Theoretical and Experimental Investigations of Large Stokes Shift Fluorophores Based on a Quinoline Scaffold

Abstract

A series of novel styrylquinolines with the benzylidene imine moiety were synthesized and spectroscopically characterized for their applicability in cellular staining. The spectroscopic study revealed absorption in the ultraviolet–visible region (360–380 nm) and emission that covered the blue-green range of the light (above 500 nm). The fluorescence quantum yields were also determined, which amounted to 0.079 in the best-case scenario. The structural features that are behind these values are also discussed. An analysis of the spectroscopic properties and the theoretical calculations indicated the charge-transfer character of an emission, which was additionally evaluated using the Lippert–Mataga equation. Changes in geometry in the ground and excited states, which had a significant influence on the emission process, are also discussed. Additionally, the capability of the newly synthesized compounds for cellular staining was also investigated. These small molecules could effectively penetrate through the cellular membrane. Analyses of the images that were obtained with several of the tested styrylquinolines indicated their accumulation in organelles such as the mitochondria and the endoplasmic reticulum.

White light employing luminescent engineered large (mega) Stokes shift molecules: a review

“…This privileged structure has been widely used as a core molecular fragment in pharmaceuticals, biocompatible substance, stimulated emission depletion (STED) microscopy, and FRET imaging. 52 False-positive outcomes from overlapping in the emission and excitation spectra of the donor and acceptor molecule, respectively, can be resolved by integrating a large Stokes shi dye. 52,53 The provision of such integral would allow scientists to perform robust intermolecular FRET assays to investigate the molecular interactions.…”

“…52 False-positive outcomes from overlapping in the emission and excitation spectra of the donor and acceptor molecule, respectively, can be resolved by integrating a large Stokes shi dye. 52,53 The provision of such integral would allow scientists to perform robust intermolecular FRET assays to investigate the molecular interactions. Styrylquinolines developed by Czaplińska and coworkers displayed a remarkable push-pull capability.…”

Heterocyclic Schiff Bases of 3-Aminobenzanthrone and Their Reduced Analogues: Synthesis, Properties and Spectroscopy

“…Such compounds exhibit different properties in the ground and excited states. The difference in energy between the Frank–Condon state and the ICT state is responsible for the large Stokes shift, which is preferred in most fluorescence methods due to the reduced chromatic aberration and increased resolution in bioimaging applications [ 39 , 40 ].…”

Thiourea Derivatives, Simple in Structure but Efficient Enzyme Inhibitors and Mercury Sensors

“…This temporary dipole alternation led to larger changes in dipole moments and to the relaxation of the structure. The energy difference between the Frank-Condon state and the ICT state was the predominant reason for the large Stokes shift, which is ideal in fluorescence methods [46,47]. The fluorescence behavior of these compounds shows that all the compounds at concentration as low as 10 µg mL −1 could be used for fabrication of fluorescence-based sensing tools for detection of environmental pollutants especially pesticides, toxic heavy metals and drugs.…”