Smart phosphorescence from solid to water through progressive assembly strategy based on dual phosphorescent sources

Developing smart room‐temperature phosphorescence (RTP) materials with facile and efficient strategies have attracted increasing attention. Herein, tunable RTP materials with two phosphorescent sources and stepwise enhanced phosphorescence in water are obtained through an in‐situ self‐assembly strategy based on the sensitization of phosphors by trimesic acid (TMA) through simple doping and the rigidification of phosphors by hydrogen‐bonded organic frameworks (HOFs). As expected, doped TMA+phosphors simultaneously promote the RTP emission of phosphors and maintain TMA phosphorescence. In‐situ assembled HOF(MA‐TMA)@phosphors facilitate smart RTP emission in water due to the coexistence of phosphorescent HOF(MA‐TMA) host and phosphors guest. Additionally, such RTP materials with good processability demonstrate the application potential in information security, benefitting from their varied afterglow lifetimes and easy luminous recognition in the darkness. This work will inspire the design of dual phosphorescent source RTP systems and provide new strategies for the development of smart RTP materials in water.

][54][55][56][57][58] Therefore, developing a new generation of RTP materials with simultaneous long lifetime, high efficiency, and good stability via a facile, green, and cost-effective strategy is of great significance, although challenging.
[64][65] Multiple hydrogen bonding interactions and the coassembly performance between polymer matrices and organic phosphors are beneficial to restrain nonradiative decay, stabilize triplet excitons, and promote intersystem crossing (ISC), thus, realizing attractive RTP.In addition to the energetic research on polymer-based RTP materials, [66][67][68][69][70] rigid host matrixes with favorable hydrogen bonding are unlocking more possibilities for efficient RTP materials. [39,63,71]Ma, Tian, and coworkers decorated phosphor moieties to β-cyclodextrin (β-CD) and demonstrated that hydrogen bonding between the obtained β-CD derivatives fixed the phosphors to suppress the nonradiative decay and protected phosphors from quenchers to achieve RTP. [29]uang and coworkers reported cyanuric acid with abundant interaction positions could serve as the host matrix to facilitate efficient phosphorescence of phthalic acid derivatives guests through multi-hydrogen bonding interactions. [72]in and coworkers selected boric acid with rich hydrogen bonding sites as a host to suppress the nonradiative relaxation of guest triplet exciton. [9]Hydrogen-bonded organic frameworks (HOFs), as one of the potential crystal materials comparable to metal-organic frameworks and HOFs, [73] possess favorable hydrogen bonding as well as diverse and adjustable rigid structures, which are beneficial for the enhancement of RTP. [74]Chen and coworkers [75] proposed that embedding phosphors into HOFs would endow them with unique RTP properties.Inspired by the above considerations, a unique host matrix simultaneously possesses favorable hydrogen bonding sites, and remarkable luminescence is expected to prompt unexpected phosphorescent performance.If the stability and RTP properties of the abovementioned host-guest materials can be further improved by forming HOFs, such constantly enhanced RTP strategy will enlighten and promote the development of smart RTP materials even in water.
In light of the intrinsic RTP properties of trimesic acid (TMA) crystal and its three carboxyl moieties which can facilitate the n-π* transition, spin-orbit coupling, [72] and hydrogen bonding interactions, TMA is selected as a host matrix and organic phosphors such as 4-bromo-1,8naphthalic anhydride (NPA) is used as a guest in this work.As expected, the obtained TMA+NPA doped material prepared via a facile, green, and cost-effective strategy not only promoted the RTP of NPA but also inherited the phosphorescent property of TMA.More than that, such TMA+NPA doped material displayed different luminescence under the excitation of 254/365 nm, providing a universal and convenient path to construct efficient and RTP materials observable by the naked eye under ambient conditions.What is lacking in the beauty is that the RTP performance of the TMA+NPA doped system cannot resist the destruction of quenching agent water.Because multiple hydrogen bonding microenvironments help to suppress the nonradiative decays of phosphors, inhibit the penetration of triplet exciton quenchers, and promote the ISC process, we endeavored to achieve persistent and effective RTP emission in water based on the above TMA+NPA binary system by adding melamine (MA) as the hydrogen bonding linker.Hydrothermal synthetic HOF(MA-TMA)@NPA via the in-situ selfassembly strategy showed desirable and responsive RTP performance in water with high stability.Interestingly, both advocated approaches, that is, TMA+phosphors doped strategy and HOF(MA-TMA)@phosphors in-situ self-assembly strategy, showed desirable universality to prompt double phosphorescent emission and regulation.The upgraded ver-sion was that the in-situ self-assembly method of forming HOF(MA-TMA)@phosphors further realized smart RTP in water.This work in designing tunable RTP materials and cascade-enhanced RTP in water based on double phosphors (Scheme 1) not only enlightens a universal strategy to fabricate efficient RTP materials with a simple, green, low-cost method but also gives a new insight to tune RTP luminescence for various lifetime and color-resolved applications.

RESULTS AND DISCUSSION
The TMA powder and different amounts of NPA were evenly mixed by grinding to obtain TMA+NPA-doped materials.As shown in Figure 1A and Figure S1A,B, the TMA+NPA materials possessed distinct luminescence with different molar ratios of TMA and NPA under the excitation of 365 and 254 nm, which may be attributed to the coexistence of fluorescence and phosphorescence of TMA and NPA as well as the different luminescence ratio of TMA when changed the excitation wavelength (Figure S1C).To verify our hypothesis, the prompt emission spectra of TMA+NPA with different molar ratios of TMA and NPA were measured on HITACHI F-7000.The fluorescence intensity at 400-500 nm increased with the decrease of NPA under the excitation of 365 nm (Figure 1B) because the aggregation-caused quenching of NPA was gradually weakened.Meanwhile, a new phosphorescence emission signal gradually appeared at about 560 nm, however, a single NPA showed no phosphorescence emission under 365 nm excitation (Figure S2A).Under the excitation of 254 nm, the phosphorescence emission at 560 nm showed enhanced intensity with the decrease of NPA until the molar ratio of TMA:NPA was 125:1 (Figure 1C and Figure S2B).This extraordinary phenomenon indicated that TMA could serve as an active host to sensitize NPA by energy transfer (ET). [74,75]According to the observed excitation photos and fluorescence results, TMA+NPA with the molar ratio of TMA to NPA at 125:1 was used for the subsequent investigation.It was speculated that UV-lights excited the host TMA to its singlet state S 1 A and S 1 A quickly transformed to triplet state T 1 A to populate T 1 NPA by Dexter ET, or through Förster ET to form S 1 NPA and then T 1 NPA for the visible pink RTP emission.As observed in Figure S2C, the excitation spectrum of NPA almost did not overlap with the emission spectrum of TMA excited by 365 nm, although 254 nm excitation showed the prerequisite for Förster ET, NPA itself also emitted fluorescence at about 400 nm, which was consistent with the luminous position of TMA but could not excite phosphorescence under the excitation of 254 nm (Figure S2B).Therefore, the Dexter ET contributed to the primary energy transfer from TMA to NPA to sensitize T 1 NPA (Figure S2D) because TMA was an efficient phosphor with facile ISC and spin-orbit coupling.In addition, 254 nm failed to excite NPA phosphorescence even at 77 K (Figure S3), while individual TMA materials possessed RTP performance, and the obtained TMA+NPA materials also exhibited obvious NPA phosphorescence under the excitation of 254 nm (Figure 1 and Figure S2), further verifying the Dexter ET from TMA to NPA prompted the RTP of NPA.
