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REV. CHIM. (Bucureºti) ♦ 58 ♦ Nr. 9 ♦ 2007

MEMBRIAlexandru T. BALABANTexas A&M University at Galveston, SUAIon BOLOCANUniversitatea Petrol Gaze PloieºtiMiron Teodor CÃPROIUInstitutul de Chimie Organicã “C.D. Neniþescu” BucureºtiAndrei F. DÃNEÞUniversitatea BucureºtiCorneliu Mircea DAVIDESCUUniversitatea Politehnica TimiºoaraLaurenþiu FILIPESCUUniversitatea Politehnica BucureºtiIonel HAIDUCAcademia RomânãValeriu V. JINESCUUniversitatea Politehnica BucureºtiHenry V. KEHIAIANITODYS, Université Paris 7, FranþaConstantin LUCAUniversitatea Politehnica BucureºtiAngela LUPUUniversitatea Politehnica BucureºtiGheorghe D. MATEESCUCase Western Reserve University, Cleveland SUALucian MOÞIUAGER Consulting SRLMircea MRACECInstitutul de Chimie Timiºoara al Academiei RomâneMargareta NICOLAUECOIND BucureºtiIon OPREANInstitutul de Chimie “Raluca Ripan” Cluj-Napoca

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REVISTA DE CHIMIEBUCUREªTI ROMÂNIA

COLEGIUL EDITORIALEditor ªefPetru FILIP

Institutul de Chimie Organicã “C.D. Neniþescu” BucureºtiEditor ªef Adjunct

Gheorghiþa JINESCUUniversitatea Politehnica Bucureºti

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CUPRINS

Ileana Rãu, Fr. KajzarCatenane ºi rotaxane-noi clase de molecule cu componente mobile cu aplicaþii în fotonicã...........................................861Eleonora-Mihaela Ungureanu, Luisa Pilan, Aurelia Meghea, F.Le Floch J.P. Simonato, G.BidanTeste preliminare pentru grefarea 4-N,N-dietilanilinei pe nanotuburi din carbon...............................................................866G.C.Papanicolaou , D.E.Mouzakis, A.G.Xepapadaki, D.Fakos, E.KoundourakiFabricarea ºi testarea cimentului polimeric ranforsat cu UD-CFRP........................................................................................871Mãdãlina Capoºi, Daniela Ioniþã, F. Miculescu, Ioana DemetrescuTratarea electrochimicã a suprafeþelor firelor de TiNi folosite pentru implanturi...............................................................875Simona Popescu, Ioana Demetrescu, A.GleizesPregãtirea ºi caracterizarea peliculelor subþiri de TiO2- MOCVD depuse pe titancu aplicaþii în medicinã...............................................................................................................................................................880Maria Magdalena Sovar, Graþiela Teodora Tihan, F. Miculescu, Valentina MitranEfectul pH-ului din salivã asupra stabiliþatii electrochimice a aliajului Co-Cr-Mocu suprafaþa modificatã prin tratament biochimic...................................................................................................................886Codruþa Varodi, Delia Gligor, Andrada Mãicãneanu , Liana M.MureºanElectrozi din pastã de cãrbune cu zeoliþi schimbatori de calciu modificaþi cu albastrude metil pentru detectarea ampermetricã a NADH-ului.........................................................................................................890Raluca Ciubãr, Cristina Ciofrîngeanu, Valentina Mitran, Aniºoara Cîmpean,Aurelia Stãnescu, Dana IordãchescuEfectul ionilor de plumb asupra eritrocitelor umane in vitro..................................................................................................895Mihaela Mîndroiu, Erkem Cicek, F. Miculescu, Ioana DemetrescuInfluenþa tratamentului de oxidare termicã asupra stabilitaþii electro-chimice aaliajelor de TiAlV ºi TiAlFe ºi aplicarea lor potenþialã ca biomateriale..................................................................................898Laura Bancu, Aurelia MegheaSinteza hibrizilor CdS fluorescentã – amino acid.....................................................................................................................904Daniele Þurcanu Cãrunþiu, Alina Murariu, Maria Giurginca, Ileana Rãu, Aurelia MegheaMetode spectrale complementare folosite pentru autentificarea operelor de artã.............................................................907Cornelia Nichita, Maria Giurginca, Cristina Bâzdoacã, Lucia Pîrvu, Aurelia MegheaAntioxidanþi vegetali obþinuþi din Hypercum Perforatum........................................................................................................910Lucia Pârvu, Cornelia Nichita, Maria Giurginca, Aurelia MegheaExtracte de plante cu aplicaþii în terapia sindromului oboselii cronice.................................................................................914Elena Aldea, Nicoleta Badea, Ioana DemetrescuEvaluarea bioactivitãþii aliajelor de titan din punctul de vedere al capacitãþii deformare a hidroxiapatitei.............................................................................................................................................................918Maria Giurginca, Nicoleta Badea, Lucreþia Miu, Aurelia MegheaTehnici spectrale pentru identificarea agenþilor de colorare pentru produsele depiele antichizate...........................................................................................................................................................................923Maria Mihaly, Ioana Lãcãtuºu, Aurelia MegheaCromofor ftaleinsulfonã ca probã molecularã în sisteme micelare......................................................................................929C.Pârvu, R.Stancu, Maria Magdalena SovarProprietãþile anticorosive ale acoperirilor hibride organic (polipirol)-anorganice(zinc)pe suprafeþele de oþel..................................................................................................................................................................933Silvia Neamþu, Adriana Mariana Borº, Sabina ªtefanEvaluarea riscurilor unor poluanþi organici persistenti asupra mediului ºi sãnãtãþii............................................................938

