Computational Prediction of 1H and 13C Chemical Shifts: A Useful Tool for Natural Product, Mechanistic, and Synthetic Organic Chemistry

“Smart tuning” of optical properties in three azo dyes containing intramolecular hydrogen bonding is realized by the judicious control of solvents, when the dyes are in solution or adsorbed onto titanium dioxide nanoparticles. In solution, certain solvents destabilizing intramolecular hydrogen bonding induce a distinctive ≈70 nm “blue-shifted” absorption peak, compared with other solvents. In parallel, the optical properties of azo dye/TiO2 nanocomposites can be tuned using solvents with different hydrogen-bond accepting/donating abilities, giving insights into smart materials and dye-sensitized solar cell device design. It is proposed that intramolecular hydrogen bonding alone plays the leading role in such phenomena, which is fundamentally different to other mechanisms, such as tautomerism and cis–trans isomerization, that explain the optical control of azo dyes. Hybrid density functional theory (DFT) is employed in order to trace the origin of this optical control, and these calculations support the me...

Radim Holuša

Papers

A 1H, 13C and 15N NMR spectroscopic and GIAO DFT study of ethyl 5-oxo-2-phenyl-4-(2-phenylhydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate