Solid State Structure and Lyotropic Mesomorphism of Rare-Earth Trisdodecylsulphates in the Water-Eth

JOURNAL OF RARE EARTHSVol.2I ,No.2 , Apr.2003 ,p. 101Solid State Structure and Lyotropic Mesomorphism of Rare- Earth Trisdode-cylsulphates in the Water-Ethylene Glycol SystemLiesbet Jongen , Koen Binnemans( Katholiehe Universiteit Lewen , Department of Chemistry , Celestijnenlaan 200F , B-3001 Lewen , Belgium )Abstract :The phase behaviour of lanthanide( I ) dodecylsulphates , Ln( C12H2sSO4 )，by thermo-optical microscopy usingLawrence penetration technique was investigated . The lyotropic phase behaviour of lanthanidd II ) dodecylsulphates in ethy-lene glycol water in mixtures hereof , depends on the composition of the solvent. For pure ethylene glycol and mixtures ofethylene glycol and water three different mesophases are formed ri.e. a lamellar a cubic and a hexagonal phase , whereaswhen water is used as solvent no cubic phase is formed . The size of the lanthanide ion has no influence on the mesomorphismof these metallomesogens , although the smaller the lanthanide ion the lower the solubility .Key words :inorgamic chemistry ; lanthanides ; liquid crystals ; lyotropic mesophases ; metallomesogens ; surfactants ; rare earthsCLC number :0641Document code :AArticle ID : 1002 - 0721( 2003 )02 - 0101 -04Rare earth( II ) alkylsulphates are well known forLinkam THMS 600 hot stage and a Linkam TMS 93their catalytic activity in several types of organic reac-programmabletemperature-controller.Thermo-tions 1-4. A large advantage of these so-called Lewisgravimetric curves were obtained using a Polymer Labo-acid-surfactant-combined catalysts is their water stabili-ratories STA 1000-H TG-DTA apparatus. X-ray diffrac-ty. Therefore no harmful organic solvents have to btograms were measured on a STOE Transmission Powderused to carry out these organic reactions. Stable disper-Diffractometer System STADI P , using monochromaticsion systems including the catalyst and organic sub-Cu-Ka( λ = 0.154 nm ) radiation. FT-IR spectra werestrates are formed in water. Lyotropic mesophases inrecorded on a Bruker IFS-66 spectrometer , using thelanthanide II ) alkylsulphates were used for the synthe-KBR pellet method. Reagents and solvents were usedsis of nanostructural polymers , although these scientistsas received without further purification.did not use pure lanthanide( II ) alkysulphates5 5-7].Lanthanide( II ) alkylsulphates have been used in the2Results and Discussionlast few years as counter ions in for example liquidThe lanthanide( ll ) dodecylsulphates were synthe-crystalline lanthanide Schiff's base complexes 8~11] ,orsized via a metathesis reaction between sodium dodecyl-in crown-ether complexe5 12].Moreover，our group .sulphate and a lanthanide nitrate 9. To an aqueous so-found that lanthanide( Il ) dodecylsulphates show lylution of sodium dodecylsulphate the desired lanthanideotropic mesomorphism in the presence of water andion dissolved in water was added dropwise. The lan-ethylene glycof 131 ,and this work has been extended bythanide( II ) alkylsulphate precipitated immediately .Galyametdinov and coworkers 14]. However , no infor-The product was filtered off , washed with deionised wa-mation is available on the structure and thermal beter and dried in vacuum for 24 h. The purity of thehaviour of these complexes. In this paper ，we describethe solid state structure and the lyotropic mesomorphismcompounds was checked by elemental analysis. All theof the lanthanide( II ) dodecylsulphates , Ln( C12 H2scompounds of the series Ld( C12H2sSO4 ) were found toSO4 )XLn=La~Lu , except Pm ).be monohydrates ，which was confirmed by thermo-gravimetry. The analysis results are given in Table 1.1 ExperimentalA typical TG curve shows a first mass loss from 85 ~ 95CH elemental analyses were performed on a CECthe leaving of waterInstruments EA-1110 elemental analyser. Optical texmol中国煤化工，ss loss occurs betweentures of the mesophase were observed with an Olympus150:YHCN M H G. The DTA eurve( whichBX60 polarised optical microscope equipped with ais si-Received date :2002 - 12 - 04 ;revised date :2002 - 12- 30Biogrphy蹬Binnemans( 1970 - ), Male , PrfessrCorresponding uthor( E-mail : Koen. Binnemans @ chem. kuleuven . ac. be )102JOURNAL OF RARE EARTHS , Vol.2l ,No.2 , Apr.2003Table 1 Analysis results of lanthanide( I )dodecylsulphatesCompoundsC/% *H/%*Ld CzHzsS0.) H2045.83(45.37) 8.20(8. 