TY - JOUR
T1 - Synthesis and charge transfer interactions of cyclobis(4,4′-azopyridinium-p-phenylene)
AU - Nakagawa, Masaru
AU - Rikukawa, Masahiro
AU - Sanui, Kohei
AU - Ogata, Naoya
N1 - Funding Information:
The authors are grateful for financial support from Grant-in-Aid for Science Researcho n Priority Areas (No. 262) from the Japanese Ministry of Education, Sciencea nd Culture, and SasagawaS cientificR esearch Grant from the Japan ScienceS ociety.
PY - 1996
Y1 - 1996
N2 - A new tetracationic cyclophane, cyclobis(4,4′-azopyridinium-p-phenylene) (2·4PF6), was synthesized via template-directed synthesis and characterized by MS and NMR spectroscopy. For the preparation of π-electron-deficient 2·4PF6, the use of π-electron-rich templates such as 1,4-bis[2-(2-hydroxyethoxy)ethoxy]benzene (4) and 1,5-bis[2-(2-hydroxyethoxy)ethoxy]naphthalene (5) enhanced the cyclophane formation in 17 and 19% yields, respectively. 1H NMR spectra of the reaction mixture revealed that the cyclophane precursor 1·2PF6 formed supramolecular assembling complexes with hydroquinone derivatives 4 and 5 before the ring formation. The intermolecular charge transfer interaction and the stability constants (Ka) of complexes generated between the electron-acceptor 2·4PF6, and electron-donors 1,4-dimethoxybenzene 3, 4, and 5 were evaluated using UV-vis, spectroscopy and spectroscopic titration. The absorption bands attributable to CT interactions were centred at 580 nm for 3, 635 nm for 4, and 646 nm for 5, with stability constants of 17±2, 2100±200, and 2400±300, respectively.
AB - A new tetracationic cyclophane, cyclobis(4,4′-azopyridinium-p-phenylene) (2·4PF6), was synthesized via template-directed synthesis and characterized by MS and NMR spectroscopy. For the preparation of π-electron-deficient 2·4PF6, the use of π-electron-rich templates such as 1,4-bis[2-(2-hydroxyethoxy)ethoxy]benzene (4) and 1,5-bis[2-(2-hydroxyethoxy)ethoxy]naphthalene (5) enhanced the cyclophane formation in 17 and 19% yields, respectively. 1H NMR spectra of the reaction mixture revealed that the cyclophane precursor 1·2PF6 formed supramolecular assembling complexes with hydroquinone derivatives 4 and 5 before the ring formation. The intermolecular charge transfer interaction and the stability constants (Ka) of complexes generated between the electron-acceptor 2·4PF6, and electron-donors 1,4-dimethoxybenzene 3, 4, and 5 were evaluated using UV-vis, spectroscopy and spectroscopic titration. The absorption bands attributable to CT interactions were centred at 580 nm for 3, 635 nm for 4, and 646 nm for 5, with stability constants of 17±2, 2100±200, and 2400±300, respectively.
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U2 - 10.1016/S0968-5677(96)00047-8
DO - 10.1016/S0968-5677(96)00047-8
M3 - Article
AN - SCOPUS:0030393954
VL - 3
SP - 215
EP - 220
JO - Supramolecular Science
JF - Supramolecular Science
SN - 0968-5677
IS - 4
ER -