Aggregation behavior of a series of anionic sulfonate gemini surfactants and their corresponding monomeric surfactant

A series of anionic sulfonate gemini surfactants with the general structure of [(Cn H2n+1)(C3H6SO(-)3) NCsN(C3H6SO(-)3)(CnH2n+1)].2Na+ have been synthesized. While the spacer group Cs represents p-xylyl or (CH2)3, the surfactants are abbreviated as CnCpxCn(SO3)2 (n=8,10,12) or C12C3C12(SO3)2(n=12), respectively. A corresponding monomeric surfactant C12H25N(CH3)(C3H6SO(-)3).Na+(C12NSO3) has also been prepared. The aggregation behavior of these surfactants has been studied at pH 9.2 and ionic strength of 30 mM. The gemini surfactants exhibit stronger aggregation tendencies and much less endothermic enthalpy changes of micellization (DeltaH mic) compared with the monomeric surfactant. The critical micelle concentrations (CMC) of the gemini surfactants decrease with the increase of the hydrophobic chain length from C8CpxC8(SO3)2 to C10CpxC10(SO3)2, but the CMC values of C10CpxC10(SO3)2 and C12CpxC12(SO3)2 are very close. The DeltaH mic values vary from endothermic for C8CpxC8(SO3)2 to almost zero for C12CpxC12(SO3)2. Besides, vesicles are observed above the CMC for all these surfactants. The water-mediated intermolecular hydrogen bonding between the tertiary nitrogen groups may assist C12NSO3 and C12C3C12(SO3)2 in their vesicle formation, while the pi-pi interaction between aromatic rings should be another additional driving force for the vesicle formation of CnCpxCn(SO3)2. Meanwhile, the hydrogen bonding, pi-pi interaction, and strong hydrophobic interaction provide the possibility of a multilayer formation for C12CpxC12(SO3)2 and C12C3C12(SO3)2 at the air/water interface, which is a possible reason for the extremely small minimum area occupied per surfactant molecule at the air/water interface for these two gemini surfactants.     

Stern-Gerlach experiments of one-dimensional metal-benzene sandwich clusters: Mn(C6H6)m (M = Al, Sc, Ti, and V)

A molecular beam of multilayer metal-benzene organometallic clusters Mn(C6H6)m (M = Al, Sc, Ti, and V) was produced by a laser vaporization synthesis method, and their magnetic deflections were measured. Multidecker sandwich clusters of transition-metal atoms and benzene Scn(C6H6)n+1 (n = 1, 2) and Vn(C6H6)n+1 (n = 1-4) possess magnetic moments that increase monotonously with n. The magnetic moments of Al(C6H6), Scn(C6H6)n+1, and Vn(C6H6)n+1 are smaller than that of their spin-only values as a result of intracluster spin relaxation, an effect that depends on the orbital angular momenta and bonding characters of the orbitals containing electron spin. While Ti(C6H6)2 was found to be nonmagnetic, Tin(C6H6)n+1 (n = 2, 3) possess nonzero magnetic moments. The mechanism of ferromagnetic spin ordering in M2(C6H6)3 (M = Sc, Ti, V) is discussed qualitatively in terms of molecular orbital analysis. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition-metal atoms are formally zerovalent.     

Reaction of Cationic Vanadium Oxide Clusters with Ethylene in a Flow Tube Reactor

A time of °ight mass spectrometer coupled with a cluster formation and reaction source is employed to study the reactivity of cationic vanadium oxide clusters (VmOn+) toward ethylene (C2H4) in the gas phase. The cationic vanadium oxide clusters with m=1-10 and n=1-26 (depending on m) are generated by reaction of laser ablation created vanadium plasma with O2 in a supersonic expansion and then reacted with the ethylene in a °ow tube reactor. Hydrogen atoms are attached in most of the oxygen saturated clusters(2n?5m) in our experimental condition. The reactivity of VmOn+ toward C2H4 is usually higher than that of hydrogen containing clusters, VmOnH2x+. Larger clusters show less reactivity than smaller ones. Most of the observed products are in the forms of VmOnC2H4+ and VmOnH2xC2H4+ due to direct association. C2H4 clustering products ((C2H4)n+, n=2-6) are also observed.     

