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0D Hybrid Zn/Cd Halied for Color-Time-Dual-Resolved Security Applications: We devise a family of zero-dimensional (0D) hybrid metal halides based RTP materials with dual phosphorescence performance and adjustable lifetime scale, which realize color-lifetime-dual-resolved encoding ability, showcasing potential applications in multilevel anti-counterfeiting and information security. [Display omitted] • A new optical multiplexing concept of simultaneously utilizing the varied emission color and lifetime as dual temporary codes was proposed. • A new family of zero-dimensional (0D) organic metal halides was directly synthesized accompanied by tailorable lifetime at the same molecular platform. • High-security anti-Counterfeiting and 4D information encryption-decryption were demonstrated. Luminescent materials with engineered optical properties play an important role in anti-counterfeiting and information security technology. However, conventional luminescent coding is limited by fluorescence color or intensity, and high-level multi-dimensional luminescent encryption technology remains a critically challenging goal in different scenarios. To improve the encoding capacity, we present an optical multiplexing concept by synchronously manipulating the emission color and decay lifetimes of room-temperature phosphorescence materials at molecular level. Herein, we devise a family of zero-dimensional (0D) hybrid metal halides by combining organic phosphonium cations and metal halide tetrahedral anions as independent luminescent centers, which display blue phosphorescence and green persistent afterglow with the highest quantum yields of 39.9 % and 57.3 %, respectively. Significantly, the luminescence lifetime can be fine-tuned in the range of 0.0968–0.5046 μs and 33.46–125.61 ms as temporary time coding through precisely controlling the heavy atomic effect and inter-molecular interactions. As a consequence, synchronous blue phosphorescence and green afterglow are integrated into one 0D halide platform with adjustable emission lifetime acting as color- and time-resolved dual RTP materials, which realize the multiple applications in high-level anti-counterfeiting and information storage. The color-lifetime-dual-resolved encoding ability greatly broadens the scope of luminescent halide materials for optical multiplexing applications. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Monitoring of sweat pH plays important roles in physiological health, nutritional balance, psychological stress, and sports performance. However, the combination of functional MOFs with phosphorescent material to acquire the real‐time physiological information, as well as the application of dual mode anti‐counterfeiting, has seldom been reported. Herein, we developed multifunctional gel films based on MOFs and phosphorescent dyes which responded to H+ ions and the related mechanism was studied in detail. Upon exposure to H+, the composite gel film exhibited decreased fluorescent signal but enhanced room temperature phosphorescence (RTP), which could be utilized for sweat pH sensing through a dual‐mode. Moreover, multifunctional gel films exhibited a potential application in information encryption and anti‐counterfeiting by designing of stimulus responsive multiple patterns. This research provided a new avenue for portable and non‐invasive sweat pH monitoring methods while also offering insights into stimulus‐responsive multifunctional materials. [ABSTRACT FROM AUTHOR]

Polymer‐based room‐temperature phosphorescence (RTP) materials, especially polysaccharide‐based RTP materials, earn sustained attention in the fields of anti‐counterfeiting, data encryption, and optoelectronics owing to their green regeneration, flexibility, and transparency. However, those with both ultralong phosphorescence lifetime and excitation wavelength‐dependent afterglow are rarely reported. Herein, a kind of amorphous RTP material with ultralong lifetime of up to 2.52 s is fabricated by covalently bonding sodium alginate (SA) with arylboronic acid in the aqueous phase. The resulting polymer film exhibits distinguished RTP performance with excitation‐dependent emissions from cyan to green. Specifically, by co‐doping with other fluorescent dyes, further regulation of the afterglow color from cyan to yellowish‐green and near‐white can be achieved through triplet‐to‐singlet Förster resonance energy transfer. In addition, the water‐sensitive properties of hydrogen bonds endow the RTP property of SA‐based materials with water/heat‐responsive characteristics. On account of the color‐tunable and stimuli‐responsive afterglows, these smart materials are successfully applied in data encryption and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Polymer‐based organic room‐temperature phosphorescent (RTP) materials have recently attracted significant attention. In most of the previous works, 'chemical approaches' were applied to improve the performance of RTP materials, such as designing certain phosphors or selecting specific polymeric matrixes. However, enhancing triplet emission through facile 'physical approaches' is rarely reported. In this study, enhanced RTP emissions of phosphor‐doped polymers are reported by thermal annealing. By doping a difluoroboron β‐diketonate derivative into poly(diacetone acrylamide) (PDAAM), green RTP emissions can be obtained. After thermal annealing at 125 °C for 5 min, the afterglow duration of RTP increases from 2.6 to 5.3 s and also the brightness of RTP emission exhibits a threefold increase. Such post‐treatment is applicable for various polymeric matrixes. The mechanism underlying thermal‐annealing enhanced RTP is investigated. Moreover, it demonstrates that controlled RTP by thermal annealing can be used in information encryption and anti‐counterfeiting. This work provides new insight into the development of organic RTP materials with tunable emissions. [ABSTRACT FROM AUTHOR]

Room temperature phosphorescent (RTP) materials have triggered wide interests because of their excellent performance and various promising applications. However, conventional RTP materials possessing color‐tunable and ultralong afterglow often suffer from low phosphorescent emission efficiency. Herein, a long lifetime and high‐efficiency RTP emission system composed of boric acid as the host matrix and organic phosphors as guest molecules is constructed by suppressing the non‐radiative transition process and promoting the triplet exciton of the phosphors. The synergistic effect of the physically limited domain and supramolecular anchoring also contributes to the ultralong lifetime (up to 1.85 s) and high phosphorescence quantum yield (up to 53%). The afterglow can be visually observed for 30 s. With a large overlap of π‐conjugated chromophores, the emission peak of RTP redshifted, realizing cyan, green, and red afterglow in the monochromatic domain. In addition, the emission of colorful afterglow and white afterglow is adjustable with the different co‐doping ratios. Finally, the application of RTP materials to anti‐counterfeiting encryption is demonstrated. [ABSTRACT FROM AUTHOR]

Organic materials showing reversible changes in persistent room‐temperature phosphorescence (RTP) upon exposure to external stimuli have attracted considerable attention in recent years. One potentially groundbreaking development in this area is the introduction of the gating concept for organic persistent RTP materials. This refers to a material where a desired responsive ability only occurs when it is triggered by a specific stimulus, but it remains a formidable challenge. In this study, photoirradiation‐gated excitation‐dependent (Ex‐De) persistent RTP is achieved. A series of molecules, triphenylphosphine and carbazole derivatives connected through flexible carbon chains, are designed and prepared. Upon removal of ultraviolet (UV) irradiation, all these compounds doped polyvinyl alcohol (PVA) films exhibit obvious blue or green afterglow RTP. Among them, (2‐(9H‐[3,9′‐bicarbazol]−9‐yl)ethyl)triphenylphosphonium bromide (TPP‐2C‐Cz) doped PVA film initially exhibits blue persistent RTP after removal of 300 nm excitation but no RTP upon ceasing 365 nm irradiation. Interestingly, upon UV irradiation with a power density of 0.05 W cm−2 (UVA) for 50 min, the Ex‐De RTP behavior of TPP‐2C‐Cz doped PVA film is activated. Eventually, photoirradiation‐gated Ex‐De afterglow emission will be used for a wide range of applications, including the quantitative determination of UV irradiation dose and the permanent record of UV irradiation history, and read on‐demand. [ABSTRACT FROM AUTHOR]

