Tuned Cd2+ Selectivity: Showcase of Electronic and Regio-Effect of π-Extended Di-2-Picolylamine-Substituted Quinoline-Based Tolans

π-Extended di-2-picolylamine (DPA)-substituted 8-hydroxyquinoline (8-HQ) tolans (2) were synthesized for testing electronic and regio-effects. The electron-poor CN-tolan (2b) showed clear selectivity for Cd2+ (>>Zn2+) over other metal ions via turn-on fluorescence, while the electron-rich MeO-tolan (2a) displayed no clear metal selectivity. Furthermore, considering that there was no significant energy difference between the Cd2+ complexes of 1 and 2b, the intended regio-effect (7- vs. 5-substituted effect) did not induce steric hindrance. Thus, the regio-effect is mainly electronic. Considering the above, 2a and 2b constitute a complete showcase in which electronic and regio-effects modulate the metal selectivity. The fluorescence titration of 2b (10 mM) with Cd2+ showed that the limit of detection (LOD) of the Cd2+-selective 2b was 158 nM in PBS (phosphate-buffered saline) (10 mM, pH 7.2) containing 50% MeOH.

Each phenyl group performs its own functions on luminescence: phenyl substituted effect in tetraphenylpyrazine

Three phenyl groups of TPP derivatives affect the luminescence process in various modes. TPPs show AIE thanks to the ortho substituted groups, while meta and para groups can modulate their luminescence in different extents.

The N-allyl substituted effect on wormlike micelles and salt tolerance of a C22-tailed cationic surfactant

The N-allyl substituted effect on wormlike micelles and salt tolerance of a C22-tailed cationic surfactant is investigated.

DFT Study of Substituted Effect on Absorption and Emission Spectra of Naphthoquinone Derivatives

The density functional theory (DFT) is used to compute the ground-state geometries of naphthoquinone derivatives, and lowest singlet excited-state geometries of them have been investigated by the singles configuration interaction (CIS) method. The absorption and emission spectra are calculated by time-dependent DFT (TDDFT) on the basis of the ground- and excited-state geometries, respectively. Our calculations are in good agreement with the available experimental results. The calculated results show that with the introduction of hydroxyl the red-shift was found in the absorption and emission, and the range of spectra reach the visible region. Furthermore, in the absorptions electron transition type was identified from the point-view of molecular orbitals. Study of the effect of hydroxyl and site on spectra can provide the helpful information on further designing molecular devices.