Hydrophilicity of Polar and Apolar Domains of Amphiphiles

The hydrophilicity of polar and apolar domains of various amphiphiles was systematically estimated for their homologues and analogues by measuring the molar adiabatic compressibility of an aqueous solution at infinite dilution. The homologues of protic alkyl H(CH(2))(n)-, perfluoroalkyl F(CF(2))(n)-, and alkylphenyl H(CH(2))(n)(C(6)H(5))- groups (n=0-10) were chosen to represent apolar hydrophobic domains. The polar hydrophilic domains tested were -SO(4)Na, -SO(3)Na, -COONH(4), -N(CH(3))(3)Br, N(C(m)H(2m+1))(4)Br (m=1-5), and -NH(CH(2))(n)SO(3) (n=3, 4) groups. Also tested were the tetraphenyl ionic compounds (C(6)H(5))(4)MX (M=B/X=Na, M=P/X=Cl, M=As/X=Cl) to study the effect of the ionic sign of the core atom across the tetraphenyl apolar shell, the polyethylene glycols H(OCH(2)CH(2))(m)OH (m=1-4) to study the role of apolar -CH(2)- units in the hydrophilic oxyethylene group, and the zwitterionic dimethylaminoalkylsulfonate (CH(3))(2)NH(CH(2))(n)SO(3) homologues to study the effect of intramolecular salt formation on the hydrophilicity of the zwitterion. The adiabatic compressibility of the solution was calculated from measurement of the sound velocity and density of solutions. The introduction of laboratory automation and the numerical control of the system improved the accuracies and efficiencies of the measurements a great deal. The range of the temperature scan was 0-40 degrees C with an effective accuracy of +/-0.001 degrees C and the concentration was automatically scanned down to far below the cmc of the surfactant. The hydrophilicity of various polar and apolar substances was estimated as the decrease of molar adiabatic compressibility of the aqueous solution with increased concentration of their homologues and analogues. The hydrophobic hydration of nonpolar substances was found to be very small at room temperature and was barely detected above 40 degrees C; however, it became large as the temperature was lowered and attained a maximum at 0 degrees C. The cationic charge of quaternary ammonium N(+)(C(n)H(2n+1))(4) was found to enhance the hydrophobic hydration of methylene groups located at a distance of 4 to 6 ? from the core nitrogen atom, while the terminal negative charge of the anionic surfactant R-SO(4)(-), R-SO(3)(-), or R-COO(-) was found to decrease the hydrophobic hydration of -CH(2)- units within the same range. The hydrophilicity of quaternary ammonium and the tetraphenyl ions should be synergistically given by both hydrophobic and ionic hydrations. The hydrophilicity of the perfluoromethylene unit -CF(2)- was found to have a value comparable to that of the protic methylene unit -CH(2)-. The hydrophobic hydration seems to offer a good measure of the hydrophilicity of apolar substances; however, it does not necessarily represent the "hydrophobicity" of the apolar segment when the "surface activity" of the amphiphile is concerned. Copyright 2000 Academic Press.     

Experimental and theoretical studies of the interaction of silver cluster cations Ag(n)+ (n = 1-4) with ethylene

Reactions of silver cluster cations Ag(n)+ with ethylene have been studied using a reflectron time-of-flight mass spectrometer. Chemisorbed Ag(n)(C2H4)(m)+ (n = 1-3, m = 1-6) complexes were observed. For a given value of n, the abundances of Ag(n)(C2H4)(m)+ (n = 1-3, m = 1-6) species first increase and then decrease, with the maximum of the intensity distribution usually at m = 4. This maximum does not change with the ethylene concentration in the mixed gas, the stagnation pressure of the mixed gas, or the size of Ag(n) + (n = 1-3). A complementary extensive theoretical study on the structure and binding of Ag(n)(C2H4)(m)+ (n = 1-4, m = 1-4) is also reported. Preferred binding sites, binding energies, geometries, vibrational frequencies, and ionization potentials are determined using density functional theory.     

