Thermoinduced S0 → T-transitions in electron-rich Zn(II) 1,10- phenanthrocyanines, DNA complexones containing dihydro-1,10-phenanthroline cycles related to NADH

Abstract

Manifestation of paramagnetic properties for electron-rich Zn(II) 1,10-phenanthrocyanine: [(phen)2Zn(μ-phencyanine)Zn(phen)2 ](OAc)4 (Zn1), [(phen)2Zn(μ-phencyanine−)Zn(phen)2] (OAc)3 (Zn2), (phen)Zn(μ-phencyanine−)Zn(phen)(OAc)3 (Zn3), (en)Zn(μ-phencyanine−)Zn(en) (OAc)3 (Zn4) and Zn(μ-phencyanine−)Zn(OAc)3 (Zn5) (phen —1,10-phenanthroline, en — ethylenediamine, OAc− — acetate ion, μ-phencyanine and μ-phencyanine−-bridge 1,10-phenanthrocyanines, dihydro-bi-1,10-phenanthrolines), DNA complexones containing related to NADH dihydro- 1,10-phenanthroline cycles were investigated by ESR spectroscopy. Compounds of Zn1–Zn5 are derived using methodologies of metal-mediated nondehydrogenative CH−CH coupling of coordinated 1,10-phenanthroline in ionic melts of respective complexes-precursors. In ESR spectra of derived 1,10-phenanthrocyanines of Zn(II) signals are detected in the values area of g-factor 2.0018–2.0031 with unexpectedly high intensity. Abnormal increase of intensity of ESR line halfwidth with growth of temperature from 77 to 450 K were found. Appearance of paramagnetism for these compounds was correlated with their electron-rich nature and as result of thermoinduced S0 → T-transitions were interpreted that can be associated with structural phase transitions. Refs 21. Figs 1. Tables 1.