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Bucureºti-RomâniaChem. Abs.: RCBUAU 58 (9) (861-942)

ISSN 0034-7752Vol. 58, nr. 9, septembrie 2007


CONTENTS

Ileana Rau, Fr. KajzarCatenanes and Rotaxanes-New Classes of Molecules with Mobile parts forApplication in Photonics..............................................................................................................................................................861Eleonora-Mihaela Ungureanu, Luisa Pilan, Aurelia Meghea, F.Le Floch, J.P. Simonato, G. BidanPreliminary Tests for N,N-Diethylaniline Grafting on Carbon Nanotubes..............................................................................866G.C.Papanicolaou, D.E.Mouzakis, A. G.Xepapadaki, D. Fakos, E.KoundourakiManufactoring and Testing of Polymer Concrete Reinforced with UD-CFRP.........................................................................871Madalina Caposi, Daniela Ionita, F. Miculescu, Ioana DemetrescuSurface treatments in Electrochemical Beheviour of TiNi Wires for Implant Purposes......................................................875Simona Popescu, Ioana Demetrescu, A.N.GleizesPreparation and Characterization of MOCVD-Fabricated TiO2 Thin Films DepositedOn Titanium for Biomedical Applications.................................................................................................................................880Maria Magdalena Sovar, Gratiela Teodora Tihan, F.Miculescu, Valentina MitranEffect of Saliva pH on Electrochemical Stability of Co-Cr-Mo Bioalloy witha Bio-chemically Modified Surface............................................................................................................................................886Codruta Varodi, Delia Gligor, Andrada Maicaneanu, Liana M.MuresanCarbon Paste Electrode Incorporating Calcium-Exchanged Zeolite Modified with Methylene Bluefor Amperometric Detection of NADH.......................................................................................................................................890Raluca Ciubar, Cristina Ciofrangeanu, Valentina Mitran, Anisoara Cimpean,Aurelia Stanescu, Dana IordachescuThe Effect of Lead Ions on Human Erythrocytes in Vitro........................................................................................................895Mihaela Mindroiu, Ekrem Cicek, F.Miculescu, Ioana DemetrescuThe Influence of Thermal Oxidation Treatment on the ElectrochemicalStability of TiAlV and TiAlFe Alloys and Their Potential Application as Biomaterials...........................................................898Laura Bancu, Aurelia MegheaSynthesis of Fluorescent CdS-Amino Acid Hybrids..................................................................................................................904Daniela Turcanu Carutiu, Alina Murariu, Maria Giurginca, Ileana Rau, Aurelia MegheaComplementary Spectral Techniques for Authentication of Artistic Production..................................................................907Cornelia Nichita, Maria Giurginca, Cristina Bazdoaca, Lucia Parvu, Aurelia MegheaVegetal Antioxidants Obtained from Hyperycum Perforatum Species..................................................................................910Lucia Parvu, Cornelia Nichita, Maria Giurginca, Aurelia MegheaSelective Plant Extracts with Application in the Therapy of Chronic Fatigue Sindrome......................................................914Elena Aldea, Nicoleta Badea, Ioana DemetrescuEvaluation Titanium Alloys Bioactivity in Terms of Hydroxyapatite(HA) Forming Capability..............................................918Maria Giurginca, Nicoleta Badea, Lucretia Miu, Aurelia MegheaSpectral Technics for Identifying Tanning Agents in the Heritage Leather Items.................................................................923Maria Mihaly, Ioana Lacatusu, Aurelia MegheaSulphonephtalein Chromophore as Molecular Probe in Micelle Systems.............................................................................929C. Pirvu, R.Stancu, Maria Magdalena SovarAnticorrosive Properties of Hybride Organic (Polypyrrole) Inorganic(Zinc)Coatings on Steel Surface ...........................................................................................................................................................933Silvia Neamtu, Adriana Mariana Bors, Sabina StefanRisk Assesment of Some Persistent Organic Pollutants on Environment and Health..........................................................938

