Through a Glass Darkly—Some Thoughts on Symmetry and Chemistry

This article reviews the development of concepts of chirality in chemistry. The story follows the parallel development of the optical properties of materials and the understanding of chemical structure until the two are fused in the recognition of the tetrahedral carbon atom in 1874. The different types of chiral molecule that have been identified since the first concept of the asymmetric carbon atom are introduced as is the notation used in various disciplines of chemistry to describe the relative or absolute configuration. In the final section, a polemical case for a unified nomenclature is presented.

(R,S)-2-{[4-(4-Methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol

4-(4-Methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-thiol (4) was alkylated to 2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not yet been reported in the literature. All the synthesized compounds were characterized by IR, 1D and 2D 1H-1H, 1H-13C and 1H-15N NMR spectroscopy and by elemental analysis.

(R,S)-2-{[4-(4-Methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl] thio}-1-phenyl-1-ethanol

4-(4-Methoxyphenyl)-5-phenyl--4H-1,2,4-triazole-3-thiol (4) was alkylated to 2-{[4-(-4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not been reported yet in the literature. All the synthesized compounds were characterized by IR, 1D and 2D NMR 1H-1H, 1H-13C and 1H-15N-NMR spectroscopy and by elemental analysis.

Asymmetric Carbon Nanotube Dimers for Novel Sensing Applications

In this work, we study the use of asymmetric carbon nanotube (CNT) dimers for the contactless detection of foreign nano-particles. Asymmetric CNT dimers create a unique field distribution, through the electromagnetic coupling, which in turn generates two distinct resonances representing the bonding and anti-bonding modes. The presence of a foreign nano-particle (NP) in the vicinity of the CNT dimer perturbs the dimer’s field distribution and causes the bonding and anti-bonding resonances to shift by unequal amounts depending on the NP location. By studying the difference in the shift of the bonding and the anti-bonding resonances, we show that the NP relative location can be reconstructed. The computational experiments performed in this work show how asymmetric CNT dimers can be used for novel sensing applications.