In the last decade, our understanding of the chemistry of olive oil has dramatically improved. Here, the essential chemistry of olive oil and its important minor constituents is described and related to the typical sensory categories used to rate and experience oils: color, aroma, bitterness, and pungency. We also describe experiments to explore some of the characteristics of olive oil related to its status as a new health food. Simple qualitative experiments on olive oil can be done in conjunction with tastings of the oil. First, we establish the relationship between the color of an object and the absorption of light by its molecular constituents using gummy candies and laser pointers. Then, the color of the various oils can be measured quantitatively using an iPhone app (Irodori). Illuminating the oil with a green laser produces a startling red fluorescence in the presence of the natural chlorophyll in some olive oils. Relatively straightforward colorimetric assays can reveal the presence of unsaturated fatty acids, healthy antioxidants such as phenols (unique to olive oils), contaminating peroxides, and the level of free fatty acid that is a telltale sign of poorly treated or stale oils. A final comparison of the sensory observations from tasting with the chemical and spectroscopic analysis provides an introduction to the science behind food standards and the sensitivity of our own sensory apparatus.

The title radical (F4BImNN) is a stable nitronylnitroxide that forms hydrogen-bonded NH... ON chains in the solid state. The chains assemble the F4BImNN molecules to form stacked contacts between the radical groups, in a geometry that is expected to exhibit ferromagnetic (FM) exchange based on spin polarization (SP) models. The experimental magnetic susceptibility of F4BImNN confirms the expectation, showing 1-D Heisenberg chain FM exchange behavior over 1.8-300 K with an intrachain exchange constant of Jchain/k = +22 K. At lower temperatures, ac magnetic susceptibility and variable field heat capacity measurements show that F4BImNN acts as a quasi-1-D ferromagnet. The dominant ferromagnetic exchange interaction is attributable to overlap between spin orbitals of molecules within the hydrogen-bonded chains, consistent with the SP model expectations. The chains appear to be antiferromagnetically exchange coupled, giving cusps in the ac susceptibility and zero field heat capacity at lower temperatures. The results indicate that the sample orders magnetically at about 0.7 K. The magnetic heat capacity ordering cusp shifts to lower temperatures as external magnetic field increases, consistent with forming a bulk antiferromagnetic phase below a Néel temperature of TN(0) = 0.72 K, with a critical field of Hc approximately 1800 Oe. The interchain exchange is estimated to be zJ/k congruent with (-)0.1 K.

The magnetism of purely organic open-shell molecules has been much-pursued 1 since the discovery that one phase of 2-(p-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (pNO2PhNN) is ferromagnetic 2 (FM) at very low temperature. Attempts to increase the magnetic transition temperatures of such molecules require creation or strengthening of reproducible crystal packing motifs that yield extended (beyond dimeric) dimensionalities of exchange interactions. Several radicals show quasi-onedimensional chain exchange of ∼10 K (84 J/mol) or larger. 3 2-(Benzimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (BImNN) is a particularly interesting example, forming 3a-c hydrogen-bonded one-dimensional chains with significant FM exchange. But, this magnetostructural motif can change significantly with even small molecular changes. 4 Because 4,5,6,7-tetrafluorobenzimidazole (F4BIm) exhibits very different crystallography from nonfluorinated benzimidazoles, 5 we synthesized 2-(4,5,6,7-tetrafluorobenzimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (F4BImNN) to investigate effects of extensive aryl fluorination on the magnetism of the BImNN variants.F4BImNN was made as shown in Scheme 1 and crystallized as blue-black prisms 6 for which room-temperature single-crystal X-ray diffraction shows 7 a monoclinic P2 1 /c lattice with intermolecular close contacts as shown in Figure 1. The dihedral angle ∠N1-C1-C8-N3 ) 22.1(5)°be-tween the benzimidazole unit and the NN ring. Hydrogenbonded chains along the c axis link N1-H in each F4BImNN to O2-N4 of the NN group in a neighboring molecule. The Markova, T. Carbon-based magnetism: An oVerView of the magnetism of metal-free carbon-based compounds and materials; Elsevier: Amsterdam, 2006. (2) Kinoshita, M.; Turek, P.; Tamura, M.; Nozawa, K.; Shiomi, D.; Nakazawa, Y.; Ishikawa, M.; Takahashi, M.; Awaga, K.; Inabe, T.; Maruyama, Y. Chem. Lett. 1991, 1225. (3) (a) Yoshioka, N.; Irisawa, M.; Mochizuki, Y.; Aoki, T.; Inoue, H. Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A 1997, 306, 403. (b) Yoshioka, N.; Irisawa, M.; Mochizuki, Y.; Kato, T.; Inoure, H.; Ohba, S.

Stable radicals 1-(4-(N-tert-butyl-N-aminoxyl)phenyl)pyrrole (BNPP) and 1-(4-(N-[para-methoxyphenyl]-N-aminoxyl)phenyl)pyrrole (MNPP) were synthesized and characterized by crystallography and magnetism. BNPP crystals exhibit 1-D chains of intermolecular nitroxide NO to nitroxide CH3 contacts, but polycrystalline magnetic susceptibility measurements show quite small antiferromagnetic (AFM) exchange interactions. MNPP shows stronger AFM exchange interactions that appear to be associated with a 2-D planar mesh of crystallographic nitroxide to nitroxide (N)O...N(O) contacts of 4.0-4.2 A. The AFM behavior of MNPP can be fitted to a 2-D square planar Heisenberg antiferromagnetic exchange model with J/k = (-)0.78 +/- 0.04 K and mean field constant theta = (-)0.77 +/- 0.12 K.

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