Room‐temperature phosphorescence (RTP) materials are normally prepared by doping guest materials into space‐limited host materials to inhibit nonradiative decay. This work aims to prepare a long afterglow excitation‐dependent emission RTP material by doping a small amount of 4‐carboxyphenylboronic acid into the boric acid matrix, followed by heat‐treating. The calculation of density functional theory shows that the electron cloud distribution and electron transfer trend of the selected material reduces the energy requirement to excite the RTP properties of the obtained materials. The obtained RTP materials can be excited by UV light at 310 and 365 nm for dark blue and green phosphorescence emission, respectively. The results demonstrate the long phosphorescence lifetimes of 1.97 and 0.62 s and the high absolute photoluminescence quantum yields of 17.4% and 15.6%. These results show that the obtained RTP materials have potential prospects as information coding and phosphorescent anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Bandgap engineering plays an important role in the regulation of the photophysical properties of semiconductor materials. Developing the facile and powerful strategy to achieve bandgap tunability is highly desired. Herein, the bandgap tunability of scandium microspheres prepared by the hydrothermal treatment of Sc3+ ions/l‐glutamine (Sc3+/Gln) complexes is achieved. The continuously decreased bandgap is directly attributed to the increase of carbon element and the decrease of scandium element in scandium microspheres controlled by the Gln ligand, which causes the red‐shifted room temperature phosphorescence from Sc/Gln‐0.15 (3.17 eV, green) to Sc/Gln‐0.25 (2.53 eV, yellow). Meanwhile, scandium microspheres have an excitation‐dependent emission ranged from green to red color, revealing their multi‐color imaging capability. Further increase of Gln ligand can further reduce the bandgap to 1.62 eV (Sc/Gln‐0.3), realizing the transition from photoluminescence to photothermal properties of scandium microspheres. Because of their superior optical properties, scandium microspheres can be well used for advanced anti‐counterfeiting and multicolor imaging. This new finding not only offers a deeper insight into the photophysical structure of rare earth semiconductor materials, but also provides a scalable method for the preparation of scandium microspheres with the desired bandgaps. [ABSTRACT FROM AUTHOR]

[Display omitted] Stimuli-responsive materials with dynamically switched room-temperature phosphorescence (RTP) aroused great interest. However, the dynamic control of RTP with a color-tunable persistent afterglow by external stimuli is still challenging. Herein, an appealing strategy for constructing dynamic hydrogen-bond networks based on boron-doped carbon quantum dots (BCQDs) was proposed to generate sequence-dependent stimuli-responsive RTP. The BCQDs exhibited bright RTP in paper matrix after successive stimulation by water and heat, demonstrating a fascinating regulation based on an AND logic gate. The RTP generated experienced a reversible switching without attenuation fatigue when BCQDs were heated and exposed to air. The switching of hydrogen-bond network from that among BCQDs to that between BCQDs and paper could facilitate the population of triplet-state BCQDs. The RTP can last a long timie of 10 s after the ceasation of excitation light source. Furthermore, the AND logic gate stimuli-responsive RTP with different colors in papers were obtainded for the first time after blending with various non-RTP dyes. The BCQDs with controllable and on-demand afterglow were further applied for advanced multi-level information encryption and anti-counterfeiting materials. The finding provided assistance to understand the origin and mechanism of the stimuli-responsive RTP of smart materials and offered opportunities for developing multiple continuous stimuli-responsive intelligent RTP materials. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence carbon dots (CDs) show the highlighted advantages in chemical sensing and bioimaging owing to its long lifetime, however, acquiring the efficient phosphorescence of carbon dots is still encountering difficulty due to the spin prohibition. Here, we synthesized one type of CDs through one-step hydrothermal method. To be specific, the CDs displayed the blue fluorescence in aqueous, and emitted the bright green phosphorescence when being coated on the filter paper. Importantly, introducing coumarin to the CDs resulted in the distinct quenching of both its fluorescence and phosphorescence. Based on this phenomenon, we successfully established a dual-channel detection of coumarin. The fluorescence detection channel exhibited a linear range of 5–350 μM with a detection limit of 0.196 μM, while the phosphorescence detection channel achieved a linear range of 50–1000 μM with a detection limit of 0.268 μM. The further investigation revealed that IFE and SQE were mainly responsible for the fluorescence quenching of CDs, while the phosphorescence quenching was originated from the increased energy gap between the singlet and triplet states (ΔE ST) of CDs, thus obstructing the ISC process. Moreover, we employed the CDs as the phosphorescent ink for anti-counterfeiting. [Display omitted] [ABSTRACT FROM AUTHOR]

