Synthesis and Structure of [9]Cycloparaphenylene Catenane: An All-Benzene Catenane Consisting of Small Rings

Abstract

A catenane consisting of two [9]­cyclo­para­phenyl­enes ([9]­CPPs) has been synthesized. Density functional theory calculations suggested that [n]­CPPs (n = 5, 6) are highly strained upon the formation of catenanes compared with the corresponding uncatenated CPPs, whereas [n]­CPP catenanes (n ≥ 7) are not strained. The synthesis of ([9]­CPP)([9]­CPP)­catenane was accomplished via the following route: (i) a spirosilylation, (ii) a nickel(0)-mediated macrocyclization, (iii) a desilylation, and (iv) reductive aromatization reactions. An X-ray diffraction analysis revealed a catenated structure of ([9]­CPP)([9]­CPP)­catenane.

Structural deformation and host–guest properties of doubly-reduced cycloparaphenylenes, [n]CPPs2− (n = 6, 8, 10, and 12)

“…20 Some latest works have been focused on the preparation of new CPP-based nanocarbons with different framework topologies, such as heteroatom-doped CPPs, [21][22][23] p-surface extended CPPs, [24][25][26] polymeric CPPs, 27,28 catenanes and trefoil knots. [29][30][31] Meanwhile, more extensive studies of [n]CPPs aimed at their structure-property relationships revealed their unique sizedependent optoelectronic properties and interesting supramolecular behavior. [32][33][34][35][36][37] While the syntheses of [n]CPPs have been well developed, 5,6 their solid-state structures remained unknown until the rst Xray diffraction characterization of [12]CPP was accomplished by Itami and coworkers in 2011.…”

Covalently Templated Syntheses of Mechanically Interlocked Molecules

“…Dilithiation of 7 and 9 followed by a reaction with a complex of trichlorosilane and TMEDA (tetramethylethylenediamine) successfully formed spirosilanes 8, 10, 29 DFT calculations showed that this discrepancy originates from the higher strain energy within the [9]CPP pseudocatenanes upon ring closure. 30 Remarkably, proton and carbon NMR spectra of homocatenanes 14 and 16 contained only one resonance due to the rapid pirouetting of the interlocked rings. Calculations on homocatenane 14 showed that its LUMO and LUMO+1 were delocalized over both rings, while the HOMO and HOMO-1 covered a single ring.…”

“…Scheme 3 Itami's synthesis of all-benzene catenanes 14, 15, and 16. 29,30 The first proof of principle was provided in 2017 in the synthesis of what were deemed quasi [1]catenanes and quasi [1]rotaxanes (Scheme 6). 32 The center of the inverted spiro compound diastereomer of 25 and the unwound isomer of 27 (not shown) were synthesized by altering the order of reactions.…”

“…Dilithiation of 7 and 9 followed by a reaction with a complex of trichlorosilane and TMEDA (N,N,N′,N′-tetramethylethylenediamine) successfully formed spirosilanes 8, 10, 29 and a [9]CPP/ [9]CPP catenane precursor (not shown). 30 Ring closing was achieved through Ni(0)-mediated aryl-aryl coupling, after which desilylation gave catenanes 11, 12, and 13. Reductive aromatization of the dialkoxycyclohexadiene moieties then yielded the corresponding catenanes 14, 15, and 16 as well as non-interlocked CPP side products.…”

Feeding a Molecular Squid: A Pliable Nanocarbon Receptor for Electron-Poor Aromatics

“… 18 , 19 In these systems, the receptor function can be precisely controlled by the type and extent of curvature and by adjusting the cavity dimensions. The curvature facilitates formation of interlocked structures, i.e., rotaxanes, 20 , 21 catenanes, 22 − 25 and molecular knots. 24 While the synthesis of curved aromatics is often challenging, 26 they provide structural rigidity, variable curvature types, 27 − 29 topologically nontrivial π conjugation, 23 , 30 − 32 , 19 chirality, 33 and unusual chromophore properties.…”