Luminescent Click‐Pyrenyl Nucleosides: as Novel Building Blocks for Nucleic Acids: Synthesis, Photophysics, Confocal Microscopy Studies, and Oligonucleotide Conjugation

Three artificial dinucleoside phosphate analogues with a pyrenyl‐triazole‐N‐(triazole) 2 linker substituting the natural phosphodiester linkage are reported. These novel compounds are prepared by the copper‐catalyzed azide alkyne cycloaddition reaction (CuAAC) of a suitably designed pyrenyl‐dialkyne with 3′‐azido thymidine and 5′‐azido adenosine building blocks, respectively. The pyrenyl chromophore confers luminescent properties to these dinucleosides. In diluted dichloromethane (DCM) and dimethyl sulfoxide (DMSO) solutions, the compounds show structured fluorescence emission in the blue region of the spectrum, while at higher concentrations or in the solid state, a featureless and broad excimer emission with λ em ≈ 470 nm is observed. Studied compounds are devoid of anticancer activity against a panel of five human cancer cell lines as well as in noncancerous human microvascular endothelial cells. The demonstrated lack of toxicity in combination with excimer emission allows for the assessment of dinucleoside distribution inside cancer Michigan cancer foundation (MCF)‐7 cells with confocal luminescence microscopy. Compounds exhibit affinity to membranous structures as well as accumulate in the perinuclear region of the cells. Moreover, a selected dinucleoside is successfully conjugated to the deoxyribonucleotide 5′‐d(TTT CTT TCC CTC)‐3′. The resulting conjugate remains capable of forming a stable B‐type DNA duplex with a complementary oligonucleotide strand.