Light enhanced proton conductivity in a terbium phosphonate photochromic chain complex

Crystalline complexes that exhibited light switchable proton conductivity are of great interest but still a challenge in material science.Herein,a terbium phosphonate chain complex was synthesized through assembly of electron-rich phosphonate units,electron-deficient polypyridine components and paramagnetic Tb^(3+)ions.Via light irradiation and heat treatment,the photogenerated radicals could simultaneously and reversibly tune the photochromic,luminescent and magnetic properties.Originating from the abundant hydrogen bonding networks formed between PO_3 groups and lattice water molecules,proton conductive behaviour was explored with high proton conductivity of(1.74±0.19)×10^(-3)S cm^(-1)at 80°C and 100%relative humidity.Importantly,accompanied with the colorless sample changed to blue,the proton conductivity increased about 20%after room temperature light illumination,implying that light irradiation could act as an external stimulus to enhance the conductive properties of original material.This work innovatively realized the light responsive conductive property in the electron transfer photochromic materials,providing a novel strategy for the construction of smart materials.

Azulenoisoindigo: A building block for π-functional materials with reversible redox behavior and proton responsiveness

Azulene, one of representative nonbenzenoid aromatic hydrocarbons, exhibits unique molecular structure and distinctive physical and chemical properties. Herein, azulenoisoindigo(Az II), an azulene-based isoindigo analogue, is designed and synthesized, which has a twisted molecular backbone and R/Sisomers in single crystals. Interestingly, Az II shows the characteristics of both isoindigo and azulene,such as reversible redox behavior and reversible proton responsiveness. UV-vis-NIR,^(1)H NMR and electron paramagnetic resonance(EPR) measurements were carried out to get insights into the possible mechanism of the proton-responsive property of Az II. The results demonstrated that only one azulenyl moiety of molecule of Az II was protonated and deprotonated, and the protonated Az II can be further oxidized to form azulenium cation radicals.

Highly Efficient Multifunctional Luminescent Radicals

Stable organic luminescent radicals are a special class of compounds integrating optical,electrical,and magnetic properties.Luminescent radicals not only have potential applications in the field of the organic light-emitting diodes(OLEDs)but can also be applied in the fields of fluorescence sensing,bioimaging,and so forth.Nevertheless,due to the adverse effects of solvent polarity on the luminescent performance of radicals,no feasible approaches have been found in the literature toward fluorescent sensing.In this work,we report two luminescent radicals,2αPyID-TTM and 2δPyID-TTM,whose emissions show high efficiency and less dependence on solvent polarity.Both radicals show remarkable protonation–deprotonation properties.Besides,2αPyID-TTM exhibits significant fluorescence quenching and colorimetric response toward Fe^(3+)in aqueous solution.This suggests the possibility of a fluorometric/colorimetric dual-channel probe for Fe^(3+).Moreover,an optimized OLED using 2δPyID-TTM as an emissive dopant shows pure red emission and a maximum external quantum efficiency(EQE)of 10.6%.These results show promise for luminescent radicals as fluorescent probes and electroluminescent emitters.