Molecular Materials and Functional Polymers for Advanced




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COST Action 518


COST Action 518


"Molecular Materials and Functional Polymers for Advanced

Devices"


ANNUAL REPORT - 1998


edited by W Blau and P Lobotka


General:


The aim of the COST 518 Action is to stimulate co-operative research in the area of advanced

multifunctional molecular and polymeric materials. A particular focus is on molecular and

polymeric assemblies with potentially useful chemical, optical, electrical and magnetic

behaviour. Ultimately it is intended to initiate contacts and transfer know-how about these

materials to the whole range of European industrial sectors.


The Action is in it's second year of activity. By now, 16 countries have signed the

memorandum of understanding and are sending members to the Management

Committee .


Prof. W. Blau, IE, was elected as Chairman, and Prof. M. Hanack, DE, as Vice-Chairman of

this Action.


Scientific Details:


The Action is divided into 3 working groups:


WG1 Modified Ordered Arrays Coordinator: Prof. Schubert AT

WG2 Molecular Materials Coordinator: Profs. Hanack/Torres DE

WG3 Functional Polymers Coordinator: Prof. Bolognesi TR


Up to now, 14 projects have been approved, some of which span more than one working

group and are therefore equivalent to a horizontal action.


Areas of activity in these projects are Phthalocyanines, Low Band Gap Materials, Nonlinear

Optical Materials, Molecular Magnets, Holographic Polymers, Light Emitting Functional

Materials, Thin Film Preparation, Surface Modified Clusters, Materials for Sensing and Sol-

Gel Hybrids


Meetings and Workshops:


In 1998, two Management Committee meetings were held


22-23 July 1998 Bratislava SK


13-14th November Roma IT


Associated with the MC meeting in Bratislava was a one-day workshop. As previously

indicated, workshops provide an excellent mechanism for defining national areas of

expertise and initiating scientific collaboration and exchange visits.


Technical Progress Reports


These were prepared by the WG Leaders and demonstrate excellent progress. It should be noted that some projects are more active than others. A few are actively engaged in seeking Science and Technology Framework 4 & 5 support.


WORKING GROUP 1: Modified Ordered Arrays"


The first meeting of the working group was held on Nov. 15, 1998, in Nemi / Italy. In 13 oral contributions and a lifely discussion, the activities in the various projects were presented.


Several short-term scientific missions served to establish and maintain links between the groups working in the various projects.


Scientific activities:


Part of the acitivities are directed towards the characterization of oxometallate clusters and oxide nanoparticles, and their use in the preparation of hybrid inorganic-organic polymers. Because such clusters are formed as primary hydrolysis products in the sol-gel processing of metal alkoxides (M(OR)n; M = Ti, Zr, Sn, etc.) or organically substituted alkoxides, a detailed understanding of their formation and structure is essential for the deliberate development of new hybrid polymers by this method. A variety of characterization techniques (liquid and solid state NMR, XANES-EXAFS, SAXS, light scattering, FTIR, etc.) was applied all the way from molecular precursors to the resulting gels, xerogels, and aerogels. Several species, particularly carboxylate-substituted derivatives, were structurally characterized by X-ray

diffraction. The structure of magnetic polyoxometallates, and their metallic and miconducting properties was also investigated. The well defined oxometallate species are used as precursors for the building blocks of organized hybrid materials.


Various types of hybrid organic-inorganic materials were developed, their properties depending on their composition and microstructure. In order to tailor the physical properties of hybrids materials prepared by sol-gel processing, one of the most significant goal is to achieve the control on the structural arrangement of the various building blocks. In order to obtain new nanostructured materials which exhibit ordered molecular texture, the self-assembly of molecular inorganic species with organic molecules, macromolecules or even biomolecules is studied. The structural arrangement of the building blocks in multi-precursor sol-gel materials and the network formation processes was investigated in detail for organically modified silica aerogels.


Efforts are directed towards the development of hybrid materials with special optical (non linear optics, photochromism, luminescence, photocatalysis), mechanical and structural properties. Anisotropic nanomaterials were obtained by covering inorganic aggregates with an oriented layer. Furthermore, the possibility to anisotropize materials and to investigate these materials through an anisotropic interaction like quadrupolar NMR is studied. Putting some order inside these disordered structures allow to measure some solvent-material interactions, local mechanical properties and also to study the behavior of ionic species complexed inside polymers.


