Luminescent materials, including phosphorescent and fluorescent materials, have aroused great interests in recent years and have been fruitfully reported in the field of functional materials for their wide applications in bioimaging, [1] optical sensors, [2] molecular switches, [3] anti-counterfeiting materials[4] and organic light-emitting diodes (OLEDs).[5] Pure organic luminescent materials have received special attention for their low toxity and easy preparation.[6] These features are especially important for room-temperature phosphorescence (RTP), which traditionally involves noble metals such as platinum and iridium[7] in order to facilitate the intersystem crossing (ISC) process.
In recent years, our group has utilized supramolecular chemistry in designing phosphorescent and fluorescent materials. For RTP materials, methods such as polymerization were employed to provide rigid environments for bromo- or oxygen-containing phosphors (Figure 1a). In this approach, RTP in amorphous state has been effectively achieved.[8]
(a) Room-temperature phosphorescent materials in amorphous state; (b) stimuli responsive materials with multi-color including white color emission
For multi-color emissive materials, host-guest interactions, hydrophobic effects, multiple hydrogen bonding and π-π stacking have also been used to adjust the conformation, vibration or electron distribution of luminophores. Since these noncovalent interactions are sensitive to external conditions such as temperature and pH, fluorescent or phosphorescent materials are endowed with stimuli responsive feature by introducing these noncovalent interactions. Furthermore, photochromic diarylethenes (DAEs), spiropyrans (SPs) and azobenzene can reversibly change their chemical structures upon ultraviolet or visible light irradiation, and hence light responsive luminescent materials containing these units have been constructed (Figure 1b). The stimuli responsive materials can emit light of different colors when the external conditions change and white light emission has also been acquired.[9]
Besides luminescent materials in solid state and solution, several hydrogels based on noncovalent interactions have also been prepared, many of which have properties such as rapid self-healing and stimuli response, indicating future applications of supramolecular luminescent soft materials.[10]
Crystallization, which is able to effectively inhibit the nonradiative decay from the excited triplet state to the ground singlet, has become a feasible way of constructing pure organic RTP materials in solid state.[11] Although great advances have been made, crystals still require strict growth conditions and have low processability, highlighting the significance of amorphous RTP materials. To overcome these shortcomings, we have presented several general design strategies to provide rigid environment for phosphors, inhibiting their nonradiative decay. The amorphous materials obtained are characterized with simple preparation and great processability.[12]
Polymer matrix proved to be an ideal choice to provide rigid environment for phosphors. Among all kinds of polymers, polyacrylamide stands out because of its rigid hydrogen bonding network. Several phosphorescent acrylamide copolymers were therefore designed and synthesized with simple radical binary copolymerization.
Since heavy atoms can promote the ISC process, three bromo-containing phosphors, which are non-emissive in amorphous state, were copolymerized with acrylamide to give phosphorescence materials of different colors (poly- BrBA, poly-BrNp and poly-BrNpA, Figure 2a). The maximum quantum yield exceeded 10%. Spin-orbit coupling enhancement by heavy atoms was verified by using the same luminophores but without bromo substitution, which showed no obvious RTP emission. The effect of water was studied by preparing suspension of the polymers in N, N'-dimethylformamide (DMF)/H2O solvent with different volume ratio of water. The results showed that the phosphorescence emissions could be quenched by water, indicating potential applications in encryption ink. Special printer ink was prepared by dissolving one of the phosphorescent polymers in water and the letters were printed with this ink, followed by a drying process. Under 365 nm UV irradiation, the letters were clearly observed when they were dried and returned dark after the paper was wetted again[8a] (Figure 2c). Similar copolymerization strategy was used for 2-bromocarbazole derivatives, emitting blue phosphorescence.[8f] Furthermore, by using iodo-substituted dipyrromethene boron difluoride (BODIPY) dyes, the emission wavelength was extended to near-infrared region.[10b]
(a), (b) and (c) were reproduced with permission from Ref. [8a]. Copyright 2016 Wiley-VCH Verlag GmbH & Co. KGaA
Other functional groups, like oxygen-containing carbonyl, can also promote the ISC process. We therefore designed a series of phosphors containing carbonyl groups. Copolymerization of acrylamide with these phosphors was carried out to yield copolymers with ultra-long room- temperature phosphorescence (URTP) that could last for several seconds and be observed by naked eye. We proved the general applicability of this strategy by preparing ten polymers with URTP (Figures 3a, 3b). The polymer with the longest phosphorescence lifetime (up to 537 ms) and a quantum yield of 15% is P3 (i.e., the copolymer of compound 3 with acrylamide).[8b]
(a), (b) and (c) were reproduced with permission from Ref. [8b]. Copyright 2018 Wiley-VCH Verlag GmbH & Co. KGaA]
Besides copolymerizing phosphors with acrylamide, rigidity provided by hydrogen bonding can also be acquired using cyclodextrins (CDs) since CDs can form hydrogen bonds with each other aided by hydroxyl groups. We modified several phosphors with heavy atoms onto β-CD (Figure 4a). The hydrogen bonding network of β-CD can effectively suppress the nonradiative relaxion of phosphors and hence improve the phosphorescence quantum yield.[8b] Just like the case of polymerization, phosphors without heavy atoms were modified onto CDs as well. Several phosphors with carbonyl groups were attached to β-CD to yield efficient room-temperature phosphorescence (Figure 4b). Calculations were implemented to reveal that β-CD did not affect the frontier molecular orbitals of the phosphors. Given that CDs have no unsaturated groups, it is safe to conclude that all CDs would only provide rigid environment for phosphors but would not affect their electronic properties, providing a general approach to achieve RTP in amorphous state.[8d-8e]
(a) and (b) were reproduced with permission from Ref. [8b]. Copyright 2018 American Chemical Society
X-ray powder diffraction (XRPD) was carried out for all the materials mentioned above, proving their amorphous state without obvious crystal structures, which ensures that they are easy to prepare and process.
With the introduction of dynamic structures, luminescent copolymers are endowed with stimuli responsive characters. Polyacrylamide itself is a responsive structure since its hydrogen bonding network can be broken by water, reducing the rigidity of the matrix. Acrylamide was copolymerized with small amount of tetraphenylethylene (TPE) units to yield TPE-PAM (Figure 5a). The resulting polymer showed strong blue emission which, however, did not come from the well-known aggression-induced emission (AIE) character of TPE, but came from the rigidity provided by the polymer matrix and the hydrogen bonding network since the molar ratio of TPE units was so low in the copolymer that the self-aggregation was minimized. As expected, the copolymer exhibited decreasing emission intensity when it was suspended in H2O/DMF solvent and the volume fraction of water increased from 0% to 80%. Inspired by this phenomenon, a ternary copolymer TPE- RhB-PAM (Figure 5a) was prepared, which was composed of TPE units with blue fluorescence and AIE character and RhB units with red fluorescence but without AIE character, resulting in tunable multi-color emission including a white-light one in H2O/DMF solvent under UV irradiation (Figure 5b)[9k].
(a) and (b) were reproduced with permission from Ref. [9k]. Copyright 2017 The Royal Society of Chemistry