To further investigate the RTP performance of TMA+NPA doped materials, the prompt and delayed emission spectra of TMA+NPA (125:1) were recorded on an FLS 1000 instrument.As in Figure S2E-H, the phosphorescence emission peak of abrasive TMA centered at 560 nm under the excitation of 365 nm and 254 nm with phosphorescence lifetimes were measured to be 7.04 and 3.65 ms, respectively.Comparing the prompt emission spectra of TMA and TMA+NPA (125:1), it was evident that the phosphorescence emission of TMA+NPA (125:1) obviously appeared at 560 nm under the excitation of 365 nm (Figures S1D and 2E).When irradiated by 254 nm, TMA+NPA (125:1) exhibited significantly enhanced phosphorescence at 560 nm, and the shoulder phosphorescence peak attributed to NPA appeared near 590 nm (Figure 1E and Figure S2G).Meanwhile, the phosphorescence lifetimes of TMA+NPA (125:1) at 560 nm and 590 nm were 6.51/5.99ms and 6.32/6.20 ms, respectively, under the excitation of 365 and 254 nm (Figure 1F,G), further indicating the presence of RTP emission of NPA in TMA+NPA.As shown in the surface electrostatic potential analysis and the FTIR spectra (Figure S4), despite individual NPA showing no RTP emission, the potential matching and the shift of carboxylic stretching vibration peaks caused by the hydrogen bonding interactions between TMA and NPA promoted the RTP emission of TMA+NPA doped materials. [65]In addition, π-π stacking between aromatic rings in TMA and NPA enhanced the rigidity of TMA+NPA, which was beneficial for promoting phosphorescence emission. [76]imultaneously, the RTP performances of the abovementioned materials were more vividly displayed in the videos (Videos S1-S4), also showing that the obtained TMA+NPA possessed distinct luminescence and phosphorescence performance compared with that of individual TMA.
Based on the above results, we devoted ourselves to studying RTP in an aqueous environment and expected to expand the applications of RTP materials.Unfortunately, both the TMA and TMA+NPA showed no RTP performance in aqueous solutions (Figure S5), suggesting the TMA+NPA doped material could not inhibit the quenching effect in the water.Considering the fact that multiple hydrogen bonding can provide a rigid microenvironment to reduce nonradiative decay and can serve as a shield for quenching agents in water, we used MA with rich hydrogen bonding sites as a linker to connect with TMA and further construct hydrogenbonded network protector for desirable RTP in aqueous solutions.Therefore, we further prepared the host-guest system based on HOFs via a hydrothermal self-assembly strategy to explore the influence of the microenvironment on the RTP properties.Initially, HOF(MA-TMA) was prepared according to the previous report with minor modifications [77] and HOF(MA-TMA)@NPA materials were obtained via the in-situ encapsulation method (Supporting Information).The disappearance of N-H vibration peaks in MA and the shifts of the C=O stretching peak in TMA suggested the formation of hydrogen bonds between MA and TMA (Figure 2A). [78,79]The successful encapsulation of NPA in HOF(MA-TMA) was further proved by the UV absorbance spectra of HOF(MA-TMA) and HOF(MA-TMA)@NPA, as shown in Figure S6, significant UV absorption of NPA appeared in HOF(MA-TMA)@NPA.The PXRD patterns of the solid samples in Figure 2B showed a well-defined crystalline structure of HOF(MA-TMA) before and after the encapsulation of NPA guest compared with that of the simulated one.Meanwhile, the as-prepared HOF(MA-TMA) possessed high stability (Figure 2C) and its microrod-like morphology remained unchanged before and after in-situ encapsulation of NPA (Figure 2D,E).Similar to the doped TMA+NPA, the obtained HOF(MA-TMA)@NPA materials also displayed different luminescence under the excitation of 365 and 254 nm due to the coexistence of different luminous species and luminous ratio (Figure 2F).