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Bucureºti-RomâniaChem. Abs.: RCBUAU 58 (9) (861-942)

ISSN 0034-7752Vol. 58, nr. 9, septembrie 2007


Catenanes and Rotaxanes – New Classes of Molecules with MobileParts for Application in Photonics

ILEANA RAU1*, FRANCOIS KAJZAR2

1Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, Polizu Str., no 1-7, 011061,Bucharest, Romania2Université d’Angers, UFR Sciences, Laboratoire POMA CNRS UMR 6136, Angers, France

Catenanes and rotaxanes are new classes of mechanically interlocked molecules composed movingparts, representing a great interest for potential applications in photonics, particularly in all opticaland electro-optic switching. Both catenanes and rotaxanes can be functionalized and their physico-chemical properties can be tailored by an adequate substitution. They can be also processed into goodoptical quality thin films. The linear and nonlinear optical properties of these films were studied byvarious techniques and the results of these investigations are reviewed and discussed. A particularattention to the rotational mobility of these molecules and/or their parts is paid.

Keywords: rotaxanes, catenanes, nonlinear optics, THG, DWFM, Z-scan, refractive index

The possibilities of controlling macroscopicproperties of materials by addressing the material onmolecular level on one hand and to reproducemechanical functions on molecular level on the secondhand are one of the important nowadays challenges theresearchers are trying to address. This challenge becomesto be more and more realistic with the successfulsynthesis of the so called molecular motors, i.e.molecules which moving subparts. In particular itconcerns two classes of molecules: catenane androtaxanes [1-4]. These, hydrogen bond molecules offerunique architectural and structural properties [5-6].

The name of catenanes originates from latin catenawhich means a chain. Indeed these supramolecules arefundamentally made from interlocked macrocycles (fig.1a) with an ability of a relative rotational movement ofone macrocycle with respect to the another one(s)(pirouetting). Another possible movement is the bendingof the chain composed by microcycles. The number ofmacrocycles is included in the used notation: [n]catenanes denote n interlocked chains. Up to nowsupramolecules of up to 4 macrocycles were synthesized(fig. 1a). Large catenanes (M

w=105 g/mol) are present

in nature, e.g. in DNA as intermediates during thereplication, transcription, and recombination process.Since the first two-ring catenane was obtained in eartlysixties, smaller synthetic catenanes (M

w=103 g/mol) have

attracted the interest of chemists and physicists.The name of rotaxanes takes its origin in latin too.

