Dimer

About: Dimer is a research topic. Over the lifetime, 18291 publications have been published within this topic receiving 433645 citations.

Photoinduced Polymerization of Solid C60 Films

Abstract: We report experimental evidence for the photopolymerization of C7o films under irradiation with visible or UV fight. The tendency of C7o to dimerize is also confirmed by molecular dynamics calculations which find that the lowest energy dimer configuration contains a four-membered ring between monomers, similar to that calculated for the Ceo dimer or 'bucky dumbeU'. However, the cross section for this phototransformation is found to be considerably smaller than observed for Ceo, and this is attributed to a reduction in the number of reactive double bonds from 30 in Ceo to only 5 in each polar cap of a C7o molecule.

Origin of Attraction and Directionality of the π/π Interaction: Model Chemistry Calculations of Benzene Dimer Interaction

Abstract: A model chemistry for the evaluation of intermolecular interaction between aromatic molecules (AIMI Model) has been developed. The CCSD(T) interaction energy at the basis set limit has been estimated from the MP2 interaction energy near the basis set limit and the CCSD(T) correction term obtained by using a medium size basis set. The calculated interaction energies of the parallel, T-shaped,and slipped-parallel benzene dimers are -1.48, -2.46, and -2.48 kcal/mol, respectively. The substantial attractive interaction in benzene dimer, even where the molecules are well separated, shows that the major source of attraction is not short-range interactions such as charge-transfer but long-range interactions such as electrostatic and dispersion. The inclusion of electron correlation increases attraction significantly. The dispersion interaction is found to be the major source of attraction in the benzene dimer. The orientation dependence of the dimer interaction is mainly controlled by long-range interactions. Although electrostatic interaction is considerably weaker than dispersion interaction, it is highly orientation dependent. Dispersion and electrostatic interactions are both important for the directionality of the benzene dimer interaction.

Oligonucleotide interactions. 3. Circular dichroism studies of the conformation of deoxyoligonucleotides.

Abstract: The circular dichroism (CD) spectra of the four usual deoxymononucleosides, all sixteen deoxydinucleotides, and a number of trinucleotides have been measured. The dimer spectra are quite different from the sum of the spectra of their constituent monomers. This indicates the presence of base-stacked conformations analogous to those found for ribonucleoside diphosphates. The CD spectra of several deoxytrinucleotide diphosphates and single-strand f 1 DNA can be calculated fairly well by using a semi-empirical nearest-neighbor approach. There is little or no effect of terminal phosphate or of salt concentration on the optical properties of most deoxy oligomers. The possibility of simultaneous analysis of mixtures of deoxypurine or deoxypyrimidine sequence isomers has been examined. This seems to be a viable approach for the analysis of purine runs but cannot promise much success for pyrimidine runs.