14)C( C2H2SO4) H2045.68(45.31 )8.14(8.13 )P( C2HzS04) H2O45.84(45.27) 8.06(8.13)Nd C2H2S04) H2O45.72(45.11) 8.26(8. 10)Sm( C12H2S04) H2045.33(44.83) 8.05(8.05 )Ed CHrHsS04) H2045. 16(44.75) 8. 15(8.03 )Gd( CnH2sSO4) H2044.81(44.51 )8.14(7.99)1520 25 30'Th( C2H2S04) H2O44.60(44.43) 8.28(7.98)2 0/(° )Dy( Cr2H2sSO4) H2O44.12(44.27) 7. 98(7.95)Hd C2H2sSO4) H2O43. .93(44.16) 8.06(7.93 )Fig.1 X-ray powder difacogram of Nd C12H2sS04号H2OE( C2H2sS04ξ H2O43 .96(44.06) 8.06(7.91 )Tim( C2H2zS04) H2O43.86(43.98) 8. 10(7.89)YI( C2H2sS04) H2O43.36(43.80) 8.08(7.86)Lud Cr2H2SO4) H2043. 70(43.71) 8. 18(7.85)* The calculated values are given in bracketsmultaneously recorded ) shows for both mass losses an昌|endothermic peak. All the compounds from the seriesL( C2H2sSO4); H2O show a loss of water in the TC-DTA measurements , but the water content determined4000 3500 3000 2500 2000 1500 1000 500with this method was a little bit too high in comparisonv /cm-Ito the water amount obtained by elemental analysis .The hygroscopic character of these compounds can ex-Fig.2 Infrared spectrum of Nd C12H2sS04) H20plain this too high water value.For Nd( C12H2sSO4): H2O and for Yb( C12 H2slanthanide complexes . The assignments of the observedSO4 ) H2O room temperature X-ray diffraction analysisbands for Ne( C12H2sSO4 ) , La( C12H2sS04); H2O andwas performed. These compounds show several reflec-Nd C12H2sSO4》H2O are summarized in Table 2. Thetions in the small-angle region. The d values are in thepeak positions do not change significantly from one lan-ratio 1: 1/2: 1/3:.. 1/n ( Fig.1 ). These diffractionthanide ion to another except for a slight shift to higherpeaks correspond to the ( 001 ) eflctions and indicate awavenumber at the end of the lanthanide series for thelamellar structure . The experimental d values are aboutstretching of the C- 0 bond and for a continuous shifttwice the length of the dodecylsulphate group , hence ato higher energy for the S一0 stretching vibration forbilayer structure can be assumed. Moreover , this ex-the oxygens coordinated to the lanthanide ionperimental d value agrees very well with the d value ofThe lyotropic mesomorphism of lanthanide alkyl-a bilayered lanthanide( II ) dodecylsulphate with thesulphates was investigated by hot-stage polarised opticalalkyl chain in all trans configuration calculated bymicroscopy. We used the following lanthanid( II ) do-molecular modelling. The X-ray diffractograms showdecylsulphates :Ld C12H2sSO4); H20 ,Pr( C12H2sSO4》within the layers also a reflection at ca. 0.41 nm ,H20 , Sm( C12H2sS04) H2O , Dy( C2H2sSO4); H20caused by in-plane scattering of the alkyl chains. Theand Yb( C12H2sSO4 ): H2O. We made the followingpeak is very diffuse ，so it can be assumed the alkylmixtures of ethylene glycol/ water( EW , the first num-chains are not regularly structured .ber is the percentage of ethvlene glycol ，the secondIn Fig. 2 the infrared spectrum of Nd C12H2sSO4》num中国煤化工):EW 100/0 ,EW 75/H2O is given. If compared with the spectrum of the25 ,:YHC N MH GW 0/ 100. The lyotropicsodium dodecylsulphate ，the stretching and bendingmesomorphism' was investigated by the Lawrence pene-peaks of the alkyl chains ( 3000 ~ 2850 and 1470 cm-tration technique 15].respectively ) are the same for the complexes and for theWe investigated complexes with five different lan-sodium salt. However peaks assigned to the sulphatethanide ions to explore the effect of the ionic size. Firstgroup sho万 药数据from sodium alkylsulphates to theconclusion is that the solubility of the compound in aKiesbet J et al. Solid State Structure and Lyotropic Mesomorphism of Rare-Earth Trisdodecylsulphates03Table 2 IR assignments for Na( CnHz2SO4》, La( CzHzSO4》H2O and Nd CrzH2sSO4 H2ONd C2HsSO4 )/Ld( C2H2S04) H2O/ Nd C1H2S04) H20/Assignment“Intensity *cm-m-'cmi(0- H )water347034623411v(CH2)2956va