To verify that two phosphors could work together in HOF(MA-TMA)@NPA system, we initially investigated the existence of NPA phosphorescence in the composite materials.Compared with individual HOF(MA-TMA), HOF(MA-TMA)@NPA materials exhibited obvious phosphorescence signals at around 560 nm after encapsulating NPA under the excitation of 365 and 254 nm, whether in air or water (Figure S7A-D), indicating that embedding NPA phosphor in HOF(MA-TMA) promoted its phosphorescence emission and enhanced the stability of triplet exciton in water due to the existence of rigid microenvironment full of hydrogen bonds provided by HOF(MA-TMA).However, the phosphorescence signal of NPA at 560 nm could not be observed in HOF(MA-TMA)+NPA doped system, and such doped materials only showed luminescence similar to HOF(MA-TMA) itself (Figure S7E-H), showing that the NPA was not rigidly embedded in HOF(MA-TMA) through simple doping methods.In terms of the HOF(MA-TMA)+NPA doped system, HOF(MA-TMA) failed to provide enough host-guest interactions to ossify and sensitize NPA to prompt its RTP emission in the air and could not prevent the quenching effect of water on NPA phosphorescence.To gain further insight into the RTP performance of HOF(MA-TMA)@NPA composites, phosphorescence measurements were subsequently performed.According to the excitation spectrum and the afterglow photos of HOF(MA-TMA) (Figure S8), we systematically studied the phosphorescence performance of HOF(MA-TMA) under the excitation of 365 and 254 nm.As a result, individual HOF(MA-TMA) powder with blue fluorescence showed phosphorescence emission at 560 nm under the excitation of 365 nm as observed from its prompt and delayed emission spectra (Figure 3A) with a phosphorescence lifetime of 7.22 ms and a total quantum yield of 16.65% as well as a phosphorescence quantum yield of 10.46 % (Figure 3B and Figure S9A,C), while possessed a phosphorescence emission centered at 500 nm (Figure 3C) with a phosphorescence lifetime of 98.7 ms and a total quantum yield of 1.73% as well as a phosphorescence quantum yield of 0.65% (Figure 3D and Figure S9B,D) when excited by 254 nm.Interestingly, the delayed spectrum of HOF(MA-TMA) exhibited an obvious blue shift and significantly extended phosphorescence lifetime compared with pristine TMA when irradiated at 254 nm; we inferred that the hydrogen bonding interactions between MA and TMA induced the alteration of phosphorescence properties, as the solid-state luminescence properties were highly dependent on stacking modes and aggregation states. [80]oreover, HOF(MA-TMA)@NPA prepared with a molar ratio of MA:TMA:NPA = 125:125:1 also displayed a pink phosphorescent signal of NPA under the excitation of 365 nm with corresponding phosphorescence emission at 568 nm, and corresponding phosphorescence lifetime was measured to be 6.81 ms with a total quantum yield of 15.89% and a phosphorescence quantum yield of 11.06% (Figure 3E,F and Figure S10A,C).Meanwhile, HOF(MA-TMA)@NPA showed yellow light under the excitation of 254 nm with its phosphorescence signal center at 568 nm, and the phosphorescence lifetime monitored at 568 nm was 5.68 ms with a total quantum yield of 3.20% and a phosphorescence quantum yield of 1.75% (Figure 3G,H and Figure S10B,D).In terms of theoretical calculation, the energy gap of single-triplet excited states (∆E ST ) of NPA decreased when embedded in HOF(MA-TMA) and possessed a larger spin−orbit coupling coefficient (ξ ST ), indicating the rigid hydrogen bonding microenvironment facilitated intersystem crossing and promoted the RTP of NPA phosphors with apparent configuration distortion after embedding into HOF(MA-TMA) (Figure 3I,J).All these results confirmed that embedding NPA phosphor into a strong hydrogen bonding network of HOF(MA-TMA) could restrict its movement, inhibit nonradiative energy dissipation, and promote the return from triplet state T 1 to ground state S 0 .Furthermore, the sensitization of the HOF(MA-TMA) host to NPA also contributed to the phosphorescence emission of NPA in HOF(MA-TMA)@NPA according to the RTP performance of HOF(MA-TMA)@NPA under the excitation of 254 nm.In a word, two phosphorous sources could be obtained in one system based on the proposed in-situ encapsulation strategy prompted by phosphorescent HOF(MA-TMA).Inspiringly, we