Naphthalene diimide-amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA.

Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520-540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid-NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides.

Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown-Ether-Functionalized Perylene Bisimide Fluorophore.

The host-guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron-rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron-poor PBI host molecule. Benesi-Hildebrand plots of fluorescence titration data confirmed the formation of host-guest complexes with 1:2 stoichiometry.

Metal ion templated self-assembly of crown ether functionalized perylene bisimide dyes.

Two new perylene bisimide (PBI) derivatives possessing crown ether receptors at the 1,7 bay-positions and solubilizing ionic imide substituents were synthesized and their self-assembly properties in the presence of different metal ions were studied, revealing highly selective barium ion templated self-assembly of 15-crown-5 functionalized PBI into H-type dimer aggregates.

Synthesis and characterization of optical and redox properties of bithiophene-functionalized diketopyrrolopyrrole chromophores.

A series of six new 2,2'-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a-f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a-f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes.