Realizing Photoswitchable Mechanoluminescence in Organic Crystals Based on Photochromism.

Organic mechanoluminescent (ML) materials possessing photophysical properties that are sensitive to multiple external stimuli have shown great potential in many fields, including optic and sensing. Particularly, the photoswitchable ML property for these materials is fundamental to their applications but remains a formidable challenge. Herein, photoswitchable ML is successfully realized by endowing reversible photochromic properties to an ML molecule, namely 2-(1,2,2-triphenylvinyl) fluoropyridine (o-TPF). o-TPF shows both high-contrast photochromism with a distinct color change from white to purplish red, as well as bright blue ML (λML  = 453 nm). The ML property can be repeatedly switched between ON and OFF states under alternate UV and visible light irradiation. Impressively, the photoswitchable ML is of high stability and repeatability. The ML can be reversibly switched on and off by conducting alternate UV and visible light irradiation in cycles under ambient conditions. Experimental results and theoretical calculations reveal that the change of dipole moment of o-TPF during the photochromic process is responsible for the photoswitchable ML. These results outline a fundamental strategy to achieve for the control of organic ML and pave the way to the development of expanded smart luminescent materials and their applications.

Time restricted feeding is associated with poor performance in specific cognitive domains of Suburb-Dwelling older Chinese.

The purpose of this study was to investigate the association between time restricted feeding (TRF) and different areas of cognitive function in the elderly in Chinese communities. This study consisted of 1353 community-dwelling Chinese older adults aged 60 years and older in Chongming area, Shanghai (563 males; the mean age, 73.38 ± 6.16 years). Mild cognitive impairment (MCI) and six different cognitive domains was assessed by the Chinese-version of Mini Mental State Examination (MMSE). Recording the eating time of each meal through oral inquiry to calculate the time window between the first meal and the last meal of the average day. Participants with an eating time window duration of more than 10 h were then identified, as well as those with eating time restricted to less than 10 h (TRF). Our study found that TRF may be associated with a higher incidence rate of cognitive impairment. TRF only limited the eating time window and did not change the frequency of participants' dietary intake. We used a linear regression model to study the association of TRF with cognitive function. After adjusting for confounding variables, the results showed that TRF was related to MMSE score (P < 0.001), "Orientation to place" (P < 0.001) and "Attention/calculation" (P < 0.001) functions. Among Chinese older community-dwellers, TRF was associated with a higher prevalence of CI and negatively correlated with the "Orientation to place" and "attention/calculation" functions.

NIR TADF emitters and OLEDs: challenges, progress, and perspectives.

Near-infrared (NIR) light-emitting materials show excellent potential applications in the fields of military technology, bioimaging, optical communication, organic light-emitting diodes (OLEDs), etc. Recently, thermally activated delayed fluorescence (TADF) emitters have made historic developments in the field of OLEDs. These metal-free materials are more attractive because of efficient reverse intersystem crossing processes which result in promising high efficiencies in OLEDs. However, the development of NIR TADF emitters has progressed at a relatively slower pace which could be ascribed to the difficult promotion of external quantum efficiencies. Thus, increasing attention has been paid to NIR TADF emitters. In this review, the recent progress of NIR TADF emitters has been summarized along with their molecular design strategies and photophysical properties, as well as electroluminescence performance data of their OLEDs, respectively.