Rota and axis mean, respectively wheel and axle. In thecase of rotaxanes the macrocycle (or more of them) islocked onto a linear thread terminated on both sides withbulky stoppers (fig.1b). Rotaxanes exhibit more degreesof freedom than catenanes. The macrocycle can not onlyrotate along the thread (piroutetting as in the case ofcatenanes) but can also move along it (shuttling) betweentwo stations, noted by “1” and “2” in figure 1c. Theshuttling movement of macrocycle is limited by bulkystoppers located at the both ends of thread. Anotherdegree of freedom consists on a symmetricaldeformation of the rotaxane thread (bending) which maylead to clipping. This could be realized by an appropriate

* email: [email protected]

design of thread (a photo isomerising thread with –C =C – or –N = N – segments or their multiple). In aparticular case of clipping a rotaxane is transformed toa catenane.

Fig. 1. Schematic representation of possible movements incatenanes and in rotaxanes

One of the important challenges with these materialsis the problem of addressing and controlling differentdegrees of freedom by external stimuli. Obviously thesestimuli have to act on molecular level. The possibleexternal stimuli are obviously the low and highfrequency electric fields. In this paper we review anddiscuss some recent results obtained with thesemolecules in solid state and in solution by applyingoptical frequency electric fields.

MaterialsThe early syntheses of catenanes and rotaxanes were

mainly based on statistical threading approaches or ondirected methodologies involving chemical conversion[7]. To obtain a catenated molecule, one ring must beclosed in the presence of a second ring (“clipping”).This can be realized by a simple 2+2 condensation

861

(c)


technique of para-xylylene diamine and isophthaloylchloride, done in the presence of a base and in a suitablesolvent as it was shown recently by D. Leigh andcoworkers [8-9]. A high yield is obtained.

In the case of rotaxanes, there are three routes leadingto them:

(i) synthesis of a macrocycle and then of thread,followed by its capping on the ends;

(ii) slipping of a preformed ring over the stoppers ofa preformed dumbbell-stopped component into athermodynamically favorable site on the rod part of thedumbbell, and;

(iii) clipping of a performed dumbbell with a suitableu-type component that is subsequently cyclized.

The third route appears to be the simplest one if again,as in the case of catenane, the macrocycle is formed by2+2 condensation of para-xylylene diamine andisophthaloyl chloride in the presence of previouslysynthesized thread and done in the presence of a baseand in a suitable solvent as it was shown by the D. Leighgroup [10-12]. Again this synthetic route exhibits a highyield (of 97 %).

of about a few hundreds to thousand Daltons, they arehardly soluble. Only low concentration solutions canbe obtained, useful for spectroscopic studies, ifabsorption bands of solvent and of these molecules arewell separated, but difficult to study when the contrastof is too low, i.e. the solvent contributions is much moreimportant than that of solute. It is particularly the caseof physical quantities such as the linear and nonlinearoptical susceptibilities. In order to increase the solubilitythe phenyl ring stoppers were replaced by aliphaticchains by the D. Leigh group.

Fortunately both catenanes and rotaxanes, at least theones we have studied, can be processed into good opticalquality thin films by the controlled vacuum sublimationtechnique. Thin films with thickness varying from ca.100to 1000 nm can be easily obtained. The usual conditionsfor thin film deposition are as follows:

-initial and final level of vacuum: - 10-6 and 10-5Torr, respectively

- crucible temperatures: - 220°C;- target temperature: - 25°C;- deposition rate: - from 10 to 30 A/s.The obtained films exhibit a large transparency range

(cut off at around 300 nm in the case of rotaxanes and ataround 350 nm for fumrot [4]) and a good thicknesshomogeneity.