Though fluorescence‐tag‐based anti‐counterfeiting technology has distinguished itself with cost‐effective features and huge information loading capacity, the clonable decryption process of spatial‐resolved anti‐counterfeiting cannot meet the requirements for high‐security‐level anti‐counterfeiting. Herein, we demonstrate a spatial‐time‐dual‐resolved anti‐counterfeiting system based on new organic–inorganic hybrid halides BAPPZn2(ClyBr1−y)8 (BAPP=1,4‐bis(3‐ammoniopropyl)piperazinium, y=0–1) with ultra‐long room‐temperature phosphorescence (RTP). Remarkably, the afterglow lifetime can be facilely tuned by regulating the halide‐induced heavy‐atom effect and can be identified by the naked eyes or with the help of a simple machine vision system. Therefore, the short‐lived unicolor fluorescence and lasting‐time‐tunable RTP provide the prerequisites for unicolor‐time‐resolved anti‐counterfeiting, which lowers the decryption‐device requirements and further provides the design strategy of advanced portable anti‐counterfeiting technology. [ABSTRACT FROM AUTHOR]

Pure organic room‐temperature phosphorescence (RTP) materials have been widely utilized in security signs, anti‐counterfeiting, data encrypting, and other fields, which have attracted great attention. In the past few years, smart materials with color‐tunable organic RTP materials are reported by many researchers, while the work focused on the color‐tunable polymeric RTP materials is still rare, especially for molecular weight‐dependent polymeric RTP systems. Here, we designed and prepared three molecular weight polymers P1, P2, and P3 by different polymerization reaction times, and found that the fluorescence emissions of these polymer powders are various. Unexpectedly, the molecular weight‐dependent polymeric RTP materials are achieved through doping these polymers into polyacrylonitrile (PAN) matrix, and the International de l'Eclairage was redshift from (0.205,0.257) to (0.503,0.435). This phenomenon is ascribed to the different aggregation states formed by assembly of different molecular weight polymeric chains. Meanwhile, the electrostatic interaction between phosphor and PAN is hardly affected by water. Therefore, advanced information encryption can be achieved by using these polymeric phosphors as anti‐counterfeiting ink. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence (RTP) with a dynamic feature endows organic luminescent materials with promising application in optoelectronic fields. However, it remains a formidable challenge to obtain dynamic RTP materials. Herein, we reported a strategy for dynamic RTP via reversible transformation of radicals under external stimuli. RTP gradually disappeared with continuous UV-light irradiation owing to the conversion of NDIA to NDIA·− in NDIA/PVA film, which can be recovered by oxidation with oxygen. Regarding the excellent reversibility and repeatability, the potential applications for round-the-clock anti-counterfeiting and tag were first demonstrated. This finding not only outlines a principle to synthesize new RTP materials with dynamic behavior, but also expands the scope of applications of dynamic RTP materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic room-temperature phosphorescence (RTP) materials have garnered extensive attention owing to their long-lived excited states, low cost, good processability, and promising applications in domains such as anti-counterfeiting and information encryption, afterglow displays, biological imaging, and sensing. However, most current organic RTP materials are derived from artificial phosphors and petroleum-based polymers, hindering their practical applications owing to issues such as complicated synthesis and purification procedures, poor colour tunability, and lack of renewability and sustainability. Fortunately, the conversion of natural polysaccharides to RTP materials can address the issues. In this review, we summarize the recent advancements in natural polysaccharide-based RTP materials, including their design principles, underlying mechanisms, advanced luminescence characteristics, and potential applications. Special emphasis is placed on representative natural polysaccharide-based RTP systems exhibiting remarkable properties rarely observed in artificial phosphors. The discussion also focuses on intrinsic structure–performance relationships and outlines key challenges and perspectives for future development in this intriguing field. Overall, this review aims to detail guidelines and provide inspiration for the development of eco-friendly polysaccharide-based RTP materials, shedding new light on the high-value utilization of natural polysaccharides. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three new carbazole isomers were designed and synthesized. • The isomers show high-contrast RTP and mechanochromism. • The isomers show time-dependent RTP by host–guest doping. • The isomers show unusual anti-Kasha behaviors. • Lo-CzAD and Lp-CzAD simultaneously show RTP and TADF emission in PPh 3 matrix. To explore the intrinsic mechanism of pure organic room temperature and clustering-induced phosphorescence and investigate mechanochromism and structural-function relationships, here, 4-(2-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lo-CzAD), 4-(3-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lm-CzAD), and 4-(4-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lp-CzAD) were designed and synthesized by choosing self-made carbazole and 3, 5-dicyanopyridine (DCP) unit as electron acceptor and electron donor in sequence. Compared with crystals Lm-CzAD and Lp-CzAD, crystal Lo-CzAD shows better room temperature phosphorescence (RTP) performance, with RTP lifetimes of 187.16 ms, as well as afterglows 1s, which are attributed to twisted carbazole unit and donor–acceptor (D-A) molecular conformation, big crystal density and spin orbit coupling constant ξ (S 1 → T 1 and S 1 → T 2), as well as intermolecular H type stacking and small ξ (S 0 → T 1). By choosing urea and PPh 3 as host materials and tuning doping ratio, four doping systems were successfully constructed, significantly improving RTP performance of Lo-CzAD and Lp-CzAD, as well as showing different fluorescence and RTP. The lifetimes and afterglows of pure organic Urea/Lo-CzAD and Urea/Lp-CzAD systems are up to 478.42 ms, 5 s, 261.66 ms and 4.5 s in turn. Moreover, Lo-CzAD and Lp-CzAD show time-dependent RTP in doping systems due to monomer and aggregate dispersion, as well as clustering-induced phosphorescence. Based on the different luminescent properties, multiple information encryptions were successfully constructed. [ABSTRACT FROM AUTHOR]

