Expanded Super molecules

Other species that are potentially aromatic such as the annulenes and radialenes have also been discussed, based on DFT computations and several experimentally prepared structures [112, 113]. The key conclusion of these studies is that aromaticity is an important consideration for these types of structures but the considerable strain often found in these molecules can override some of the aromatic stabilization. Owing to their cyclic delocalization virtually all carbomers are excellent electron acceptors, as evident from their high electron affinities [113]. 

Superb experimental skills led to the construction of the first substituted three-dimensional alkane carbomer, C56 carbo-cubane (38, the experimental structure carries eight methoxy groups for every hydrogen), containing linear dialkyne -C=C-C=C, buta-l,3-diynediyl) fragments as the first member of the expanded 

Strain energies for 36-38 are 111.8, 113.1, and 107.8 kcal mol respectively. As the strain energy of 7 is 155-161 kcal mol [118] the reason for the instability of 38-(OMe)g must lie in its substitution pattern that allows stabilization of otherwise kinetically higher lying transition structures or intermediates along the decomposition pathways. 

As Nature offers diamondoids in large quantities from crude oil [4, 127], one ought to explore their chemistry especially in view of their potential applications in nanoelectronic devices [128]. The first challenge is to understand systematically the reactivity patterns of diamondoids, especially with respect to their selective peripheral C-H bond functionalization. This difficulty is emphasized when one considers that even triamantane (3) reacts with typical electrophiles (e.g., Br2) with very low selectivity [129]. What alternatives are there - will ionic, radical, and radical ionic C-H activation reactions eventually lead to higher C-H bond selectiv-ities These questions can, in part, be answered by computational methods when considering the very different stabilities of the cations, radicals, and radical cations of the respective diamondoids in the first step. These purely thermodynamic stabilities very often translate nicely into selectivities, at least for cationic structures. As this is often not the case for radicals, transition structures also have to be considered which makes the prediction of selectivities far more elaborate [130]. 

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The threshold of the pulse energy to induce the laser tsunami is relatively low for a femtosecond laser compared with nanosecond and picosecond lasers. The laser tsunami expands to a volume of (sub pm)3 around the focal point, when an intense laser pulse is focused into an aqueous solution by a high numerical aperture objective lens. When a culture medium containing living animal cells is irradiated, they could be manipulated by laser tsunami. Mouse NIH 3T3 cells cultured on a substrate can be detached and patterned arbitrarily on substrates [36]. We have also demonstrated that the laser tsunami is strong enough to transfer objects with size of a few 100 pm [37], which is impossible by conventional optical tweezers because the force due to the optical pressure is too weak. In addition we demonstrated for the first time the crystallization of organic molecules and proteins in their super-saturated solution by laser tsunami [38-40]. 

Figure 12.3 A single crystal X-ray stmcture of the Jt-expanded borazine macrocycle 12.8 (Scheme 13.4). (a) Sketch of the super-structure, viewed along the c-crystallographic axis and (b) graphical illustration of the molecular conformation in the solid state. Carbon atoms are shown in gray, nitrogens in blue, and borons in green. Hydrogen atoms and solvent molecules have been omitted for the sake of clarity.

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