Syntheses, Experimental and Theoretical Studies on Absorption/Emission Properties of Pyrazoline-Containing Aryl/Methoxynaphthyl Substituents

Abstract

5-Aryl-3-(2-methoxynaphthalen-6-yl)-1-phenylpyrazoline derivatives were synthesized starting from (E)-1-(3-aryl)-(2-methoxynaphthalen-6-yl)-prop-2-en-1-one and phenylhydrazine. The compounds were characterized by 1 H and 13 C nuclear magnetic resonance (NMR), elemental analyses and mass spectrometry. Some compounds showed promising luminescence properties in solution and in solid state; the absorption and emission characteristics were measured and the fluorescence quantum yield of two of the derivatives [4,5-dihydro-3-(2-methoxynaphthalen-6-yl)-5-(3,4,5-trimethoxyphenyl)-1-phenyl-1H-pyrazoline and 5-(4-chlorophenyl)-4,5-dihydro-3-(2-methoxynaphthalen-6-yl)-1-phenyl-1H-pyrazoline] were found to have excellent values compared to rhodamine B standard. Theoretical calculations at time-dependent density functional theory (TD-DFT) level are in agreement with the experimental measurements and are helpful to explain the electronic behavior.

Comparison of various synthesis methods and synthesis parameters of pyrazoline derivates

“…One of the simplest methods was the conventional method which was carried out with conventional equipment such as reflux with the reaction shown in Figure 5 . [ 36 ] The heating reaction was slow but also caused hot surfaces at certain reaction sites, which led to the decomposition of the substrate, reagents, and products over time of synthesis. [ 11 ] In contrast to this, green chemistry techniques assisted by microwave energy allowed the heating of vessels over a long distance to be more uniform, resulting in relatively smaller decomposition products.…”