The development of an accurate phosphorescent regulation strategy is key to customizing carbon dots (CDs) for anti-counterfeiting applications. To this target, we design a simple substrate regulation technique to manipulate phosphorescence of nitrogen-doped CDs (NCD). In this work, a cost-effective and environmentally friendly approach is proposed for combining NCD with urea (UA), boric acid (BA) and silica (SiO 2) through hydrogen bonding or covalent bonding, a series of RTP composites were designed and synthesized. The RTP wavelength and lifetime of the composites can be tuned effectively, by preparing composite materials (NCD/UA , NCD/BA and NCD/SiO 2) composed of NCD and different substrate (UA; BA; SiO 2). The average RTP lifetime of NCD/UA , NCD/BA and NCD/SiO 2 are 332.26 ms, 652.05 ms and 1587.22 ms, respectively. Furthermore, the RTP mechanism is verified. This facilitates the application of RTP materials and the adjustment of properties to practical requirements. Owing to the different phosphorescent wavelength and lifetime of NCD/UA , NCD/BA and NCD/SiO 2 , time-dependent multiple anti-counterfeiting can be achieved. Cell experiments show that NCD , NCD/BA , NCD/UA and NCD/SiO 2 have low cytotoxicity and good biocompatibility. This result indicates these RTP materials can be potentially used to realize multicolor and time-dependent anti-counterfeiting. [Display omitted] • The RTP lifetimes and colors tuning of NCD are realized by substrates regulation. • The photophysical properties and RTP mechanism were investigated systematically. • The average lifetimes of these materials were calculated to be 0.3–1.5 s. • These materials can realize multicolor and time-dependent anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Ultralong organic room-temperature phosphorescence (RTP) materials have attracted tremendous attention recently due to their diverse applications. Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully. However, complicated synthesis and high expenditure are still inevitable in these studies. Herein, we develop a series of novel host-guest organic phosphorescence systems, in which all luminophores are electron-rich, commercially available and halogen-atom-free. The maximum phosphorescence efficiency and the longest lifetime could reach 23.6% and 362 ms, respectively. Experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest, but also show a synergistic effect to the guest through Förster resonance energy transfer (FRET). The commercial availability, facile preparation and unique properties also make these new host-guest materials an excellent candidate for the anti-counterfeiting application. This work will inspire researchers to develop new RTP systems with different wavelengths from commercially available luminophores. [ABSTRACT FROM AUTHOR]

Developing metal-free and long lifetime room-temperature phosphorescence (RTP) materials has received tremendous interest due to their numerous potential applications, of which stable triplet-excited state is the core challenge. Here, boron carbon oxynitride (BCNO) dots, emitting stable blue fluorescence and green RTP, are reported for the first time. The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s, lasting over 8 s to naked eyes. The effective doping of carbon and oxygen elements in boron nitride (BN) actually provides a small energy gap between singlet and triplet states, facilitating the intersystem crossing (ISC) and populating of triplet excitons. The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature. Based on the water-soluble feature of BCNO dots, a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption. This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials. [ABSTRACT FROM AUTHOR]