further systematically investigated the phosphorescence properties of HOF(MA-TMA)@NPA materials in water.The phosphorescence emission of individual HOF(MA-TMA) was initially monitored, as exhibited in Figure 4A, HOF(MA-TMA) dispersed in water showed no obvious delayed luminescence under the excitation of 365 nm, while significant green afterglow could be observed under the 254 nm irritation.Therefore, the prompt and delayed emission spectra of HOF(MA-TMA) in water were recorded, it was the same as what we observed, HOF(MA-TMA) in water showed no phosphorescent signal under the excitation of 365 nm but presented phosphorescence emission centered at 500 nm with a phosphorescence lifetime of 205 ms when irritated by 254 nm (Figure 4B-D).As observed in the crystal structures of TMA [81] and HOF(MA-TMA) [77] (Figure S11), the stacking of TMA in HOF(MA-TMA) retained a portion similar to the head-to-tail stacking pattern in the TMA structure but with a longer distance.This was the reason why HOF(MA-TMA) exhibited phosphorescence in the air under 365 nm excitation similar to that of TMA.The quenched phosphorescence of HOF(MA-TMA) in water (365 nm excitation) might attribute to that a large number of water molecules formed hydrogen bonding interactions with HOF(MA-TMA), leading to changed accumulation of TMA in HOF(MA-TMA) and resulting in the quenching of phosphorescence contributed by this part.According to the crystal structure of HOF(MA-TMA), apparent hydrogen bonding interactions between MA and TMA were observed; moreover, four molecules of water could be captured by hydrogen bonding in an MA-TMA network; these water molecules were linked to the upper and lower molecules respectively by various hydrogen bonds, which made significant contributions to hinder molecular motions for suppressing nonradiative transition of triplet excitons and promoting RTP of HOF(MA-TMA). [59]Based on the above assumptions and the structures of HOF(MA-TMA) as well as its prolongation of phosphorescence lifetime at 500 nm in water, we inferred that a large number of water molecules participated in the formation of hydrogen bonding interactions with HOF(MA-TMA) and making a more rigid hydrogen bonding microenvironment to prompt RTP emission in water under the excitation of 254 nm.
More impressively, HOF(MA-TMA)@NPA in water exhibited emerging phosphorescence emission at 568 nm with a phosphorescence lifetime of 7.08 ms at 365 nm excitation (Figure 4E,F).This could be attributed to the fact that HOF(MA-TMA) provided a rigid microenvironment for NPA, inhibited its nonradiative transition, and thus promoted the phosphorescence emission of NPA in water.Unlike single HOF(MA-TMA), HOF(MA-TMA)@NPA in water not only possessed inherent phosphorescent signal at 500 nm but also showed phosphorescence emission of NPA at 568 nm with its phosphorescence lifetime measured to be 5.87 ms under the excitation of 254 nm (Figure 4G,H), further verified that inserting NPA into HOF(MA-TMA) was beneficial to realize its RTP in water, even achieve double phosphorescence emission in water due to the presence of phosphorescent HOF(MA-TMA) host and NPA phosphor guest.HOF(MA-TMA)@NPA RTP materials possessed high stability in water, and the phosphorescence emission and phosphorescence lifetime showed no noticeable change even placed in water for 3 days (Figure S12A-C).Meanwhile, the HOF(MA-TMA)@NPA still possessed good phosphorescence emission even the temperature reached 70 • C (Figure S12D).Such desirable RTP performance could be attributed to the formation of the crystal structure of HOF(MA-TMA), which provided intense restriction on phosphors.Based on the above systematic research, we could achieve high-performance phosphorescence emission in water by forming a HOF shelter via an in-situ self-assembly strategy.Simultaneously, different luminescence and RTP performances at different excitation wavelengths could be obtained in one system by constructing TMA-based phosphorescent HOFs and introducing guest phosphors.It was worth noting that different microenvironment of TMA in these systems will affect their phosphorescence emission, which is a very interesting phenomenon, in the follow-up work, we will continue to study the relationship between TMA-based structure and their RTP performance.
