Search results for "Intermolecular"
showing 10 items of 396 documents
Solution-processed thin films based on sandwich-type mixed (phthalocyaninato)(porphyrinato) europium triple-deckers: Structures and comparative perfo…
2012
The solution-processed thin films of a series of three sandwich-type mixed (phthalocyaninato)(porphyrinato) europium complexes with different numbers of hydroxyl groups at the meso-substituted phenyl groups of porphyrin ligand 1–3 were prepared by a quasi-Langmuir–Shafer (QLS) method. Examination by spectroscopic methods revealed that J-type aggregates have been formed with the increasing degree of order of molecular stacking 1 < 2 < 3 films. The IR and XRD results reveal that, a dimeric supramolecular structure was formed depending mainly on the π–π interaction between the tetrapyrrole cores of neighboring triple-decker molecules, which, as the building blocks, self-assembled into the targ…
Formation of linear Ni nanochains inside carbon nanotubes: Prediction from density functional theory
2013
Abstract First principles calculations have been performed to investigate the ground state properties of monoperiodic single-walled carbon nanotubes (CNTs) containing nanochain of aligned Ni atoms inside. Using the PBE exchange-correlation functional ( E xc ) within the framework of density functional theory (DFT) we predict the clusterization of Ni filaments in ( n ,0) CNTs for n ⩾ 9 and for ( n , n ) CNTs for n ⩾ 6. The variations in formation energies obtained for equilibrium defective nanostructures allow us to predict the most stable Ni@CNT compositions. Finally, the electronic charge redistribution has been calculated in order to explore intermolecular properties leading to stronger…
Hexachlororhenate(IV) salts of organic radical cations
2005
Abstract The ionic salts ( p -rad) 2 [ReCl 6 ] ( 1 ) and ( m -rad) 2 [ReCl 6 ] ( 2 ) ( p / m -rad = 2-(4/3- N -methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazol-1-oxyl-3- N -oxide) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The nitronyl nitroxide cations in compound 1 show a layered disposition, whereas the [ReCl 6 ] 2− units are placed between these layers. The nitronyl nitroxide cations in compound 2 adopt an hexagonal array but they do not result in layers. Bulk magnetic properties of 1 and 2 have been investigated in the temperature range 2–300 K. Both compounds show weak but significant intermolecular antiferromagnetic …
Restricting Magnetic Interaction Pathways in Polyoxometalate Salts of Cationic Nitronyl Nitroxide Free Radicals
2004
Abstract : Salts 1 and 2 that combine the [W 6 O 19 ] 2- Lindqvist anion with the cationic nitronyl nitroxide (NN) free radicals p -MepyNN + and n Bu 3 NCH 2 NN + , respectively, have been synthesized and their structural and magnetic properties have been studied. Keywords: Nitroxide radicals, polyoxometalates, magnetism. Introduction Ferromagnetism based on purely organic materials has raised a lot of interest during the last decade [1]. Most of the studies have been performed with nitronyl nitroxide (NN) radicals due to their persistence, stability and ease of functionalization [2]. Bulk ferromagnetism in these compounds arises from ferromagnetic interactions between open-shell molecules …
Modeling hole transfer in DNA: Low-lying excited states of oxidized cytosine homodimer and cytosine–adenine heterodimer
2008
Abstract Charge transport in DNA strands has been studied by characterizing on theoretical grounds the lowest doublet states of the oxidized cytosine homodimer (CC + ) and adenine–cytosine heterodimer (CA + ) along the intermolecular separation of the monomers. The high-level quantum-chemical ab initio CASPT2 method and accurate one-electron basis sets have been employed. Both cationic species are found to be bound with comparable binding energies as those of neutral CC and reduced CC − . The results suggest that charge transport in DNA and the distinct photophysical attributes related to the polymer can be described within the framework of a unified theory. A cooperative micro-hopping mech…
Low-pressure pyrolysis of tBu2SO: synthesis and IR spectroscopic detection of HSOH.
2005
Sulfenic acid (HSOH, 1) has been synthesized in the gas-phase by low-pressure high-temperature (1150 degrees C) pyrolysis of di-tert-butyl sulfoxide (tBu(2)SO, 2) and characterized by means of matrix isolation and gas-phase IR spectroscopy. High-level coupled-cluster (CC) calculations (CCSD(T)/cc-pVTZ and CCSD(T)/cc-pVQZ) support the first identification of the gas-phase IR spectrum of 1 and enable its spectral characterization. Five of the six vibrational fundamentals of matrix-isolated 1 have been assigned, and its rotational-resolved gas-phase IR spectrum provides additional information on the O-H and S-H stretching fundamentals. Investigations of the pyrolysis reaction by mass spectrome…
Improving the Robustness of Organic Semiconductors through Hydrogen Bonding
2021
Molecular organization plays an essential role in organic semiconductors since it determines the extent of intermolecular interactions that govern the charge transport present in all electronic applications. The benefits of hydrogen bond-directed self-assembly on charge transport properties are demonstrated by comparing two analogous pyrrole-based, fused heptacyclic molecules. The rationally designed synthesis of these materials allows for inducing or preventing hydrogen bonding. Strategically located hydrogen bond donor and acceptor sites control the solid-state arrangement, favoring the supramolecular expansion of the π-conjugated surface and the subsequent π-stacking as proved by X-ray d…
Molecular interactions in 1-pentanol +2-methyl-2-butanol mixtures: Static dielectric constant, viscosity and refractive index investigations at 5, 25…
1989
Static dielectric constants, refractive indices and viscosities of 1-pentanol +2-methyl-2-butanol mixtures were measured at 5, 25 and 45°C. The results show that the mixing of the two isomers modifies the polarizability and the resistence of viscous flow of the system depending on the composition and temperature. Short range intermolecular interactions producing hetero-alcohol open dimers are considered.
In-situ pressure crystallization and X-ray diffraction study of 1,1,2,2-tetrachloroethane at 0.5 GPa
2004
Abstract 1,1,2,2-Tetrachloroethane, C2H2Cl4 (denoted TCE, m.p. 230 K) has been in-situ pressure crystallized in a Merrill-Bassett diamond-anvil cell, and its structure has been determined at 0.5 GPa and 295 K from the single-crystal X-ray diffraction data. TCE crystallizes in the monoclinic space group P21 /c with the molecules located at the inversion centers. The molecules are in the s-trans conformation, while they assume the gauche conformation in the crystal obtained by cooling. This implies that a phase transition may exist between the low-temperature and high-pressure phases of TCE. In the high-pressure phase the HC–CH moiety of the C2H2Cl4 molecule is disordered in two sites, one re…
High-pressurein-situcrystallization, structure and phase transitions in 1,2-dichloroethane
2004
AbstractThe single crystal of 1,2-dichloroethane, C2H4Cl2wasin-situcrystallized in a Merrill-Bassett diamond-anvil cell, and its structure determined at 0.7 GPa and 280 K. The crystals are monoclinic, space groupP21/c. The C2H4Cl2molecules in thes-transconformation are located at the inversion centers. The —H2C—CH2—ethylene group is disordered in two sites, with equal occupancies, one rotated by 180° to the other about the Cl⋯Cl axis of the molecule. The crystal cohesion forces have been attributed mainly to Cl⋯Cl intermolecular interactions, and their role in the mechanism of the phase transition at 177 K has been analysed. It was found that the order-disorder phase transition in the struc…