Organic materials with long‐lived, color‐tunable phosphorescence are potentially useful for optical recording, anti‐counterfeiting, and bioimaging. Herein, we develop a series of novel host–guest organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra‐long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color‐tunable inks have already been developed using visible dyes, solution‐processed security inks that are temperature dependent and display time‐resolved printed images are unprecedented. This strategy can provide a crucial step towards the next‐generation of security technologies for information handling. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) with dual‐emissive, robust, and aggregation‐induced RTP characteristics are reported for the first time. The TA‐CDs are prepared via hydrothermal treatment of trimellitic acid and exhibit unique white prompt and yellow RTP emissions in solid state under UV excitation (365 nm) on and off, respectively. The yellow RTP emission of TA‐CDs powder should be resulted from the formation of a new excited triplet state due to their aggregation, and the white prompt emission is due to their blue fluorescence and yellow RTP dual‐emissive nature. The RTP emission of TA‐CDs powder was highly stable under grinding, which is very rare amongst traditional pure organic RTP materials. To employ the unique characteristics of TA‐CDs, advanced anti‐counterfeiting and information encryption methodologies (water‐stimuli‐response producing RTP) were preliminarily investigated. [ABSTRACT FROM AUTHOR]

• Novel 3D Ca-MOFs with a visible afterglow lasting about 13 s. • Scaled-up Synthesis of Ca- MOFs with Wide Range of pH Stability. • Long Afterglow Anti-Counterfeiting Measures: Enabling Long Afterglow for Dynamic Anti-Counterfeiting Procedures. • Dynamic Applications and Program Design of Phosphorescent Ca-MOFs in Anti-Counterfeiting. Calcium-based metal–organic frameworks (Ca-MOFs) with room-temperature phosphorescence (RTP) properties are promising for applications. Herein, two 3D Ca-MOFs with robust RTP have been successfully synthesized with scaled-up production. The afterglows of these two Ca-MOFs are visible to the naked eye in darkness that lasts for approximately 13 s once they are excited with 365 nm UV light. It is mainly attributed to the rigid and dense structures of 3D Ca-MOFs via 4,5-Imidazole dicarboxylic acid tugging Ca2+ elucidated by means of single-crystal X-ray diffraction and density functional theory (DFT). Furthermore, a program was designed for dynamic anti-counterfeiting based on the long afterglow properties of Ca-MOFs, which can be extended for all kinds of material with long afterglow. [ABSTRACT FROM AUTHOR]

The development of tunable pure organic room temperature phosphorescence and single-molecule white light emitters still faces a great challenge due to ineffective intersystem crossing and sensitive triplet excitons. Here, two phenothiazine based luminogens named PtzIP and PtzIPCN were designed and synthesized. PtzIP exhibits mechanochromic activity with hypsochromic shift of 25 nm, tunable room temperature phosphorescence from 613 nm to 530 nm and 560 nm, then to 540 nm and 585 nm by crushing and grinding, and single-molecule near-white light emission with the (CIE: Commission International de I'Eclairage) CIE coordinates of (0.33, 0.25), but PtzIPCN shows mechanochromism and room temperature phosphorescence inertness in crystalline state. By choosing polymethyl methacrylate (PMMA) and 4-fluorobenzophenone(F-BP) as host materials, as well PtzIP and PtzIPCN as guest materials, a series of host-guest doping systems were constructed and optimized by tuning doping ratio. PtzIP/PMMA and PtzIPCN/PMMA doping systems present concentration dependent fluorescence and phosphorescence emission, and RTP lifetime and afterglow of PtzIPCN/PMMA are up to 185.31 ms of 2.0 s. Furthermore, the lifetime of F-BP/PtzIPCN increases to 216.63 ms at doping ratio of 1:1000 for F-BP and PtzIPCN. Based on different luminescent properties of PtzIP and PtzIPCN in the doping systems, a series of high-level digital encryption and anti-counterfeiting patterns were successfully constructed. More importantly, the underlying mechanism behind luminescent properties were explored in detail by photophysical testing, crystal analysis, and theoretical calculations. • Two novel dyes were designed and synthesized. • Crystal PtzIP exhibits mechanochromism and tunable RTP. • PtzIP shows single-molecule near-white light emission in PMMA film. • PtzIP and PtzIPCN show concentration dependent fluorescence and phosphorescence emission. • A series of high-level digital encryption and anti-counterfeiting patterns were constructed. [ABSTRACT FROM AUTHOR]