Bisthenylethene (BTE) is one of the most promising candidates for photochromic materials and has been used as another stimuli responsive unit. BTE units undergo reversible changes between the colorless ring-open form and colored ring-closed form via photoisomerization. A ternary copolymer poly(MMA-co-DPC-co-BTE) was therefore synthesized by copolymerizing methyl methacrylate (MMA) with BTE units as photochromic units and DPC units as fluorophores (Figure 6a). The flexible polymer chain does not affect the photoisomerization of BTE units but prevents DPC groups from aggression, avoiding the aggression-caused quenching (ACQ) effect. Upon excitation, the copolymer exhibits bright orange fluorescence at the initial state. The fluorescence can be gradually quenched when the copolymer is continuously irradiated with 365 nm UV lamp, because the ring-closed form of BTE generates. The process can be reversed when the polymer is exposed to visible light. Fಮrster Resonance Energy Transfer (FRET) mechanism is the reason for the reversible fluorescence quenching, which is proved with the overlapped absorption spectrum of the ring-closed form of BTE units and the emission spectrum of DPC units.[9d] The phenomenon was observed both in solid film and in solution (Figures 6b, 6c). Another set of fluorophore and photochromic unit, namely TPE and spiropyrans (SP), were also employed, yielding similar results.[9i]
(a), (b) and (c) were reproduced with permission from Ref. [9i]. Copyright 2019 Wiley-VCH Verlag GmbH & Co. KGaA
Besides singlet energy transfer, triplet energy transfer between luminophores and photochromic units is also utilized. Spiropyrans have been extensively used in the field of photochromic materials since SPs could convert from closed-loop forms to open-loop forms upon UV irradiation and recover when exposed to visible light (Figure 7a). To achieve photo-responsive luminescence, SP and phosphors were copolymerized with acrylamide (Figures 7b, 7c, 7d). When exposed to 365 nm UV irradiation, open-loop SP formed and energy transfer emerged. Both singlet and triplet energy transfer were observed for P1, P2 and P3, resulting in the gradual change of emission color with continues UV irradiation. Taking P1 as an example, the emission color changed from green to yellow to orange under 365 nm UV irradiation (Figure 7e). Because the RTP emission can be quenched by water and that SPs are temperature-responsive, these polymers also exhibit humidity- and temperature-responsive properties.[9h]
(a) to (e) were reproduced with permission from Ref. [9d]. Copyright 2020 American Chemical Society
Host-guest interactions, as mentioned above, can endow photoluminescent materials with stimuli responsive character while the interaction between macrocycle and small molecule is an essential part of them. Cucurbit[8]uril (CB[8]) has been commonly used as a host molecule to include luminescent guests, which process is mainly driven by hydrophobic effect as a noncovalent interaction. We elaborated a novel host-guest system based on CB[8] macrocycle and N, N'-dimethyl-2, 5, -bis(4-pyridinium)thi- azolo[5, 4-d] thiazole ditosylate (TMV) fluorophore (Figure 8a), which exhibited reversible response to temperature and humidity. TMV can self-assemble into the cavity of CB[8] in aqueous solution by two binding modes. The molar ratio between the host and the guest can be either 1:1 or 1:2 (Figure 8a). Upon excitation, TMV exhibits blue monomer emission in the former case and greenish-yellow dimer emission in the latter case (Figure 8b), where two TMV molecules stack closely with each other in CB[8] cavity. When printing 1/2 CB[8]/TMV solutions on substrates such as paper and silica, the emission color can reversibly change from greenish-yellow in wet conditions to blue in dry conditions because of the hydrophobic-effect-driven nature of the host-guest interaction. Moreover, heat can accelerate the free shuttle movement of TMV, achieving temperature-tunable emission. With the elevation of temperature, the blue emission can be enhanced. By mixing CB[8]/TMV complex with other temperature-responsive luminescent materials, namely glutathione-modified gold nanoclusters (GSH-AuNCs), a tunable, multicolor, temperature-dependent emitter was fabricated, covering a wide temperature range[9a] (Figure 8c).
(a) (b) and (c) were reproduced with permission from Ref. [9a]. Copyright 2019 American Chemical Society
Molecules with vibration-induced emission character were discovered by our group and attracted continuous attention.[13] A water-soluble VIE molecule of N, N'-di-phenyldihydrodibenzo[a, c]phenazines derivative (DPAC- AB, Figure 9a) was chosen as another guest, which could be included into the cavity of the host molecule of bis-p-sulfonatocalix[4]arene (BSC4, Figure 9a). By mixing the two substance in water, dual fluorescence was observed (Figure 9b). The vibration of DPAC-AB along the N—N axis could be suppressed via host-guest interaction.