CH3)2918以CH)287328726CH2)28508(C-H)m1469以S-0)12201209(S-0*)108511081105(C-0* )106510671061101810141013Long chain rocking w21237218(S03)36622625a(SO3)9180* The asterisk indicates the oxygen bridging the sulphur and the alkyl chain ;v denotes stretching ,δ bending ;* # s= . strong,m = medium ,w= weak and b= broadcertain solvent mixture decreases with decreasing ionicsolution occurs above 70 C when heating at 1 Cradius. Compounds with a small ionic radius ( i. e.min -1. When cooled from the isotropic liquid ,only the :Dyl and Ybl ) dissolve slower at room temperature ,orhexagonal and the lamellar phase are formed , the cubicthe dissolution temperature at heating is higher. Thisphase is not longer observed. Moreover , when the sam-effect is often seen for lanthanide compounds. Second-ple is left in contact with the solvent for a long time( i.ly ,the mesomorphic behaviour does not depend on thee. more than 3 h ), the hexagonal phase seems to belanthanide ion. This means that all the lanthanide II )the most stable mesophase .dodecylsulphates show the same mesophases at almostAt lower ethylene glycol concentrations( EW 25/the same temperatures for a given solvent composition .75 and EW 0/100 ) the thermal behaviour of the lan-In contrast to the ionic size , the composition ofthanid( II ) dodecylsulphates is quite different . Imme-the solvent has an influence on the mesomorphic be-diately after contact with the solvent a hexagonal phasehaviour. We will describe the observations for Sn( C12is formed. Almost the entire crystalline product is rear-H2sSO4》, although for the other lanthanide complexesranged to this mesophase. By heating the lamellarthe behaviour is quite the same( as stated above ). Forphase is formed at about 25 C. Further heating causesthe solvent mixtures EW 100/0, EW 75/25 and EWthe formation of a grey two-phase region comparable to50/50 at 20 9C a mesophase is formed immediately afterthe one described for the higher ethylene glycol concen-contact with the solvent. At thermal equilibrium thistrations. When a mixture of ethylene glycol and watermesophase seems to be a normal hexagonal phasewith a concentration of only 25% ethylene glycol is( H ). Heatingat 1 C min-1 gives rise at ca.25 C toused , this two-phase region is transformed to a cubicthe formation of a lamellar phase La over a small con-phase at much higher temperatures as for higher con-centration range on the borders of the crsalline phase .centrations of ethylene glycol( i.e. ca. 60 9C). Fur-By further heating a distinct grey zone between thether heating does not affect the phase behaviour. Disso-lamellar and the hexagonal mesophase is formed at ca.lution is very slow , even at elevated temperatures ( >30 C. This grey zone is a two-phase region and exists85 9C ). When the sample is cooled down to room tem-while the cubic mesophase forms. The cubic phase canperature 。thr entire nroduct is transformed in a hexago-be recoginzed ，because it appears dark betweennal中国煤化工m.crossedpolarizers and because this mesophase is situat-TYHC N M H G solvent , the two-phaseed at a concentration range between the hexagonal andregion does not change to a cubic phase and the disso-the lamellar phase. Finally ,at ca. 40 C the lamellar ,lution of the compound is very slow. This different be-cubic and hexagonal mesophase are stable. Furtherhaviour by using different solvents is often observed 16].heating does. not affect the presence of the differentThe polarity of the solvent explains this behaviour. Wa-phases althong振compound dissolves. Complete dis-ter is a very polar solvent and can creep easily between104JOURNAL OF RARE EARTHS , Vol.2l ,No.2 , Apr.2003the lanthanide ions and the alkyl sulphate groups. This[3] Mori Y , Kakumoto K , Manabe K ,et al. Michael reac-causes a fast rearrangement of the aliphatic chains totions in water using Lewis acid-surfactant combined cata-form a stable lamellar and hexagonal mesophase.lysts[J] Tetrahedron Lett. ,2000 ,41 :3107.