Magnetic hybrid materials were obtained by the combination of the organic donor BEDT-TTF with several inorganic clusters as for example the polyoxometalate [P2W18O62] and the borate [B10I10].


In project #4 two other classes of materials which exhibit magnetic properties together with other useful chemical or physical (electrical or optical) properties are additionally studied: Novel bimetallic magnetic lattices Na-Cr have been obtained, and the ground-state properties of tetranuclear cobalt (II) and nickel (II) clusters encapsulated by polyoxometalates was studied in detail a variety of techniques including Inelastic Neutron Scattering, magnetization and specific heat measurements. This study has allowed to obtain direct information on both the magnetic exchange interactions and the spin anisotropy in the clusters.


There were several activities concerning films obtained by the Langmuir-Blodgett (LB) technique. Novel organic/inorganic magnetic materials were obtained as thin films using this technique. The most important result in this respect has been the preparation of well-organized monolayers of single-molecule Mn12 nanomagnets which exhibit a marked magnetic hysteresis below the blocking temperature (4 K).


Amphiphilic oligomers based on 3(3-thienyl)glutaric acid were synthesized, and the conditions for the LB deposition were optimized. Measurements of the electrooptical properties were carried out on MIM, MIS structures. Important effects and parameters such as carrier mobilities, lifetimes, conductivities, trap distribution, role of electrical contacts and the effect of molecular conformation were obtained using the following techniques: steady state and transient conductivity, photoconductivity, photo- and electroluminiscence, C-V, I-V-t, Q DLTS. These materials have proven to have perspective for applications in sensors and displays.


An apparatus for the measurement of Maxwell’s displacement currents (MDC) in monomolecular organic layers at the air/water interface was designed and constructed. The equipment was tested in the standard regime in which the molecular conformational changes induced by surface pressure variations were studied.


National Institute of Chemistry


Laboratory for Spectroscopy of Materials


Dr. Boris Orel


In the laboratory for Spectroscopy of Materials the work was oriented in 1998 in the following areas:


(i) intercalation compounds (electrochromic, ion-storage films),


(ii) ion (H+ or Li+)-conductors (ormolytes) for EC device applications and fuel cells,


(iii) gasochromic films as an alternative to the "smart" windows for building applications.


For COST 518 action mainly materials mentioned in (ii) and (iii) are important because they exhibit multifunctional properties (mechanical stability and electrical (ionic or electronic) conductivity combined with optical properties).


(i) The bulk of the work in the laboratory was made in view of obtaining ion-storage materials. The aim was to make films via the sol-gel synthesis which exhibit ion-storage capacity above 20 - 25 mC/cm2. Such an ion-storage capacity is required in EC devices to compensate charge which is needed fully colour WO3 active EC film. Various materials were synthesised and tested (see the list of publications). Among various ion-storage films listed in Table 1 only two typical examples will be briefly mentioned: amorphous V/Ti-oxide films because the corresponding sputtered films are currently used as an counter-electrodes in

commercial EC devices made by Pilkington plc (UK) and the crystalline CeVO4. The later films are important because they are a typical sol-gel product which could be hardly made by sputtering deposition. The ion-storage capacity is up to 28 mC/cm2, i.e. a few mC/cm2 smaller with respect to that of sputtered V/Ti-oxide films, however, the optical transmittance of the films in charged and discharged states is nearly the same. The optical passiveness of the film is beneficial for their application in EC devices because the original colouration of WO3 film is retained in charged and discharged states and in addition, the optical transmittance of EC device in bleached states is higher than 65 % because of the inherent transparency of CeVO4 films in charged state. Initial studies were done in our laboratory, but further

investigations were performed also in Rome with the cooperation of Prof. F. Decker, Dr. F. Varsano and Dr. D. Dini. The latter two visited our laboratory using COST 518 funding.


Further development of counter electrodes will be oriented in the preparation of different orthovanadates in the thin film form. Recently we succeeded to make crystalline FeVO4 and Fe2V4O13 films and compared their electrochemical and EC properties with those of corresponding amorphous Fe/V-oxide films prepared at lower temperatures (~ 300 ° C). Results are promising showing that the films synergise good optical passiveness and ion-storage capacity with the electrochemical stability. Further collaboration with Prof. F. Decker group is planned to fully understand EC properties of (Fe,Ce)VO4 and FeVO4 films.


