The sterically congested tetraarylpyrenes 1-3, which can be readily accessed by Suzuki coupling, exhibit no-aggregation (pi-stacking) behavior in both solution and solid states. The indisposed tendency of 1-3 toward crystallization and their moderate molecular dimensions permit exploitation as blue light emitting materials in OLEDs with respectable device performances.
There is an upsurge of interest in contemporary theoretical and experimental research to unravel the structural details of water clusters. [1±8] The clusters are believed to be the perfect means for characterizing the structural changes and bonding mechanisms in passing from isolated molecules to a macroscopic collection, namely, bulk water, whose anomalous properties still remain mysteries. [1,2,9] A variety of modern theoretical and experimental methods have been employed to characterize the clusters. Both experiment and theory strongly suggest that the water trimer, tetramer, and pentamer have cyclic and quasiplanar minimum-energy structures. The larger clusters are expected to have 3D geometries, with the hexamer behaving as the transition from 2D to 3D structures. [1,2] The X-ray structural characterization of a decamer [10] and an octamer water cluster (cubic [11] and cyclic [12] forms) have been reported recently. Theoretical calculations for the hexamer have revealed the existence of several energy minima corresponding to ™ring∫, ™book∫, ™bag∫, ™cage∫, and ™prism∫ topologies within 0.7 kcal mol À1 . [13±15] The lowest energy conformer is the ™cage∫ followed by the ™book∫ and ™prism∫ structures, which are less than 0.1 and 0.2 kcal mol À1 higher in energy, respectively. [13±15] The ™ring∫ and ™bag∫ structures have been shown to be 0.5 and 0.7 kcal mol À1 higher in energy than the ™cage∫. To date, ™chair∫ [16,17] and ™boat∫ [18] cyclic hexamers included in host lattices have been characterized by X-ray crystallographic analysis. While Saykally and co-workers characterized the cage form of the hexamer, [15] Nauta and Miller reported the detection of a ™quasiplanar∫ hexamer in a helium droplet. [19] Herein, we report the first Xray structural characterization of the high-energy cyclic form of the water hexamer trapped in an organic supramolecular complex with the bimesityl dicarboxylic acid 4. The planar ring constitutes the basic structural motif of the high-pressure Ice II modification, [20] and is also one of the prominent morphologies found in the computer simulation of liquid water. [21] COMMUNICATIONS
The methyl groups in TetMe-IBX lower the activation energy corresponding to the rate-determining hypervalent twisting (theoretical calculations), and the steric relay between successive methyl groups twists the structure, which manifests in significant solubility in common organic solvents. Consequently, oxidations of alcohols and sulfides occur at room temperature in common organic solvents. In situ generation of the reactive TetMe-IBX from its precursor iodo-acid, i.e., 3,4,5,6-tetramethyl-2-iodobenzoic acid, in the presence of oxone as a co-oxidant facilitates the oxidation of diverse alcohols at room temperature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.