Preparation of novel cobalt(III) complexes with dithiocarbimates derived from sulfonamides

Reaction of potassium N-R-Sulfonyldithiocarbimates, K2(RSO2N=CS2) (R=Me, Ph, 4-MeC6H4, 2-MeC6H4, 4-ClC6H4, 4-BrC6H4), with CoCl2·6H2O, yielded the complex CoIII anions [Co(RSO2N=CS2)3]3-, which were isolated as their Bu4N+ salts. Elemental analyses, i.r. spectra and u.v.-vis. data were consistent with the formation of cobalt-sulfur diamagnetic octahedral (D3) complexes. The 1H and 13C n.m.r. spectra showed the expected signals for the Bu4N+ cation and the dithiocarbimate moieties. The 1H n.m.r. integrations were consistent with a 3:1 cation:anion ratio.     

On the gas-phase reactivity of complexed OH+ with halogenated alkanes

OH(+) is an extraordinarily strong oxidant. Complexed forms (L--OH(+)), such as H(2)OOH(+), H(3)NOH(+), or iron-porphyrin-OH(+) are the anticipated oxidants in many chemical reactions. While these molecules are typically not stable in solution, their isolation can be achieved in the gas phase. We report a systematic survey of the influence on L on the reactivity of L--OH(+) towards alkanes and halogenated alkanes, showing the tremendous influence of L on the reactivity of L--OH(+). With the help of with quantum chemical calculations, detailed mechanistic insights on these very general reactions are gained. The gas-phase pseudo-first-order reaction rates of H(2)OOH(+), H(3)NOH(+), and protonated 4-picoline-N-oxide towards isobutane and different halogenated alkanes C(n)H(2n+1)Cl (n=1-4), HCF(3), CF(4), and CF(2)Cl(2) have been determined by means of Fourier transform ion cyclotron resonance measurements. Reaction rates for H(2)OOH(+) are generally fast (7.2x10(-10)-3.0x10(-9) cm(3) mol(-1) s(-1)) and only in the cases HCF(3) and CF(4) no reactivity is observed. In contrast to this H(3)NOH(+) only reacts with tC(4)H(9)Cl (k(obs)=9.2x10(-10)), while 4-CH(3)-C(5)H(4)N-OH(+) is completely unreactive. While H(2)OOH(+) oxidizes alkanes by an initial hydride abstraction upon formation of a carbocation, it reacts with halogenated alkanes at the chlorine atom. Two mechanistic scenarios, namely oxidation at the halogen atom or proton transfer are found. Accurate proton affinities for HOOH, NH(2)OH, a series of alkanes C(n)H(2n+2) (n=1-4), and halogenated alkanes C(n)H(2n+1)Cl (n=1-4), HCF(3), CF(4), and CF(2)Cl(2), were calculated by using the G3 method and are in excellent agreement with experimental values, where available. The G3 enthalpies of reaction are also consistent with the observed products. The tendency for oxidation of alkanes by hydride abstraction is expressed in terms of G3 hydride affinities of the corresponding cationic products C(n)H(2n+1) (+) (n=1-4) and C(n)H(2n)Cl(+) (n=1-4). The hypersurface for the reaction of H(2)OOH(+) with CH(3)Cl and C(2)H(5)Cl was calculated at the B3 LYP, MP2, and G3(m*) level, underlining the three mechanistic scenarios in which the reaction is either induced by oxidation at the hydrogen or the halogen atom, or by proton transfer.     

用密度泛函方法研究质子化苯基丙酮-水团簇

The structure and growth trend of the protonated acetophenone-water clusters have been investigated using the DFT-B3LYP method combined with the standard 6-31+G(d,p) basis set. In order to obtain more accurate single-point energy the B3LYP/6-311++G(3df,2p) method was adapted. The results show that the formation of H+C8H8O-H2O is a barrierless reaction process and the equilibrium distance between the proton and the O atom in C8H8O molecule is 1.015 A. For H+C8H8O-(H2O)n(n=1,2,3) clusters, the proton lies between the acetophenone molecule C8H8O and the water molecule H2O. The distance between the proton and the O atom of the C8H8O molecule increased from n=1 to n=3; C8H8O-H+-H2O can be regarded as an solvation shell. For H+C8H8O (H2O)n (n=4,5,6,7,8) clusters, the proton lies between the two H2O molecules forming a H5O2+ structure, C8H8O-H5O2+ is an important structure, which the other H2O molecules will attack from different sides.     

Bond-formation versus electron transfer: C-C-coupling reactions of hydrocarbon dications with benzene

The bimolecular reactions of several hydrocarbon dications C(m)H(n)(2+) (m = 6-10, n = 4-9) with neutral benzene are investigated by tandem mass spectrometry using a multipole instrument. Not surprisingly, the major reaction of C(m)H(n)(2+) with benzene corresponds to electron transfer from the neutral arene to the dication resulting in the pair of monocationic products C(m)H(n)(+) + C(6)H(6)(+). In addition, also dissociative electron transfer takes place, whereas proton transfer from the C(m)H(n)(2+) dication to neutral benzene is almost negligible. Interestingly, the excess energy liberated upon electron transfer from the neutral arene to the C(m)H(n)(2+) dication is not equally partitioned in the monocationic products in that the cations arising from the dicationic precursor have a higher internal energy content than the monocations formed from the neutral reaction partner. In addition to the reactions leading to monocationic product ions, bond-forming reactions with maintenance of the two-fold charge are observed, which lead to a condensation of the C(m)H(n)(2+) dications with neutral benzene under formation of intermediate C(m+6)H(n+6)(2+) species and then undergo subsequent losses of molecular hydrogen or neutral acetylene. This reaction complements a recently proposed dicationic route for the formation of polycyclic aromatic hydrocarbons under extreme conditions such as they exist in interstellar environments.     

Intracluster ion-molecule reactions of Ti+ with C2H5OH and CF3CH2OH clusters: influence of fluorine substituents on chemical reactivity

A laser ablation-molecular beam/reflectron time-of-flight mass spectrometric technique was used to investigate the ion-molecule reactions that proceed within Ti+(ROH)n (R = C2H5, CF3CH2) heterocluster ions. The mass spectra exhibit a major sequence of cluster ions with the formula Ti+(OR)m(ROH)n (m = 1, 2), which is attributed to sequential insertions of Ti+ into the O-H bond of C2H5OH or CF3CH2OH molecules within the heteroclusters, followed by H eliminations. The TiO+ and TiOH+ ions produced from the reactions of Ti+ with C2H5OH are interpreted as arising from insertion of Ti+ into the C-O bond, followed by C2H5 and C2H6 eliminations, respectively. When Ti+ reacted with CF3CH2OH, by contrast, considerable contributions from TiFOH+, TiF2+, and TiF2OH+ ions were observed in the mass spectrum of the reaction products, indicating that F and OH abstractions are the dominant product channels. Ab initio calculations of the complex of Ti+ with 2,2,2-trifluoroethanol show that the minimum energy structure is that in which Ti+ is attached to the O atom and one of the three F atoms of 2,2,2-trifluoroethanol, forming a five-membered ring. Isotope-labeling experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by the presence of fluorine substituents and cluster size. The reaction energetics and formation mechanisms of the observed heterocluster ions are discussed.     

Rhenium ethoxy- and hydroxycarbene complexes with thiophene substituents

Reaction of mono- and dilithiated thiophene (a), bithiophene (b) and 2,5-dibromothiophene (c) with [Re(2)(CO)(10)] afforded, after subsequent alkylation with triethyloxonium tetrafluoroborate, tetra- and binuclear Fischer carbene complexes, [Re(2)(CO)(9){C(OEt){C(4)H(2)S}(n)X}], n = 1, X = H (1a); n = 2, X = H (1b); n = 1, X = Br (1c); n = 1, X = C(OEt)Re(2)(CO)(9), (2a); n = 2, X = C(OEt)Re(2)(CO)(9) (2b), as major products. The dirhenium acylate intermediates from this reaction not only gave the expected novel ethoxycarbene complexes with alkylation but after rhenium-rhenium bond breaking afforded a number of minor products. The (1)H NMR spectrum of the crude reaction mixture revealed the formation of four metal hydride complexes and aldehydes. Protonation with HBF(4) instead of alkylation with Et(3)OBF(4) significantly increased the yields of the hydride complexes, which enabled the positive identification of three of these complexes. In addition to the known compounds [Re(CO)(5)H] and [Re(3)(CO)(14)H] (3), a unique complex displaying a hydroxycarbene fragment connected to an acyl fragment via an O-H···O hydrogen bond and a Re···H···Re bond linking the two Re centers, [(μ-H){Re(CO)(4)C(OH){C(4)H(2)S}(n)H}{Re(CO)(4)C(O){C(4)H(2)S}(n)H}], n = 1 (4a) or n = 2 (4b), were isolated. The formation of thiophene aldehydes, H{C(O)}(m){C(4)H(2)S}(n)C(O)H (m = 0 or 1 and n = 1 or 2), were observed and the novel monocarbene complexes with terminal aldehyde groups, [Re(2)(CO)(9){C(OEt){C(4)H(2)S}(n)C(O)H}], n = 1 (5a) and n = 2 (5b) could be isolated. A higher yield of 5b was obtained after stirring crystals of 2b in wet THF. The crystal structures of 1a, 2a, 4a and 5b are reported.     

