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Satoshi Tanaka, Ryoko Oyama, [Mitsuharu Suzuki](https://orcid.org/0000-0002-0121-2561), [Hironobu Hayashi](https://orcid.org/0000-0002-7872-3052), [Hiroko Yamada](https://orcid.org/0000-0002-2138-5902), [Naoki Aratani](https://orcid.org/0000-0002-3181-6526)

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[Planar versus Twist: Two Conformers of a 5,7,12,14-Tetrakis(triisopropylsilylethynyl)pentacene in the Solid State](https://mdr.nims.go.jp/datasets/e11c0e41-481d-4849-a48b-b49a6f392385)

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Planar versus Twist: Two Conformers of a 5,7,12,14-Tetrakis(triisopropylsilylethynyl)pentacene in the Solid StatePlanar versus Twist: Two Conformers of a 5,7,12,14-Tetrakis(triisopropylsilylethynyl)pentacene in the Solid StatePublished as part of Organic Letters special issue “π-Conjugated Molecules and Materials”.Satoshi Tanaka, Ryoko Oyama, Mitsuharu Suzuki, Hironobu Hayashi, Hiroko Yamada,*and Naoki Aratani*Cite This: Org. Lett. 2025, 27, 12255−12258 Read OnlineACCESS Metrics & More Article Recommendations *sı Supporting InformationABSTRACT: We synthesized 4TIPS-pen, a pentacene derivativebearing TIPS-ethynyl groups at the 5,7,12,14-positions via a modifiedroute. The compound showed polymorphism, forming green crystalswith a twisted backbone and blue crystals with a planar backbone.UV−vis spectra and theoretical calculations revealed distinct opticalbehaviors linked to structural differences. 4TIPS-pen is photo-unstable, and we confirmed the product structure using X-rayanalysis. These results highlight structure−property relationships andoffer design guidelines for extended π-conjugated pentacenes.Acenes are renowned for their exceptional optical proper-ties, which result from effective conjugation, and areutilized in electronic materials such as organic transistors.1 Asthe conjugated system expands, the carrier mobility and otherfunctions of acenes improve. At the same time, higher acenesbeyond pentacene show significantly reduced stability andsolubility in organic solvents, making pentacene the moststudied compound both practically and in fundamentalresearch.2 One of the most direct strategies to address theseissues is the introduction of suitable substituents. Theformation of parent pentacene and higher acenes withoutsubstituents is currently limited to experimental techniquessuch as on-surface synthesis under inert conditions.3The triisopropylsilyl (TIPS)-ethynyl-substituted pentaceneat the 6,13-positions (TIPS-pen) is frequently examined as abenchmark for pentacene derivatives (Figure 1).4 TIPS-penwas first reported by Anthony in 2001, and various analogueshave been designed since then.4,5 The advantages of the TIPS-ethynyl groups include 1) improved molecular solubility due tothe bulky and stable TIPS groups, 2) expanded conjugationwhile maintaining planarity due to the acetylene triple bond, 3)control of packing in crystals, and 4) reversible detachment ofthe oxygen molecule at the 6,13-positions, resulting instabilization against oxygenation.6Most pentacene derivatives, including TIPS-pen, aredisubstituted compounds introduced at the 6,13-positions.Compounds with substituents introduced at the otherpositions or with more than two substituents are rare.7 4Ph-pen has phenyl-ethynyl groups introduced at 5,7,12,14-positions, exhibiting a long-wavelength shift in the maximumabsorption wavelength to 705 nm in o-dichlorobenzene.7 But ithas the disadvantage of being insoluble in most organicsolvents. No examples have been reported for nearly half acentury, since the introduction of the same substituent thatdirectly extends π-conjugation at the 5,7,12,14-positions.8Recently, Bunz reported the synthesis of 4-fold TIPS-ethynylpentacene 4TIPS-pen (Figure 1) to octacene and theirphysical properties as well as their stability in solution.9Meanwhile, in our independent efforts to create pentacenederivatives that exhibit absorption in the long-wavelengthregion by introducing four TIPS-ethynyl groups, we gainedinteresting insights into the crystal polymorphism of 4TIPS-pen.Received: August 31, 2025Revised: September 27, 2025Accepted: October 