A semi-empirical P.P.P. type s.c.f.m.o. method has been developed to calculate, with practical accuracy, heats of atomization (at 25 °C), bond lengths, and resonance energies benzenoid hydrocarbons. Sigma E σb are estimated simultaneously the pi πb in this method. Self-consistent field lengths obtained, by minimization total energy, + , respect each individual length. The empirical calculated a new term, stabilization energy per CC bond, is introduced.

The 35 Cl nuclear quadrupole resonance (n.q.r.) frequencies at 77 °K of twenty-two chloroformates, twenty-eight acid chlorides, two thiocarbonyl molecules, and five carbamyl chlorides are reported.

The 35Cl n.q.r. frequencies of eleven sulphinyl and sulphenyl chlorides, nine substituted alkyl sulphonyl five halo oxysulphonyl four N-substituted N-sulphonyl ten halobenzene six methylbenzene p-methoxybenzene nitrobenzene chlorides seven carboxy sulphone benzene are reported for 77 K. interpreted in terms the sulphur orbital electronegativity, inductive effects substituents possible dπ orbitals on sulphur. most coherent explanation is that —SO2— group behaves like pseduo-united atom germanium.

Everybody form a circle: Careful design of ligand strands and their reaction with Cu2+ ions leads to the formation title helicates. Incorporation differing numbers N-donor units within strand containing phenyl spacer results in pentanuclear head-to-tail circular helicate, whereas two different ligands heteroleptic helicate (see picture; green: Cu, red blue: ligands). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not...

E. A. C. Lucken and M. Whitehead, J. Chem. Soc., 1961, 2459 DOI: 10.1039/JR9610002459

A careful conformational analysis of poly(styrene-alt-maleic anhydride) at different pH values is presented. It found that a strong internal hydrogen bond formed intermediate pH, which induces change in the conformation polymer chain, becomes linear. This linearity does not depend on chirality polymer. The chain occurs only and can explain association among chains observed by dynamic light scattering 7.

The formation of either dinuclear double-stranded or pentanuclear circular helicates from a ligand containing two tridentate domains separated by phenylene unit can be controlled inter-ligand steric interactions which themselves are governed the size metal ion.

The self-assembly into nanotubes in solution of an amphiphilic copolymer is characterized by small-angle neutron scattering (SANS). This study confirmed the shape and size tubular association 3-D tubes predicted molecular orbital theory. Moreover, characterization stability has revealed that addition a very small amount salt to increases association. When more added, decreases, structure altered. was found be independent temperature therefore stable.

The self-assembly of poly(styrene-alt-dimethyl-N,N-propylamide) (SMI) polymers into nanotubes was studied using semiempirical PM3 calculations. Ordered polymer results from π-stacking styrenes and van der Waals interactions between the maleimide chains. Every styrene, half chains, in a racemo-di-isotactic SMI form π-stacks chain−chain pairs with neighboring polymer. Racemo-di-isotactic bent associations minimum-energy nanotube structure. Nanorods were observed experimentally diameters ∼5 nm.

To twist or not to twist? A ditopic ligand, L1, that contains a potentially tetradentate pyridyl–thiazole ligand chain and “external” crown ether unit is presented. Reaction of L1 with Cu+ Zn2+ ions results in the formation dinuclear double helicate [Cu2(L1)2]2+ mononuclear [ZnL1]2+ species. This system changes its preference for on inclusion s-block-metal at binding site (e.g., Sr2+ as shown scheme). There are numerous examples field metallosupramolecular chemistry demonstrate careful...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and nuclear quadrupole resonance interpretation of the structure cyclo-tri-.mu.-nitrido-dichlorophosphorusbis(oxochlorosulfurRuth Clipsham, R. M. Hart, A. WhiteheadCite this: Inorg. Chem. 1969, 8, 11, 2431–2436Publication Date (Print):November 1, 1969Publication History Published online1 May 2002Published inissue 1 November 1969https://pubs.acs.org/doi/10.1021/ic50081a036https://doi.org/10.1021/ic50081a036research-articleACS...

Abstract The characterization of the association an alternating copolymer was performed using theoretical methods (quantum mechanics and molecular mechanics) experimental (cryo-Transmission Electron Microscopy (cryo-TEM), neutron reflectivity scattering). most stable conformation obtained for self-association at pH 7 is a tubular structure in which eight SMA molecules make one twist helix. tubes can grow length by continued regular stacking benzene rings. nanotubes have inner outer diameters...

The CNDO/BW theory is applied to triatomic and polyatomic molecules ions calculate their spectroscopic ground states, equilibrium geometries, bonding energies, force constants. calculated results are compared the experimental of other CNDO methods.

Mathematical expressions for the electronegativities of elements are derived exactly using Hartree–Fock–Slater equations and Mulliken’s definition electronegativity. Relaxation effects neglected. These same ones used by Bartolotti, Gadre, Parr. They generalized spin-polarized case calculations done helium to krypton. Results show that ionization potentials closer experiment than non-spin-polarized trend in obtained from is as one Bartolotti et al. a program.

The local-spin-density (LSD) generalized-exchange (GX) theory is corrected for self-interaction by splitting the single-particle Fermi hole into pure-exchange and holes. An analysis of these components shows that non-self-interaction-corrected GX scheme overestimates pure exchange while underestimating self-interaction. This self-interaction-corrected called GX-SI scheme. Using this method correcting self-interaction, two other approximate (SIC) schemes can be derived in which (1) GX-LSD-SI...

The LW–SCF–PPP–LCAO–MO (π+σ) method is extended to molecules containing the C–O and C–N bonds. Several modifications are made, including a new minimization of total energy with respect geometry. Calculations use both Hinze–Jaffe Thorhallson, Fisk, Fraga valence state ionization potentials electron affinities, these compared. Heats atomization, ΔHa, bond lengths, Rij 50 heteroatomic conjugated calculated.Ionization derived from levels using Koopmans' theorem, used assign determined by recent...

Geometric characterization of 3,5-dihydroxybenzyl alcohol (DHBA)-based dendrimers has been achieved using molecular mechanics MM+ method and the PM3 semi-empirical orbital theory. Optimization DHBA-based dendrimer generations 1–5 (DG1–5) showed that DG1–3 have a relatively open structure with no internal spaces any particular size or shape, while DG4 5 assume more globular well-defined cavities. Encapsulation disperse red 1 (DR1) into cavities these dimethylsilyl linked led to blue shift in...