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Hanen Mechi, Arthur Mantel, Vipin Mishra, [Yuto Urano](https://orcid.org/0009-0004-3646-2781), [Ryo Kitaura](https://orcid.org/0000-0001-8108-109X), Hidetsugu Shiozawa

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[Fluorescence from pentacyanopropenide in melamine](https://mdr.nims.go.jp/datasets/a2fbbbfa-0af4-4e53-a738-219c04881b40)

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Fluorescence from pentacyanopropenide in melamine5884 |  Mater. Adv., 2025, 6, 5884–5891 © 2025 The Author(s). Published by the Royal Society of ChemistryCite this: Mater. Adv., 2025,6, 5884Fluorescence from pentacyanopropenide inmelamine†Hanen Mechi,a Arthur Mantel,a Vipin Mishra,a Yuto Urano,bc Ryo Kitaura bc andHidetsugu Shiozawa *adAggregation-induced optical phenomena are at the forefront of modern materials science. In this work,tetracyanoethylene (TCNE) is reacted and encapsulated within melamine. Crystallization from aqueoustetrahydrofuran solutions containing melamine and TCNE at varying concentrations yields colorful crystalsexhibiting multi-wavelength fluorescence emission. Combined infrared spectroscopy and mass spectrometryreveal that the crystals are melamine doped with trace amounts of 1,1,2,3,3-pentacyanopropenide.Fluorescence excitation–emission spectral mapping elucidates the concentration dependence of fluorescenceemission in both the precursor solutions and the resulting crystals. Density functional theory calculations attri-bute the observed multi-wavelength emission to dimers of the pentacyanopropenide. Encapsulating reactivemolecules within crystalline melamine, as demonstrated with 1,1,2,3,3-pentacyanopropenide and its dimer,offers a versatile strategy for stabilizing a wide range of otherwise unstable species.1 IntroductionConcentration-dependent luminescence is a fascinating phe-nomenon in which the intensity or color of emission changesas the concentration of a luminophore varies. The exact beha-vior depends on various factors, including the properties of theluminophore, environmental conditions, and whether the sam-ple is a solid or a solution. In several important applications,such as organic light-emitting diodes (OLEDs),1 bioimaging2and chemical sensing,3 the relationship between concentrationand luminescent properties is a critical factor to consider.In many aggregates or solids of fluorophores, fluorescencetends to be quenched.4–6 The optical properties of monomers,dimers and trimers in solution have been studied extensivelyfor known fluorophores, such as rhodamine G,7–11 whichrevealed lowered quantum efficiencies for aggregates. Isolatedfluorophores in solids12 or diluted solutions6 can exhibitenhanced emission. Conversely, there are cases where fluores-cence is enhanced or even induced by aggregation.6,13In this work, tetracyanoethylene (TCNE) is reacted in a 1 : 1 (v/v)mixture of THF and water to yield 1,1,2,3,3-pentacyanopropenide,which is subsequently encapsulated within melamine crystals. Dueto the strong electron affinity of the pentacyano group, 1,1,2,3,3-pentacyanopropenide is stable under ambient conditions onlywhen paired with a cation in salts.14 As a result, the optical proper-ties of its neutral or isolated form have not been accessible for study.Melamine (2,4,6-triamino-1,3,5-triazine) has been chosen as the hostmatrix due to its ability to incorporate dopants effectively.15 Beingcolorless and absorbing only in the ultraviolet region, melamine istransparent in the visible range and exhibits fluorescence only in theultraviolet region, making it an ideal host material for encapsulatingreactive species and studying their optical properties.We observed that colorful 1,1,2,3,3-pentacyanopropenide-doped melamine crystals exhibit fluorescence across multiplewavelengths in the visible spectrum. The emission wavelengthincreases systematically with the concentration of 1,1,2,3,3-pentacyanopropenide. Density functional theory (DFT) calcu-lations suggest that this concentration-dependent fluorescencebehavior arises from the formation of pentacyanopropenideaggregates within the crystal structure.2 Results and discussion2.1 SynthesisDoped melamine crystals were synthesized via crystallization ofmelamine in a 1 : 1 (v/v) mixture of deionized water and THF,with varying concentrations of TCNE. For further details, seethe ESI.