2, 2025Published: October 6, 2025Figure 1. Pentacene derivatives bearing multiple π-conjugatedsubstituents.Letterpubs.acs.org/OrgLett© 2025 The Authors. Published byAmerican Chemical Society12255https://doi.org/10.1021/acs.orglett.5c03674Org. Lett. 2025, 27, 12255−12258This article is licensed under CC-BY-NC-ND 4.0Downloaded via NATL INST FOR MATLS SCIENCE (NIMS) on December 9, 2025 at 10:33:08 (UTC).See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.https://pubs.acs.org/curated-content?journal=orlef7&ref=featurehttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Satoshi+Tanaka"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Ryoko+Oyama"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Mitsuharu+Suzuki"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hironobu+Hayashi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroko+Yamada"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Naoki+Aratani"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Naoki+Aratani"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.orglett.5c03674&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?goto=articleMetrics&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?goto=recommendations&?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?goto=supporting-info&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=tgr1&ref=pdfhttps://pubs.acs.org/toc/orlef7/27/44?ref=pdfhttps://pubs.acs.org/toc/orlef7/27/44?ref=pdfhttps://pubs.acs.org/toc/orlef7/27/44?ref=pdfhttps://pubs.acs.org/toc/orlef7/27/44?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig1&ref=pdfpubs.acs.org/OrgLett?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://doi.org/10.1021/acs.orglett.5c03674?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://pubs.acs.org/OrgLett?ref=pdfhttps://pubs.acs.org/OrgLett?ref=pdfhttps://acsopenscience.org/researchers/open-access/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/Here, we synthesized 4TIPS-pen using a modified route thatwas not previously reported. 4TIPS-pen exhibited crystallinepolymorphism, yielding green and blue single crystals from thesame solvent system. Single-crystal X-ray analysis revealed thatthe blue crystal has a structure where the pentacene skeleton isplanar, while the green crystal has a twisted pentacene skeletonstructure. The color difference was also examined bycomparing the UV−visible absorption spectra of each singlecrystal.In synthesizing 4TIPS-pen, we referred to the report byYamashita et al. in 2009.10 They used commercially available5,7,12,14-pentacene-tetraone as the starting material andsynthesized the compound with TIPS-ethynyl groups intro-duced at the diagonal 5,12-positions (2TIPS-dione) (Scheme1). They reported that only two positions reacted even whenan excess amount of TIPS-acetylene was added; thus, weconsidered that by isolating this 2TIPS-dione and performingthe same reaction once again, it would be possible to introduceTIPS-ethynyl groups into the two remaining ketone positions.The synthesis of 4TIPS-pen was performed according toScheme 1. Although Bunz’s group directly obtained 4TIPS-pen from pentacene-tetraone in 29% yield, they need a largeexcess amount of lithiated TIPS-acetylene (100 equiv) inhexane.9 In our synthetic route, 3 equiv of TIPS-ethynyllithium were reacted with 2TIPS-dione at room temperaturefor 24 h and the corresponding diol was reduced with SnCl2under hydrochloric acid conditions at 60 °C in an oil bath toobtain 4TIPS-pen as a dark-green solid with a yield of 21%.When the reduction was carried out at room temperature, theyield was reduced to 10%.The UV−vis absorption spectrum of 4TIPS-pen showed along-wavelength shift relative to those of pristine pentaceneand TIPS-pen due to the introduction of the ethynyl groups.The maximum absorption wavelength in the absorptionspectrum was observed to be slightly affected by the polarityof the solvents: in hexane (675 nm), dichloromethane (684nm), chloroform (684 nm), chlorobenzene (687 nm), andtetrahydrofuran (690 nm) (Figure S7). No fluorescentemission was observed, probably because the thermal rotationof the bulky TIPS groups accelerated the nonradiative decay.When the single crystals of 