(a) (b) and (c) were reproduced with permission from Ref. [9c]. Copyright 2018 Wiley-VCH Verlag GmbH & Co. KGaA
Therefore, free state and fixed state of DPAC-AB with different conjugated area and emission properties coexisted in the aqueous solution, resulting in different fluorescence color from orange-red to white to blue (Figure 9c) with the change of the molar ratio between the two forms. Competitive guest like acetylchloride, a neurotransmitter, can affect the inclusion effect between DPAC-AB and BSC4, resulting in recovered fluorescence signal of free-state DPAC-AB, which provides a potential strategy for VIE systems to be applied in areas including responsive biological imagining.[9c]
Combining the concept of host-guest interaction and excitation-dependent emission, a fluorescent molecule BPC (Figure 10a) bearing a pyridinium binaphthol unit (PBN) and a coumarin group with dual sensitivity towards excitation wavelength and the CD host molecule was designed (Figure 10b). The two-arm donor-accepter-donor molecule BPC exhibits dual emissions in aqueous solution, which comes from PBN group (blue-green band) and coumarin to pyridinium intramolecular charge-transfer (ICT) emission (red band), respectively. Further investigation shows that the blue emission originates from locally excited PBN, while the green emission is due to excited-state charge- transfer (CT) mechanism, giving the blue-green band excitation-wavelength-dependent character since the relative intensity of the two excited states could change with the excitation wavelength. In addition, the intensity of the red band can be enhanced by adding γ-CD, as this host molecule can immobilize closely stacked PBN and coumarin groups in the folded state, leading to promoted ICT emission. To sum up, the relative intensity of red (R), green (G), and blue (B) emissions of BPC can be orthogonally modulated based on external conditions, giving multi-color including white emission[9e] (Figure 10c).
(a), (b) and (c) were reproduced with permission from Ref. [9e]. Copyright 2016 American Chemical Society
Substances with AIE characters (AIEgens) have attracted intensive attractions for its distinctive luminescence properties.[14] By grafting TPE units onto pillar[5]arene, an AIE-active host (H) was successfully synthesized (Figure 11). Bithienylethene (BTE) derivative (G) was used as the guest for its photochromic property (Figure 11). The guest contains two cyano-triazole branches and can bind with the host in a 1:2 manner in solution (Figure 11). The host-guest complex (G⊂H) and the free H both exhibit AIE character in H2O/THF solution while the former emits significantly stronger fluorescence than the latter, attributed to the fact that one G binds with two H, restricting the intramolecular rotation of TPE. Upon 254 nm UV irradiation, the BTE unit in G gradually converts from the open form to the closed isomer, transforming G to G-C, which generates a new absorption peak at 516 nm. The FRET process between H and G quenches the fluorescence emission of TPE, since the absorption peak of G-C overlaps with the emission peak of H. When being exposed to visible light, the open form of G regenerates and the fluorescence recovers. The morphology of G⊂H in H2O/THF mixed solution can change upon UV irradiation or with the proportion of water, verifying its optical properties.[9j]
Reproduced with permission from Ref. [9j]. Copyright 2018 The Royal Society of Chemistry
In order to take a step further, we utilized a different fluorescent guest, TBP, along with CB[8] as the host (Figure 12a). Results showed that the blue fluorescent TBP solution could be modulated by adding different molar ratios of CB[8]. Similar to but not the same with the case mentioned above, CB[8] allowed two TBP molecules to form a structure-restricted dimer (Figure 12b), exhibiting yellow emission, which was verified with single-crystal X-ray diffraction (XRD). The dimer proved to be a new charge-transfer triplet state upon visible-light excitation (395 nm, Figure 4o), bringing about RTP in aqueous solution, which was rarely reported before. By changing the concentration of CB[8], the relative emission intensity of the monomer and the dimer changed. The solution therefore exhibited different emission colors including white color (Figure 12c). Adding competitive guests could yield similar result as TBP/CB[8] complex disassociates.[9f]
Inset in (c): photographs of TBP with different amounts of CB[8] in water. (a) to (d) were reproduced with permission from Ref. [9f]. Copyright 2020 Wiley-VCH Verlag GmbH & Co. KGaA
The assembling behavior of the supramolecular systems mentioned above was confirmed by several methods such as 1D and 2D 1H NMR, UV-Vis titration, isothermal calorimetry and/or theoretical calculation.
Pure organic luminescent materials have attracted much attention for their low toxicity and cost. We have utilized supramolecular approach to design diversified phosphorescent and fluorescent materials. Taking advantage of rigidification induced by polymerization, efficient room- temperature phosphorescent materials in amorphous state have been developed. Several phosphors including bromo- containing ones and heavy-atom free ones have been used to construct these polymers. Modification of β-CD with phosphors also generated RTP with the aid of hydrogen bonding. These pure organic, amorphous materials avoided the disadvantages of toxic metals and crystal growth. Regarding multi-color emitting luminescent materials, several noncovalent interactions as well as photosensitive units have been employed to fabricate color-tuning systems based on a single luminophore, which is sensitive to external stimuli. Multi-color emission including white color emission both in solution and in solid state opens the possibility of applications in various fields, including the next generation of smart materials.
Certainly, much effort is still required to design and develop luminescent materials based on pure organic macromolecules. The performance of amorphous RTP materials remains to be improved. The concept of performance includes not merely quantum yields, but also properties like brightness and the range of emission wavelength. For example, the proportion of phosphors in phosphorescent copolymers is limited because more phosphors would weaken the rigid environment provided by polymer matrix and introduce possible quenching effect.[8a-8c, 8f] This will result in limited absorbance despite a competitive quantum yield. If the quantum yield is at least kept unchanged and the absorbance is enhanced, the overall emission intensity could be improved. Also, amorphous RTP materials with NIR phosphorescence have much room for improvement. As to stimuli responsive luminescent systems, more kinds of responsiveness are expected to be integrated into a single luminophore. In other words, more external stimuli are expected to modulate the emission properties of the luminescent molecules orthogonally. Compared to the all-in- one method that involves many luminophores, this one-for- all strategy is much more promising both in theory and practice, proving its great potential in the field of stimuli responsive smart materials. Furthermore, such luminescent macromolecules with diverse emission properties pave the way for their application as a substructure in more complex molecular machines, evidenced by a phosphorescent molecular shuttle developed by our group.[15] In summary, by introducing various pure organic luminescent supramolecular materials and putting forward relative perspectives, we believe this account would be a helpful guide for designing and developing emissive materials.
(a) Gao, R.; Mei, X.; Yan, D.; Liang, R.; Wei, M. Nat. Commun. 2018, 9, 2798.
(b) Miao, Q.; Xie, C.; Zhen, X.; Lyu, Y.; Duan, H.; Liu, X.; Jokerst, J. V.; Pu, K. Nat. Biotechnol. 2017, 35, 1102.
(c) Zhen, X.; Tao, Y.; An, Z.; Chen, P.; Xu, C.; Chen, R.; Huang, W.; Pu, K. Adv. Mater. 2017, 29, 1606665.
(a) Zhou, Y.; Qin, W.; Du, C.; Gao, H.; Zhu, F.; Liang, G. Angew. Chem., Int. Ed. 2019, 131, 12230.
(b) Kim, H. N.; Guo, Z. Q.; Zhu, W. H.; Yoon, J.; Tian, H. Chem. Soc. Rev. 2011, 40, 79.
Ma, X.; Zhang, J.; Cao, J.; Yao, X.; Cao, T.; Gong, Y.; Zhao, C.; Tian, H. Chem. Sci. 2016, 7, 4582. doi: 10.1039/C6SC00769D
Jiang, K.; Zhang, L.; Lu, J.; Xu, C.; Cai, C. Angew. Chem., Int. Ed. 2016, 55, 7231. doi: 10.1002/anie.201602445
Lambert, J. S.; Li, H. C.; Wang, Q.; Liu, X. X.; Olivier, J.; Joë lle, R. B.; Liao, L. S.; Jiang, Z. Q.; Cyril, P. Angew Chem., Int. Ed. 2019, 58, 3848. doi: 10.1002/anie.201813604
(a) Xiong, Q.; Xu, C.; Jiao, N.; Ma, X.; Zhang, Y.; Zhang, S. Chin. Chem. Lett. 2019, 30, 1387.
(b) Qu, G.; Zhang, Y.; Ma, X. Chin. Chem. Lett. 2019, 30, 1809.
(c) Wang, C.; Jiang, T.; Ma, X. Chin. Chem. Lett. 2020, DOI: 10.1016/j.cclet.2020.03.021.
(d)Xu,C.;Xu,L.;Ma,X.Chin.Chem.Lett.2018,29,970.
(e)Wang,S.;Wang,F.;Li,C.;Li,T.;Cao,D.;Ma,X.Sci.China:Chem.2018,61,1301.
(f)Liu,X.;Ma,X.J.EastChinaUniv.Sci.Technol.(Nat.Sci.Ed.)2019,45,517(inChinese).(刘秀军,马骧,华东理工大学学报(自然科学版),2019,45,517.)
(g)Wang,H.;Shi,H.;Ye,W.;Yao,X.;Wang,Q.;Dong,C.;Jia,W.;Ma,H.;Cai,S.;Huang,K.;Fu,L.;Zhang,Y.;Zhi,J.;Gu,L.;Zhao,Y.;An,Z.;Huang,W.Angew.Chem.,Int.Ed.2019,58,18776.
(h)Tian,H.;Zhang,T.;Ma,X.;Wu,H.;Zhu,L.;Zhao,Y.Angew.Chem.,Int.Ed.2019,59,11206.
(i)Li,X.;Li,C.;Wang,S.;Dong,H.;Ma,X.;Cao,D.DyesPigm.2017,142,481.(j)Wang,S.;Xu,M.;Huang,K.;Zhi,J.;Sun,C.;Wang,K.;Zhou,Q.;Gao,L.;Jia,Q.;Shi,H.;An,Z.;Li,P.;Huang,W.Sci.China:Chem.2019,63,316.
(k)He,Z.;Cai,X.;Wang,Z.;Chen,D.;Li,Y.;Zhao,H.;Liu,K.;Cao,Y.;Su,S.J.Sci.China:Chem.2018,61,677.
(l)Ke,K.;Chen,J.X.;Zhang,M.;Wang,K.;Shi,Y.Z.;Lin,H.;Zheng,C.J.;Tao,S.L.;Zhang,X.H.Sci.China:Chem.2018,62,719.
Gan, N.; Shi, H.; An, Z.; Huang, Wei. Adv. Funct. Mater. 2018, 28, 1802657. doi: 10.1002/adfm.201802657
(a) Chen, H.; Yao, X.; Ma, X.; Tian, H. Adv. Opt. Mater. 2016, 4, 1397.
(b) Ma, X.; Xu, C.; Wang, J.; Tian, H. Angew. Chem., Int. Ed. 2018, 57, 10854.
(c) Wang, D.; Yan, Z.; Shi, M.; Dai, J.; Chai, Q.; Gui, H.; Zhang, Y.; Ma, X. Adv. Opt. Mater. 2019, 7, 1901277.
(d) Li, D.; Lu, F.; Wang, J.; Hu, W.; Cao, X. M.; Ma, X. J. Am. Chem. Soc. 2018, 1916.
(e) Zhao, C. X.; Jin, Y. H.; Wang, J.; Cao, X.; Ma, X. Chem. Commun. 2019, 55, 5355.
(f) Zhang, T.; Chen, H.; Ma, X.; Tian, H. Ind. Eng. Chem. Res. 2017, 56, 3123
(a) Jiang, T.; Wang, X.; Wang, J.; Hu, G.; Ma, X. ACS Appl. Mater. Interfaces 2019, 11, 14399.
(b) Li, D.; Hu, W.; Wang, J.; Zhang, Q.; Cao, X. M.; Ma, X.; Tian, H. Chem. Sci. 2018, 9, 5709.
(c) Wang, J.; Yao, X.; Liu, Y.; Zhou, H.; Chen, W.; Sun, G.; Su, J.; Ma, X.; Tian, H. Adv. Opt. Mater. 2018, 6, 1800074.
(d) Wang S.; Li, T.; Zhang, X.; Ma, L.; Li, P.; Yao, X.; Cao, D.; Ma, X. ChemPhotoChem 2019, 3, 568.
(e) Zhang, Q. W.; Li, D.; Li, X.; Paul, W.; Jasmin, M.; Ma, X.; Ågren, H.; Tian, H. J. Am. Chem. Soc. 2016, 138, 13541.
(f) Wang, J.; Huang, Z.; Ma, X.; Tian, H. Angew. Chem., Int. Ed. 2020, 59, 9928..
(g) Zhang, T.; Chen, H.; Ma, X.; Tian, H. Ind. Eng. Chem. Res. 2017, 56, 3123.
(h) Gu, F.; Ding, B.; Ma, X.; Tian, H. Eng. Chem. Res. 2020, 59, 1578.
(i) Gu, F.; Zhang, C.; Ma, X. Macromol. Rapid. Commun. 2019, 40, 1800751. (j) Ma, L.; Wang, S.; Li, C.; Cao, D.; Li, T.; Ma, X. Chem. Commun. 2018, 54, 2405.
(k) Zhang, C.; Yao, X.; Wang, J.; Ma, X. Polym. Chem. 2017, 8, 4835.
(a) Chen, H.; Ma, X.; Wu, S.; Tian, H. Angew. Chem., Int. Ed. 2014, 53, 14149.
(b) Zhang, T.; Ma, X.; Tian, H. Chem. Sci. 2020, 11, 482.
Yuan, W.; Shen, X.; Zhao, H.; Lam, J.; Tang, L.; Lu, P.; Wang, C.; Liu, Y.; Wang, Z.; Zheng, Q.; Sun, J.; Ma, Y.; Tang, B. J. Phys. Chem. C 2010, 114, 6090.
(b) Gong, Y.; Chen, G.; Peng, Q.; Yuan, W.; Xie, Y.; Li, S.; Zhang, Y.; Tang, B. Adv. Mater. 2015, 27, 6195.
(c) Luo, W.; Zhang, Y.; Gong, Y.; Zhou, Q.; Zhang, Y.; Yuan, W. Chin. Chem. Lett. 2018, 29, 1533.
(d) Bian, L. F.; Shi, H. F.; Wang, X.; Ling, K.; Ma, L.; Li, M.; Cheng, Z.; Ma, C.; Cai, S.; Gan, N.; Xu, X.; An, Z.; Huang, W. J. Am. Chem. Soc. 2018, 140, 10734.
(e) Cai, S.; Shi, H.; Li, J.; Gu, L.; Ni, Y.; Cheng, Z.; Wang, S.; Xiong, W. W.; Li, L.; An, Z.; Huang, W. Adv. Mater. 2017, 29, 1701244.
(f) Cai, S.; Shi, H.; Tian, D.; Ma, H.; Cheng, Z.; Wu, Q.; Gu, M.; Huang, L.; An, Z.; Peng, Q.; Huang, W. Adv. Funct. Mater. 2018, 28, 1705045.
(g) Chen, Z.; Shi, H.; Ma, H.; Bian, L.; Wu, Q.; Gu, L.; Cai, S.; Wang, X.; Xiong, W. W.; An, Z.; Huang, W. Angew. Chem., Int. Ed. 2017, 57, 678.
(h) Li, C.; Tang, X.; Zhang, L.; Li, C.; Liu, Z.; Bo, Z.; Dong, Y.; Tian, Y. H.; Dong, Y.; Tang, B. Adv. Opt. Mater. 2015, 3, 1184
(a) Fang, M. M.; Yang, J.; Li, Z. Chin. J. Polym. Sci. 2019, 37, 383.
(b) Gan, N.; Shi, H.; An, Z.; Huang, W. Adv. Funct. Mater. 2018, 28, 1802657.
Zhang, Z.; Wu, Y. S., Tang, K. C.; Chen, C. L.; Ho, J. W.; Su, J.; Tian, H.; Chou, P. T. J. Am. Chem. Soc. 2015, 137, 8509. doi: 10.1021/jacs.5b03491
(a) Gu, X.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Biomaterials 2017, 146, 115.
(b) Li, C.; Wu, T.; Hong, C.; Zhang, G.; Liu, S. Angew. Chem., Int. Ed. 2012, 51, 455.
(c) Yang, J.; Ren, Z.; Xie, Z.; Liu, Y.; Wang, C.; Xie, Y.; Peng, Q.; Xu, B.; Tian, W.; Zhang, F.; Chi, Z.; Li, Q.; Li, Z. Angew. Chem., Int. Ed. 2016, 56, 880.
