A soluble complexan polymer in organic solvents, derived from 1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA), was synthesized and used as a polymer chelate precursor to YBa2Cu3O7-x thin films. Five complexan polymers (3) were prepared by a ring-opening polyaddition of CyDTA dianhydride (1) with several diamines (2). The polymer (3e) prepared with 1,2-diaminocyclohexane (2e) was soluble in water, dimethyl sulfoxide (DMSO), methanol, and ethanol. A clear aqueous solution (pH 8) containing 3e and 1/2 equivalent molar amount of metal nitrates of Y, Ba, and Cu (1 : 2 : 3 in molar ratio) was poured into tetrahydrofurane (THF) to precipitate a polymer–metal chelate. The chelate formations of each metal were confirmed by C=O stretching bonds. The polymer chelate precursor was soluble in methanol, DMSO, and water, and partially soluble in ethanol. The polymer–metal chelate was dissolved in methanol, of which the metal concentration was adjusted to 3 wt%. This solution was spin-coated onto SrTiO3 (100) and MgO (001) substrates for preparing YBa2Cu3O7-x thin films. According to an X-ray diffraction analysis, YBa2Cu3O7-x film with a c-axis orientation was formed on a SrTiO3 substrate; even the precursor film was sintered at 780 °C for 1 h under air. Superconducting YBa2Cu3O7-x films with a c-axis orientation were also prepared on a MgO (001) substrate.

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