)-1-phenylprop-2-en-1-one compounds have been synthesized. All the synthesized compounds were characterized by infrared, ¹H NMR, ¹³C NMR, distortionless enhancement polarization transfer, and mass and elemental analysis techniques. The cation recognition property for benzo crown ether enamine 8a was studied by absorption and fluorescence spectroscopy.     

Novel Sensors for Batch and Flow Injection Analysis of Histamine Based on Crown Ethers

Six types of histamine potentiometric sensors are developed. They are based on using dibenzo‐30‐crown‐10 (DB30C10) with potassium tetrakis(p‐chlorophenyl)borate lipophilic additive (Type I), dibenzo‐30‐crown‐10 without additive (Type II), dibenzo‐24‐crown‐8 (DB24C8) with the same additive (Type III), dibenzo‐24‐crown‐8 without additive (Type IV), dibenzo‐18‐crown‐6 with the additive (Type V) and dibenzo‐18‐crown‐6 without additive (Type VI) as neutral carriers for histamine. Sensors based on dibenzo‐30‐crown‐10 with (PTp‐C1PB) lipophilic additive (Type I) and dibenzo‐30‐crown‐10 without additive (Type II) show good response. The other sensors Types III–VI show poor response in terms of calibration range and slope.     

Stepwise Reduction of Azapentabenzocorannulene

Mono‐ and dianions of 2‐tert‐butyl‐3a²‐azapentabenzo[bc,ef,hi,kl,no]corannulene ( 1 a ) were synthesized by chemical reduction with sodium and cesium metals, and crystallized as the corresponding salts in the presence of 18‐crown‐6 ether. X‐ray diffraction analysis of the sodium salt, [{Na⁺(18‐crown‐6)(THF)₂}₃{Na⁺(18‐crown‐6)(THF)}( 1 a ^2?)₂], revealed the presence of a naked dianion. In contrast, controlled reaction of 1 a with Cs allowed the isolation of singly and doubly reduced forms of 1 a , both forming π‐complexes with cesium ions in the solid state. In [{Cs⁺(18‐crown‐6)}( 1 a ^?)]?THF, asymmetric binding of the Cs⁺ ion to the concave surface of 1 a ^? is observed, whereas in [{Cs⁺(18‐crown‐6)}₂( 1 a ^2?)], two Cs⁺ ions bind to both the concave and convex surfaces of the dianion. The present study provides the first successful isolation and characterization of the reduced products of heteroatom‐containing buckybowl molecules.     

4‐Methoxyanilinium tetrafluoroborate–dibenzo‐18‐crown‐6 (1/1)

In the structure of the complex of dibenzo‐18‐crown‐6 [systematic name: 2,5,8,15,18,21‐hexaoxatricyclo[20.4.0.0^9,14]hexacosa‐1(26),9,11,13,22,24‐hexaene] with 4‐methoxyanilinium tetrafluoroborate, C₇H₁₀NO⁺·BF₄⁻·C₂₀H₂₄O₆, the protonated 4‐methoxyanilinium (MB‐NH₃⁺) cation forms a 1:1 supramolecular rotator–stator complex with the dibenzo‐18‐crown‐6 molecule via N—H...O hydrogen bonds. The MB‐NH₃⁺ group is attached from the convex side of the bowl‐shaped crown, in contrast with similar ammonium cations that nest in the curvature of the bowl. The cations are associated via C—H...π interactions, while the cations and anions are linked by weak C—H...F hydrogen bonds, forming cation–crown–anion chains parallel to [011].     

Extraction of uranium from hydrochloric acid solutions by alkylated crown ethers

The extraction recovery of uranium from 1–10 mol/L hydrochloric acid solutions into solutions of alkylated crown ethers di-tert-butyldibenzo-18-crown-6 (DTBDB18C6) and di-tert-butyldicyclohexyl-18-crown-6 (DTBDCH18C6) in organic solvents (nitrobenzene, 1,2-dichloroethane, chloroform, 1-octanol) was studied. It was found that with increasing HCl concentration, the value of the distribution coefficients of uranium (D) between the organic and aqueous phases increased to a maximum value at 9 mol/L HCl for DTBDB18C6 and 6–7 mol/L HCl for DTBDCH18C6. The properties of the solvent also greatly affect the values of D, reaching a maximum in the application of nitrobenzene, dichloroethane, or their mixture. Under these conditions, D for a 0.01 mol/L solution of DTBDCH18C6 in nitrobenzene is 830, which is the highest of known values. It was determined by the slope method and the complete saturation method that the extracted complexes of the studied alkylated crown ethers with uranyl ions have the 2 : 1 composition. Thus, new supramolecular extractants of uranium from hydrochloric acid solutions have been studied, having an extremely high extraction capacity, which can be used in the analytical and preparative chemistry of uranium.     

Stability of crown-ether complexes with alkali-metal ions in ionic liquid-water mixed solvents

Stability constants of sodium and cesium ion complexes with 18-crown-6 (18C6) and dibenzo-18-crown-6 (DB18C6) in N-butyl-4-methyl-pyridinium tetrafluoroborate [BMP][BF₄] aqueous solutions were measured using the ²³Na and ¹³³Cs NMR technique at 23 °C. To the best of our knowledge, the estimated values of stability constants reported in this study are the first such values given for ionic liquid solutions. The cationic exchange between the free and complexed species is rapid, and only formation of the 1:1 complexes [M(18C6)]⁺ and [M(DB18C6)]⁺ (M = Na⁺, Cs⁺) were observed. The complex formation constants demonstrated a strong dependence on the [BMP][BF₄] concentration. For [M(18C6)]⁺, in solutions with a 0.33–0.70 mole fraction of water in [BMP][BF₄], lg K values are found to be more than one unit higher than the lg K values measured in pure aqueous solutions, although no information concerning the influence of [BMP][BF₄] on the complex formation selectivity could be observed. DB18C6 complexes revealed significantly lower stability under the same conditions. An extrapolation to zero water content gave the lg K = 2.42 for [Cs(18C6)]⁺ in [BMP][BF₄]. It was discovered that when added to water, [BMP][BF₄] increases the solubility of crown ethers and decreases the solubility of alkali metal nitrates. Complex formation with crown ethers enhances the solubility of alkali metal salts in [BMP][BF₄].     

Molecular complexes of crown ethers. Part 3. Effect of cations on charge transfer complexes with TCNE

The intermolecular charge transfer complexes (CT) of two crown ethers (CE), viz, B15C5 and DB18C6 (as donors), and tetracyanoethylene (TCNE), as acceptor, were studied in the UV-visible region in dichloroethane (DCE), at 298.2 K. The sequence of addition of the cation was varied in the case of B15C5 such that in one system the sequence was (CE+Cation)+TCNE and in the other (CE+TCNE)+cation. These two systems were found to be non-interchangeable, even under reflux conditions, giving differentK _c values which were explained as being due to the different geometries of the CE. For the first sequence, the values most affected depended on the fit of the metal cation with the ether cavity, thus in B15C5, Na⁺ showed the greatest effect, while for DB18C6 it was K⁺.     

Fluorescence of auramine O and its binding to poly(vinylbenzo-18-crown-6) and to polyvinylbenzoglyme in water

Binding of the cationic dye auramine O (AuO) to the polysoap-type polymers poly(vinylbenzo-18-crown-6) (P18C6) and polyvinylbenzoglyme (PVBG) in water were studied by fluorimetry and dialysis. The quantum yield of P18C6-bound AuO was found to be 0.028, the value being 0.018 for AuO bound to PVBG. The intrinsic binding constants were found to be 2.2 × 10⁴M^?1 (P18C6) and 1.2 × 10⁴M^?1 (PVBG), the respective first binding constants being 317 and 63M^?1. Addition of crown-ether-complexable cations such as K⁺, Tl⁺, or Cs⁺ converts the neutral poly(crown ether) into a polycation, causing repulsion of the cationic dye and a strong decrease in the AuO fluorescence. AuO fluorescence was also studied in the absence of polymer in ether solvents, giving θ values of 0.011 and 0.018 in THF and dioxane. Traces of water rapidly form a nonfluorescent species. Solutions of AuO in water without polymer present exhibit very strong fluorescence on addition of BPh₄ anions owing to formation of AuO⁺, BPh₄^? ion pairs and higher aggregates.     

