ISSN:
0887-624X
Keywords:
coordination polymer
;
formation constant
;
Ni(II)
;
o,o′-dihydroxyazobenzene
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Equilibrium constant (KCP) for coordinative polymerization is measured for the first time. Constant KCP is defined as [L]cp/[M][L], where [L]cp represents the concentration of the ligand present in the coordination polymer. Plot of absorbance changes measured for 3, a water-soluble derivative of o,o′-dihydroxyazobenzene, against the concentration of Ni(II) ion indicates formation of a 1 : 1-type complex in water at pH 7.74 and 25°C when Ni (II) is added in excess of 3. The 1 : 1-type complex can be either Ni3, the monomeric complex, or (Ni3)n, the coordination polymer. The equilibrium constant for formation of the 1 : 1-type complex is estimated as 1013.10 by using UO22+ ion as the competing metal ion. For the Ni(II) complex of an o,o′-dihydroxyazobenzene derivative attached to poly(ethylenimine), the formation constant is estimated as 105.36. Due to the structure of the polymer, possibility of coordinative polymerization is excluded for the polymer-based ligand. The much greater equilibrium constant for formation of the Ni(II) complex of 3, therefore, indicates formation of (Ni3)n instead of Ni3. The value of KCP for (Ni3)n shows that only 10-7% of the initially added 3 is left unpolymerized when Ni(II) is added in excess of 3 by 10-4 M. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1825-1830, 1997
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
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