The usually used solution cast techniques lead to verythin films, because of limited solubility. Due to theirpolycrystalline structure these films scatter strongly thelight.

As already mentioned thin films with well definedthickness can be obtained. Even, using this technique asingle layer can be deposited [13]. The second harmonicgeneration (SHG) studies on mono – and multilayers ofrotaxanes [14] have shown a high order, as measuredby the ratio of the off diagonal and the diagonal SHGsusceptibilities , where Z is normal direction tothe thin film. This order is decreasing with increasingnumber of layers. However it is still observed in thicker,about 1 µm thick films, as it will be discussed in nextchapter.

Fig. 2. Chemical structure of benzylic amid [2] catenane

We have studied the benzylic amid [2] catenanes(fig. 2) and three different rotaxanes synthesizedsupplied by D. Leigh, now at University of Edinburg.In the second case three different compounds: withfumaric (fumrot, Fig. 3a), nitrone (norot, fig. 3b) thread,both with two phenyl rings as stoppers and another onewith aliphatic chains as stoppers – end groups of anitrone thread (fig. 3c) were used.

One of the big problem in studying these moleculesis their solubility. As large molecules, molecular mass

Fig. 3. Chemical structures of norot (a), fumrot (b), macrocycle (c) and of a norot modification (d)

862


Linear optical propertiesThe index of refraction of thin films of catenanes and

rotaxanes was measured by the m-line technique. Thistechnique allows a precise determination of thin filmthickness, refractive index and its anisotropy, finger printof an order. The precision depends on the number ofmodes which can be excited in the studied film and onthe refractive index difference between thin film andsubstrate. Larger is this difference and thicker is film,more modes may propagate in thin film and higherprecision can be obtained.

As an exemple figures 4 and 5 show refractive indicesand their dispersion for thin films of benzylic acid [2]catenane (fig. 4) and of norot (fig. 5). The dispersioncan be well described by the Sellmeier formula:

(1)

where λ is the wavelength, n0 is the index of refraction

at zeroth frequency and λ0 is a constant. The fits are

shown by solid lines in figures 4-5. In both cases abirefringence in studied thin films is observed. Therefractive indices are larger than usually observed intransparent organic thin films. It is due not only to thepresence of conjugated π electrons in both catenanesand rotaxanes but also to the good packing. Indeed, ifto the macrocycle is chemically added one(monosubsitution) or two (disubstitution) groups therefractive indices are decreasing as well as does thebirefringence as it was observed in thin films offunctionalized fumrot [15] (fig. 6). In the case ofdisubstituted fumrot the films are isotropic with lowerrefractive index.

Nonlinear optical propertiesThe nonlinear optical properties of catenanes and

rotaxanes were studied by various techniques, such asoptical SHG, optical third harmonic generation (THG),electro-optic Kerr effect, Z-scan and degenerate fourwave mixing (DFWM).

The SHG experiments on thin films of benzylic acid[2] catenanes show low χ

zzz(-2ω;ω,ω) susceptibilities of

the order of 0.03 pm/V [16]. Fresh rotaxanes thin filmsdo not show, within experimental accuracy, SHG signal.However these films can be poled and the value as largeas ca 7 pm/V for χ

zzz(-2ω;ω,ω) susceptibility can be

obtained, as it was shown in the case of fumrot [17].The poling and relaxation kinetics show very similartemperature dependence as observed in electro-opticpolymers.