Neutron activation analysis in forensic investigations: Trace elements characterization of cigarettes

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO₂-P, was prepared by impregnating a crown ether derivative, 4,4￠,(5￠)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO₂-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO₃ This revised version was published online in July 2006 with corrections to the Cover Date.     

ACE applied to the quantitative characterization of benzo‐18‐crown‐6‐ether binding with alkali metal ions in a methanol–water solvent system

ACE was applied to the quantitative evaluation of noncovalent binding interactions between benzo‐18‐crown‐6‐ether (B18C6) and several alkali metal ions, Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺, in a mixed binary solvent system, methanol–water (50/50 v/v). The apparent binding (stability) constants (K_b) of B18C6–alkali metal ion complexes in the hydro‐organic medium above were determined from the dependence of the effective electrophoretic mobility of B18C6 on the concentration of alkali metal ions in the BGE using a nonlinear regression analysis. Before regression analysis, the mobilities measured by ACE at ambient temperature and variable ionic strength of the BGE were corrected by a new procedure to the reference temperature, 25°C, and the constant ionic strength, 10 mM . In the 50% v/v methanol–water solvent system, like in pure methanol, B18C6 formed the strongest complex with potassium ion (log K_b=2.89±0.17), the weakest complex with cesium ion (log K_b=2.04±0.20), and no complexation was observed between B18C6 and the lithium ion. In the mixed methanol–water solvent system, the binding constants of the complexes above were found to be about two orders lower than in methanol and about one order higher than in water.     

Kinetics of the adsorption of strontium(II) by a novel silica-based 4,4'',(5'')-di(tert-butylcyclohexano)-18-crown-6 extraction resin in nitric acid medium

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO₂-P, was prepared by impregnating a crown ether derivative, 4,4,(5)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO₂-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO₃ medium. It was found that Sr(II) exhibits a strong adsorption onto the extraction resin, while the other fission product elements show almost no or only weak adsorption. The adsorption kinetics of Sr(II) was explained by assuming as the rate-controlling step the complex-formation reaction between Sr(II) and DtBuCH18C6 contained in the extraction resin. The rate equation of Sr(II) adsorption was determined as:-d[Sr(II)]/dt = k[Sr(II)][DtBuCH18C6][NO₃ ^–]^0.5.     

Conformational Studies of Dibenzo-30-crown-10 Complexes. Syntheses and Crystal Structures of Potassium and Ammonium Hexafluorophosphate Complexes

Abstract

Crown ether complexes formed by the dibenzo–30-crown–10 (DB30C10) with potassium and ammonium hexafluorophosphate have been prepared and their crystal structures have been determined by single crystal X-ray analyses. The potassium complex (compound 1) consists of [K(DB30C10)]⁺ cation and PF₆ ^? anion. Crystals are monoclinic, space group P2/n, with a = 11.9106(3), b = 9.8382(5), c = 14.3062(3) Å, β = 97.581(3)°, V = 1661.7(1) ų, D_c = 1.440 g cm^?3, Z = 4, R = 0.0675 for 2528 unique observed reflections. The potassium atom is coordinated to the ten oxygen atoms of the crown ligand at the distance from 2.859(3) to 2.930(3) Å. The ammonium complex (compound 2) has also 1:1 crown—cation ratio. Crystals are monoclinic, space group P2₁/n, with a = 12.5061(6), b = 19.3724(5), c = 14.2203(9) Å, β = 102.476(5)°, V = 3363.8(3) ų, D_c = 1.501 g cm^?3, Z = 4, R = 0.0677 for 4172 unique observed reflections. The ammonium cation is completely enclosed with crown oxygen atoms forming seven hydrogen bonds. The conformation of previously reported dibenzo-30-crown-10 complexes with potassium salts were investigated using polar coordinate maps.