4TIPS-pen were prepared usingdichloromethane as the good solvent and methanol as the poorsolvent at room temperature, green and blue crystals wereobtained (Figure 2).11 Under optical microscope observation,the number of blue crystals was less than that of green crystals(Figure S8). Analysis by single-crystal X-ray diffraction wassuccessful for both.12 It was found that the molecular structurein the green crystal (4TIPS-pen(G)) has a twisted pentaceneskeleton (20.0°) while that in the blue crystal (4TIPS-pen(B))has a flat pentacene skeleton with TIPS-ethynyl groups bentoutward. The blue and green crystals had similar molecularpackings within the crystals (Figure S9).The ΔG of each molecule in the crystal was calculated usingdensity functional theory (DFT) methods (B3LYP/3-21G*level), and it was found that the structure in the blue crystalhad a higher energy (ΔΔG = 1.48 kcal/mol) than that in thegreen crystal. This result indicates that to mitigate therepulsion of bulky TIPS groups, twisting the pentacene planecan be achieved at a lower energy than distorting the fourTIPS-ethinyl groups, which possess higher flexibility. That is,the blue crystals represent a kinetic product that precipitates ata relatively fast rate while the structure in the green crystals is athermally stable one. According to these energy calculations,the phase-transition behavior between crystal polymorphs wasinvestigated by heating the blue crystal by using a melting-point apparatus. As shown in Figure S10, the color of a crystalwas observed to change from blue to green at 270−280 °C.Once the crystal color changed to green upon heating, thecrystals did not regain their blue color even after cooling.The UV−vis absorption spectra of these single crystals wererecorded (Figure 3). That of 4TIPS-pen(G) exhibits relativelylarge absorption at 400−440 nm for the S0 → S2 transitioncompared to the 550−700 nm range for the S0 → S1 transition.On the other hand, that of 4TIPS-pen(B) exhibitscomparatively small absorption at 400−440 nm. The factthat the oscillator strengths at 536 and 467 nm are zero for4TIPS-pen(B), based on the time-dependent (TD)-DFTcalculations, suggests that the S0 → S2 absorption issymmetry-forbidden. In contrast, the oscillator strength atthe same wavelengths is nonzero for 4TIPS-pen(G), indicatingthat S0 → S2 absorption becomes partially allowed due to thetwisting of the backbone. The absorption on the blue side(400−440 nm) could result in the green color of the crystal,which agrees with the experimental absorption spectrum.Scheme 1. Synthesis of 4TIPS-penFigure 2. Single-crystal X-ray structures of (a) 4TIPS-pen(G) and(b) 4TIPS-pen(B) (top and side views) and photographs of crystalsobserved under an optical microscope. The ellipsoids are scaled at50% probability. Hydrogen atoms and disordered parts were omittedfor clarity.Organic Letters pubs.acs.org/OrgLett Letterhttps://doi.org/10.1021/acs.orglett.5c03674Org. Lett. 2025, 27, 12255−1225812256https://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=sch1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=sch1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig2&ref=pdfpubs.acs.org/OrgLett?ref=pdfhttps://doi.org/10.1021/acs.orglett.5c03674?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asHigher acenes form endoperoxides by adding an oxygenmolecule to the central benzene ring of the parent skeletonwhen exposed to light in the presence of oxygen.6,13 Weevaluated the photostability of 4TIPS-pen by leaving it in achloroform solution under ambient conditions. 4TIPS-penpeaks in the 1H NMR spectra completely disappeared after 2weeks (Figure S11).9 When a chloroform solution of 4TIPS-pen was left in the dark, no significant changes were observedon the same time scale. This confirmed that 4TIPS-pen isstable in solution under atmospheric conditions as long as it isprotected from light.The structure of the 4TIPS-pen(O2) photodegradationproduct was identified by 1H NMR spectroscopy and single-crystal X-ray structural analysis (Figure 4).12 The crystalstructure confirms that the addition of an oxygen moleculecauses the pentacene skeleton to bend at the central benzenering and break the conjugation. The literature claims thatanthracene endoperoxide readily converts to the correspondingquinone,14 yet there are also reports indicating that theanthracene skeleton can be restored by heating.15 Weconfirmed that heating 4TIPS-pen(O2) in degassed tetra-chloroethane-d2 at 120 °C in an oil bath resulted in itscomplete decomposition within 1 h.In summary, we synthesized pentacene derivative 4TIPS-pen with TIPS-ethynyl groups introduced at the 5,7,12,14-positions via the modified synthetic route and evaluated itsphysical properties. 