Octulene: A Hyperbolic Molecular Belt that Binds Chloride Anions

Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold‐in method. This new hydrocarbon macrocycle contains a large 24‐membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π‐conjugated surface. The consequences of distortion in octulene were explored using photophysical methods, which revealed a reduced electronic band gap and greater flexibility of the π system. Octulene contains a functional cavity with a diameter larger than 5.5 Å that is capable of efficiently binding the chloride anion in a nonpolar solvent (K_a= 2.2(4)×10⁴ m ^?1, 1 % dichloromethane (DCM) in benzene). The octulene–chloride interaction is stabilized by eight weak C(sp²)H???Cl bonds, providing the first example of a hydrocarbon‐based anion receptor.     

Nitration of Norcorrolatonickel(II): First Observation of a Diatropic Current in a System Comprising a Norcorrole Ring

A one‐pot reaction of 5,14‐bis(mesityl)‐norcorrolatonickel(II) with isoamyl nitrite under mild reaction conditions resulted in the consecutive formation of 3‐nitro‐, 3,12‐dinitro‐ and 3,16‐dinitro‐, 3,7,12‐trinitro‐, and 3,7,12,16‐tetranitro‐norcorrolatonickel(II) in 50–80 % yield. The substituted macrocycles retained their antiaromatic character. The observed regioselectivity of the substitution was analyzed by comparing the relative energies of the DFT energy‐optimized models of the radical or arenium cationic intermediates that can be formed upon reaction with NO₂. The nitrated systems were characterized by high‐resolution mass spectrometry, NMR and UV/Vis spectroscopy, X‐ray diffraction analysis, cyclic voltammetry, and DFT calculations. A significant and systematic cathodic shift of the redox couples was observed to correlate with an increasing number of the NO₂ group. A decrease of the LUMO energies in the tri‐ and tetra‐nitrated products stabilizes mono‐ and bis‐reduced complexes of these ligands. The reduction takes place on the macrocycle rather than on the metal ion leading to the consecutive formation of stable paramagnetic monoanion radicals and water‐soluble diamagnetic dianions with an aromatic character, which were revealed by ESR and ¹H NMR measurements, respectively. The electronic structures of the reduced forms were analyzed by extensive TD‐DFT calculations.     

NOTE: Polymerization of Cyclic Esters Using Aminoacid Initiators

The low-molecular weight poly(? -caprolactone) and polylactide were obtained by the polymerization of cyclic esters in the presence of amino acid initiators. The polymer structures were elucidated by means of MALDI TOF, NMR and IR studies. Effects of temperature, reaction time and initiator dosage on the polymerization process were examined.     

Bent-core 6-thioxoverdazyl: a comparison of mesogenic properties with the 6-oxo analogue

Two bent-core verdazyl radicals, 2[16] and 3[16], containing 6-thioxo and 6-oxo groups, respectively, were prepared and their physical properties were compared. Analysis of binary mixtures with bent-core mesogen 1[12] gave virtual N-I ([T_NI]) and N-I_re ([T_NIre]) transition temperatures. Results indicate that the thioxo derivative 2[16] has greater stabilising effect on the nematic phase than the 6-oxo analogue 3[16], presumably due to the higher dipole moment of the core (1.90 D vrs 0.83 D) despite the less favourable conformational properties.     

Small scale adiabatic dewar techniques to determine exothermic onset temperatures

The heightened focus on safety in the chemical process industry has resulted in a growing trend to provide reliable thermochemical information before process scale-up. The exothermic onset temperature of compounds is of key concern. The small scale adiabatic dewar age (SSAD) test, developed at Merck Research laboratories, is used to determine exothermic onset temperatures. These tests are conducted under nearly adiabatic conditions using specially designed dewar sample cells and commercially available programmable calorimeters. The dewar cell method offers a rapid and accurate method to enhance standard test procedures and allows measurement of auto catalytic behavior using small samples.The SSAD technique is applicable to both solids and liquids and has the following advantages: 1) small sample size, 2) ability to handle compounds in which exothermic activity is accompanied by large pressure increases without damaging experimental equipment, 3) accurate determination of exothermic onset temperature, 4) ease of experiment set-up, 5) ease of data interpretation and 6) rapid experimental turn around time.The determination of the exothermic onset temperature using the SSAD technique will be presented and compared to data obtained using standard and isothermal age techniques.     

On nonlinear Koopman''s construction

We show that there exists a possibility for a nonlinear variant of Koopman's construction. This gives a natural way for introducing nonlinear quantum maps. Applications to quantum chaos are indicated.     

Anisotropic Triebel-Lizorkin spaces with doubling measures

We introduce and study anisotropic Triebel-Lizorkin spaces associated with general expansive dilations and doubling measures on ℝⁿ with the use of wavelet transforms. This work generalizes the isotropic methods of dyadic ϕ-transforms of Frazier and Jawerth to nonisotropic settings. We extend results involving boundedness of wavelet transforms, almost diagonality, smooth atomic and molecular decompositions to the setting of doubling measures. We also develop localization techniques in the endpoint case of p = ∞, where the usual definition of Triebel-Lizorkin spaces is replaced by its localized version. Finally, we establish nonsmooth atomic decompositions in the range of 0 < p ≤ 1, which is analogous to the usual Hardy space atomic decompositions.