The fast, electronic origin THG χ (-3ω;ω,ω,ω)

susceptibility exhibit values which are in agreement withthe bond additivity model, as expected for weaklyconjugated π electron systems, known to be highlypolarizable and can be well accounted for by the bondadditivity model, as it was shown in the case of catenanefilms [18] (table 1). Indeed no contributions, benefitingfrom the specific structures of catenanes and rotaxanesto the cubic susceptibility at optical frequency areexpected. These contributions may come at lowerfrequencies and benefit from the rotational mobilitiesof these large molecules or their subparts. In order tocheck it three kinds of experiments were performed:

- electro-optic Kerr effect measurements;- Z-scan;- polarization dependent degenerate four wave

mixing.The quadratic electro-optic Kerr effect allows

measuring the rotational mobility of molecules, or itssubparts, by measuring induced optical birefringencecreated by applying a low frequency AC field. Theinduced birefringence is given by

(2)

where nII, n ⊥ are refractive indices parallel and

perpendicular to the applied electric field, λ is thewavelength of the incident light, E is the strength of the

Fig. 4. Anisotropy and dispersion of refractive index in a thinfilm of benzylic acid [2] catenane

Fig. 5. Anisotropy and dispersion of refractive index in a thinfilm of norot

Fig. 6. Refractive index dispersion in vacuum sublimated thinfilms of pure (trangles), monosubstitued (circles) and

disubstitued fumrot (squares). Full figures show ordinary (TE)whereas the open the extraordinary (TM) index of refraction.

Solid lines are Sellmeier fits

(2)

(2)

863

(2)


applied electric field, and B is the Kerr constant. Forpractical application in electro-optic switching importantis the value of Kerr constant B. But this technique, asalready mentioned, allow evidencing the rotationaldegrees of freedom. This is done by measuring the Kerrconstant B as function of the exciting field frequency.The presence of resonances is a finger print of rotationalmobility. Indeed, using this technique, it was found thatthe macrocycle rotate in fumrot and norot molecules ata low frequency, of about 50 Hz at the field strength of0.35 V/µm [23], and at significantly higher frequencyin benzylic amide [2] catenane, of about 2000 Hz (fieldstrength of 1.6 V/µm [24]). In both molecules thefrequency of rotation depends on the strength of theapplied electric field and decreases with its increase.The experiments were performed in a non polar solventand the generated signal in a very dilute solution (10-7

mol/dm3) of fumrot was half of that of the liquidnitrobenzene; considered as reference material.

The two other techniques allows to measure theoptical birefringence created at optical frequencies. Inthe closed aperture z-scan technique the sample issubmitted to a varying light intensity when the sampleis translated through the focal point of a light focusinglength. If the variation of refractive index given by:

(3)

where I is the light intensity and n2 is the nonlinear index

of refraction, is positive (self focusing), the observedlight intensity shows a dip when sample is before thefocal point (on the side of the laser source) and amaximum when is after. Opposite effect (self

defocusing) is observed for n2 negative. The

measurements can be calibrated by doing the sameexperiment on a liquid with known n

2 coefficient.

Usually CS2 is used as standard. The nonlinear index of

refraction is linked to the Kerr susceptibility χ (-ω;ω,−

ω,ω) by the following relation:

(4)

Thus knowing n2 one can derive the value of

χ (-ω;ω,−ω,ω) susceptibility. Inverse is applicabletoo. This was done by using the third technique –DFWM, in the phase conjugation (PC) geometry. In thisgeometry the sample is illuminated by 3 light beams(for details see ref. [20]), from which two arecounterpropagating (pump beams) and the probe beamsmakes an angle with them. The PC geometry fulfils thephase matching condition for k vectors of interactingbeams and the signal beam is counter propagating tothe third beam, called the probe beam. It’s intensitydepends on Kerr susceptibility of the sample, samplethickness and the intensities of interacting beams. Alsoits special part of phase is complex conjugate to the phaseof probe beam. Thus this technique allows to measurenot only the χ

(-ω;ω,−ω,ω)susceptibility of the

sample but also correct the wave front deformations ofthe probe beam (phase conjugate mirror). Themeasurements were again calibrated with CS

2 and the

molecular second hyperpolarizabilities were derivedγ(-ω;ω,−ω,ω). They are linked to the macroscopiccubic susceptibilities by the following relation:

(5)

Table 1MOLECULAR HYPERPOLARIZABILITIES FOR ROTAXANES, CHLOROFORM AND CS2 AS

DETERMINED BY DIFFERENT TECHNIQUES

(3)

(3)

(3)

864


where the local field factor fω takes account of the

screening of external field by the local, microscopic fieldand N is the density of molecules.

