Synthesis, Optical Characterization in Solution and Solid-State, and DFT Calculations of 3-Acetyl and 3-(1'-(2'-Phenylhydrazono)ethyl)-coumarin-(7)-substituted Derivatives.

Intramolecular charge transfer (ICT) effects are responsible for the photoluminescent properties of coumarins. Hence, optical properties with different applications can be obtained by ICT modulation. Herein, four 3-acetyl-2-chromen-2-ones (-) and their corresponding fluorescent hybrids 3- (phenylhydrazone)-chromen-2-ones (-) were synthesized in 74-65% yields. The UV-Vis data were in the 295-428 nm range. The emission depends on the substituent in position C-7 bearing electron-donating groups. Compounds - showed good optical properties due to the D-π-A structural arrangement. In compounds -, there is a quenching effect of fluorescence in solution. However, in the solid, an increase is shown due to an aggregation-induced emission (AIE) effect given by the rotational restraints and stacking in the crystal. Computational calculations of the HOMO-LUMO orbitals indicate high absorbance and emission values of the molecules, and gap values represent the bathochromic effect and the electronic efficiency of the compounds. Compounds - and - are good candidates for optical applications, such as OLEDs, organic solar cells, or fluorescence markers.