To verify the universality of this strategy, 4-(4bromophenyl) pyridine (named as BPPy) was also tested as a guest phosphor.Taking the same proportion of raw materials as the NPA system as the research system, the solid TMA+BPPy doped system showed blue fluorescence emission and took 490 nm as the phosphorescence emission center under the excitation of 365 nm with a phosphorescence lifetime of 5.77 ms (Figure S13A,B).Not surprisingly, TMA+BPPy in water showed no phosphorescence emission (Figure S13C).Meanwhile, under the excitation of 254 nm, such solid TMA+BPPy doped material displayed a conspicuous green glow with its phosphorescence emission centered at 490 nm might be due to the sensitization of TMA to BPPy and the existence of a rigid microenvironment between TMA and BPPy (Figure S13D).Although the phosphorescence lifetime of solid material excited at 254 nm was 5.16 ms, the quenching effect of phosphorescence by water could not be prevented (Figure S13E,F), which was consistent with the phenomenon of the abovementioned NPA system, indicating that without rigid hydrogen-bonded network, protection layer could not prevent water from quenching the phosphorescence.
Unsurprisingly, the strategy of forming HOFs to in-situ encapsulate guest molecules was still applicable to the BPPy system.The obtained HOF(MA-TMA)@BPPy powder showed blue fluorescence with phosphorescence emission centered at 490 nm and displayed a minor phosphorescence emission center at 560 nm under the excitation of 365 nm (Figure 5A).And the phosphorescence lifetime at 490 and 560 nm were 7.78 and 8.42 ms, respectively (Figure 5B).Compared with that of individual HOF(MA-TMA) (Figure 3A), under the excitation condition of 365 nm, the phosphorescence at 490 nm was mainly attributed to the phosphorescence emission of BPPy phosphor, and the phosphorescent signal at 560 nm originated from the HOF(MA-TMA) host due to the stacking of TMA, because peak at 6.2 • corresponded to 100 planes indicating π−π stacking of TMA in one direction [82] obviously appeared after embedding phosphors (Figure S14).When excited at 254 nm, the HOF(MA-TMA)@BPPy powder mainly displayed a green glow, and its corresponding phosphorescence emission center was at 490 nm with a phosphorescence lifetime of 6.03 ms (Figure 5C,D).At the same time, the HOF(MA-TMA)@BPPy material maintained similar phosphorescence emission performance in water (Figure 5E-H).Consequently, we could conclude that the two proposed phosphorescence enhancement strategies, that is, TMA+phosphor doped strategy and HOF(MA-TMA)@phosphor in-situ selfassembly strategy, were universal.Moreover, with TMA, a molecule that could not only provide hydrogen bonding sites but also serve as phosphor, as the basic structure to construct phosphorescent HOFs and then fixed guest phosphors via one-pot synthesis facilitated the phosphorescence emission in water and promoted the luminescence regulation due to the presence of two phosphorous light sources-phosphorescent HOFs and guest phosphors.
In light of the facilely prepared efficient multicolor luminescent RTP materials, tuning afterglow color through the change of excitation wavelength would be possible to achieve information encryption.Since HOF(MA-TMA)@phosphor possessed good stability and processability, they were processed into flexible luminescent film materials by doping with polydimethylsiloxane (PDMS) substrate (Figure 6A).The acquired RTP films still maintained their luminous property in water and displayed distinct luminous colors under 365/254 nm irradiation with different afterglow duration performances (Figure 6B,C).Further, colorful anti-counterfeiting patterns of quick response were similarly fabricated using the highly stable multicolor RTP matrix, that was, the flower part was composed of HOF(MA-TMA)@NPA materials, and the blade position was filled with HOF(MA-TMA)@BPPy.Under daylight, such a flower pattern was full of white, under the irritation of 365 nm, the flower part showed pink flowers and the leaves exhibited blue luminescence, however, the flower part became yellow flowers and the leaves turned green glow after irritation by 254 nm.In addition, encrypted flowers showed a certain degree of delayed luminescence no matter whether they were irradiated at 254 or 365 nm (Figure 6D).

CONCLUSION
In conclusion, this work established facile, efficient, lowcost, and universal strategies, that was, TMA+phosphors doped strategy and HOF(MA-TMA)@phosphors in-situ selfassembly strategy, to construct enhanced RTP materials with good responsiveness even in water.TMA with both phosphorescent properties and hydrogen bonding points was regarded as archetype molecules, TMA+phosphor RTP materials with tunable luminescence were readily available by simply doping phosphors and TMA thanks to the sensitization effect of TMA on phosphors.The catch was that such a simple doped method could not achieve RTP in water because the water environment accelerated the molecular movement and the nonradiative transition of TMA/phosphors.Therefore, we further introduced the third component (MA) to construct a hydrogen-bonded network shield to ossify phosphors, inhibit nonradiative transition, and promote RTP emission in water.As expected, HOF(MA-TMA)@phosphors obtained by in-situ self-assembly strategy could not only ensure RTP emission in water but also realized phosphorescence regulation in water because the formation of hydrogen-bonded network structure maintained the rigidity of the phosphors in water, promoting the dual RTP emission of HOF(MA-TMA) and the guest phosphors.Moreover, HOF(MA-TMA)@phosphors RTP materials showed high stability in water because HOF(MA-TMA) possessed an ordered and dense hydrogen-bonded network structure to resist the interference of water quenching agent and ossify the phosphor guest.Besides, these RTP materials could be easily processed into luminescent films by mixing with PDMS, and they showed good potential in the field of encryption/anti-counterfeiting due to the existence of two phosphorous light sources (phosphorescent HOF(MA-TMA) host, phosphor guest) induced different luminescence colors and durations under the excitation of 365 and 254 nm.We envisage that these high-performance RTP materials prepared via TMA+phosphor doped strategy and HOF(MA-TMA)@phosphor in-situ self-assembly strategy hold great potential for large-scale preparation and applications of smart RTP materials.

EXPERIMENTAL SECTION
TMA+phosphors doped materials: To an agate mortar, TMA and phosphors such as NPA and BPPy with different molar ratios were mixed evenly and ground with the amount of TMA remained unchanged.HOF(MA-TMA) materials: First, MA (31.5 mg, 0.25 mmol) and TMA (52.5 mg, 0.25 mmol) were dis-solved in 25 mL water at 70 • C, respectively.Then, the as-prepared reaction solution was cooled down to room temperature and mixed together to obtain a mixture.Subsequently, the mixed system was stirred for 1 h, precipitation was separated and washed with water and ethanol, and white HOF(MA-TMA) powder was finally obtained under vacuum at 60 • C.
HOF(MA-TMA)@phosphors materials: The synthesis of HOF(MA-TMA)@phosphors was similar to that of HOF(MA-TMA).The only difference was the addition of NPA during the synthesis of HOF(MA-TMA).Taking HOF(MA-TMA)@NPA (125:125:1) as an example, 0.5 mL NPA solution (DMF) with a concentration of 1.1 mg/mL was added into the MA aqueous solution (0.25 mmol dissolved in 25 mL water), then mixed with as-prepared TMA aqueous solution (0.25 mmol dissolved in 25 m water) and stirred for 1 h.The white powder product HOF(MA-TMA)@NPA (125:125:1) was obtained by filtration and washed with water and ethanol.The preparation method of other proportions of HOF(MA-TMA)@NPA was similar, only the molar amount of NPA was changed.The synthesis of HOF(MA-TMA)@BPPy also referred to this procedure, except NPA was replaced by BPPy.