† The inset of Fig. 1 shows micrographs of crystalsa J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences,Dolejskova 3, 182 23 Prague 8, Czech Republic.E-mail: hide.shiozawa@jh-inst.cas.czb Research Center for Materials Nanoarchitectonics, National Institute for MaterialsScience, 1-1 Namiki, Tsukuba 305-0044, Japanc Graduate School of Chemical Science and Engineering, Hokkaido University,Kita13, Nishi 8, Kita-ku, Sapporo 060-8628, Japand Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.E-mail: hidetsugu.shiozawa@univie.ac.at† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d5ma00400dReceived 25th April 2025,Accepted 1st July 2025DOI: 10.1039/d5ma00400drsc.li/materials-advancesMaterialsAdvancesPAPEROpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article OnlineView Journal  | View Issuehttps://orcid.org/0000-0001-8108-109Xhttps://orcid.org/0000-0003-0603-2508http://crossmark.crossref.org/dialog/?doi=10.1039/d5ma00400d&domain=pdf&date_stamp=2025-07-16https://doi.org/10.1039/d5ma00400dhttps://doi.org/10.1039/d5ma00400dhttps://rsc.li/materials-advanceshttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400dhttps://pubs.rsc.org/en/journals/journal/MAhttps://pubs.rsc.org/en/journals/journal/MA?issueid=MA006017© 2025 The Author(s). Published by the Royal Society of Chemistry Mater. Adv., 2025, 6, 5884–5891 |  5885prepared by mixing 1 mL of a 100 mM aqueous solution ofmelamine with 1 mL of THF solutions of TCNE at concentra-tions of 0.2 mM (bottom left) and 20 mM (bottom right).2.2 Infrared spectroscopyFig. 1 displays the infrared absorption spectra of melamine,TCNE, and doped melamine crystals. The spectrum of mela-mine exhibits characteristic modes of the triazine ring at 814,1026, 1436 and 1551 cm�1, a bending mode of –NH2 at1652 cm�1, and stretching modes of –NH2 at 3130, 3333, 3419and 3469 cm�1.16 The spectrum of TCNE shows peaks at 555and 579 cm�1, corresponding to stretching vibrations of theCQC–C group.17 Peaks at 959 and 1155 cm�1 are attributed tothe stretching vibrations of the CQC bond, while those at2227 and 2261 cm�1 correspond to the stretching vibrationsof the CN bond in the cyano group. Importantly, the spectrumof the doped melamine retains all the peaks of pure melamine,but no peaks from TCNE, suggesting that the color of thecrystals arises from impurity species embedded within themelamine structure.2.3 Mass spectrometryMass spectrometry is a powerful analytical tool used to obtaininformation about the chemical structure and composition ofcompounds. Fig. 2 presents the mass spectra of a THF solutionof TCNE, an aqueous solution of melamine, and a 1 : 1 (v/v)aqueous THF solution of TCNE and melamine (TCNE–mela-mine), measured in both the positive ion mode (panel (a)) andthe negative ion mode (panel (b)). In the positive ion spectra ofall samples, multiple mobile phase peaks are observed. Theintense peaks at m/z = 42.04 and 82.67 correspond tothe protonated acetonitrile [ACN + H]+ (molecular mass of42.06 g mol�1) and its dimer [2ACN + H]+ (83.11 g mol�1),respectively. Additionally, the mass spectra of melamine andTCNE–melamine display distinct peaks at m/z = 101.8, 126.7and 167.6. The peak at m/z = 126.92 corresponds to the[melamine + H]+ ion (molecular mass of 127.13 g mol�1),18,19while m/z = 167.6 is attributed to an adduct of melamineand