Gong, Y. F.; Chen, H.; Ma, X.; Tian, H. ChemPhysChem 2016, 17, 1934. doi: 10.1002/cphc.201500901
Figure 1 Design strategy of pure organic luminescent materials
(a) Room-temperature phosphorescent materials in amorphous state; (b) stimuli responsive materials with multi-color including white color emission
Figure 2 (a) Structures of poly-BrBA, poly-BrNp and poly- BrNpA; (b) photographs of the solid powder of the three polymers under 365, 254 and 365 nm UV light, respectively, and their phosphorescence spectra (excitation wavelength＝350, 286 and 350 nm, respectively); (c) photographs of letters written using aqueous poly-BrNpA solution before and after drying under 365 nm UV light
(a), (b) and (c) were reproduced with permission from Ref. [8a]. Copyright 2016 Wiley-VCH Verlag GmbH & Co. KGaA
Figure 3 (a) General synthetic route of polymers with URTP, (b) structures of compounds 1~10, and (c) photographs of P3 powder under and after removal of 254 nm UV lamp
(a), (b) and (c) were reproduced with permission from Ref. [8b]. Copyright 2018 Wiley-VCH Verlag GmbH & Co. KGaA]
Figure 4 (a) Structures of BrNp-β-CD, BrHb-β-CD, BrBp-β- CD and BrNpA-β-CD, and (b) photographs of the solid powder of the four small molecules under 254, 254, 254 and 365 nm UV light, respectively
(a) and (b) were reproduced with permission from Ref. [8b]. Copyright 2018 American Chemical Society
Figure 5 (a) Structures of TPE-PAM and TPE-RhB-PAM, and (b) photographs of TPE-RhB-PAM in H2O/DMF mixed solvent with different volume fraction of water under 365 nm UV lamp
(a) and (b) were reproduced with permission from Ref. [9k]. Copyright 2017 The Royal Society of Chemistry
Figure 6 (a) Illustration of photoswitchable fluorescent polymer poly(MMA-co-DPC-co-BTE), and fluorescence emission spectral changes of poly(MMA-co-DPC-co-BTE) in (b) CH2Cl2 solution and (c) solid state (excitation wavelength＝480 nm)
(a), (b) and (c) were reproduced with permission from Ref. [9i]. Copyright 2019 Wiley-VCH Verlag GmbH & Co. KGaA
Figure 7 (a) Photosensivity of the SP derivative; Structures of (b) P1, (c) P2 and (d) P3, and (e) photographs showing the emission colors of P1 and P3 in DMF under 365 nm UV radiation and P2 after the removal of UV lamp
(a) to (e) were reproduced with permission from Ref. [9d]. Copyright 2020 American Chemical Society
Figure 8 (a) Illustration of CB[8]/TMV system, (b) fluore- scence spectra and photographs of TMV and TMV/CB[8] (n:n＝2/1) in aqueous solutions under 365 nm UV lamp, (c) photog- raphs of CB[8]/TMV-GSH-AuNCs solution under 365 nm UV lamp
(a) (b) and (c) were reproduced with permission from Ref. [9a]. Copyright 2019 American Chemical Society
Figure 9 (a) Illustration of DPAC-AB and the corresponding interaction with BSC4, (b) photoluminescence spectra of DPAC-AB (10－5 mol•L－1) with different ratio of BSC4 in DMSO/H2O (V:V＝1:9) mixed solution, and (c) chromaticity coordinate of DPAC-AB solutions
(a) (b) and (c) were reproduced with permission from Ref. [9c]. Copyright 2018 Wiley-VCH Verlag GmbH & Co. KGaA
Figure 10 (a) Structure of BPC, (b) simulated structure of the 1:1 complex BPCY, and (c) chromaticity of BPC at different excitation wavelength and with different amounts of γ-CD
(a), (b) and (c) were reproduced with permission from Ref. [9e]. Copyright 2016 American Chemical Society
Figure 11 Structures of H and G, and the illustration of fluorescence switching of the complex
Reproduced with permission from Ref. [9j]. Copyright 2018 The Royal Society of Chemistry
Figure 12 (a) Structures of TBP and CB[8], (b) side and top views of XRD structure of (TBP)2•CB2[8], (c) chromaticity coordinate of TBP with different CB[8] ratios in water in accordance with spectra, and (d) excitation-phosphorescence emission mapping of TBP (50 μmol/L) with 1.0 equiv. of CB[8]
Inset in (c): photographs of TBP with different amounts of CB[8] in water. (a) to (d) were reproduced with permission from Ref. [9f]. Copyright 2020 Wiley-VCH Verlag GmbH & Co. KGaA
扫一扫看文章
扫一扫关注我们
下载:
下载: