Formation of nitrogen‐containing heterocycles using di(imidazole‐1‐yl)methanimine

A mild and efficient synthesis of five‐ and six‐membered nitrogen containing heterocyclic compounds, in which di(imidazole‐1‐yl)methanimine serves as a one‐carbon source, is reported.     

Assignment of the vibrational bands of the B1u ← A1g transition in solid benzene films

Low temperature absorption spectra of benzene films were observed in the ¹B_1u ← ¹A_1g transition region. The origins of the two progressions of the totally symmetric vibration v₂(a_1g) are assigned to the crystal-field-induced 0—0 transition and to the false origin 0 + v_1g(e_2g).     

Protein surface recognition by synthetic receptors based on a tetraphenylporphyrin scaffold

[structure: see text] Receptors based on a tetraphenylporphyrin scaffold bearing different charged and hydrophobic groups have been synthesized. The interactions of these with horse heart cytochrome c were studied by fluorescence spectroscopy. Receptor 4 was identified to be the strongest synthetic receptor (K(d) = 20 nM) for cytochrome c. The differences in affinity among the receptors reflected a dependence on the number of anionic and hydrophobic groups.     

Nonadiabatic alignment of asymmetric top molecules: rotational revivals

The rotational revival structure of asymmetric top molecules, following irradiation by an intense picosecond laser pulse, is explored theoretically and experimentally. Numerically we solve nonperturbatively for the rotational dynamics of a general asymmetric top subject to a linearly polarized intense pulse, and analyze the dependence of the dynamical alignment on the field and system parameters. Experimentally we use time-resolved photofragment imaging to measure the alignment of two molecules with different asymmetry, iodobenzene, and iodopentafluorobenzene. Our numerical results explain the experimental observations and generalize them to other molecules. The rotational revival structure of asymmetric tops differs qualitatively from the intensively studied linear top case. Potentially it provides valuable structural information about molecules.     

High-resolution laser spectroscopy of the AΠu-XΠg system of Br2

The laser excitation spectrum of the Br₂⁺ molecular ion was observed at rotational resolution for the first time, with the ions being generated by Penning ionization. In contrast to Cl₂⁺ and F₂⁺ but in agreement with recent theoretical work, no vibrational or rotational perturbations are observed. The data from a number of vibrational bands are fitted simultaneously to give reliable estimates of the Dunham rotational and vibrational constants. This fit indicates that the vibrational numbering used in previous studies should be increased by 1 in the upper state.