HOF(MA-TMA)+NPA doped materials: HOF(MA-TMA)+NPA doped materials were prepared via the post-synthesis method, in which the HOF(MA-TMA) was firstly prepared and then DMF solution of NPA was stirred with the obtained HOF(MA-TMA) in 50 m water for 1 h.HOF(MA-TMA)+NPA doped materials were finally obtained by filtration.
HOF(MA-TMA)@phosphors films: Taking HOF(MA-TMA)@NPA film as an example, 15 mg of HOF(MA-TMA)@NPA was dispersed in 0.2 mL ethyl acetate under ultrasonic conditions.Then, 1.0 g PDMS and 0.1 g curing agent were added to the above dispersion with vigorous stirring.The mixture was dropped into a mold and cured at 100 • C for 30 min to obtain HOF(MA-TMA)@NPA/PDMS film.The preparation method of HOF(MA-TMA)@BPPy/PDMS film was similar just replacing HOF(MA-TMA)@NPA with HOF(MA-TMA) @BPPy.

A C K N O W L E D G M E N T S
This work was supported by the National Natural Science Foundation of China (No. 22178187), the Natural Science Foundation of Shandong Province (Nos.ZR2020QB111 and ZR2022QB018), and the Natural Science Foundation of Jilin Province (No. 20230101052JC).

C O N F L I C T O F I N T E R E S T S TAT E M E N T
The authors declare no conflict of interest.

D ATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available in the supplementary material of this article.

S
C H E M E 1 (A) Schematic illustration of the preparation of TMA+phosphors doped RTP materials and their smart room-temperature phosphorescence (RTP) performance in the air as well as proposed photophysical processes; (B) Schematic representations of the preparation of HOF(MA-TMA)@phosphors and their smart RTP performance in water environment as well as encryption application.(Red ball: oxygen atom, Blue ball: nitrogen atom, White ball: hydrogen atom).

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I G U R E 3 (A-D) Prompt and delayed emission spectra of HOF(MA-TMA) powder in the air and corresponding lifetime decay spectra irradiated by 365/254 nm; (E-H) Prompt and delayed emission spectra of HOF(MA-TMA)@NPA powder in the air and corresponding lifetime decay spectra irradiated by 365/254 nm; (I, J) TD-DFT calculated energy levels, spin−orbit coupling (SOC) constants and configurations for 4-bromo-1,8-naphthalic anhydride (NPA) before and after embedding into HOF(MA-TMA).

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I G U R E 4 (A) Photos of the luminous duration of HOF(MA-TMA) in water; (B) Prompt and delayed emission spectra of HOF(MA-TMA) in water under the excitation of 365 nm; (C, D) Prompt and delayed emission spectra of HOF(MA-TMA) in water and corresponding lifetime decay spectra under 254 nm excitation; (E-H) Prompt and delayed emission spectra of HOF(MA-TMA)@NPA in water and corresponding lifetime decay spectra irradiated by 365/254 nm.

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I G U R E 5 (A-D) Prompt and delayed emission spectra of solid HOF(MA-TMA)@BPPy and corresponding lifetime decay spectra under 365 and 254 nm excitation; (E, F) Prompt and delayed emission spectra of HOF(MA-TMA)@BPPy in water and corresponding lifetime decay spectra under 365 and 254 nm excitation.F I G U R E 6 (A) Photos of processed films; (B) Luminescence display of corresponding films in water under 365 and 254 nm excitation; (C) Photos of the luminous duration of corresponding films under 365 and 254 nm excitation; (D) Anti-counterfeiting pattern and its controllable luminescence under 365 and 254 nm excitation.