Hydrated Hydroxide Complex Dominates the AIE Properties of Nonconjugated Polymeric Luminophores

Abstract

Nontraditional intrinsic luminescence (NTIL) which always accompanied with aggregation‐induced emission (AIE) features has received considerable attention due to their importance in the understanding of basic luminescence principle and potential practical applications. However, the rational modulation of the NTIL of nonconventional luminophores remains difficult, on account of the limited understanding of emission mechanisms. Herein, the emission color of nonconjugated poly(methyl vinyl ether‐alt‐maleic anhydride) (PMVEMA) can be readily regulated from blue to red by controlling the alkalinity during the hydrolysis process. The nontraditional photoluminescence with AIE property is from the new formed p‐band state, resulting from the strong overlapping of p orbitals of the clustered O atoms through space interactions. Hydrated hydroxide complexes embedded in the entangled polymer chain make big difference on the clustering of O atoms which dominates the AIE property of nonconjugated PMVEMA. These new insights into the photoluminescence mechanism of NTIL should stimulate additional experimental and theoretical studies and can benefit the molecular‐level design of nontraditional chromophores for optoelectronics and other applications.

Activation of H2O tailored by interfacial electronic states at nanoscale interface for enhanced electrocatalytic hydrogen evolution

“…Recently, with the help of steady and transient absorption and emission spectrum, we unambiguously confirmed that SWs adsorbed or confined at nanoscale interface in the form of OH -•H 2 O could emit bright colors as non-conjugation luminophors [36][37][38][39] , which answers a century of debate on that water is colored or colorless liquid 40,41 . Differing from the traditional hydrogen bonding of water, the hydroxyl (hydroxide) groups and water molecules in structural water are mainly combined through the spatial interaction between the p orbitals of O atoms, which is a new kind of weak interaction with the characteristics of conjugated π bond and transient feature (Scheme 1c).…”

“…Fluorescence spectra of different AMOH (AM + = Li + , Na + , K + , Rb + , Cs + ) solution with DMSO as solvent (a) and at varied concentration of KOH (b); Time-resolved luminescence decay profiles of KOH (c) and LiOH solution (d).Excitation and emission spectrum of varied alkali metal hydroxide DMSO solution verified the above assumption that Li + could form more stable SWs for photoluminescence emission due to its stronger hydration ability, which could provide additional reaction channels for surface electron and proton transfer (Scheme 1c). As we earlier reported[36][37][38][39] , in fact the PL emission of SWs was independent on the type of adsorbed metal, herein the alkali metal cations, and that, all the AMOH solution with DMSO as solvent showed a very broad emission peak centered at ca. 450 nm with a shoulder at ca.…”

“…2 a-b). This hydrous hydroxide complex was recently proposed to be structural water molecules (SWs), which could be acted as the intermediate species to tune the surface electron and proton transfer by space interaction (Scheme 1d) [36][37][38][39][47][48][49] . Thus, we hypothesized that the interfacial adsorbed SWs probably provide alternative channel for electron and proton transfer, which promoted the dissociation (or activation) of water at the electrode and consequently accelerated the HER reaction kinetics.…”

“…The XPS O 1s spectra analyses verified the presence of hydrous hydroxide complex on the Co metal centers of the Co/NC-T catalysts, and very interestingly, when the ratio of OH* to H 2 O was close to 1:1 (TableS2), Co/NC-800 catalyst exhibited the best catalytic performance of HER (Fig.2a-b). This hydrous hydroxide complex was recently proposed to be structural water molecules (SWs), which could be acted as the intermediate species to tune the surface electron and proton transfer by space interaction (Scheme 1d)[36][37][38][39][47][48][49] . Thus, we hypothesized that the interfacial adsorbed SWs probably provide alternative channel for electron and proton transfer, which…”

“…295 nm and ca. 370 nm on excitation spectrum (Fig.5a, dash lines) , which were featured bands of SWs confined in the nanospaces or at the nanoscale interfaces[36][37][38][39] . Very interestingly, with the increase of the concentration of KOH, the intensity of PL emission at ca.…”