Highly Chromic, Proton-Responsive Phenyl Pyrimidones

Abstract

Aryl pyrimidones are pharmacologically relevant compounds whose optical properties have only been partially explored. We report the synthesis and optical characterization of a series of aryl- and diaryl-2(1H)-pyrimidones. The electronic transitions of these chromophores are modulated by the extent of conjugation between the pendant phenyl ring and the pyrimidone core as well as the presence of electron-donating auxochromes. Monoprotonation of the pyrimidone ring results in large hyperchromic and bathochromic shifts as well as switching of fluorescence making these phenyl pyrimidones of interest as sensory materials.

Turn-On, Fluorescent Nuclear Stains with Live Cell Compatibility

“…Both the HOMO and HOMO –1 exhibit greater orbital contributions from the pendant aryl arms, while the LUMO shows a greater contribution from the electron-withdrawing core. The polarization of the HOMO and LUMO confirms the notion of an excited state with CT character which has been previously described for structurally related 4,6-diaryl-pyrimidones. , This CT state should be stabilized in polar solvents leading to the observed fluorescence quenching.…”

“…1 and 2 were designed as DNA-targeting, ‘turn-on’ fluorescent probes and incorporate three key design elements (Figure ). First, their optical properties are addressed through the incorporation of a donor–acceptor–donor π-system that enables excitation and emission wavelengths in the visible spectrum as well as high sensitivity toward their microenvironment. , Second, the pendant aryl arms control optical switching with emission enhancements expected when rotation is limited. Finally, recognition units may be incorporated via 4-amino positions of the arms; for 1 and 2 , N -methylpiperazine was chosen, as, at physiological pH, protonation will result in a dicationic species suitable for electrostatic interactions with the phosphate backbone of DNA.…”

From 2-Hydroxypyridine to 4(3H)-Pyrimidinone: Computational Study on the Control of the Tautomeric Equilibrium

“…4-Hydroxypyrimidine can exist in tautomeric equilibrium with two ketonic forms, , 4(3 H )-pyrimidinone and 4(1 H )-pyrimidinone, and is a simpler system than the pyrimidine nucleobases cytosine, thymine, and uracil, being present in nature in equilibrium among several conformations and tautomeric forms . This compound also constitutes a moiety of pharmacologically relevant − and photophysically active − molecules, and supramolecular polymers. − This study will focus on the understanding of the tautomeric equilibrium of pyrimidine derivatives.…”

Emission Switching of 4,6-Diphenylpyrimidones: Solvent and Solid State Effects

“…Fluorescent pyrimidines are a class of highly responsive, multisensing probes that have found applications as nucleoside analogs and metal ion sensors. , Although the pyrimidine moiety alone exhibits optical transitions at relatively high energies, chemical modification allows tuning of absorption and emission to more useful energies through extension of conjugation and introduction of auxochromes. Extending the conjugation of the pyrimidine core can be accomplished via benzofusion or addition of a rotatable aryl group; examples of the former include the expanded nucleobases of Kool and Moreau whereas the latter are typified by the pyrimidine constructs reported by Tor and others. , We recently reported a series of phenylpyrimidones that exhibit large proton-induced enhancements in molar absorptivity (i.e., hyperchromicity) as well as substantial bathochromic shifts in their absorption maxima . These chromic shifts are coupled to changes in emission and two specific constructs, 1 and 2 (Figure ) are of particular interest.…”