4TIPS-pen exhibited polymorphic behav-ior, yielding green and blue single crystals from the samesolvent system. Single-crystal X-ray analysis revealed that theblue crystal had a planar pentacene skeleton with TIPS-ethynylgroups bent outward while the green crystal had a twistedpentacene skeleton. It was found that the structure in the bluecrystal had a higher energy than that in the green crystal. Thisindicates that the blue crystals represent a kinetic productwhile the structure in the green crystals is a thermally stableone. The color differences were also examined by comparingthe UV−visible absorption spectra of each single crystal andTD-DFT calculations. The instability of 4TIPS-pen wasmonitored by 1H NMR, and we confirmed the structure ofthe endoperoxide product. These characteristics are unique to4TIPS-pen, which lacks substituents at positions 6 and 13.This study experimentally demonstrates insights into thephysical properties and reactivity of the 5,7,12,14-tetrasub-stituted pentacene derivative and provides useful guidelines forthe molecular design of novel pentacene derivatives withextended π-conjugation.■ ASSOCIATED CONTENTData Availability StatementThe data underlying this study are available in the publishedarticle and its Supporting Information.*sı Supporting InformationThe Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674.Experimental procedures, compound characterizationdata, spectral data, X-ray structural data, and computa-tional details (PDF)Accession CodesDeposition Numbers 2483982−2483984 contain the supple-mentary crystallographic data for this paper. These data can beobtained free of charge via the joint Cambridge Crystallo-graphic Data Centre (CCDC) and FachinformationszentrumKarlsruhe Access Structures service.■ AUTHOR INFORMATIONCorresponding AuthorsNaoki Aratani − Division of Materials Science and MediluxResearch Center, Nara Institute of Science and Technology(NAIST), Ikoma 630-0192, Japan; orcid.org/0000-0002-3181-6526; Email: aratani@ms.naist.jpHiroko Yamada − Institute for Chemical Research, KyotoUniversity, Uji, Kyoto 611-0011, Japan; orcid.org/0000-0002-2138-5902; Email: hyamada@scl.kyoto-u.ac.jpFigure 3. UV−vis absorption spectra of single crystals of 4TIPS-pen(G) (green) and 4TIPS-pen(B) (blue) along with that in CHCl3solution (black).Figure 4. Single-crystal X-ray structure of the photodegradationproduct of 4TIPS-pen. The ellipsoids are scaled at 50% probability.The disordered parts were omitted for clarity.Organic Letters pubs.acs.org/OrgLett Letterhttps://doi.org/10.1021/acs.orglett.5c03674Org. Lett. 2025, 27, 12255−1225812257https://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?goto=supporting-infohttps://pubs.acs.org/doi/suppl/10.1021/acs.orglett.5c03674/suppl_file/ol5c03674_si_002.pdfhttps://summary.ccdc.cam.ac.uk/structure-summary?pid=ccdc:2483982&id=doi:10.1021/acs.orglett.5c03674https://summary.ccdc.cam.ac.uk/structure-summary?pid=ccdc:2483984&id=doi:10.1021/acs.orglett.5c03674http://www.ccdc.cam.ac.uk/structureshttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Naoki+Aratani"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-3181-6526https://orcid.org/0000-0002-3181-6526mailto:aratani@ms.naist.jphttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Hiroko+Yamada"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-2138-5902https://orcid.org/0000-0002-2138-5902mailto:hyamada@scl.kyoto-u.ac.jphttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.orglett.5c03674?fig=fig4&ref=pdfpubs.acs.org/OrgLett?ref=pdfhttps://doi.org/10.1021/acs.orglett.5c03674?