Synthesis, characterization, emission and DNA binding properties of four alkynylplatinum(II) terpyridine complexes

• Terpyridines influenced the emission ability of their alkynylplatinum complexes.
• Four alkynylplatinum terpyridine complexes are soluble in water.
• Four alkynylplatinum complexes interacted with DNA in different modes.

Four novel alkynylplatinum(II) terpyridine complexes, [Pt(CCPhR)L]Cl (L = (E)-4′-(4- N, N-bis(2-(2-methoxyethoxy)ethylamino)styrylphenyl)-2,2′:6′,2″-terpyridine (O4TPY) or 4′-p-N, N-bis(2-hydroxyethyl)aminobenzyl-2,2′:6′,2″-terpyridine (TPYOH) and R = n-Bu or H), were synthesized and characterized using 1H NMR, 13C NMR, MALDI-TOF-MS and elemental analysis. All Pt(II) complexes were weakly emissive at ambient temperature in a mixed solution of acetonitrile and water, in which two alkynylplatinum(II) complexes of TPYOH showed much longer emission maximum than those of O4TPY (677 nm for [Pt(CCPh) (TPYOH)]Cl vs 581 nm for [Pt(CCPh) (O4TPY)]Cl and 689 nm for [Pt(CCPhBu) (TPYOH)]Cl vs 595 nm for [Pt(CCPhBu) (O4TPY)]Cl). UV–vis titration experiments indicated that only two alkynylplatinum(II) complexes of O4TPY can bind CT-DNA and the binding constant Kb was 1.9 × 105 for [Pt(CCPh) (O4TPY)]Cl and 1.1 × 105 for [Pt(CCPhBu) (O4TPY)]Cl, respectively. The circular dichroism results indicted that the complexes [Pt(CCPhR) (O4TPY)]Cl can change the helicity of DNA, while the complexes [Pt(CCPhR) (TPYOH)]Cl could interact with the DNA base pair. The influence of ligands in the four complexes on their emission and DNA binding properties were discussed.

The four alkynylplatinum(II) terpyridyl complexes were emissive from 3MLCT excited state at ambient temperature in solution. The cations in the four complexes showed different interactions with ct-DNA.Figure optionsDownload as PowerPoint slide