acetonitrile, [melamine + ACN + H]+ (168.18 g mol�1).20m/z = 101.8 may correspond to a decomposition product ofmelamine.In the negative ion mode, three distinct peaks are observedat m/z = 90.6, 114.6 and 166.5 in the spectra of both TCNE andTCNE–melamine. The negative ion mode generates peaks formolecules with a higher electron affinity or those that readilyaccept electrons. No peaks corresponding to the radical anion[TCNE]�� (molecular mass of 128.09 g mol�1) are observed. Thelargest peak at m/z = 166.5 can be attributed to 1,1,2,3,3-pentacyanopropenide [C3(CN)5]� (molecular mass of166.12 g mol�1).20 The molecular structure is illustrated inthe bottom right of Fig. 2. The peak at m/z = 114.6 indicates theformation of [C3(CN)3]� (molecular mass of 114.087 g mol�1).21The peak at m/z = 90.6 is attributed to tricyanomethanide[C(CN)3]� (molecular mass of 90.065 g mol�1).20,22 The peakat m/z = 218.6, observed only in TCNE–melamine, suggests thepresence of an adduct anion of TCNE products and melamine,such as [C3(CN)5 + 2(CN)]�.It has been reported that TCNE reacts in water to form 1,1,2,3,3-pentacyanopropenide [C3(CN)5]� (molecular mass of 166.12 g mol�1)under basic conditions20,23 and tricyanoethanolate [C2(CN)3O]�Fig. 1 (a) Infrared absorption spectra of pure melamine and doped melamine crystals. Insets: Micrographs of crystals (bottom left and bottom right)crystallized from precursor solutions prepared by mixing 1 mL of a 100 mM aqueous solution of melamine with 1 mL of THF solutions of TCNE atconcentrations of 0.2 mM (top left) and 20 mM (top right). (b) Infrared spectrum of TCNE crystals. The samples were finely ground and blended withspectroscopic-grade KBr in a ratio of approximately 1 : 100 (sample : KBr) before being compressed into pellets.Paper Materials AdvancesOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d5886 |  Mater. Adv., 2025, 6, 5884–5891 © 2025 The Author(s). Published by the Royal Society of Chemistry(molecular mass of 118.075 g mol�1) under neutral and acidicconditions.24 In our case, aqueous melamine acts as a weakbase. Fig. 3 shows a possible reaction pathway leading to theformation of 1,1,2,3,3-pentacyanopropenide.It should be noted that the observed ion species could alsobe generated via electron ionization. However, mass spectro-metry using inert buffer gas detected [TCNE]�� (molecular massof 128.09 g mol�1) as the major adduct anion,21,25 with noevidence of 1,1,2,3,3-pentacyanopropenide [C3(CN)5]� (molecu-lar mass of 166.12 g mol�1). This suggests that 1,1,2,3,3-pentacyanopropenide was present in the measured THFsolution of TCNE and the 1 : 1 (v/v) aqueous THF solution ofTCNE and melamine. Since water is part of the mobile phase inthe HPLC–MS system, TCNE should have reacted with water toyield 1,1,2,3,3-pentacyanopropenide. Therefore, the main UV-Vis absorption features observed for both the aqueous THFsolution of TCNE and the aqueous THF solution of TCNE andmelamine (Fig. 4b and c) should correspond to 1,1,2,3,3-pentacyanopropenide. Hence, 1,1,2,3,3-pentacyanopropenideis likely the species embedded in the melamine crystals.2.4 Ultraviolet-visible absorption spectroscopyFig. 4 shows the UV-Vis absorption spectra of aqueous solutionsof TCNE at concentrations of 0.2, 2.0, 10, 20 and 100 mM (panelFig. 