Cosolvent effects on the spontaneous formation of vesicles from 1:1 anionic and cationic surfactant mixtures

This paper aims to provide a practical catanionic vesicle-boosting method by means of cosolvent addition in water and to propose a theoretical explanation which can delineate the general trend of cosolvent effects and elucidate the possible role of cosolvent in the formation of catanionic vesicles. Effects of four homologous cosolvents (methanol, ethanol, 1-propanol, and 1-butanol) on the spontaneous formation of vesicles from eight 1:1 anionic-cationic mixed surfactant systems, sodium alkyl sulfates-alkyltrimethylammonium bromides (C(n)SO4Na-C(m)N(CH3)3Br; n = 12, 14; m = 8, 10, 12, 14), at a total surfactant concentration of 10 mM were systematically studied. The experimental results revealed that varied changes in vesicle formability of different mixed surfactant systems may result from various kinds and amounts of cosolvent. Four types of cosolvent effects, however, can be classified. Among them, cosolvent effects type 2 and type 3 would serve the purpose and were exemplified by C12SO4Na-C10N(CH3)3Br, C14SO4Na-C10N(CH3)3Br, and C12SO4Na-C12N(CH3)3Br mixed surfactants. Furthermore, the effectiveness of vesicle boosting increases in the order 1-butanol > 1-propanol > ethanol > methanol. An explanation of cosolvent effects based on the medium dielectric constant was then proposed.     

碳氟-碳氢表面活性剂混合水溶液在油面上铺展

本文研究RfCONH(CH2)3N(C2H5)2CH3I/CnH2n 1,COONa及RfCOONa/CmH2m 1N(CH3)3Br(Rf=F[CF(CF3)CF2O]2CF(CF3);n=7,8.11,13;m=8,10,12)两类正，负离子碳氟－碳氢表面活性剂混合水溶液在油面上的铺展及对油面的密封性能。研究表明在碳氟表面活性剂中加入异电性碳氢表面活性剂可大大降低碳氟表面活性剂水溶液的铺展浓度，也可使一些因素表面张力较高而不能铺展的碳氟表面活性剂水溶液在油面上铺展。在碳氟表面活性剂中加入异电性碳氢表面活性剂可提高水膜对油面的密封性。若在混合表面活性剂中加入黄原胶，水膜的密封性能更好。     

Analysis of triacetone triperoxide (TATP) and TATP synthetic intermediates by electrospray ionization mass spectrometry

The explosive triacetone triperoxide (TATP) has been analyzed by electrospray ionization mass spectrometry (ESI-MS) on a linear quadrupole instrument, giving a 62.5 ng limit of detection in full scan positive ion mode. In the ESI interface with no applied fragmentor voltage the m/z 245 [TATP + Na](+) ion was observed along with m/z 215 [TATP + Na - C(2)H(6)](+) and 81 [(CH(3))(2)CO + Na](+). When TATP was ionized by ESI with an applied fragmentor voltage of 75 V, ions at m/z 141 [C(4)H(6)O(4) + Na](+) and 172 [C(5)H(9)O(5) + Na](+) were also observed. When the precipitates formed in the synthesis of TATP were analyzed before the reaction was complete, a new series of ions was observed in which the ions were separated by 74 m/z units, with ions occurring at m/z 205, 279, 353, 427, 501, 575, 649 and 723. The series of evenly spaced ions is accounted for as oligomeric acetone carbonyl oxides terminated as hydroperoxides, [HOOC(CH(3))(2){OOC(CH(3))(2)}(n)OOH + Na](+) (n = 1, 2 ... 8). The ESI-MS spectra for this homologous series of oligoperoxides have previously been observed from the ozonolysis of tetramethylethylene at low temperatures. Precipitates from the incomplete reaction mixture, under an applied fragmentor voltage of 100 V in ESI, produced an additional ion observed at m/z 99 [C(2)H(4)O(3) + Na](+), and a set of ions separated by 74 m/z units occurring at m/z 173, 247, 321, 395, 469 and 543, proposed to correspond to [CH(3)CO{OOC(CH(3))(2)}(n)OOH + Na](+) (n = 1,2 ... 5). Support for the assigned structures was obtained through the analysis of both protiated and perdeuterated TATP samples.     

Experimental and theoretical study of the reactions between neutral vanadium oxide clusters and ethane, ethylene, and acetylene

Reactions of neutral vanadium oxide clusters with small hydrocarbons, namely C2H6, C2H4, and C2H2, are investigated by experiment and density functional theory (DFT) calculations. Single photon ionization through extreme ultraviolet (EUV, 46.9 nm, 26.5 eV) and vacuum ultraviolet (VUV, 118 nm, 10.5 eV) lasers is used to detect neutral cluster distributions and reaction products. The most stable vanadium oxide clusters VO2, V2O5, V3O7, V4O10, etc. tend to associate with C2H4 generating products V(m)O(n)C2H4. Oxygen-rich clusters VO3(V2O5)(n=0,1,2...), (e.g., VO3, V3O8, and V5O13) react with C2H4 molecules to cause a cleavage of the C=C bond of C2H4 to produce (V2O5)(n)VO2CH2 clusters. For the reactions of vanadium oxide clusters (V(m)O(n)) with C2H2 molecules, V(m)O(n)C2H2 are assigned as the major products of the association reactions. Additionally, a dehydration reaction for VO3 + C2H2 to produce VO2C2 is also identified. C2H6 molecules are quite stable toward reaction with neutral vanadium oxide clusters. Density functional theory calculations are employed to investigate association reactions for V2O5 + C2H(x). The observed relative reactivity of C2 hydrocarbons toward neutral vanadium oxide clusters is well interpreted by using the DFT calculated binding energies. DFT calculations of the pathways for VO3+C2H4 and VO3+C2H2 reaction systems indicate that the reactions VO3+C2H4 --> VO2CH2 + H2CO and VO3+C2H2 --> VO2C2 + H2O are thermodynamically favorable and overall barrierless at room temperature, in good agreement with the experimental observations.     

Complex Salts Derived from the Reactions of Organotin(IV) with 6-Methylpyridine-2-Carboxaldehyde Phenylhydrazone: X-Ray Crystal Structure of BIS[6-Methylpyridine- 2-Carboxaldehydehydrazodium]- Tetrachlorodimethylstannate(IV)

Reactions of organotin(IV) chloride (Me 2 SnCl 2 , PhSnCl 3 and n -BuSnCl 3 ) with the Schiff base 6-methylpyridine-2-carboxaldehyde phenylhydrazone ( L ) result in the formation of organotin(IV) anionic complexes. Me 2 SnCl 2 reacts with L in dichloromethane to form [ L H + ] 2 [Me 2 SnCl 4 ] 2 m . X-ray structural analysis has been carried out on the complex salt bis[6-methylpyridine-2-carboxaldehydehydrazodium]tetra-chlorodimethylstannate(IV), [ L H + ] 2 [Me 2 SnCl 4 ] 2 m wherein the tin moieties exist as monomers. Reactions of PhSnC1 3 and n -BuSnCl 3 with L form the complexes [ L H + ] 2 [PhSnCl 5 ] 2 m and [ L H + ] 2 [ n- BuSnCl 5 ] 2 m . Compounds were also characterized by FTIR, 1 H and 13 C NMR spectroscopy.     

