Polynorbornene-Based Double-Stranded Ladderphanes with Cubane, Cuneane, Tricyclooctadiene, and Cyclooctatetraene Linkers

Abstract

Double-stranded ladderphanes 2, 3, and 5 having cubane, cuneane, and cyclooctatetraene linkers are synthesized by ring-opening metathesis polymerization (ROMP) of the corresponding bisnorbornene monomers 10, 11, and 13, respectively. Attempts to polymerize the corresponding tricyclooctadiene-linked bisnorbornene 12 are not successful, starting monomer being recovered. Polymer with this tricyclic diene linker 4 is obtained from the rhodium-catalyzed isomerization of 2. The scanning tunneling microscopic (STM) image of 2 shows an ordered pattern on the graphite surface by self-assembly.

Cyclooctatetraenes through Valence Isomerization of Cubanes: Scope and Limitations

“…With ar ange of mono-and 1,4-disubstituted cubane derivatives (i.e., [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]i nh and the valence isomerization to COT derivatives could be explored. [Note:T here are at least 20 valence isomers with the general formula( CH) 8 ; [34] however,t he only interconversion of cubanea sr eported by Eaton was COT].…”

End Group Modification of Polynorbornenes

“…We have previously established that, upon treatment with the first‐generation Grubbs catalyst 3 , norbornenes fused with N ‐arylpyrrolidine 4 afford the corresponding polynorbornenes 5a (Figure ) with isotactic stereochemistry and all double bonds in trans ‐configuration . Thus, when the ROMP was quenched with 2 , 5b with an allyl acetate end group was obtained in 85% yield.…”

“…Upon treatment with the first generation of Grubbs catalyst, norbornenes fused with N ‐arylpyrrolidene moiety undergo ROMP stereoselectively giving the corresponding 2D comb‐like polynorbornenes with isotactic stereochemistry and all double bonds in trans ‐configuration . These protocols have recently been used for the construction of a series of polynorbornene‐based double‐stranded ladderphanes 1 9 having a range of aromatic, antiaromatic, and 3D organic and organometallic linkers, L, with diverse structural variety. Significant interactions between aromatic linkers in these ladderphanes may take place as evidenced by fluorescence quenching, excimer formation, as well as Soret band splitting (in prophyrin‐containing ladderphanes).…”

Cubane: 50 Years Later

“…The STM images show an ordered pattern by self-assembly on highly ordered pyrolytic graphite (HOPG) with the bright stripe width of 2.7 nm which is consistent with the estimated width of the cubane containing ladderphane 219 ( Figure 18). 175 Other work has evaluated the synthesis of cubane oligomers which form rode-like structures with very poor solubility and they have been proposed for use in small gap polymers. 176 The oligomers are synthesized by reacting cubyllithium 226 with 1,4-diiodocubane (43) in ether, and halogen exchange equilibrium occurs to give 227 and 228.…”