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Interplanar Distance (interplanar + distance)
Selected AbstractsHigh-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic DiimidesADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Joon Hak Oh Abstract Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure,property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close ,-plane distance (3.3,3.4,Å), a large ,-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046,2.091,g,cm,3). These features result in excellent field-effect mobilities of up to 1.43,cm2,V,1,s,1 with minimal hysteresis and high on,off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4,Å, resulting in a high mobility (up to 0.44,cm2,V,1,s,1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics. [source] MP2, DFT-D, and PCM study of the HMB,TCNE complex: Thermodynamics, electric properties, and solvent effects,INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2008Ondrej Kysel Abstract Geometry, thermodynamic, and electric properties of the ,-EDA complex between hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) are investigated at the MP2/6-31G* and, partly, DFT-D/6-31G* levels. Solvent effects on the properties are evaluated using the PCM model. Fully optimized HMB,TCNE geometry in gas phase is a stacking complex with an interplanar distance 2.87 × 10,10 m and the corresponding BSSE corrected interaction energy is ,51.3 kJ mol,1. As expected, the interplanar distance is much shorter in comparison with HF and DFT results. However the crystal structures of both (HMB)2,TCNE and HMB,TCNE complexes have interplanar distances somewhat larger (3.18 and 3.28 × 10,10 m, respectively) than our MP2 gas phase value. Our estimate of the distance in CCl4 on the basis of PCM solvent effect study is also larger (3.06,3.16 × 10,10 m). The calculated enthalpy, entropy, Gibbs energy, and equilibrium constant of HMB,TCNE complex formation in gas phase are: ,H0 = ,61.59 kJ mol,1, ,S = ,143 J mol,1 K,1, ,G0 = ,18.97 kJ mol,1, and K = 2,100 dm3 mol,1. Experimental data, however, measured in CCl4 are significantly lower: ,H0 = ,34 kJ mol,1, ,S = ,70.4 J mol,1 K,1, ,G0 = ,13.01 kJ mol,1, and K = 190 dm3 mol,1. The differences are caused by solvation effects which stabilize more the isolated components than the complex. The total solvent destabilization of Gibbs energy of the complex relatively to that of components is equal to 5.9 kJ mol,1 which is very close to our PCM value 6.5 kJ mol,1. MP2/6-31G* dipole moment and polarizabilities are in reasonable agreement with experiment (3.56 D versus 2.8 D for dipole moment). The difference here is due to solvent effect which enlarges interplanar distance and thus decreases dipole moment value. The MP2/6-31G* study supplemented by DFT-D parameterization for enthalpy calculation, and by the PCM approach to include solvent effect seems to be proper tools to elucidate the properties of ,-EDA complexes. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Polyaniline-multiwalled carbon nanotube composites: Characterization by WAXS and TGAJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008T. Jeevananda Abstract Polyaniline/carboxylated multi-walled carbon nanotube (PAni/c-MWNT) nanocomposites have been synthesized by micellar aided emulsion polymerization with various c-MWNTs compositions, viz., 0.5, 1, 5, and 10 wt %. The microcrystalline parameters such as the nanocrystal size (,N,), lattice strain (g), interplanar distance (dhkl), width of the crystallite size distribution, surface weighted crystal size (Ds), and volume of the ordered regions were calculated from the X-ray data by using two mathematical models, namely the Exponential distribution and Reinhold distribution methods. The effects of heat ageing on the microcrystalline parameters of the PAni/c-MWNT nanocomposites were also studied and the results are correlated. The thermal stability and electrical resistivity of the PAni/c-MWNT nanocomposites were examined with thermogravimetric analysis (TGA) and a conventional two-probe method. The TGA data indicate that the thermal stability of the nanocomposites improved after the incorporation of c-MWNTs. The influence of temperature on the resistivity of the nanocomposites was also measured. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Synthesis and characterization of styrene butadiene rubber,Bentonite clay nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 7 2009Sugata Chakraborty In the present study, naturally occurring unfractionated bentonite clay was used to prepare styrene butadiene rubber/bentonite clay nanocomposite by latex stage blending. The bentonite clay was organo-modified by in situ resol formation by the reaction of resorcinol and formaldehyde. The latex clay mixture was co-coagulated with acid. The resulting clay masterbatch was compounded and evaluated by Fourier Transform Infrared spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetric analysis, and Differential Scanning Calorimetry. XRD showed that the interplanar distance of the in situ resol-modified bentonite clay increased from 1.23 to 1.41 nm for the unmodified bentonite. TEM analysis indicated partial exfoliation and/or intercalation. EDS (Si and Al mapping) of the clay revealed the nature of the dispersion in the nanocomposites vis-à-vis the conventional styrene-butadiene rubber (SBR)/bentonite clay composite. Thermogravimetric analysis was used to compare the decomposition trends of the SBR/clay nanocomposites