2 The mass spectra of a THF solution of TCNE, an aqueous solution of melamine, and a 1 : 1 (v/v) aqueous THF solution of TCNE and melamine(TCNE–melamine), measured in the (a) positive ion mode and (b) negative ion mode.Materials Advances PaperOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d© 2025 The Author(s). Published by the Royal Society of Chemistry Mater. Adv., 2025, 6, 5884–5891 |  5887(a)), 1 : 1 (v/v) aqueous THF solutions of TCNE at the sameconcentrations (panel (b)), and precursor solutions prepared bymixing a 100 mM aqueous solution of melamine with THFsolutions of TCNE at concentrations of 0.2, 2.0, 10, 20 and100 mM (panel (c)). For each solutions, the spectral shaperemains unchanged with varying concentrations. The spectraof the THF solutions of TCNE exhibit intense peaks in the UVrange, with a sharp upper-wavelength edge at 280 nm. Lessintense absorption peaks are observed at longer wavelengths.According to mass spectrometry, TCNE reacts with water toyield 1,1,2,3,3-pentacyanopropenide in a 1 : 1 (v/v) mixture ofTHF and water. As a result, the UV-Vis absorption spectraof aqueous TCNE solutions differ significantly from those ofTCNE in pure THF. They display two distinct absorptionfeatures, as shown in Fig. 4b. The first peak appears atapproximately 298 nm. The second feature is a band consistingof multiple absorption lines, located within the wavelengthrange of 350–450 nm. Similar absorption lines have beenreported for a 1,1,2,3,3-pentacyanopropenide salt.23Finally, Fig. 4c shows the UV-Vis absorption spectra of TCNEand melamine dissolved in a 1 : 1 (v/v) mixture of THF andwater (the precursor solutions for the doped melamine crystals,in which TCNE is fully converted into 1,1,2,3,3-pentacyanopropenide according to mass spectrometry). These spectraexhibit the UV absorption edge of melamine around 250 nmand a weak absorption near 470 nm, in addition to the peaksobserved for pure TCNE in the THF–water mixture. As theabsorption at 470 nm is not observed for pure melamine orTCNE in aqueous THF (as shown in panel (b)), it is likely due toan interaction between 1,1,2,3,3-pentacyanopropenide andmelamine or a change in the state of 1,1,2,3,3-pentacyanopropenide induced by the presence of melamine, whichacts as a weak base in the solution.2.5 FluorescenceThe doped melamine crystals are not only colorful but alsofluorescent. In this section, we present a comprehensive ana-lysis of the fluorescence properties of individual crystals bymapping luminescence intensity as a function of both excita-tion wavelength (lex) and emission wavelength (lem) across theUV-visible spectrum.26 The left panels in Fig. 5a show fluores-cence excitation–emission maps for aqueous THF solutions ofTCNE and melamine. These were prepared by mixing a 100 mMaqueous solution of melamine with THF solutions of TCNE atmolar concentrations of 0.2 mM (0.2%), 2.0 mM (2.0%), 10 mM(10%), 20 mM (20%), 100 mM (100%), and 200 mM (200%),where the values in parentheses indicate the molar percentageof TCNE relative to melamine. For comparison, the map for a100 mM aqueous THF solution of pure melamine is also shownat the bottom.The corresponding integrated excitation and emission pro-files are shown in Fig. 5b. The pure melamine solution exhibitsa strong fluorescence emission at lex = 310 nm (Mex1 ) and lem =368 nm (Mem1 ). As the relative TCNE concentration increasesfrom 0 to 20%, the M1 emission of melamine gradually weak-ens, while a new emission feature emerges at lex = 368 nm (Sex1 )and lem = 480 nm (Sem1 ). At concentrations above 100%, boththe M1 emission of melamine and the S1 emission vanish, andmultiple new peaks centered around lex = 493 nm (Sex2 ) andlem = 593 nm (Sem2 ) appear. Note that subscript indices havebeen assigned so that the corresponding excitation–emissionpeak pairs share the same number.Fig. 3 Chemical equation illustrating the formation of 1,1,2,3,3,-pentacyanopropenide in aqueous melamine.Paper Materials AdvancesOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d5888 |  Mater. Adv., 2025, 6, 5884–5891 © 2025 The Author(s). Published by the Royal Society of ChemistryFig. 