Langmuir-Blodgett monolayers of a donor-acceptor diad TTF-sigma-(trinitrofluorene) (8) with an extremely low HOMO-LUMO gap (0.3 eV) have been used to create molecular junction devices that show rectification behavior. By virtue of structural similarities and position of molecular orbitals, 8 is the closest well-studied analogue of the model Aviram-Ratner unimolecular rectifier (TTF-sigma-TCNQ). Compressing the monolayer results in aligning the molecules, and is followed by a drastic increase in the rectification ratio. The direction of rectification depends on the electrodes used and is different in n-Si/8/Ti and Au/8/C16H33S-Hg junctions. The molecular nature of such behavior was corroborated by control experiments with fatty acids and by reversing the rectification direction with changing the molecular orientation (Au/D-sigma-A versus Au/A-sigma-D).
W. S. Johnson's total synthesis of the sesquiterpenoid longifolene is a classic example of the power of cationic polycyclizations for constructing complex molecular architectures. Herein we revisit the key polycyclization step of this synthesis using hybrid Hartree-Fock/density functional theory calculations and validate the feasibility of Johnson's proposed mechanism. We also explore perturbations to the 3-center 2-electron bonding array in a key intermediate that result from changing the polycyclic framework in which it is embedded.
Purpose: To determine the clinical and radiological variables that are associated with the undertaking of the Latarjet procedure, rather than a Bankart procedure, for anteroinferior shoulder instability.Methods: Clinical and radiological (CT scan) data was evaluated retrospectively, on a cohort of 66 patients who had undergone surgery for recurrent anteroinferior, glenohumeral instability.Odds ratios (95%confidence intervals) were calculated for each variable to determine its association with performance of the Latarjet procedure as opposed to an arthroscopic soft-tissue reconstruction.Results: Linear glenoid bone loss and ipsilateral, previous stabilization surgery were the two variables demonstrated to be associated with a significantly higher likelihood of the patient undergoing a Latarjet procedure.Age at surgery, treating surgeon, and sports involvement were not associated with an increased likelihood of the patient undergoing a Latarjet procedure.
Conclusion:None of the clinical parameters analyzed demonstrated an association with an increased likelihood of undergoing a Latarjet procedure for anteroinferior shoulder instability.Consistent with the published literature, we identified 19% linear glenoid bone loss as our cut-off for undertaking a Latarjet procedure for anteroinferior shoulder instability.
The role of diads…︁ in molecular electronics has been investigated with the recently synthesized tetrathiafulvalene‐σ‐trinitrofluorene diad (depicted on the cover). As determined by cyclic voltammetry, the HOMO–LUMO gap of this diad is as low as ∼0.3 eV, close to that of the theoretical Aviram–Ratner TTF‐σ‐TCNQ molecular rectifier. The rectification behavior of this molecule was tested as a function of electrode material (Si/Ti and Au/Hg), alignment, and orientation of the molecules in the junction. For more information, see the paper by J. R. Heath, D. F. Perepichka et al. on page 2914 ff.
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