Influence of terminal group on sensing performance of a series of N-monoalkylated diketopyrrolopyrrole-based two-photon fluorescent fluoride anion probes

Effect of substitution site on two-photon absorption and excited States properties of lipid droplets detection NAPBr dyes: A theoretical perspective

Two-photon fluorescence dyes have shown promising applications in biomedical imaging. However, the substitution site effect on geometric structures and photophysical properties of fluorescence dyes is rarely illustrated in detail. In this work, a series of new lipid droplets detection dyes are designed and studied, molecular optical properties and non-radiative transitions are analyzed. The intramolecular weak interaction and electron-hole analysis reveal its inner mechanisms. All dyes are proven to possess excellent photophysical properties with high fluorescence quantum efficiency and large stokes shift as well as remarkable two-photon absorption cross section. Our work reasonably elucidates the experimental measurements and the effects of substitution site on two-photon absorption and excited states properties of lipid droplets detection NAPBr dyes are highlighted, which could provide a theoretical perspective for designing efficient organic dyes for lipid droplets detection in biology and medicine fields.

Anion-Responsive Molecules That Exhibit Switching of Two-Photon Optical Properties

Two-photon-excited fluorescent probes are important for two-photon microscopy for biomedical studies. In contrast to the many examples of probes for cationic species, such as metal ions, there have been fewer reports on the control of two-photon optical properties by anions because in such systems it is difficult to control the associated π-electronic states. This Minireview summarizes anion-responsive molecules that exhibit changes in two-photon optical properties and describes their molecular design and anion-response mechanisms, which are driven by changes in covalent bonds and noncovalent interactions. Results from a recent study of two-photon systems, where geometries and optical properties are modulated by anion binding, are also discussed.

Structure-property relationships and third-order nonlinearities in diketopyrrolopyrrole based D-π-A-π-D molecules

Nine new quadrupolar chromophores based on diketopyrrolopyrrole were designed and prepared by cross-coupling reactions. The property tuning has been achieved by structural variation of the peripheral substituents (donor) and enlargement of the π-system. Fundamental properties of target molecules were studied by differential scanning calorimetry, electrochemistry, and absorption and emission spectra. Nonlinear optical properties were studied by measuring the third harmonic generation. The experimental data were completed by quantum-chemical calculations and structure–property relationships were elucidated.