4 (a) UV-Vis spectra of aqueous solutions of TCNE at concentrations of 0.2, 2.0, 10 and 20 mM. (b) UV-Vis spectra of aqueous THF solutions ofTCNE at concentrations of 0.2, 2.0, 10 and 20 mM. (c) UV-Vis spectra of precursor solutions prepared by mixing a 100 mM aqueous solution of melamineand a THF solution of TCNE at concentrations of 0.2 mM (0.2%), 2.0 mM (2.0%), 10 mM (10%) and 20 mM (20%), where the percentages in parenthesesrepresent the molar concentration ratios of TCNE to melamine.Fig. 5 (a) Fluorescence excitation–emission wavelength maps for the precursor aqueous THF solutions of TCNE and melamine (left panels) and thecorresponding single crystals (right panels). The solutions were prepared by mixing a 100 mM aqueous solution of melamine with THF solutions of TCNEat molar concentrations of 0.2 mM (0.2%), 2.0 mM (2.0%), 10 mM (10%), 20 mM (20%), 100 mM (100%), and 200 mM (200%), where the values inparentheses indicate the molar percentage of TCNE relative to melamine. Maps for a 100 mM aqueous THF solution of pure melamine and for a puresolid melamine crystal are shown at the bottom for reference. (b) Integrated excitation and emission wavelength profiles for the precursor aqueous THFsolutions. (c) Integrated excitation and emission wavelength profiles for the corresponding single crystals.Materials Advances PaperOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d© 2025 The Author(s). Published by the Royal Society of Chemistry Mater. Adv., 2025, 6, 5884–5891 |  5889The right panels in Fig. 5a present the fluorescence excita-tion–emission wavelength maps of single crystals preparedfrom the respective precursor solutions. Their integrated exci-tation and emission profiles are shown in Fig. 5c. The M1emission of a pure melamine crystal appears at lex = 312 nm(M ex1 ) and lem = 358 nm (M em1 ), which diminishes withincreasing TCNE concentration and disappears entirely at20%. Doped melamine crystals display multiple emissionfeatures, with distinct patterns depending on the TCNE concen-tration. At concentrations of 0.2% and 2.0%, three emissionpeaks labeled Cem1 , Cem2 , and Cem3 are observed. At higherconcentrations, additional emissions labeled Cem4 andFig. 6 (a) Fluorescence decay profiles measured at an excitation wavelength of 490 nm at various temperatures. (b) Corresponding fluorescencelifetimes as a function of temperature.Fig. 7 UV-Vis absorption spectra simulated for aqueous solutions of (a) TCNE, (b) the neutral TCNE radical, (c) the tricyanomethanide anion, (d) thepentacyanopropenide anion, and (e) neutral pentacyanopropenide. (f) Simulated UV-Vis spectrum of the 1,1,2,3,3-pentacyanopropenide radical dimercompared with that of the monomer. Insets show the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO).Paper Materials AdvancesOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d5890 |  Mater. Adv., 2025, 6, 5884–5891 © 2025 The Author(s). Published by the Royal Society of ChemistryCem5 emerge at longer wavelengths, while the Cem1 , Cem2 , andCem3 emission peaks remain detectable even at the highestconcentration studied.2.6 Fluorescence lifetimeFig. 6a shows the fluorescence decay curves measured for the2.0% doped crystal at an excitation laser wavelength of 490 nmat various temperatures ranging from 10 to 300 K. The instru-ment response function (IRF) measured at 10 K is shown inblack for reference. The decay curves are well described by aconvolution of the IRF with a single-exponential decay func-tion. For details on the fitting analysis, refer to the ESI.† Theextracted lifetimes are 4.02, 3.88, 3.82, 3.58, 3.65, and 4.00 ns at10, 50, 100, 150, 200, and 300 K, respectively, as plotted inFig. 6b. No clear systematic dependence on temperature isobserved, and the average lifetime is 3.83 ns.2.7 Density-functional theory calculationsFig. 7 presents the UV-Vis spectra simulated using density-functional theory calculations. Based on mass spectrometrydata, the major species present in the precursor solutions areidentified as 1,1,2,3,3-pentacyanopropenide (panel (e)) andtricyanomethanide anions (panel (c)). The calculated UV-Visspectra for both anions exhibit their most intense absorptionpeaks in the wavelength range of 325–330 nm, which can becorrelated with the experimental band observed at 298 nm inFig. 4b and c. Notably, neither species shows any strongabsorption bands at longer wavelengths. In contrast, the neu-tral TCNE radical (panel (b)) features a prominent absorptionband at 400 nm, but this species is absent in the precursorsolutions, as confirmed by the mass spectrometry resultsshown in Fig. 2.To account for the experimentally observed absorptionfeatures in the wavelength range from 350 to 450 nm, addi-tional DFT calculations were performed on a dimer of 1,1,2,3,3-pentacyanopropenide. Fig. 7f compares the calculatedabsorption spectrum of the dimer with that of the monomer.The dimer displays a strong absorption band at 449 nm,corresponding to the HOMO–LUMO transition, which matcheswell with the absorption band observed in the range between350 and 450 nm in the experimental UV-Vis spectrum (Fig. 4band c), the Sex2 peak in the excitation wavelength profiles for the100% and 200% aqueous THF solutions (Fig. 5b), and theCex3 and Cex 03 peaks in the excitation wavelength profiles forthe 2–100% crystals (Fig. 5c). These results strongly support theconclusion that the 1,1,2,3,3-pentacyanopropenide dimer isthe primary chromophore responsible for the color observedin the doped melamine crystals.3 Conclusions1,1,2,3,3-Pentacyanopropenide was synthesized and encapsu-lated in solid melamine at different concentrations. The long-wavelength absorption and emission observed at higher con-centrations were attributed to the pentacyanopropenide dimer.Encapsulated in melamine, 1,1,2,3,3-pentacyanopropenidebecomes highly stable, which serves as a means to tailormultifunctional optical materials.Author contributionsH. M. performed the synthesis, UV-Vis absorption, and fluores-cence spectroscopy and wrote the manuscript. A. M. conductedthe synthesis, fluorescence spectroscopy, and DFT calculations.V. M. carried out the synthesis. Y. U. and R. K. performedfluorescence spectroscopy and lifetime measurements at var-ious temperatures. H. S. conceptualized and supervised theproject, provided resources, carried out data curation and DFTcalculations, and wrote the manuscript.Conflicts of interestThere are no conflicts of interest to declare.Data availabilityThe data supporting this article have been included as part ofthe ESI.†AcknowledgementsH. S. acknowledges the financial support from the AustrianScience Fund (FWF; Grant DOI: 10.55776/PIN9127924), theCzech Science Foundation (GACR; project 22-23407S), and theMinistry of Education, Youth and Sports of the Czech Republic(MEYS) through the V4-Japan joint research program (project8F21010). We thank J. Köhler, S. Loyer and A. Stangl fortechnical assistance.References1 J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks,K. Mackay, R. H. Friend, P. L. Burns and A. B. Holmes,Light-emitting diodes based on conjugated polymers,Nature, 1990, 347(6293), 539–541.2 Y. Yang, Q. Zhao, W. Feng and F. Li, Luminescent chemo-dosimeters for bioimaging, Chem. Rev., 2013, 113(1),192–270.3 B. Zhang, C. Ge, J. Yao, Y. Liu, H. Xie and J. Fang, Selectiveselenol fluorescent probes: design, synthesis, structuraldeterminants, and biological applications, J. Am. Chem.Soc., 2015, 137(2), 757–769.4 A. P. Green and A. R. 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Shiozawa, Synchronous electrochromism and elec-trofluorochromism in a zirconium pyrenetetrabenzoatemetal-organic framework, Adv. Electron. Mater., 2024,10(7), 2300854.Paper Materials AdvancesOpen Access Article. Published on 03 July 2025. Downloaded on 12/24/2025 2:44:22 AM.  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.View Article Onlinehttp://creativecommons.org/licenses/by/3.0/http://creativecommons.org/licenses/by/3.0/https://doi.org/10.1039/d5ma00400d