• Ultralong polyacrylamide-based RTP materials have been facilely prepared. • Reversible RTP responsiveness to water and heat stimuli has been achieved. • Color-tunable phosphorescence emission with varied excitation wavelength has been realized. • These new RTP materials show potential application in anti-counterfeiting and information encryption. Pure organic room-temperature phosphorescent (RTP) materials have evoked increasing attention due to their potential application in many fields. However, the preparation of ultralong and color-tunable RTP materials were still facing challenges. Herein, two facile strategies were applied to construct ultralong RTP materials based on non-covalent and covalent linking of sulfanilic acid (SA) on amorphous polyacrylamide (PAM) framework. The hydrogen bonding in PAM/SA and poly(acrylamide- co -4-acrylamidobenzenesulfonic acid) (PAMABS) can effectively help to suppress non-radiative transition, and induce ultralong RTP emission at ambient condition. The RTP emission intensity and lifetime of PAM/SA can be controlled by the molar ratio of acrylamide to SA. Remarkably, PAMABS shows excitation-dependent color-tunable phosphorescence emission. Due to the destructive effect of water on the system rigidity, PAM/SA and PAMABS both exhibit RTP responsiveness to water and heat stimuli. Furthermore, the convenient preparation and excellent properties enable these new organic RTP materials extremely suitable for anti-counterfeiting and information encryption. [ABSTRACT FROM AUTHOR]

Developing durable room temperature phosphorescent carbon dot-based materials with high stability and easy preparation has been a great challenge. Here, through a one-step hydrolysis-assisted carbonization treatment, nitrogen-doped carbon dots encapsulated in silica (N-CDs@silica) are obtained, with outstanding stability and durable room temperature phosphorescence (RTP) lifetime (1.81 s, nearly 9 s to naked eye). Further investigations reveal that C O bonds from N-CDs are the main luminescence centers. The formation of Si–O–C bonds covalently linking N-CDs and silica matrice together within silica sphere, as well as the efficient crosslinking effect within N-CDs, are responsible for RTP emission. Based on the unique optical properties of N-CDs@silica, we have developed the RTP strip probe for selective Fe3+ detection. In addition, we explored N-CDs@silica as security ink for advanced anti-counterfeiting. This work not only provides a strategy to synergistically optimizes the structural and luminescent properties of N-CDs@silica in a simple and efficient manner, but more importantly opens a new perspective for developing simple RTP strip probes for sensor applications. [Display omitted] • N-CDs confined in silica were prepared by one-step hydrothermal method. • Efficient crosslinking induced by triethylenetetramine promotes RTP emission. • Room-temperature phosphorescence lifetime reaches 1.81 s. [ABSTRACT FROM AUTHOR]

Trace water is known to be an impurity in organic solvents, having an adverse effect on the chemical reaction or environmental safety. Developing a green, facile and non-toxic method for detecting trace water in various organic solvents is still a challenge. Distinct form conventional fluorescent probes, room-temperature phosphorescence (RTP) test paper (TP) has aroused wide concern owing to its characteristic optical performance, including long afterglow and non-background interference. Herein, we fabricated a new kind of RTP-TP on the basis of chitosan carbon dots (CDs). The anchoring effect of polyvinyl alcohol (PVA) promoted the restriction of vibration/rotation and hindered the non-irradiative quenching of CDs by forming intermolecular hydrogen bonds. However, water molecules could interrupt these hydrogen bonds and therefore the RTP phenomenon would be disappeared. Further, the RTP-TP was used to detect trace water in various organic solvents with high efficiency, excellent stability, and reliability. In addition, the CDs-PVA solution can be also used as anti-counterfeiting ink via various printing methods. • RTP phenomenon was observed by embedding chitosan CDs to hydroxy-rich polymers. • An RTP-TP was designed with CDs-PVA for detecting trace water in organic solvents. • The mechanism for RTP origination of RTP-TP and its response to water were investigated in detail. • The CDs-PVA solution was applied as optical security ink via various printing methods. [ABSTRACT FROM AUTHOR]