Responsive circularly polarized ultralong room temperature phosphorescence materials with easy-to-scale and chiral-sensing performance.

Circularly polarized room temperature phosphorescence materials represent a state-of-the-art frontier of optical materials and exhibit promising applications in various fields. Herein, we fabricate a series of full-color circularly polarized room temperature phosphorescence materials, based on anionic cellulose derivatives and achiral luminophores. The ionic achiral substituents promote the spontaneous formation of chiral helical structure of cellulose derivatives via the electrostatic repulsion effect. There are multiple interactions between anionic cellulose derivatives and the doped luminophores, thus the chirality is transferred to luminophores and the non-radiative transition is inhibited. The resultant materials can be easily processed into large-scale film and flexible 3D objects with repeatable folding and curling properties. In addition, their phosphorescence performance shows to be excitation-dependence, time-dependence, visible-light excitation, and multi-responsiveness to humidity, temperature as well as pH value. Importantly, they recognize many enantiomers in an instrument-free visual mode, including amino acids, hydroxyl acids, organic phosphate and hydrobenzoin. These results provide insights into design of advanced optical materials which can be applied in multilevel information handling and chiral sensing.

Cellulose-Based Photothermal Coating: A Sustainable Solution for Seed Protection and Long-Term Grain Storage.

High-output modern agriculture based on synthetic chemicals (biocides, pesticides, and fertilizers) feeds the growing global population. To completely abandon the use of pesticides and fertilizers will undoubtedly cause a severe food crisis worldwide, and sustainable alternative solutions are urgently demanded to stop biocides and fertilizers overuse. Herein, a versatile and green strategy is proposed for seed protection and long-term storage of grains using a cellulose-based photothermal coating (PDA NPs@Cell-N+) that consists of photothermal polydopamine nanoparticles (PDA NPs) and a positive-charged cellulose derivative (Cell-N+) to eradicate seed-borne bacteria and fungi simply under infrared irradiation. In vitro and in vivo assays and the seedling-stage phenotypes of mung bean (Vigna radiata) suggest that pathogenic microbes, including the tough Aspergillus flavus (inhibition ratio >99%), can be efficiently eliminated by photothermal therapy. Thus, the seed-borne diseases of mung beans can finally be prevented. Owing to excellent solubility and biocompatibility, the PDA NPs@Cell-N+ coating can be washed off and recycled without food safety concerns. PDA NPs@Cell-N+ can be a nature-based solution for seed protection and long-term grain storage.

Aggregation-regulated room-temperature phosphorescence materials with multi-mode emission, adjustable excitation-dependence and visible-light excitation.

Constructing room-temperature phosphorescent materials with multiple emission and special excitation modes is fascinating and challenging for practical applications. Herein, we demonstrate a facile and general strategy to obtain ecofriendly ultralong phosphorescent materials with multi-mode emission, adjustable excitation-dependence, and visible-light excitation using a single organic component, cellulose trimellitate. Based on the regulation of the aggregation state of anionic cellulose trimellitates, such as CBtCOONa, three types of phosphorescent materials with different emission modes are fabricated, including blue, green and color-tunable phosphorescent materials with a strong excitation-dependence. The separated molecularly-dispersed CBtCOONa exhibits blue phosphorescence while the aggregated CBtCOONa emits green phosphorescence; and the CBtCOONa with a coexistence state of single molecular chains and aggregates exhibits color-tunable phosphorescence depending on the excitation wavelength. Moreover, aggregated cellulose trimellitates demonstrate unique visible-light excitation phosphorescence, which emits green or yellow phosphorescence after turning off the visible light. The aggregation-regulated phenomenon provides a simple principle for designing the proof-of-concept and on-demand phosphorescent materials by using a single organic component. Owing to their excellent processability and environmental friendliness, the aforementioned cellulose-based phosphorescent materials are demonstrated as advanced phosphorescence inks to prepare various disposable complex anticounterfeiting patterns and information codes.

Anionic polymerization of nonaromatic maleimide to achieve full-color nonconventional luminescence.

Nonconventional or nonconjugated luminophore without polycyclic aromatics or extended π-conjugation is a rising star in the area of luminescent materials. However, continuously tuning the emission color within a broad visible region via rational molecular design remains quite challenging because the mechanism of nonconventional luminescence is not fully understood. Herein, we present a new class of nonconventional luminophores, poly(maleimide)s (PMs), with full-color emission that can be finely regulated by anionic polymerization even at ambient temperature. Interestingly, the general characteristics of nonconventional luminescence, cluster-triggered emission, e.g., concentration-enhanced emission, are not observed in PMs. Instead, PMs have features similar to aggregation-caused quenching due to boosted intra/inter-molecular charge transfer. Such a biocompatible luminescent material synthesized from a low-cost monomer shows great prospects in large-scale production and applications, including security printing, fingerprint identification, metal ion recognition, etc. It also provides a new platform of rational molecular design to achieve full-color nonconventional luminescence without any aromatics.

Cellulose-based fluorescent sensor for visual and versatile detection of amines and anions.

It is practical and challenging to construct ultrasensitive and multi-responsive sensors for visual and real-time monitoring of the environment. Herein, a cellulose-based multi-responsive fluorescent sensor (Phen-MDI-CA) is fabricated, and realizes a visual and ultrasensitive detection of not only various amines but also three anions based on the change of the fluorescence and/or visible colors. Once exposure to various amines in both the solution and vapor state, the Phen-MDI-CA solution and test paper exhibit different fluorescence colors, which can be used to distinguish triethylamine, ethylenediamine, methylamine, aniline, hydrazine and pyrrolidine from other amines. Moreover, via combining the Phen-MDI-CA with the Phen-MDI-CA/malachite green ratiometric system, phosphate (PO43-), carbonate (CO32-) and borate (B4O72-) can be visually and accurately recognized depending on the change of the visible and fluorescence colors. In fluorescent mode, the LOD for B4O72-, PO43- and CO32- ions is as low as 0.18 nmol, 0.69 nmol and 0.86 nmol, respectively. Significantly, the Phen-MDI-CA can readily make a qualitative and quantitative detection of B4O72-, PO43- and CO32- anions in the mixture of anions. The state-of-the-art responsive behavior of Phen-MDI-CA originates from the amplification effect of cellulose polymer chain and the differentiated interactions between the sensor and analytes.