Wubiao Duan
Corresponding author, fax: +86 (0)451-86608616.
SPP full member in good standing.
Key Laboratory of Functional Inorganic Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
Wolfson Materials and Catalysis Centre, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
Zhenxin Wang
Wolfson Materials and Catalysis Centre, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
Michael J. Cook
SPP full member in good standing.
Wolfson Materials and Catalysis Centre, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom

Received 18 July 2009
Accepted 3 September 2009

The phthalocyanine salt [ZnPc(NMe₃)₄]I₄ was synthesized from 4-nitrophthalonitrile using a three-step procedure. The interaction of [ZnPc(NMe₃)₄]⁴⁺ with calf thymus DNA (CT DNA) has been investigated by UV-vis and fluorescence spectrometric methods. [ZnPc(NMe₃)₄]⁴⁺ exists in a non-monomeric form, proposed to be a dimer, in phosphate buffer solution (pH 6.82). Spectral changes show that in the presence of high concentrations of CT DNA added to the solution, [ZnPc(NMe₃)₄]⁴⁺ is bound in a monomeric state with evidence suggesting it is located in a DNA groove. At lower concentrations of DNA there is evidence of stacking of non-monomeric [ZnPc(NMe₃)₄]⁴⁺ onto the DNA. Two intrinsic binding constants for the interaction of [ZnPc(NMe₃)₄]⁴⁺ with CT DNA, 1.33 × 10⁵ and 2.56 × 10⁴ M^-1 have been obtained. Electrostatic binding is shown to play an important role in the interaction of [ZnPc(NMe₃)₄]⁴⁺ with nucleic acids.

synthesis; ZnPc(NMe₃)₄]I₄; spectrometry; interaction; calf thymus DNA