(ii) Ion-conductors for EC devices were made via the sol-gel synthesis (ormolyte) according to the procedure reported by P. Judeinstein (K. Dahmouche, M. Atik, N.C. Mello, T.J. Bonagamba, H. Panepucci, M.A. Aegerter, P. Judeinstein, Journal of Sol-Gel Science and Technology 8, 711-715 (1997)). Elastic gels were doped with LiClO4 and ionic-conductivity up to 10-5 S/cm were attained. The material is quite suitable for the use in EC devices since it is possible to dip-coated the counter-electrode and the active colouring films with the electrolyte. After pressing the glass plates together EC device is made which fulfil high optical standards (no defects) for EC devices. Different EC devices were made and extended testing were done mainly to evaluate long term (3000 cycles) cycling stability of the device.


The ormolyte was investigated also as a potential proton conductor. Using IR spectroscopic techniques the influence of the addition of the catalyst to the condensation of the ormolyte was determined. It wasfound that the Si-(OEt) group vibrational modes soon (~ 1/2 hour) after the addition of HCl (4 %)disappeared from the IR spectra and Si-O-Si mode started to emerge in the spectral range 1000 - 1150cm-1. After 5 days of ageing no changes were detected indicating that the cross linking has been completed. IR spectra also revealed that H-bonds were established between the water molecules added during hydrolysis and N- and O-sites of the backbone of the organic/inorganic hybrid.


We expanded studies on composites made by mixing in the ormolyte 12-tungstophosphoric acid (PWA-) and peroxopolytungstic acid (W-PTA). The aim was to make hybrid films which would exhibit combined optical and electrical properties because PWA and W-PTA are well known redox systems with properly balanced polaron and proton conductivity. Both materials in pure states exhibit electrochromism, however, their practical importance is low due to their unstability in dry atmosphere and at elevated temperatures (< 100 ° C).


We made composites of PWA and W-PTA with the ormolyte in which the concentration of both acids varied from 0 to 100 %. Elastic gels and films were made having proton conductivity from 10-6 up to 10-3 S/cm. Already low acid content increases the proton conductivity of the ormolyte from 10-7 to 10-5 S/cm. Films and gels made with low ormolyte content already exhibited excellent mechanical strength and the added ormolyte also improved their thermal stability. TG measurements revealed that 0.7 % of the ormolyte to W-PTA made films resistant enough to long-term exposure to the ambient atmosphere.


(iii) The addition of Pd in the form of PdCl2 to W-PTA made films gasochromic, i.e. they changed colour when exposed to H2/Ar mixture and turned to the bleach state again when flushed with air. One of the problems encountered with the gasochromic Pd:W-PTA films is the tendency of the W-PTA to change to nanocrystalline WO3.nH2O by releasing water and decomposition of peroxo groups. This process isspontaneous and takes place when films are aged at open atmosphere. The addition of 0.7 % of the ormolyte is already enough to stabilise the decomposition of peroxo groups and prevented the release of water. This stabilises proton conductivity and consequently gasochromic response of the films. The gasochromic response of the composites depended on the film thickness, Pd concentration and the content of the ormolyte. Typical composition in Pd:W-PTA/ormolyte is Pd/W = 1:125, ormolyte:W- TA=1:125.

Colouring/bleaching kinetics is fast (~ 100 s) but could be improved with the enhancing of Pd content.


Contrary to Pd:W-PTA/ormolyte films made from Pd:W-PTA/ormolyte (Pd/W=1:125 and

W-PTA/ormolyte=1:125) did not show electrochromism. This was explained by presence of the continuous W-PTA network which contrary to PWA is able to exhibit polaron conductivity.


The main trust in future COST 518 action will be oriented in the following directions:


- investigations of UV photochromism of PWA/ormolyte composites;


- improvements of gasochromic properties of Pd doped W-PTA and PWA/ormolyte composites;


- investigations of the structural properties of the composites in view of obtaining knowledge about the distribution of the active species in the composite, their interaction sites and changes which accompany the gasochromism and photochromism of the composites;


- to synthesise metal oxopolymers and oxide nanoparticles from molecular precursors such as metal alkoxides.


Table 1: Thin films made by sol-gel route in our laboratory (for electrochromic and gasochromic device applications)


Appendix


List of Papers


(in alphabetical order of the first author)


Project # 4


Magnetic Properties of Molecular and Polymeric Materials.


(1) Papers published in 1998


M. C. Muñoz, M. Julve, F. Lloret, J. Faus, M. Andruh


Influence of the counterion on the coordinating properties of (2.2'-bipyridyl)bis(oxalato)chromate(III) anion: crystal structures and magnetic properties of AsPh4[Cr(bipy)(ox)2]× H2O and [NaCr(bipy)(ox)2(H2O)]× 2H2O


J. Chem. Soc. Dalton Trans 3125-3131 (1998)


(2) Papers in press and submitted


H. Andres, J. M. Clemente-Juan, M. Aebersold, H. U. Güdel, E. Coronado, H. Büttner, G. Kearly, J. Melero, R. Burriel


Magnetic Excitations in Polyoxometalate Clusters Observed by Inelastic Neutron Scattering. Evidence for Anisotropic Ferromagnetic Exchange Interactions in the Tetrameric Cobalt(II) Cluster [Co4(H2O)2(PW9O34)2]10-. Comparison with the Magnetic and Specific Heat Properties


J. Am. Chem. Soc., submitted


J.J. Borrás-Almenar, J. M. Clemente-Juan, E. Coronado, B. S. Tsukerblat


High-nuclearity magnetic clusters: Generalized Spin Hamiltonian and its use for the calculation of the energy levels, magnetic properties and inelastic neutron scattering spectra


J. Am. Chem. Soc., submitted


J. M. Clemente-Juan, H. Andres, J. J. Borrás-Almenar, E. Coronado, H. U. Güdel, M. Aebersold, G. Kearly, H. Büttner, M. Zolliker


Magnetic Excitations in Polyoxometalate Clusters Observed by Inelastic Neutron Scattering. Evidence for ferromagnetic exchange interactions and spin anisotropy in a tetrameric Nickel(II) cluster encapsulated in the complex [Ni4(H2O)2(PW9O34)2]10-. Comparison with the magnetic properties


J. Am. Chem. Soc., submitted


M. Clemente-León, H. Soyer, C. Mingotaud, C. J. Gómez-García, E. Coronado, P. Delhaes


Langmuir-Blodgett films of magnetic clusters


Mol. Cryst. Liq. Cryst., in press


C. Giménez-Saiz, J. D. Woollins, A. M. Z. Slawin, E. Coronado, J. M. Martínez-Agudo, C. J.

Gómez-García, N. Robertson


Electrical and magnetic properties of the radical salts ET5[B10I10]× (CH2Cl2)0.8 and ET11[P2W18O62]× 3H2O


Mol. Cryst. Liq. Cryst., in press


Project # 7


Thin Film Preparation of Functional Molecular Materials


Papers published in 1998


D. Baranèok, J. Cirák, P. Tomèík, J. Vajda


Contactless detection of the orientation of molecules in an organic monolayer


Phys. Stat. Sol. (a) 169, 46-50 (1998)


D. Baranèok, J. Cirák, P. Tomèík, J. Vajda


Dynamic behaviour of diacetylene and polythiophene monolayer at the air/water interface


Proc. Europ. Conf. Electrooptical Properties of Polymers and Related Phenomena, ed. A. Bolognesi, Varenna – Italy, 1998, O29


G. Èík, D. Végh, J. Cirák, P. Tomèík, I. Èerveò


Electrochemical synthesis of the mono n-octyl-ester of 3(3-thienyl)glutaric acid and its properties


Synth. Met. 96 (1998) 71 -75


Project # 8


Development of New Polymeric Materials Based on Surface-Modified Clusters or Colloids


(1) Papers published in 1998


D. Avnir, L. C. Klein, D. Levy, U. Schubert, A. B. Wojcik


Organo-silica sol-gel materials


in „The Chemistry of Organic Silicon Compounds, Vol.2, Part 3", ISBN 0 471 96757 2, Z. Rappoport, Y.Apeloig (Eds.), J.Wiley & Sons (1998), p.2317-2362.


K. Dahmouche, M. Atik, N. C. Mello, T. J. Bonagamba, H. Panepucci, P. Judeinstein., M. A. Aegerter


Investigation of new ion conducting ormolytes


Ceramics Trans. 81, 311 (1998).


K. Dahmouche, M. Atik, N. C. Mello, T. J. Bonagamba, H. Panepucci, P. Judeinstein, M. A. Aegerter


New Li+ ion-conducting ormolytes


Solar Energy Mat. & Solar Cells 54, 1 (1998)


N. Hüsing, U. Schubert


Aerogels - Airy Materials: Chemistry, Structure, and Properties.


Angew.Chem.Int.Ed.Engl. 37, 22-45 (1998)


N. Hüsing, U. Schubert


Composition-Structure Relations in Organically Modified Silica Gels


Mat.Res.Soc.Symp. Proc. 519 (1998) in press


N. Hüsing, U. Schubert, K. Misof, P. Fratzl


Formation and Structure of Porous Gel Networks from Si(OMe)4 in the Presence of A(CH2)nSi(OR)3 (A = functional group)


Chem.Mater. 10, 3024-3032 (1998)


P. Judeinstein


Hybrid materials : intricate structures guiding complex dynamics


Mat.Res.Soc.Symp. Proc. 561 (1998), 561, in press


G. Kickelbick, U. Schubert


An unusual ring structure of an oligomeric oxotitanium alkoxide carboxylate


Europ.J.Inorg.Chem. 159-161 (1998)


G. Kickelbick, U. Schubert


Carboxylate-Substituted Oxotitanium and Oxozirconium Clusters as Structural Models for Titania- and Zirconia-Based Inorganic-Organic Hybrid Materials


Mat.Res.Soc.Symp.Proc. 519 (1998) in press


C. Lembacher, U. Schubert


Nanosized platinum particles by sol-gel processing of tethered metal complexes: influence of the precursors and the organic group removal method on the particle size


New J.Chem. 22, 721-724 (1998)


P. Lesot, S. Chapuis, J. P. Bayle, J. Rault, E. Lafontaine, A. Campero, P. Judeinstein


Structural-Dynamical Relationship in in silica PEG Hybrid Gels


J. Mater. Chem. 8, 147 (1998).


B. Orel, U. Opara Krasovec, U. Lavrencic Stangar, P. Judeinstein


All sol-gel electrochromic devices with Li+ ionic conductor, WO3 electrochromic films and SnO2 counter-electrode films


J. Sol-Gel Sci. Technol. 11, 87 (1998).


F. Ribot, C. Sanchez


Organically Functionalized Metallic Oxo-Clusters: Structurally well Defined Nanobuilding Blocks for the Design of Hybrid Organic-Inorganic Materials


Comments Inorg. Chem. (1998) in press.


E. Scolan, C. Sanchez


Synthesis and Characterization of Surface Protected Nanocrystalline Titania Particles


Chem. Mater. 10, 3217 (1998)


(2) Papers in press and submitted


N. Hüsing, U. Schubert, R. Mezei, P. Fratzl, B. Riegel, W. Kiefer, D. Kohler, W. Mader


Formation and Structure of Gel Networks from Si(OEt)4 / (MeO)3Si(CH2)3NR'2 Mixtures (NR'2 = NH2 or NHCH2CH2NH2)


Chem.Mater., 1999, in press


P. Judeinstein, V. Dessolle, J. P. Bayle, J. Courtieu, J. Rault


Investigation of anisotropic polymers by 13C NMR


J. Phys. Chem. , in press


G. Kickelbick, U. Schubert


Hydroxy Carboxylate Substituted Oxozirconium Clusters


J.Chem.Soc. Dalton, submitted


B. Lebeau, C. Sanchez


Sol-Gel Derived Hyvrid Inorganic-Organic Nanocomposites for Optics


Curr. Opinion Solid State Mat. Sci., 1999 in press


G. Kickelbick, P. Wiede, U. Schubert


Variations in Capping the Zr6O4(OH)4 Cluster Core: X-Ray Structure Analyses of

[Zr6(OH)4O4(OOCCH=CH2)10]2 (µ-OOCCH=CH2)4 and Zr6(OH)4O4(OOCR)12(nPrOH) (R = Ph, CMe=CH2)


Inorg.Chim.Acta 284, 1-7 (1999)


C. Sanchez, F. Ribot, B. Lebeau


Molecular Design of Hybid Organic-Inorganic Nanocomposites Synthesized via Sol-Gel


J. Mater. Chem. 1999 in press


C. Sanchez, A. Lafuma, L. Rozes, K. Nakatani, J.A. Delaire, E. Cordondillo, B. Viana, P. Escribano


Molecular Design of Hybrid Organic-Inorganic Nanocomposites with Emission and Photochromic Properties


SPIE, 1999 in press


WG2


MOLECULAR MATERIALS AND FUNCTIONAL POLYMERS FOR ADVANCED

DEVICES


a.Synthesis, Nonlinear Optical, Photophysical and Electrochemical Properties of

Subphthalocyanines


(CPK-model of a subphthalocyanine)


-Departments of Organic Chemistry C-I and Physics of Materials C-IV,


Universidad Autónoma de Madrid (UAM), Madrid, Spain.