The results of measurements on the solutions ofrotaxane, whose chemical structure is shown in figure3c are given and compared to those for solvent as wellas to the values obtained by THG measurements in table1. First of all it can be seen that the values of opticalKerr hyperpolarizabilities for rotaxane with aliphaticchain stoppers (fig. 3c) is about 30 times larger thanthose measured in parent fumrot and norot. Withinexperimental accuracy both DFWM and z-scanmeasurements give close values. The values measuredfor solvent, which was chloroform, are close to thosemeasured by the THG technique. It means that indeed,as expected, the rotational contributions to Kerrsusceptibility in solution of rotaxane is very large, morethan one order of magnitude larger than observed in THGexperiments. As the DFWM and z-scan measurementswere done with 3 ps duration laser pulses, it means thatthis contribution is in the picosecond time scale.

ConclusionWe have reviewed some of the results concerning

linear and non linear optical properties of two newclasses of molecular motors catenanes and rotaxaneswhich are mechanically interlocked. Both molecules canbe processed into good optical quality thin films byvacuum sublimation, forming partly orderedhomogenous thin films, as observed by the anisotropyof refractive index. The index of refraction of these filmsis large as for an organic material, what is due to both agood packing and the presence of conjugated π electrons.In the case of norot a decrease of refractive index andits anisotropy was observed when functionalizing therotaxane. This show flexibility and possibility oftailoring the physical properties of these molecules byan appropriate functionalization. Attaching e.g. twogroups of NO

2 to macrocycle kills completely order and

diminishes the packing. The third-order NLO propertiesof a rotaxane molecule were measured in solution usingtwo techniques:

- Degenerate four wave mixing techniques;- Z-scan through the nonlinear optical imaging.The measurements were compared with THG

experiments on parent rotaxanes and they show that therotational contribution to the Kerr susceptibility inrotaxanes in solution is very large, about 35 times largerthan the electronic part, derived from THGmeasurements. It is also fast, as the measurements weredone with a pulsed picosecond laser.

Acknowlegdments: A part of this work work was performed withinthe European Community project Hy3M (NMP4-CT-2004-013525).The authors would like to thank the other participants contributingto it and particularly the group of Prof. D. Leigh at University ofEdinburgh for chemical synthesis of the studied compounds. F. K.thanks also the European Community project FP6 – Marie CurieTransfer of Knowledge – MTKD – CT – 2004 – 014059 – “Transferof Knowledge to Eastern-European Reference Pole for Micro- andNanotechnologies”.

