Diquaternarization of dipyrido-[2,3-a:2',3'-c]-phenazine,(dppz) and its analogous
dipyrido-[2,3-a:2',3'-c]-dimethylphenazine,(dppx) using 1,3-dibromopropane afford
new water-soluble derivatives of phenazine, propylene-bipyridyldiylium-phenazine (1)
and propylene-bipyridyldiylium-dimethylphenazine (2). The compounds have been characterized
by means of FT-IR, NMR, elemental analysis and conductometric measurements and their
structure were determined by X-ray crystallography. The experimental studies on the
compounds have been accompanied computationally by Density Functional Theory (DFT)
calculations. The DNA binding properties of both compounds to calf thymus DNA (ctDNA)
were investigated by UV-Vis absorption and emission methods. The expanded UV-Vis spectral
data matrix was analyzed by multivariate curve resolution-alternating least squares
(MCR-ALS) technique to obtain the concentration profile and pure spectra of all reaction
species which existed in the interaction procedure. Multivariate curve resolution
may help us to give a better understanding of the 1(Cl)(2)-ctDNA and 2(Cl)(2) ctDNA
interaction mechanism. The results suggest that both compounds bind tightly to DNA
through intercalation mechanism and the DNA binding affinity of 2 is slightly lower
than that of 1 due to steric hindrance of the methyl group. Also, thermal denaturation
studies reveal that these compounds show strong affinity for binding with calf thymus
DNA. The thermodynamic parameters of the DNA binding process were obtained from the
temperature dependence of the binding constants and the results showed that binding
of both compounds to DNA is an enthalpically driven process that is in agreement with
proposed DNA intercalation capability of these compounds. (C) 2017 Elsevier B.V. All
rights reserved.