Toward Electrochemically Controllable Tristable Three‐Station [2]Catenanes

Abstract

Encouraged by the prospect of producing an electrochemical, color‐switchable red–green–blue (RGB) dye compound, we have designed, synthesized, and characterized two three‐station [2]catenanes. Both are composed of macrocyclic polyethers containing three π‐electron‐rich stations, which act as recognition sites for a π‐electron‐deficient tetracationic cyclophane. The molecular structures of the two three‐station [2]catenanes were characterized fully by mass spectrometry and 1H NMR spectroscopy. To anticipate the relative occupancies of the three stations in each [2]catenane by the cyclophane, model compounds with the same constitutions in the vicinity of the stations were synthesized. The relative ground‐state populations of the three stations occupied in both [2]catenanes were estimated from the thermodynamic parameters for 1:1 complexes between all these model compounds and the cyclophane, obtained from isothermal titration calorimetry (ITC). The electrochemical and electromechanical properties of the three‐station [2]catenanes were analyzed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and spectroelectrochemistry (SEC). The first three‐station [2]catenane was found to behave like a bistable system, whereas the second can be described as a quasi‐tristable system.

Electrochromic materials using mechanically interlocked molecules

“…The DFT calculations predicted that DNP-DEG, TTF-DEG and DFBZ should be ideal guest molecules to obtain the RGB colors. Based on this prediction, we synthesized some model compounds 7−11 (figure 3) [35,36]. Figure 4 shows the UV-Vis spectra of the CBPQT 4+ inclusion complex in MeCN.…”

“…The binding strengths of the model guests 7−11 with the CBPQT 4+ [35,36] were obtained from measurements carried out in MeCN solutions by isothermal titration calorimetry (ITC). The thermodynamic data are summarized in table 2.…”

“…DNP-TEG is the second largest (K a = 43.9 × 10 3 M −1 ). In the case of DNP-C5DEG, it is evident that the simple modification, where the second closest oxygen atoms from the naphthalene ring were replaced by methylene groups, drastically reduces the binding affinity to CBPQT 4+ [35]. X-Ray crystallographic data for the 1 : 1 complex formed between DNP-TEG and CBPQT 4+ indicates that the second closest oxygen atoms from the naphthalene ring are involved in [CH • • • O] interactions with the CBPQT 4+ ring [27][28][29].…”

“…Electrochemistry on the model compounds 7 and 9−11 was performed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) [35,36]. The half-wave potentials (E 1/2 ) were determined from the DPV peals.…”

“…Based on our preliminary investigations, we were led to propose the design of the RGB catenanes illustrated in figure 5 [11,35]. In the first generation RGB catenane (12 4+ , RGB1 4+ ), the three stations-TTF diol, BZ and DNP-were simply linked by oligoethyleneglycol chains.…”