References1.BALZANI, V., GÓMEZ-LÓPEZ, M., STODDART, J.F., Acc.Chem. Res., 31, 1998, p. 4052.BALLARDINI, R., BALZANI, V., CREDI, A., GANDOLFI,M.T. ,VENTURI, M.L. Acc. Chem. Res., 34, 2001 p. 4453.FLOOD A, H., RAMIREZ, R. J. A, DENG, W.-Q., MULLER, R.P., GODDARD, W. A., STODDART, J. F., Austr. J. Chem., 57,2004, p. 3014.NIZIOL, J., NOWICKA, K., KAJZAR, F., “Linear and nonlinearoptical properties of selected rotaxanes and catenanes”, in Nonlinearoptical properties of matter: From molecules to condensed phases,M. G. PAPADOPOULOS, J. LESZCZYNSKI , A. J. SADLEJ, Eds,Springer Dordrecht, The Nethelands, 2006, p. 6095.BLANCO M.-J., JIMENEZ M. C., CHAMBRON J.-C., HEITZV., LINKE M., SAUVAGE J.-P., Chem. Soc. Rev. 28, 1999, p. 2936.CLEGG, W., GIMENEZ-SAIZ C., LEIGH D. A., MURPHY A.,SLAWIN, A. M. Z., TEAT S. J., J. Am. Chem. Soc., 121, 1999p. 41247.AMABILINO, D. B., STODDART, J. F., Chem. Rev., 95, 1995,p. 27258.JOHNSTON , A.G., LEIGH, D.A., PRITCHARD, R.J.,DEEGAN, M.D., Angew. Chem., Int. Edn. Engl., 34, 1995, p. 12099.JOHNSTON, A. G., LEIGH, D. A., NEZHAT, L., SMART, J. P.,DEEGAN M. D., Angew. Chem., Int. Ed. Engl., 34, 1995 p.121210.JOHNSTON A. G., LEIGH D. A., MURPHY A., SMART J. P.,DEEGAN M. D., J. Am. Chem. Soc., 118, 1996, p.10662.11.LEIGH D. A., MURPHY A., SMART J. P., SLAWIN A. M. Z.,Angew Chem, Int. Ed. Engl., 36, 1997, p. 72812.CLEGG W., GIMENEZ-SAIZ C., LEIGH D. A., MURPHY A.,SLAWIN A. M. Z. AND TEAT S. J., J. Am. Chem. Soc., 121, 1999,p. 412413.DE NADAI C., WHELAN C. M., PEROLLIER C.,CLARKSON G., LEIGH D. A., CAUDANO R., RUDOLF P., Surf.Sci., 454-456, 2000, p. 11214. ARFAOUI I., BERMÚDEZ V., BOTTARI G., DE NADAI C.,JALKANEN J.-P., KAJZAR F., LEIGH D. A., LUBOMSKA M.,MENDOZA S. M., NIZIOL J., RUDOLF P., ZERBETTO F.,, J.Phys. Chem.. B, 110, 2006, p. 764815.BERMUDEZ V., CHOLLET P.-A., KAJZAR F., LORIN A.,BOTTARI, G., GATTI F. G. , LEIGH D. A., Mol. Cryst. Liq. Cryst.,374, 2002, p. 34316.GASE T., GRANDO D., CHOLLET P.A., KAJZAR F.,MURPHY A. , LEIGH D.A., Adv. Mat., 11, 1999, p.130317.BERMUDEZ V., GASE T., KAJZAR F., CAPRON N.,ZERBETTO F., GATTI F. G., LEIGH D. A., ZHANG S., Opt.Mat, 21, 2002, p. 3918.GRANDO D., GASE T., KAJZAR F., FANTI M., ZERBETTOF., MURPHY A., LEIGH D. A., Mol. Cryst. & Liq. Cryst., 353,2000, p.54519.MEREDITH G. R, BUCHALTER B., HANZLIK C., J. Chem.Phys. 78, Nr. 3, 1983, p. 154320.RAU I., CZAPLICKI R., HUMEAU A., LUC J., SAHRAOUIB., BOUDEBS G., KAJZAR F., LEIGH D. A., BERNA –CANOVAS J., Proceed. SPIE, 6343, 2006, p. 63433C - 121.KAJZAR F., MESSIER J., Phys. Rev. A, 32, Nr. 4, 1985,p. 235222.GUBLER U., BOSSHARD C., Phys. Rev. B, 61, 2000,p. 1070223.BERMUDEZ V., CAPRON N., GASE T., GATTI F. G.,KAJZAR F., LEIGH D. A., ZERBETTO F., ZHANG S., Nature,406, 2000, p. 60824.NOWICKA K., CHOLLET P. A., KAJZAR F., BOTTARI G.,GATTI F. G., LEIGH D. A., Nonl. Optics & Quantum Optics, 32,2004, p. 175

Manuscript received: 30.07.2007

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