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asAuthorsSatoshi Tanaka − Division of Materials Science, Nara Instituteof Science and Technology (NAIST), Ikoma 630-0192,JapanRyoko Oyama − Division of Materials Science, Nara Instituteof Science and Technology (NAIST), Ikoma 630-0192,JapanMitsuharu Suzuki − Division of Applied Chemistry, GraduateSchool of Engineering, The University of Osaka, Osaka 565-0871, Japan; orcid.org/0000-0002-0121-2561Hironobu Hayashi − Center for Basic Research on Materials,National Institute for Materials Science (NIMS), Ibaraki305-0047, Japan; orcid.org/0000-0002-7872-3052Complete contact information is available at:https://pubs.acs.org/10.1021/acs.orglett.5c03674Author ContributionsThe manuscript was written through the contributions of allauthors.NotesThe authors declare no competing financial interest.■ ACKNOWLEDGMENTSThis work was supported by the Japan Society for thePromotion of Science (JSPS) KAKENHI grant nos.JP24K01553 (M.S.), JP24K01576 (H.H.), JP23K26480(N.A.), JP25K01751 (H.Y.), JP24K23087 (R.O.), andJP20H05833 (Transformative Research Areas “DynamicExciton”), Casio Science Promotion Foundation (J41-23)funds, and the Masuyakinen Basic Research Foundation. Wethank Yoshiko Nishikawa (NAIST) for the MS measurements.This work was partially supported by the ARIM Program ofthe Ministry of Education, Culture, Sports, Science andTechnology (MEXT) (JPMXP1225NR5003) and Start-upFunding for Female Researchers from the Diversity andInclusion Office at NAIST. We thank Prof. T. Kawai and Prof.T. Nakashima, NAIST, for the spectroscopic measurements ofsingle crystals.■ REFERENCES(1) Kitamura, M.; Arakawa, Y. Pentacene-based organic field-effecttransistors. J. Phys.: Condens. Matter 2008, 20, 184011.(2) Dimitrakopoulos, C. D.; Mascaro, D. J. Organic thin-filmtransistors: A review of recent advances. IBM J. Res. Dev. 2001, 45,11−27.(3) (a) Tönshoff, C.; Bettinger, H. F. Pushing the Limits of AceneChemistry: The Recent Surge of Large Acenes. Chem.�Eur. J. 2021,27, 3193−3212. (b) Lerena, L.; Zuzak, R.; Godlewski, S.; Echavarren,A. M. The Journey for the Synthesis of Large Acenes. Chem.�Eur. J.2024, 30, No. e202402122. (c) Hayashi, H.; Yamada, H. 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Lett.2009, 11, 1813−1816.(11) Previous research has also analyzed the same green singlecrystal (ref 9), but since it was measured at 200 K, we aligned themeasurement conditions at 90 K this time for both.(12) 4TIPS-pen(G): C66H94Si4, Mw = 999.77, monoclinic, spacegroup C2/c (no. 15), a = 54.876(7), b = 14.8416(19), c =15.1296(18) Å, β = 94.474(2)°, V = 12285(3) Å3, Z = 8, T =90(2) K, Dcalcd = 1.081 g cm−3, R1 = 0.0619 (I > 2σ(I)), Rw = 0.1228(all data), GOF = 1.090. 4TIPS-pen(B): C66H94Si4, Mw = 999.77,monoclinic, space group P21/c (no. 14), a = 15.538(2), b =15.2022(19), c = 15.0461(19) Å, β = 118.252(2)°, V = 3130.7(7) Å3,Z = 2, T = 90(2) K, Dcalcd = 1.061 g cm−3, R1 = 0.1133 (I > 2σ(I)), Rw= 0.2776 (all data), GOF = 1.040. 4TIPS-pen(O2): C66H94O2Si4, Mw= 1031.77, orthorhombic, space group Pbca (no. 61), a = 15.986(2), b= 24.614(3), c = 32.352(4) Å, V = 12730(3) Å3, Z = 8, T = 90(2) K,Dcalcd = 1.077 g cm−3, R1 = 0.0781 (I > 2σ(I)), Rw = 0.2326 (all data),GOF = 1.172.(13) Purushothaman, B.; Bruzek, M.; Parkin, S. R.; Miller, A.-F.;Anthony, J. E. Synthesis and Structural Characterization of CrystallineNonacenes. Angew. Chem., Int. Ed. 2011, 50, 7013−7017.(14) (a) Yamashita, K.-i.; Sugiura, K.-i. Photochemical reaction ofanthracene with dioxygen catalyzed by platinum(II) porphyrin.Tetrahedron Lett. 2019, 60, 151081. (b) Do, T. A. T.; Imae, T.Photodynamic and Photothermal Effects of Carbon Dot-CoatedMagnetite- and Porphyrin-Conjugated Confeito-Like Gold Nano-particles. Bull. Chem. Soc. Jpn. 2021, 94, 2079−2088.(15) (a) De Bonfils, P.; Nun, P.; Coeffard, V. UnsymmetricalAnthracene Platforms as Singlet Oxygen Batteries: Effects ofSubstituents on Photooxygenation and Endoperoxide Thermolysis.Eur. J. Org. Chem. 2024, 27, No. e202400099. (b) Klaper, M.; Wessig,P.; Linker, T. Base catalysed decomposition of anthraceneendoperoxide. Chem. Commun. 2016, 52, 1210−1213.Organic Letters pubs.acs.org/OrgLett Letterhttps://doi.org/10.1021/acs.orglett.5c03674Org. 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