Periodic Functionalization of Surface-Confined Pores in a Two-Dimensional Porous Network Using a Tailored Molecular Building Block.

We present here the periodic functionalization of a two-dimensional (2D) porous molecular network using a tailored molecular building block. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, 1-isoDBA, having an isophthalic acid unit connected by an azobenzene linker to a C12 alkyl chain and five C14 chains, was designed and synthesized. After the optimization of monolayer preparation conditions at the 1,2,4-trichlorobezene (TCB)/graphite interface, scanning tunneling microscopy (STM) observation of the self-assembled monolayer of 1-isoDBA revealed the formation of extended domains of a porous honeycomb-type molecular network, which consists of periodically located nanowells each functionalized by a cyclic hexamer of hydrogen-bonded isophthalic acid units and those without functional groups. This result demonstrates that the present strategy based on precise molecular design is a viable route to site-specific functionalization of surface-confined nanowells. The nanowells of different size can be used for guest coadsorption of different guests, coronene COR and hexakis[4-(phenylethynyl)phenylethynyl]benzene HPEPEB, whose size and shape match the respective nanowells. STM observation of a ternary mixture (1-isoDBA/COR/HPEPEB) at the TCB/graphite interface revealed the site-selective immobilization of the two different guest molecules at the respective nanowells, producing a highly ordered three-component 2D structure.

Aroma of Turmeric: Dependence on the Combination of Groups of Several Odor Constituents.

Turmeric is a popular material that plays an important role in the flavor and fragrance industries. Although many compounds have been reported as components of turmeric, its aroma profile has not been clarified. Recently we have developed a new approach for evaluating the complex odors of materials based on recent research on the mechanism of odor recognition. Here we report the characteristic aroma properties of turmeric obtained through the investigation of its aroma profile. The hexane extract of turmeric had a turmeric-like odor, whereas the steam distillate of turmeric had a pungent, non-turmeric-like odor. We carried out bulb-to-bulb distillations of the extract and the steam distillate. For the hexane extract, two fractions with completely different odors were obtained. One was a high boiling point fraction (group A) with a turmeric-like odor, which consisted of ar-turmerone and ß-turmerone as the main components, and the other was a low boiling point fraction (group B), which consisted of α-curcumene and ß-sesquiphellandrene. In contrast, the bulb-to-bulb distillation of the steam distillate gave a fraction (group C) with a very different odor from groups A and B. Group C was composed of several kinds of alcohols that were not present in groups A and B. These results indicate that the group C fraction causes the different, pungent odor of the turmeric oil obtained by steam distillation. The variation in the aroma of turmeric depended on the combination of these three groups of odor constituents.