Electromigration of carrier-free radionuclide ions Bismuth complexes in aqueous solutions of oxalic, fumaric and succinic acids

The overall ion mobilities u of carrier-free radiobismuth have been measured in aqueous solutions of some dicarboxylic acids (H(2)L)-xalic, fumaric and succinic-by means of a new version of the electromigration method in electrolytes consisting of HClO(4)/H(2)L, 0.20m H(+), mu = 0.20m; Na(H)ClO(4)/H(2)L, 0.05m H(+), mu = 0.20m; Na(H)ClO(4)/H(2)L, 0.05m H(+), mu = 0.25m; at 298.15 K. Mathematical processing of the experimental functions u = f([L(2-)]) allowed calculation of the mean individual stability constants K(n) and ion mobilities u degrees of the complex ions [BiL(n)](3-2n), n = 1, 2: [Bi(C(2)O(4))](+), log K(1) = 7.65 (8), u degrees = +2.26 (5) x 10(-4) cm(2). sec(-1).V(-1); [Bi(C(2)O(4))(2)](-), log K(2) = 4.81 (2), u degrees = -1.63 (64) x 10(-4) cm(2).sec(-1).V(-1); [Bi(C(4)O(4)H(2))](+), log K(1) = 6.90 (20); [Bi(C(4)O(4)H(4))](+), log K(1) = 8.76 (48).     

The effect of olefinic terminal chains on the mesomorphic properties of 4,4'-disubstituted diphenyldiacetylenes

New diphenyldiacetylenes of the type with A, B = H and/or F; m = 0, 1; n = 1-4; and X = C n H 2n + 1 , F, CF 3 or CN were synthesized and their mesomorphic properties determined by hot stage polarizing microscopy and DSC. When m = 0, all of these compounds showed only a nematic phase except when X = CF 3 when both nematic and smectic A phases were seen. Both clearing and melting temperatures were higher than those reported for substitution with the corresponding alkyl chains but the much larger increase in clearing temperatures produced considerably wider nematic phases. Eutectic mixtures of a few of these olefins yielded nematic materials also having much wider temperature ranges and higher clearing temperatures than the eutectic mixtures of the alkyl compounds, while retaining their high birefringence and low viscosities. Such materials are of interest for beam-steering devices.

Four of the diacetylenes with m = 1 ( A, B = H) were also prepared ( X = C 6 H 13 , F, n = 2, 3). When X was C 6 H 13 ( n = 2), the nematic range was smaller in the 2- than in the 1-olefin but wider than in the alkyl series. When X = F, either no nematic phase or a monotropic one was observed, whereas the 1-olefins gave a much wider nematic phase. Both transition temperatures were lower than those for the corresponding 1-olefin and alkyl analogues. The compound with X = C 6 H 13 and n = 2 had a melting temperature below room temperature.     

Synthesis and Crystal Structure of a Novel One-dimensional Coordination Polymer [ （C14H18N2）（Pb2i6）]n

1 INTRODUCTION The organic-inorganic hybrid material is a new type of composite between organic and inorganic polymers, and has captured the imaginations of che- mists due to its potential applications in electric con- ductivity, magnetism, ion exchange…     

A porous coordination polymer assembled from 8-connected {Co(II)3(OH)} clusters and isonicotinate: multiple active metal sites, apical ligand substitution, H2 adsorption, and magnetism

A microporous coordination polymer, namely, [Co(3)(ina)(4)(OH)(C(2)H(5)OH)(3)](NO(3))·C(2)H(5)OH·(H(2)O)(3) (1, or MCF-38, ina = isonicotinate), with 8-connected {Co(3)(OH)} clusters as the structural secondary building units, has been solvothermally synthesized. The hydroxo-centered Co(II) cluster involves multiple active metal sites. The interesting apical ligand substitutions have been directly observed, and the corresponding products of [Co(3)(ina)(4)(OH)(G)(x)(H(2)O)(n)](NO(3))·G·(H(2)O)(m) (1 ? PrOH, G = PrOH, x = 2, n = 1, m = 3; 1 ? BuOH, G = BuOH, x = 2, n = 1, m = 1, and 1 ? MeOH, G = MeOH, x = 3, n = 0, m = 7) have also been obtained by solvothermal syntheses or crystal-to-crystal transformations. High-pressure H(2) adsorption measurement at 77 K reveals that activated 1 can absorb 2.2 wt % H(2) at 5 bar. The relative H(2) absorption at low pressure (86% of the storage capacity at 1 bar) is higher than the corresponding values reported for some typical porous coordination polymers. The magnetic studies of 1 show a dominant antiferromagnetic coupling between Co(II) ions of intra- and inter-cluster.