An Alternative Synthetic Route of [3₅](1,2,3,4,5)Cyclophane, and Structural Properties of Multibridged [3_n]Cyclophanes and Their Charge-Transfer Complexes in the Solid State¹

Abstract

To develop an improved synthetic route to [3(6)](1,2,3,4,5,6)cyclophane (CP) 2, a more practical synthetic route to [3(5)](1,2,3,4,5)CP 3 than the original one was developed, which started from [3(2)](1,3)CP 7 via [3(4)](1,2,4,5)CP 5. The fundamental structural parameters of [3(n)]CPs (n = 3-6) in the solid state were elucidated, and the observed structures were in good agreement with the most stable conformers in solution and those predicted by the theoretical calculations. In the case of [3(6)]CP 2, the most stable C(6)(h) structure was observed in the crystal structure of the 2-TCNQ-F(4) (1:1) complex, whereas the highly strained structure with a D(6)(h) symmetry was observed in the crystal structure of 2 and the 2:TCNQ:benzene (1:1:1) complex because of a severe disorder problem. [3(n)]CPs (n > 3) showed reversible redox processes, and 2 (+0.39 V vs F(c)/F(c)(+), Cl(2)CHCHCl(2)) showed the lowest first half-wave oxidation potential [E(1/2) (I)] in [3(n)]CPs. The E(1/2) (I) data support the strong donating ability of 2 and its lower homologues. This is attributed to their molecular structures where effective hyperconjugation between the benzyl hydrogens and benzene ring is possible. By taking advantage of the strong electron-donating ability of [3(n)]CPs, their CT complexes with TCNE, TCNQ, and TCNQ-F(4) were prepared, and their crystal structural properties were examined. The single-crystal conductivity data of the CT complexes indicated that the TCNQ-F(4) complexes showed higher conductivities than the corresponding TCNQ complexes mainly due to a larger charge separation. Among the [3(n)]CP-TCNQ complexes, the [3(3)](1,3,5)CP 6-TCNQ-F(4) (1:1) complex showed the highest conductivity (10(-)(4) S cm(-)(1)), and this was ascribed to the formation of an infinite column of partially overlapped acceptors with a short acceptor-acceptor distance, while the formation of such a column was not observed in the 2-TCNQ-F(4) complex. Although the conductivities of the cyclophane-CT complexes are much lower than those of the TTF related complexes, this study successfully provides the basic knowledge for understanding the CT interactions in the solid state.

C‐terminal Tensin‐like (CTEN) is an oncogene which alters cell motility possibly through repression of E‐cadherin in colorectal cancer

“…The TCNE adduct with 3 3 (1,3,5)cyclophane is reported to have a $\tilde \nu $ CN at 2134 cm −1 ,80 which suggests reduced TCNE, not TCNE 0 , as reported. Most likely this is a misprint, but perhaps it indicates formation of the electron‐transfer salt [3 3 (1,3,5)cyclophane] .+ [TCNE] .− , as also the dark purple color might indicate.…”

Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures

“…[19c] Upon revisiting this material it was reformulated as Cu 3 A C H T U N G T R E N N U N G (1,3,5)cyclophane is reported to have a ñ CN at 2134 cm À1 , [80] which suggests reduced TCNE, not TCNE 0 , as reported. Most likely this is a misprint, but perhaps it indicates formation of the electron-transfer salt [3 3 - …”

Optical and electronic properties of siloxane-bridged cyclic dimers with naphthylene or pyrenylene moieties

“…It has been well-known that cyclophane compounds possess the electron-donating ability to form the CT complexes with TCNQ. 18 On the other hand, the pyrene derivative with strong electron-donating groups, such as 1,3,6,8-tetrakis(dimethylamino)pyrene has also been reported to form CT complex with TCNQ efficiently. 19 We also confirmed that the CT complex formation of pyrene or CD2 with TCNQ by the absorption spectral change of pyrene or CD2 in the presence of TCNQ as shown in Figure 4.…”