245 research outputs found
Spectroscopic detection of carbon nanotube interaction with amphiphilic molecules in epoxy resin composites
No full textIncorporation of carbon nanotubes into epoxy resin composites has the effect of increasing electrical conductivity at low percolation levels. An amphiphilic molecule such as palmitic acid has been used to increase the surface contact area and improve the dispersion of the carbon nanotube bundles in the prepolymer. The chemical environment of the dispersed nanotubes has been probed using vibrational Raman spectroscopy. Spectroscopic Raman maps, on sample surfaces (60x60 µm2) with ratios of nanotubes to palmitic acid varying from 1:2 to 2:1 by weight, have been recorded to test the uniformity of the dispersion. Substantial spatial inhomogeneities have been observed in the G-band shift and an additional spectral band at 1450 cm-1. The 1450 cm-1 band has been attributed to the CH3 group of the amphiphilic molecules adsorbed onto the nanotube surface. The maps are correlated with the measured electrical conductivity values. The highest conductivity has been observed for the best dispersed nanotubes and nanotubes with the highest degree of interaction
Synthesis and Structure-Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells
No full textHere, the large scale synthesis of nanocrystalline ZnO spheres and tetrapods in the size range of 8-40 nm by chemical vapor synthesis using zinc metal as precursor is described. A detailed study of the effect of experimental parameters on the morphology and yield is presented. High-resolution transmission electron microscopy images of the tetrapods show that they are formed by the self assembly of four nanorods in the vapor phase. The tetrapods have optical absorption coefficients that are one order of magnitude greater than the spheres and show intense UV luminescence whereas the spheres show only the green emission. The observed differences in the optical properties are related to the presence of surface defects present in the nanospheres. The tetrapods have increased efficiencies for application in dye sensitized solar cells when compared to spheres
The delicate balance between gelation and crystallisation: structural and computational investigations
No full textPredicting the ability of low molecular weight molecules to form hydrogels is difficult. Here, we have examined the self-assembly behavior of two chemically and structurally similar functionalized dipeptides, one of which is found to form a meta-stable hydrogel (1) and the other forming a crystalline solid (2). To investigate the reasons for these differences, we have employed computational methods to explore the crystal energy landscapes of the two molecules and examined differences in their preferred packing arrangements. We show that this method accurately predicts the packing for the crystalline solid, 2. Furthermore, the predictions for the gel-former 1 suggest that one-dimensional hydrogen-bonding arranged into tightly coiled molecular columns is a preferred mode of packing for this system, but is unfavorable for 2. The different tendencies of forming these columns could provide an explanation for the different behavior of the two molecules and demonstrate that this approach could be useful for the future predictable design of low molecular weight gelators.<br/
An adaptable peptide-based porous material
No full textPorous materials find widespread application in storage, separation, and catalytic technologies. We report a crystalline porous solid with adaptable porosity, in which a simple dipeptide linker is arranged in a regular array by coordination to metal centers. Experiments reinforced by molecular dynamics simulations showed that low-energy torsions and displacements of the peptides enabled the available pore volume to evolve smoothly from zero as the guest loading increased. The observed cooperative feedback in sorption isotherms resembled the response of proteins undergoing conformational selection, suggesting an energy landscape similar to that required for protein folding. The flexible peptide linker was shown to play the pivotal role in changing the pore conformation