with the SBR/clay composite. The glass transition temperature of SBR/clay nanocomposites increased as compared with that of neat SBR. Substantial improvement in most of the other mechanical properties was also observed in case of the nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Formation of X-ray shift fringes and a new method for determination of the difference sign of interplanar distancesACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2004H. R. Drmeyan A detailed investigation of the conditions for the formation of X-ray shift fringes is carried out, aiming to apply these patterns to investigations of crystal imperfections. Expressions for the amplitudes and X-ray intensity distribution are obtained for a two-crystal interferometer, in which the interplanar distance between two reflecting planes, d, has a relative change . It is theoretically proven and experimentally confirmed that the value of the period of interference bands essentially depends on the sign of ,d. [source] Bis(4-aminopyridine)silver(I) nitrate and tris(2,6-diaminopyridine)silver(I) nitrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2000Olof Kristiansson The bis(4-aminopyridine)silver(I) cation in [Ag(C5H6N2)2]NO3 has the Ag atom on a twofold axis and displays an N,Ag,N angle of 174.43,(15)° and an Ag,N distance of 2.122,(3),Å. The two ligands are planar and the angle between the two ligand planes is 79.45,(9)°. The pyridine rings are stacked in piles with an interplanar distance of 3.614,(5),Å, a distance that strongly suggests that pyridine ,,, interactions have an appreciable importance with respect to the non-bonded crystal organization. The tris(2,6-diaminopyridine)silver(I) cation in [Ag(C5H7N3)3]NO3 has Ag,N distances of 2.243,(2), 2.2613,(17) and 2.4278,(18),Å, and N,Ag,N angles of 114.33,(7), 134.91,(7) and 114.33,(7)°. The Ag+ ion is situated 0.1531,(2),Å from the plane defined by the three pyridine N atoms. [source] Mapping of unstressed lattice parameters using pulsed neutron transmission diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2002Javier Roberto Santisteban Stress measurement by neutron diffraction depends critically on knowledge of the unstressed lattice parameter (a0) of the specimen under study. As a result, measurement of stress profiles in components where a0 is not homogeneous throughout the sample, such as welds or carburized surfaces, can be particularly difficult. An efficient solution to this problem is proposed based on the pulsed neutron transmission diffraction technique. This technique exploits the sharp steps in intensity, the so-called Bragg edges, appearing in the transmitted neutron spectra of polycrystalline materials, such steps being produced by coherent scattering from lattice planes. The position of these Bragg edges as defined by the time-of-flight technique is used to determine precisely local interplanar distances. In this work it is shown that the unstressed lattice parameter of thin specimens subjected to plane stress fields can be defined by recording transmission spectra at different sample inclinations, in complete analogy with the sin2, technique used in X-ray diffraction. Moreover, by using an array of detectors it is possible to produce a radiographic `image' of a0 for plane specimens or thin sections out of three-dimensional ones. The capability of the technique is exemplified by mapping the changes in a0 for a ferritic weld that was used as a round robin sample in an international program for standardization of stress measurements by neutron diffraction. [source] Formation of X-ray shift fringes and a new method for determination of the difference sign of interplanar distancesACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2004H. R. Drmeyan A detailed investigation of the conditions for the formation of X-ray shift fringes is carried out, aiming to apply these patterns to investigations of crystal imperfections. Expressions for the amplitudes and X-ray intensity distribution are obtained for a two-crystal interferometer, in which the interplanar distance between two reflecting planes, d, has a relative change . It is theoretically proven and experimentally confirmed that the value of the period of interference bands essentially depends on the sign of ,d. [source] Hydrogen-bonding versus,,, stacking interactions in dipyrido[f,h]quinoxaline-6,7-dicarbonitrile and 6,7-dicyanodipyrido[f,h]quinoxalin-1-ium chloride dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2008Leonid Kozlov The solvent-free title compound, C16H6N6, is an aromatic derivative of phenanthroline with an extended , system. It exhibits a remarkable ,,, columnar stacking in the crystal structure, with interplanar distances of 3.229,(3) and 3.380,(3),Å, the shorter spacing being between the two molecules within the asymmetric unit. Adjacent units along the stacked arrays are rotated in-plane with respect to one another by approximately 120°. The hydrochloride derivative, C16H7N6+·Cl,·2H2O, in which one of the phenanthroline N atoms has been protonated, crystallized as a dihydrate. The supramolecular organization in this compound is characterized by continuous hydrogen bonding between the component species, yielding two-dimensional hydrogen-bonded networks. This study demonstrates the high significance of the ,,, stacking interactions in the solvent-free aromatic system and how they can be undermined by introducing hydrogen-bonding capacity into the ligand. [source] | |||||||||||||