Multiple Hydrogen Bonds Promoted ESIPT and AIE‐active Chiral Salicylaldehyde Hydrazide

Abstract

The simpler, the better! A series of simple and highly fluorescent salicylaldehyde hydrazide molecules (41 samples) have been designed and prepared. Even though these soft materials contain a very small π‐conjugated system, they can go through multiple intramolecular and intermolecular hydrogen bonds promoted excited‐state intramolecular proton‐transfer (ESIPT) to display strong blue, green, yellow, and orange aggregation‐induced emission (AIE) with large Stokes shifts (up to 184 nm) and high fluorescence quantum yields (Ф up to 0.20). Unusual mechanochromic fluorescence enhancements are also found in some solid samples. Through coordination, hydrogen and halogen bonds, these flexible molecules can be used as Mg2+ (Ф up to 0.46) probes, universal anion (Ф up to 0.14) and unprotected amino acids (Ф up to 0.16) probes, and chiral diamine (enantiomeric selectivity and Ф up to 0.36 and 0.062, respectively) receptors. Combining their advantages of AIE and biocompatibility, these low cytotoxic dyes have potential application in living cell imaging. Furthermore, the effects of different functional groups on the molecule arrangement, ESIPT, AIE, probe, and chiral recognition properties are also examined, which provide a simple and bright paradigm for the design of multiple‐stimuli‐responsive smart materials.

Syntheses, crystal structures, chirality and aggregation-induced phosphorescence of stacked binuclear platinum(ii) complexes with bridging Salen ligands

“…In general, strong intermolecular interactions in the crystal are in the range 1.9-2.3 Å and 2.2-3.0 Å for hydrogen bonds and non-hydrogen bonds, respectively. 18,36,38,58,63,69 The X-ray single-crystal structures and arrangements of ppy-Pt-3-Cl-Ph are shown in Fig. 6 absorption and AIP properties.…”

“…6 absorption and AIP properties. 38,63,69 In this section, ppy-Pt-(S,S)Cy was discussed as an example. Since the un-conjugated Cy bridging ligand is flexible, the two Pt(II) coordination systems are not parallel with a dihedral angle of 14.121.…”

Oxovanadium(V) catalysts for the CO2 fixation into cyclic carbonates under ambient pressure

“…The as‐synthesized ligands were of sufficient purity to be used in the complexation reactions without any further purification. The synthetic procedures of ligands 1a , [ 26 ] 1b , [ 27 ] 1c , [ 28 ] 1d , [ 29 ] 1e , [ 30 ] and 1f [ 31 ] were modified based on the reported literature and the detailed procedures and corresponding spectroscopic data could be found in Data S1.…”

Effect of substitution on the solid-state fluorescence properties of styrylbenzoxazole derivatives with terminal dicyanomethylene group

“…It is well known that H-bonds open non-radiative deactivation pathways in solutions [32][33][34]. However, they usually work in the opposite direction in the solid state, because they rigidify the molecular structures and activate the SLE processes of numerous fluorophores [35][36][37]. It must be noticed that most of these fluorophores undergo intramolecular proton transfer in the excited state (ESIPT).…”