In silico design of supramolecules from their precursors: Odd–even effects in cage-forming reactions
No full textWe synthesize a series of imine cage molecules where increasing the chain length of the alkanediamine precursor results in an odd–even alternation between [2 + 3] and [4 + 6] cage macrocycles. A computational procedure is developed to predict the thermodynamically preferred product and the lowest energy conformer, hence rationalizing the observed alternation and the 3D cage structures, based on knowledge of the precursors alone
CCDC 1563838: Experimental Crystal Structure Determination
No full textADEHUP : {2,4-di-t-butyl-6-[(1Z)-1-(3,5-di-tert-butyl-6-oxocyclohexa-2,4-dien-1-ylidene)-4,5-dihydro-1H-imidazole-1,3-diium-2-id-3-yl]phenolato}-tris(tetrahydrofuran)-cobalt(ii) dihexafluorophosphate Space Group: P b c a (61), Cell: a 11.2128(3)Å b 18.8423(4)Å c 46.5193(11)Å, α 90° β 90° γ 90° Related Article: Caleb F. Harris, Michael B. Bayless, Nicolaas P. van Leest, Quinton J. Bruch, Brooke N. Livesay, John Bacsa, Kenneth I. Hardcastle, Matthew P. Shores, Bas de Bruin, and Jake D. Soper|2017|Inorg.Chem.|56|12421|doi:10.1021/acs.inorgchem.7b01906,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CCDC 1563842: Experimental Crystal Structure Determination
No full textADEJOL : (acetonitrile)-{1,3-bis[3,5-di-t-butyl-2-(oxido)phenyl]-2,3-dihydro-1H-benzimidazol-2-ylidene}-cobalt(ii) Space Group: P m c a (57), Cell: a 31.4012(8)Å b 5.81329(15)Å c 18.1630(5)Å, α 90° β 90° γ 90° Related Article: Caleb F. Harris, Michael B. Bayless, Nicolaas P. van Leest, Quinton J. Bruch, Brooke N. Livesay, John Bacsa, Kenneth I. Hardcastle, Matthew P. Shores, Bas de Bruin, and Jake D. Soper|2017|Inorg.Chem.|56|12421|doi:10.1021/acs.inorgchem.7b01906,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CCDC 1563841: Experimental Crystal Structure Determination
No full textADEJIF : (acetonitrile)-{1,3-bis[3,5-di-t-butyl-2-(oxido)phenyl]-2,3-dihydro-1H-imidazol-2-ylidene}-cobalt(ii) acetonitrile solvate Space Group: P n n m (58), Cell: a 18.645(6)Å b 31.807(10)Å c 6.804(2)Å, α 90° β 90° γ 90° Related Article: Caleb F. Harris, Michael B. Bayless, Nicolaas P. van Leest, Quinton J. Bruch, Brooke N. Livesay, John Bacsa, Kenneth I. Hardcastle, Matthew P. Shores, Bas de Bruin, and Jake D. Soper|2017|Inorg.Chem.|56|12421|doi:10.1021/acs.inorgchem.7b01906,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CCDC 1563843: Experimental Crystal Structure Determination
No full textADEJUR : (acetonitrile)-{1,3-bis[3,5-di-t-butyl-2-(oxido)phenyl]imidazolidin-2-ylidene}-cobalt(ii) acetonitrile solvate Space Group: P 21/c (14), Cell: a 14.9912(17)Å b 14.3445(17)Å c 18.638(2)Å, α 90° β 111.286(2)° γ 90° Related Article: Caleb F. Harris, Michael B. Bayless, Nicolaas P. van Leest, Quinton J. Bruch, Brooke N. Livesay, John Bacsa, Kenneth I. Hardcastle, Matthew P. Shores, Bas de Bruin, and Jake D. Soper|2017|Inorg.Chem.|56|12421|doi:10.1021/acs.inorgchem.7b01906,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CCDC 1563839: Experimental Crystal Structure Determination
No full textADEJAX : {1,3-bis[3,5-di-t-butyl-2-(oxido)phenyl]imidazolidin-2-ylidene}-tetrahydrofuran-cobalt(ii) Space Group: P 1 (2), Cell: a 10.371(3)Å b 13.964(4)Å c 24.225(6)Å, α 84.881(4)° β 81.155(4)° γ 72.358(4)° Related Article: Caleb F. Harris, Michael B. Bayless, Nicolaas P. van Leest, Quinton J. Bruch, Brooke N. Livesay, John Bacsa, Kenneth I. Hardcastle, Matthew P. Shores, Bas de Bruin, and Jake D. Soper|2017|Inorg.Chem.|56|12421|doi:10.1021/acs.inorgchem.7b01906,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
- …