-Institut Químic de Sarrià, Universitat Ramon Llull, Barcelona (Spain)


-France Telecom, CNET Paris-B; Dep. d’Electronique Quantique et Moléculaire, Bagneux; FRANCE.


Novel boron (III) subphthalocyanines (SubPcs) soluble in organic solvents containing a variety of donor and acceptor substituent groups have been synthesized by boron trihalide-induced cyclotrimerization of adequately substituted derivatives of phthalonitrile in 1-chloronaphthalene. The choice of the substituents on the 1,2-dicyanobenzene derivatives has been made taking into account the high reactivity of the Lewis acid BCl3 towards many functional groups. Considering this limitation we set out to the synthesis of phthalodinitriles equipped either with iodo-, nitro-, alkyl or arylthio-, alkyl or arylsulfonyl groups that are sufficiently stable under the required reaction conditions and also provide an easily accessible set of acceptor/donor-substituents. The quadratic and cubic hyperpolarizabilities of these compounds as well as their linear optical and electrochemical properties have been measured by several techniques including EFISH (at two wavelengths), HRS and THG, steady-state and time-resolved absorption and fluorescence, laser-induced optoacoustic calorimetry, time-resolved near-infrared emission spectroscopy, and cyclic voltammetry. b HRS has been measured at 1.46 m m where the contamination from the multiphoton-induced fluorescence can be ruled out. b HRS reachs high values that markedly depend on substitution. It shows a clear enhancement with the acceptor character of the substituents, the highest values being obtained for the compounds bearing the strongest acceptor groups. They are comparable or even superior to many efficient second-order compounds. A main outcome of these results is that an adequate choice of the substituents offers a promising route for optimisation of the quadratic response of the SubPcs. This kind of compounds are less prone to aggregation than their expanded analogues, the phthalocyanines, fluoresce with quantum yields ca. 0.25, lower than those typical for phthalocyanines, and have larger triplet quantum yields. The triplet-state lifetime is in the 100-ms time range, long enough for efficient oxygen quenching. Indeed, subphthalocyanines sensitize singlet molecular oxygen, O2(1Dg), with quantum yields ranging from 0.23 to 0.75. The ground-state oxidation potentials are similar to those of phthalocyanines, while the reduction potentials are clearly more negative, i.e., they are more difficult to reduce. In contrast, electronically excited subphthalocyanines are more easily oxidized than the corresponding phthalocyanines, by ca. 500 mV, which results in lower photostability, especially in polar solvents.


b) Gas sensing in spin-coated films of substituted sulfur containing phthalocyanines


-Departamento de Química Orgánica, Universidad Autónoma de Madrid,. Spain.


-Centre de Recherches Paul Pascal. CNRS,Pessac. France


-School of Chemical Sciences, University of East Anglia,Norwich, UK


-Health and Safety Executive, Broad Lane, Sheffield, UK


Novel Ni and Cu phthalocyanines bearing four or eight octylthio or octylsulfonyl chains have been synthesized. Conductivity has been found only for the Spin-coated films of tetraoctylthiophthalocyanines. We assume that tetrasubstitution facilitates via aggregation processes an appropriate stacked organization within the SC film. On the other hand, electron-donor subtituents also seem to favour conductivity. Such SC films can detect at r oom temperature levels until 1 ppm of NO2 gas, the response being fast, reversible and proportional tothe gas concentration. It has also been demonstrated that thin films with improved organization can be built using the LB technique, this leading us to expect improved gas detection properties (Figure 1).


concentration


Fig. 1. Response of the SC film of 5 to 1-5 ppm of NO2


b.Supramolecular organization of subphthalocyanines in Langmuir and

Langmuir-Blodgett Films and nonlinear optical properties


-Departamento de Química Orgánica (C-I), Universidad Autónoma de Madrid, Spain


-Centre de Recherche Paul Pascal, F-33600 Pessac, France


-Department of Physics of Materials,), Universidad Autónoma de Madrid, Spain


Interfacial studies of a series of subphthalocyanine (SubPc) macrocycles, differently substituted either in the periphery (with polar and donor groups) or in the axial position of the macrocycle (with a chlorine atom or a trihexylsiloxy group), have been carried out. Remarkable changes in the orientation of the macrocycles at the air-water interface have been observed by varying the number of polar groups in the periphery or adding a bulky group in the axial position. The morphology of the monolayers has been carefully studied by Brewster angle microscopy. Monolayers made of compounds could be efficiently transferred onto hydrophobic substrates. LB films of SubPcs were characterized in detail by UV-VIS and

IR spectroscopies, and X-ray diffraction and ellipsometry experiments. These studies indicate that the LB films of SubPcs are surely Y-type, formed by layers of a well-defined average thickness of ca. 16 Å. Preliminary studies on the nonlinear optical (NLO) properties of these materials have been carried out. In particular, Second Harmonic Generation (SHG) experiments have been performed on LB films of SubPcs


Publications


1. B. del Rey, U. Keller, T. Torres, G. Rojo, F. Agulló-López, S. Nonell, C. Martí, S. Brasselet, I. Ledoux, J. Zyss, J. Am. Chem. Soc. 1998, 120, 12808.


2. M. Nicolau, B. Del Rey, T. Torres, C. Mingotaud, P. Delhaes, M. Cook3, S. Thorpe, Synt. Metals, Inpress.


3. B. del Rey, M.V. Martínez-Díaz, T. Torres, B. Agricole, C. Mingotaud, N. Cuvillier,

G. Rojo, F. Agulló-López, J. Mat. Chem. In press


Working Group 3 Activity : Functional Polymers


Working Group 3 (WG3) main activity is related to the synthesis and characterization of Functional Polymers which have to be used for the preparation of advanced devices. So the activity is very wide because different contributions such as the chemistry of polymers/oligomers with their spectroscopical and structural characterization and the preparation of thin films are part of this working group. But alsovery peculiar aspect in the devices preparation are taken into consideration.


So several projects are included in this WG3, they are listed below:


Project 2: Low band gap polymers for devices


Project 3: Synthesis, characterization and optoelectronic potential of novel rigid-backbone polymers


Project 4: Magnetic properties of molecular and polymeric materials


Project 5: Polymers for olography


Project 6: Light emitting molecules and polymers


Project 7: Thin film preparation of functional molecular materials


Project 11: Possibility of converting PVC to radiation sensor


All the activity in this area has been recently the object of the WG3 meeting held in Varenna in September 1998. Another WG3 meeting is going to be organized in November/December 1999 in cooperation with the WG1 probably in Italy.


It’s difficult to give a complete review of the great amount of work which has been carried out within the WG3.


I’ll summarize what’s going on by dividing all the area in three parts:


-Synthesis


-Preparation of thin films


-Device and application


Synthesis


Most of the work has been focused in the preparation of synthetic polymers and oligomers having conjugated chains. This is because most, but not all, the devices which are of interest for the project are prepared with p conjugated materials. So materials that are currently investigated are: poly(phenylene)vinylenes, polythiophenes with different substituents, oligomers of thiophenes, carbon nanotubes, polyphenylenes.


Some of the inputs from these works are:


-Study of radical/anionic polymerization in PPV preparation


-Preparation of soluble PPV able to form polymer/nanotube composite material


-Synthesis of highly regioregular, differently substituted poly(3-alkylthiophene) and with modulated band gap


-Thiophene oligomers with well defined molecular structures


-Synthesis of polyphenylene


The above mentioned material has been prepared in order to be tested in Light Emitting Diodes devices obtaining device prototypes.


A well established material that has been studied is a "modular" polyester that was prepared as optical storage information. Their films fulfill most of the basic requirements for optical storage materials: fast response, high diffraction efficiency, long stability, erasure by heat or light and possibility to reuse (Project 5)


There is also a well established activity concerning the preparation of polymeric material with conducting and magnetic properties: electrodeposition of conducting polymers in presence of ferromagnetically coupled transition metal clusters, insertion of TTF-type molecules in between polymeric oxalato-bridged bimetallic layers and preparation of LB films with magnetic centers or clusters with high spin molecules (Project 4).


