Pyrenophanes

Systematic analysis of stabilities of cyclic dimeric pseudorotaxanes, generated from complementary homoditopic molecules, has been shown<99ACIE143, 99CC789> A new class of water-soluble cyclophanes, pyrenophane, capable of encompassing a neutral cavity has been constructed<99JA14S2>. 

A variety of arenophanes, such as naphthalenophanes, anthracenophanes, fluoreno-phanes, phenanthrenophanes, and pyrenophanes, have been reported [26]. Among... 

The effect of curvature on the aromatic character of polyaromatic hydrocarbons (PAHs) can be studied by comparing planar PAHs and their curved analogues. In order to address this issue a variety of [n](2,7)pyrenophanes (n = 7-10) in which the pyrene (22) moiety is strongly distorted from planarity have been synthesized and studied45. The degree of distortion from planarity and therefore the strain in these systems is controlled by the length and type of the tether that connects the two remote ends (positions 2 and 7) of 22. 

Three successive diamagnetic species can be detected when 22 is reduced with lithium metal in THF-rf8 (Figure 8) a protonated pyrene monoanion (22-H-), a dianion (222-) and finally a monoanion that incorporates the atoms of a former solvent molecule (solvent cleavage) (23)46. It has been shown that the reduction of the strained pyrene systems [7](2,7)pyrenophane (24), [2]metacyclo[2](2,7)pyrenophane (25), [8](2,7)pyreno-phane (26), [9](2,7)pyrenophane (27) and [10](2,7)pyrenophane (28) with lithium metal can afford totally different results than those encountered in the reduction of the planar parent pyrene system47. The reduction of these systems shows that the strain in the pyrene moiety profoundly affects its reactivity. 

Dehydrogenation of [3.3]- and [4.4]octahydropyrenophanes 267 and 269 gave fully aromatic pyrenophanes, serving as model systems for excimers in studies by Staab et al. [80]. 

Cyranski et al. examined the series of pyrenophanes where the tethering chain has 6-12 carbon atoms. The nonplanar distortion is measured as the bend angle a, defined as the angle made between the outside ring plane and the horizon, or more simply, the angle C11-C2-C7. Relative ASE is computed using Reaction... 

Abe, H. Mawatari, Y. Teraoka, H. Fujimoto, K. Inouye, M. Synthesis and molecular recognition of pyrenophanes with polycationic or amphiphilic functionalities artificial plate-shaped cavitant incorporating arenes and nucleotides in water. J. Org. Chem. 2004, 69 (2), 495-504. 

Other oxidants like thallium(III) oxide, vanadium(V) oxyfluoride, palladium ) acetate, and ruthenium(IV) tetrakis(trifluoracetate) have been developed as powerful tools for the intramolecular biaryl coupling reaction [7,93,113]. Nevertheless, DDQ is still one of the most versatile reagents in oxidative coupling reactions (see Scheme 14 and 29 [82,114]). The highly strained dioxa[8](2,7)pyrenophane (65), portraying an overall curvature of nearly 90° for the pyrene subunit, was finally obtained from the mefa-cyclophanediene (66) by dehydrogenation with DDQ in refluxing benzene in 67% yield [114]. 

Scheme 29. Reaction sequence to the curved dioxa[8](2,7)pyrenophane (65, [114]) a) (MeO)2CHBF4, CH2C12, room temperature, 2h b) fBuOK, THF, 3 h c) fBuOK, THF/ fBuOH = 1/1, room temperature, 3 h d) DDQ,benzene, A, 12 h, 65 (67%),66 (26%)...

Polycyclic aromatic hydrocarbons can be bent by bridging in a similar fashion. Two recent examples of such [n] cydophanes are azulenophane 116 [77] and 1,8-dioxa[8](2,7)pyrenophane 117 [78]. X-ray structure analysis revealed an angle of 3.7° between the azulene ring planes, whereas the pyrene moiety is bent by nearly 90°. 

Recent synthesis of pyrenophanes ° allowed us to study the dependence of the global aromaticity of the pyrene moiety on the degree of its bending and also how individual rings react to bending. ... 

Yet, several classes of non-planar aromatic compounds are also known. In most cases, such compounds contain fused benzene-like ring moieties that are bent out-of-plane by steric constraints. Molecular belts [45], pyrenophane derivatives [46, 47] and contracted porphyrinoids [48] are representative examples of these systems. In general, the study of non-planar aromatic compounds opens new opportunities for developing molecular devices with potential application in materials science. For example, porphyrinoids have recently attracted significant interest, as their curved aromatic stmctures show concave or convex n surfaces able to interact in various ways with electroactive compounds [48]. 

Water-soluble crownophane Crownophane 42 were cationic water-soluble pyrenophane with strong recognition toward anionic arenas including nucleotides in water... 

The [2.2](2,7)pyrenophane (450) has been formed in six stages from 5,3-dimethyl[2.2]metacyclophane, and the hexaoxa[6.6.6](l,3,5)cyclophane (451) made in the same number of steps from phloroglucinol... 

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