[4] Manabe K , Mori Y , Wakabayashi T ,et al. OrganicPolyethylene glycol is less polar , but is more capable tosynthesis inside particles in water : Lewis acid-surfactant-stabilise the cubic mesophase 161.combined catalysts for organic reactions in water using col-3 Conclusionsloidal dispersions as reaction media[J] J. Am. Chem.Soc. , 2000 , 122 :7202.Lanthanide( II ) dodecylsulphates are not ther-[5] Yada M , Kitamura H , Ichinose A ,et al . Mesoporousmotropic liquid crystals ，but they form lyotropicmagnetic materials based on rare earth oxides [ J ]mesophases in the presence of water and ethylene glycolAngew. Chem. Int. Ed. Engl. , 1999 ,38 :3506.and mixtures hereof. We investigated the phase be-[6] Yada M ,Kitamura H ,Machida M ,et al. Ytriun-basedporous materials templated by anionic surfactant assem-haviour via the I awrence penetration technique on theblies[J ] Inorg. Chem. ,1998 ,37 :6470.thermo-optical microscope. The lyotropic phase be-[7]YadaM,OhyaM,MachidaM,etal.Synthesis ohaviour of lanthanide( II ) dodecylsulphates depends onporous yttriurm aluminium oxide templated by dodecyl sul-the composition of the solvent. For pure ethylene glycolfate assemblies[J]. Chem. Comm. , 1998 : 1941.and mixtures of ethylene glycol and water three differ-[8] Galyametdinov Y G , Ivanova G I，Ovchinnikov 1 V ,et .ent mesophases are formed( i.e. a lamellar ,a cubical. Synthesis and mesogenic properties of azomethine com-and a hexagonal phase ) , whereas when water is used asplexes of lanthanides with alkyl sulfate anions[ J ] Russ.solvent no cubic phase is formed. The size of the lan-Chem. Bull. , 1999 ,48 : 385.[9] Van Deun R , Binnemans KMesomorphism of lanthanide ion has no influence on the mesomorphism ofthanide containing Schiff' s base complexes with dodecyllanthanidd II ) dodecylsulphates. The smaller the lan-sulphate counterions[J] Liq. Cryst. ,2001 ,28 :621.thanide ion the lower the solubility , but the phase be-[ 10] Binnemans K ,Galyametdinov Y ,CollinsonSR ,et al.haviour does not change through the lanthanide series .Reduction of the transition temperatures in mesomorphicHowever , this independence of the phase behaviour as ;lanthanide complexes by the exchange of counter- ionsa function of the lanthanide ion is often observed for[J] J. Mater. Chem. , 1998 ,8 :1551.thermotropic lanthanide complexesThis can be re-[ 11] Binnemans K , Gorler- Walrand C. Lanthanide-containingliquid crystals and surfactants[J ]. Chem. Rev. , 2002 ,lated to the similar chemical properties of the trivalent102 :2303.lanthanide ions throughout the lanthanide series .[12] Binnemans K , Gindogan , B. Synthesis and thermal be-Acknowledgement :LJ is indebted to the" Institute for the Pro-haviour of lanthanide complexes of 4' {( cholesteryloxy )motion of Innovation by Science and Technology in Flanderscarbonyl }benzo- 15-crown-5[J] J. Rare Earths ,2002 ,(IWT Y' for financial support. K B thanks the FWO-Flanders20 ,249 .( Belgium )for a postdoctoral fellowship , for a research grant( G.[ 13] Galyametdinov Y G ,Jervis HB ,Bruce D W ,etal. Ly0243 .99 )and for a" Krediet aan Navorsers" . Financial supportotropic mesomorphism of rare-earth trisalkylsulphates inby the K.U.Leuven is acknowledged( G0A 98/3 ). The authorsthe water ethylene glycol system[J]. Liq. Cryst. ,2001.thank Prof. G. Meyer and Dr. D. Hinz ( Universitat zu Koln ,28 : 1877.Germany ) for the X-ray diffraction measurements .[14 ]Zakharova L Y , Valeeva F G , Ibragimova A R ,et al.The kinetics of solvolysis of phosphorus acid esters in theReferences :ternary sodium dodecyl sulfate-ethylene glycol-Lax + micel-[1 ] Kobayashi S , Manabe K. Development of novel Lewislar system[J] J. Mol. Liq. ,2002 ,100 :229.acid catalysts for selective organic reactions in aqueous[15] Lawrence A SC. Surface Activity and Detergency[ M ]media[J]. Ace. Chem. Res. ,2002 ,35 :209.edited by K. Durham ,( London : Macmillan ), 1961 .[2] Kobayashi S , Wakabayashi T. Scandium trisdodecylsul-158.fate(STDS). A new type of Lewis acid that forms stable[16] Fairhurst C E, Fuller s,Gray J，et al. Handbook ofdispersion systems with organic substrates in water and ac-Liquid Crystals [ M ] edited by D. Demus ,J. Goodby ,celerates aldol reactions much faster in water than in or-G. W. Gray ,H. w. Spiess ,V. 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