Thin film preparation


There are some collaborations that already started (Project 7), while another project (Project 13) on deposition with high vacuum technique has been recently been approved by the MC. The study of thebehaviour of some alkylthiophenes at the air-water interface is currently done in order to have some information on the structure of the monolayer which can been transferred onto solid substrate to form thin film with particular architecture. This will give information on the disposition of the macromolecules on water surface and on the substrate after the deposition. So there is some work carried out on the relation between the structure of the polymer and its disposition on water. Moreover it has been shown by some groups that the use of the Langmuir Blodgett technique give the opportunity to prepare oriented films

useful for polarized emission in light emitting diodes.


Project 13 has been approved in November by the MC and it's beginning to work.


Device and application


There are lot of devices that in the form of prototypes are prepared and tested.


There are three main classes of devices:


There are three main classes of devices:


Light Emitting Diodes (Project 3,6,7)


Photoreceptors (Project 7)


Holographic Storage Devices (Project 5)


Radiation sensors (Project 11)


Most of the activity of the groups has been focused on LEDs. There are strong groups operating in the area both on the chemical approach and in developing new device architecture. The interaction among different groups have to be improved: we would like to focus on this area in the next WG3 meeting to be organized at the end of September. The main activity however is devoted to the test of some new polymers or oligomers as active material in LEDs. Moreover there is a growing interest in the preparation and characterization of organic photoreceptors to be used for energy conversion. Some groups of the Cost 518 are operating in this area.


As mentioned before there is also a very well established activity on device for optical storage

information which has produced a device which is still stable after six years.


The use of PVC modified in order to be used as radiation sensors is also a promising field for application in sensing with a low cost material.


This is a general view and is difficult to go into the details of a single project. I think that COST is an opportunity to cooperate and all the people of WG3 has taken this opportunity into consideration.


Short Term Scientific Missions:


This part of the Action has been a great success. By the end of the 1998, 11 applications for missions had been received by the evaluation sub-committee (Chairman plus Vice-chairman) and 6 missions had taken place from BE, IE, TR, ES, IT to DE, GB, ES, IE, SK, AT.


At the time of writing, a total of 15 applications have been received and approved.


BREAKDOWN/COLLECTION OF TECHNICAL REPORTS:


1. Orla O'Connor Uni. of Sheffield Electroluminescence 15/8-15/11/97

Dublin Irel. England


2. Wim Piet Bijnens Dieter Neher Light Emitting 26/10-31/10/97

Diepenbeek,Be. Mainz.De. Molecules


3. Gema de la Torre Werner Blau Nonlinear Optics 10/11-10/12/97

Ponce. Dublin, Ireland

Madrid, Esp.


4. Özer Bekâroglu Tomas Torres Phthalocyanines 15/11-15/12/97

Istanbul.Tk. Madrid.Esp.


5. Francesca Varsano Ulrich Schubert Surface Modified 2/12-7/12/97

Roma, It. Wien.AT & Clusters & Colloids

B.Orel,Ljubliana


6. Tomas Torres M.Hanack Phthalocyanines, 2/2-12/2/98

Madrid,Esp. Tübingen.De.


7. Dr.Danilo Dini TU-Wien Surface Modified 24/4-29/4/98

Roma, Italy Ljubljana Clusters & Colloids


8. Dr. Roberto J. Solis Electroactive & 23/5-27/5/98

Zamboni Madrid, Esp. photoactive materials.

Bologna,Italy


9. Margreet de Kok Inst. Des Materiaux PPV & PPV 27/4-7/5/98

Diepenbeek,Belgium Nantes, France


10. Ulrike Salzner B. Champagne Conducting 3/6-10/6/98

Ankara,Turkey Namur


11. Ralf Hildebrandt S. Hvilsted Polymers for 1/6/-5/6/98

Gottingen.Germany Denmark Holography


12. Diarmuid O’Brien Uni.of Sheffield Phosphorescence 17/1-29/1/99

Dublin, Ireland England Emission from

D.polymers


13. Gema Rojo Ecole Normale Sup. Phthalocyanines(Pcs) 1/3/-30/3/99

-MartinezMadrid, Cachan,France

Spain


14. Javier Solís Istituto di Spettrosc. Molecular materials 19/3/-23/3/99

Madrid,Spain Bologna


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