Cooperative Binding of 4-Aminoazobenzene and its Derivative to Quaternized Poly(vinylpyridine)

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  • 四級化ポリ(ビニルピリジン)と4-アミノアゾベンゼンおよびその誘導体との協同的結合
  • 水溶性高分子と染料の相互作用　ＩＶ　　四級化ポリ（ビニルピリジン）と４‐アミノアゾベンゼンおよびその誘導体との協同的結合

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Description

Binding of 4-aminoazobenzene (D-I) or 4-[bis(2-hydroxyethyl)amino]azobenzene (D-II) to poly (N-butyl-2- or -4-vinylpyridinium bromide) (C4P2VP or C4P4VP) or poly (N-octyl-2-vinyl-pyridinum bromide) (C8P2VP-I[Degree of Quaternization, DQ=32.2%] and C8P2VP-II [DQ=42.6%]) was determined by means of solubility measurements, spectrophotometry and dynamic dialysis technique.<BR>While the solubility of the dyes was proportional to C8P2VP-II concentration up to 7 g/l C4P2VP didn't show any solubilizing effect on these dyes (Fig. 1). Spectral shift of absorption maximum, caused by the addition of C8P2VP-II into an aqueous Sφresen buffer solution of these dyes, corresponded to the absorption spectra of these dyes in nonpolar solvent (Figs. 3 and 4). The results revealed that apparent binding constant, Kapp, obtained by solubility, spectrophotometry, and dynamic dialysis measurements, depended on the concentration of the dye (Table 2). The binding of the dyes to C8P2 VP-I in an aqueous acetate buffer solution at 25°C, observed by dynamic dialysis measurement, showed sigmoidal increase with increasing concentration of the free dye (Fig. 6). By applying McGhee and von Hippel's theory to Klotz and Scatchard plots (Figs. 7 and 8), positive cooperativity in the dye binding was confirmed. The number of consecutive residues covered by a bound dye, n, the intrinsic binding constant, K, and the cooperativity parameter, ω were as follows : 7.5, 17.5, and 350 for D-I and 16, 40, and 180 for D-II, respectively. An enhanced solubility caused by the addition of C8P2VP can be attributed to the cooperative binding of the dye on the three types of "isolated", "singly contiguous", and "doubly contiguous" sites (Fig. 9).

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1980 (2), 263-269, 1980-02-10

    The Chemical Society of Japan

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