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LB Films (lb + film)

Distribution by Scientific Domains
Polymers and Materials Science50%
Chemistry50%

Selected Abstracts

Synthesis, Characterization and OFET Properties of Amphiphilic Mixed (Phthalocyaninato)(porphyrinato)europium(III) Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2009
Pan Ma
Abstract Amphiphilic mixed (phthalocyaninato)(porphyrinato)europium(III) triple-decker complexes Eu2[Pc(15C5)4]2[T(C10H21)4P] (1) and Eu2[Pc(15C5)4]2[TPOPP] (2) [H2Pc(15C5)4 = 2,3,9,10,16,17,23,24-tetrakis(15-crown-5)phthalocyanine; H2T(C10H21)4P = meso -5,10,15,20-tetra- n -decylporphyrin, H2TPOPP = meso -5,10,15,20-tetrakis(4-pentyloxyphenyl)porphyrin] were designed and synthesized by the raise-by-one-story method. These novel sandwich triple-decker complexes were characterized by a wide range of spectroscopic methods, and they were also electrochemically studied. Highly ordered films were fabricated by the Langmuir,Blodgett (LB) technique into organic field-effect transistors (OFETs). The devices display good OFET performance with a carrier mobility in the range 0.03,0.78 cm2,V,1,s,1. As expected, the devices show a low threshold voltage range from ,1.19 to ,4.34 V. The mobility of compound 1 reaches 0.78 cm2,V,1,s,1, which is the highest value so far achieved for LB film-based OFETs, as a result of the narrow energy gap (1.04 eV) of this compound.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Glycosyltransferase Microarray Displayed on the Glycolipid LB Membrane

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003
Noriko Nagahori
Abstract ,(1,4),Galactosyltransferase expressed as a fusion protein with maltose binding protein (MBP-GalT) was displayed specifically on a Langmuir,Blodgett (LB) membrane prepared by photopolymerization of maltotriose-carrying glycolipid (1) with 1,2-bis(10,12-tricosadiynoyl)- sn -glycero-3-phosphocholine (2). The catalytic activity of MBP-GalT on the LB film was directly monitored by the surface plasmon resonance (SPR) method using a GlcNAc-carrying water-soluble polymer (3) as an acceptor substrate. Highly sensitive sigmoidal-type signals were obtained upon the addition of the acceptor substrate in the presence of the donor substrate, UDP-galactose (UDP-Gal), while the binding of 3 was not detected in the absence of UDP-Gal. The intensities of the signals were dependent on the amount of immobilized MBP-GalT on the LB film, which was estimated from the images obtained by atomic force microscope (AFM). [source]

Preparation, characterization, and electrical properties of dual-emissive Langmuir-Blodgett films of some europium-substituted polyoxometalates and a platinum polyyne polymer

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010
Li Liu
Abstract A new series of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of a rigid-rod polyplatinyne polymer coordinated with 2,7-bis(buta-1,3-diynyl)-9,9-dihexylfluorene (denoted as PtP) as the ,-conjugated organometallic molecule, an europium-substituted polyoxometalate (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film-forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by ,,A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable, well-defined, and well-organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu-based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near-white emission spectra can be obtained due to the dual-emissive nature of the mixed PtP/POM blends. These Pt-polyyne-based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13-layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between ,1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879,888, 2010 [source]

Tetrathiafulvalene-, 1,5-Dioxynaphthalene-, and Cyclobis(paraquat- p -phenylene)-based [2]Rotaxanes with Cyclohexyl and Alkyl Chains as Spacers: Synthesis, Langmuir,Blodgett Films, and Electrical Bistability,

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2007
X. Guo
Abstract The synthesis and characterization of two new (TTF-DNP-CBPQT4+) [2]rotaxanes 1 and 2 is reported, based on tetrathiafulvalene (TTF), 1,5-dioxynaphthalene (DNP), and cyclobis(paraquat- p -phenylene) (CBPQT4+) with cyclohexyl and alkyl chains as the spacers. Multilayer Langmuir,Blodgett (LB) films of [2]rotaxanes 1 and 2 are prepared. Conducting atomic force microscopy, scanning tunneling microscopy, and two-terminal junction device studies indicate that the LB films of [2]rotaxanes 1 and 2 show electrical bistability behavior. By comparing with the TTF-DNP-CBPQT4+ [2]rotaxanes reported by Stoddart et,al. previously, the present results imply that proper modification of the chemical structures of the TTF unit and the spacer have negligible effect on the electrical bistability behavior of these TTF-DNP-CBPQT4+ [2]rotaxanes. These findings will allow for the design and preparation of new multifunctional TTF-DNP-CBPQT4+ [2]rotaxanes in the future. [source]

Preparation, characterization, and electrical properties of dual-emissive Langmuir-Blodgett films of some europium-substituted polyoxometalates and a platinum polyyne polymer

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010
Li Liu
Abstract A new series of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of a rigid-rod polyplatinyne polymer coordinated with 2,7-bis(buta-1,3-diynyl)-9,9-dihexylfluorene (denoted as PtP) as the ,-conjugated organometallic molecule, an europium-substituted polyoxometalate (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film-forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by ,,A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable, well-defined, and well-organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu-based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near-white emission spectra can be obtained due to the dual-emissive nature of the mixed PtP/POM blends. These Pt-polyyne-based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13-layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between ,1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879,888, 2010 [source]

Effect of Fullerene on Photocurrent Performance of 6- O -Porphyrin-2,3-di- O -stearoylcellulose Langmuir-Blodgett Films

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2008
Keita Sakakibara
Abstract Thin films consisting of 6- O -porphyrin-2,3-di- O -stearoylcellulose (H2PCS) and fullerene (C60) were fabricated for anodic photocurrent generation systems by the Langmuir-Blodgett (LB) technique. The , -complexation between the porphyrin moiety and C60 in the LB films was investigated by means of the surface pressure (,)-area (A) isotherms, UV-vis, and fluorescence spectroscopy. The photocurrent density generated from the H2PCS,C60 LB monolayer films exhibited an increase with increasing the C60 proportion and reached a maximum at a mixing ratio of 1:2, yielding a quantum yield of 12.5% and an IPCE (incident photon-to-current efficiency) of 0.50% at a bias potential of +100 mV vs. SCE. Furthermore, the LB five-layer films could give rise to the IPCE value of 1.5% at +100 mV without significant decline of the quantum yields, which was due to the function of C60 as an electron carrier to improve the interlayer electron transfer through each layer. These results have demonstrated a promising method for preparing the donor,acceptor systems using cellulose as a scaffold in the LB films. [source]

Photoreactions and lateral patterning in Langmuir and Langmuir,Blodgett films

THE CHEMICAL RECORD, Issue 2 2007
Mutsuyoshi Matsumoto
Abstract Reversible morphological changes occur with photoisomerization of azobenzene in Langmuir,Blodgett (LB) films complexed with polycations, which contradicts an implicit assumption of the concept of free volume that two-dimensional film structures are preserved during the photoisomerization. J-aggregates of chromophores are formed by two processes. The first process is "light-induced J-aggregation" in which photoisomerized molecules form J-aggregates. The other process is "triggered J-aggregation," in which photoisomerization of one of the components triggers J-aggregation of another chemical species in the mixed films. Both processes of J-aggregation are in many cases accompanied by large morphological changes of the films. However, LB films fabricated using processes under isobaric conditions do not change their morphology during light-induced J-aggregation and are patterned with J-aggregates using ultraviolet illumination through a photomask. Phase separation in mixed LB films gives rise to two-dimensional patterns, which are used to fabricate templates by using an amphiphilic silane-coupling agent as one of the components in the mixed LB films. Nanopatterns are also fabricated. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 69,77; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20099 [source]

In Situ Spectroscopic Characterization of Rectifying Molecular Monolayers Self-Assembled on Gold

CHEMPHYSCHEM, Issue 15 2007
Alberto Girlando Prof.
Abstract We report visible, Raman, and infrared spectra of self-assembled monolayers (SAMs) formed by the donor-(,-bridge)-acceptor chromophore, Z -,-[N -(,-acetylthioalkyl)-4-quinolinium]-,-cyano-4-styryldicyanomethanide (CH3CO-S-CnH2n -Q3CNQ where n=8, 10), on gold-coated substrates. The data are compared with the spectra collected for the same compound in solution and in the solid state, and with those obtained for a Langmuir,Blodgett (LB) monolayer of C16H33 -Q3CNQ deposited on gold. Spectral analysis confirms that in solution, in the solid state and in the LB film the chromophore has a zwitterionic (D+ -,-A,) ground state. At variance with this well-known result, our data show that in SAMs deposited on gold the chromophore has a more neutral, quinoid ground state. We relate this difference to the different packing of the molecules in the two different films: in SAMs in fact the chromophores stand almost vertical with respect to the substrate, whereas in LB films they make an angle of about 45 degrees. The Q3CNQ molecule is a well-known molecular rectifier, and for SAMs we were able to check the direction of electron flow at forward bias on the same samples that have been characterized spectroscopically, shedding light on the rectification mechanism. [source]