{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T19:16:40Z","timestamp":1788290200297,"version":"build-2803163510"},"reference-count":40,"publisher":"American Chemical Society (ACS)","issue":"34","license":[{"start":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T00:00:00Z","timestamp":1786924800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T00:00:00Z","timestamp":1786924800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T00:00:00Z","timestamp":1786924800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22073001"],"award-info":[{"award-number":["22073001"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22103003"],"award-info":[{"award-number":["22103003"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22203004"],"award-info":[{"award-number":["22203004"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013461","name":"Anhui Normal University","doi-asserted-by":"publisher","award":["2023GFXK160"],"award-info":[{"award-number":["2023GFXK160"]}],"id":[{"id":"10.13039\/501100013461","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,8,27]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Triplet\u2013triplet energy transfer (TTET) via the Dexter mechanism is central to many photochemical applications, yet a quantitative structure\u2013kinetic relationship for bimolecular quenching rate constants (kq) is still lacking. Here, using two photosensitizers and a series of anthracene-based acceptors with tailored steric profiles, we systematically investigate how nonconjugated substituents regulate kq. The most significant results are when the triplet energy gap exceeds \u223c0.2 eV, kq is governed solely by steric hindrance and the suppression originates from spin-density-free units that block donor\u2013acceptor wave function overlap. We establish a quantitative model in which the effective collision probability \u03b7 equals the product of the van der Waals surface fractions carrying triplet spin density (P) for both donor and acceptor, giving kq,calc = kdiffuse \u00d7 \u03b7. Predicted rates match experimental values well and are further validated against literature systems.<\/jats:p>","DOI":"10.1021\/acs.jpclett.6c01840","type":"journal-article","created":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T06:02:38Z","timestamp":1786946558000},"page":"9777-9785","source":"Crossref","is-referenced-by-count":0,"title":["The Effect of\nSteric Hindrance on Triplet\u2013Triplet\nEnergy Transfer Rates: A Predictive Model Based on Spin-Density-Bearing\nvan der Waals Surfaces"],"prefix":"10.1021","volume":"17","author":[{"given":"Jiahui","family":"Cheng","sequence":"first","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ying","family":"Li","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cheng","family":"Yang","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0519-2131","authenticated-orcid":true,"given":"Zhongfa","family":"Sun","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8527-0381","authenticated-orcid":true,"given":"Zhou","family":"Lu","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0728-6577","authenticated-orcid":true,"given":"Yaxiong","family":"Wei","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. China, 241002"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinsheng","family":"Xu","sequence":"additional","affiliation":[{"name":"Anhui Normal University , , ,","place":["Wuhu, P. R. 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Biomol.\nChem."},{"issue":"3","key":"2026090114434427400_cit3","doi-asserted-by":"publisher","first-page":"1068","DOI":"10.1039\/D3CS00190C","article-title":"Energy transfer photocatalysis: exciting modes of reactivity","volume":"53","author":"Dutta","year":"2024","journal-title":"Chem. Soc. Rev."},{"issue":"8","key":"2026090114434427400_cit4","doi-asserted-by":"publisher","first-page":"8993","DOI":"10.1021\/jacs.5c22244","article-title":"Triplet Energy Transfer as a Handle to Tune 1,2-Dialkyldiazene\nFragmentation in Radical C(sp3)\u2013C(sp2) Cross-Coupling","volume":"148","author":"Scriven","year":"2026","journal-title":"J. Am. Chem. Soc."},{"issue":"29","key":"2026090114434427400_cit5","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202402774","article-title":"Novel Photocatalyst\nBased on Through-Space Charge Transfer Induced Intersystem Crossing\nEnables Rapid and Efficient Polymerization Under Low-Power Excitation\nLight","volume":"63","author":"Liang","year":"2024","journal-title":"Angew. Chem., Int. Ed."},{"issue":"17","key":"2026090114434427400_cit6","doi-asserted-by":"publisher","first-page":"2385","DOI":"10.1039\/D3CC06017A","article-title":"Red-light operable photosensitizer\nwith symmetry-breaking charge transfer induced intersystem crossing\nfor polymerization of methyl methacrylate","volume":"60","author":"Mahmood","year":"2024","journal-title":"Chem.\nCommun."},{"issue":"37","key":"2026090114434427400_cit7","doi-asserted-by":"publisher","first-page":"16114","DOI":"10.1002\/anie.202005269","article-title":"Elucidation of the Intersystem Crossing Mechanism in a Helical BODIPY\nfor Low-Dose Photodynamic Therapy","volume":"59","author":"Wang","year":"2020","journal-title":"Angew. Chem.,\nInt. 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Phys."},{"issue":"23","key":"2026090114434427400_cit12","doi-asserted-by":"publisher","first-page":"18942","DOI":"10.1021\/acs.energyfuels.1c02130","article-title":"Triplet Photosensitizers Showing\nStrong Absorption of Visible Light and Long-Lived Triplet Excited\nStates and Application in Photocatalysis: A Mini Review","volume":"35","author":"Zhao","year":"2021","journal-title":"Energy Fuels"},{"key":"2026090114434427400_cit13","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.77.155122","article-title":"Upconversion-induced\ndelayed fluorescence\nin multicomponent organic systems: Role of Dexter energy transfer","volume":"77","author":"Monguzzi","year":"2008","journal-title":"Phys. Rev. B"},{"issue":"5","key":"2026090114434427400_cit14","doi-asserted-by":"publisher","first-page":"836","DOI":"10.1063\/1.1699044","article-title":"A theory\nof sensitized luminescence in solids","volume":"21","author":"Dexter","year":"1953","journal-title":"J. Chem.\nPhys."},{"issue":"49","key":"2026090114434427400_cit15","doi-asserted-by":"publisher","first-page":"14442","DOI":"10.1021\/jp508901d","article-title":"Ionic liquid dependence of triplet-sensitized photon\nupconversion","volume":"118","author":"Murakami","year":"2014","journal-title":"J. Phys. Chem. B"},{"issue":"1","key":"2026090114434427400_cit16","doi-asserted-by":"publisher","first-page":"2698","DOI":"10.1038\/s41467-018-05160-1","article-title":"Ratiometric nanothermometer in vivo\nbased on triplet sensitized upconversion","volume":"9","author":"Xu","year":"2018","journal-title":"Nat.\nCommun."},{"issue":"33","key":"2026090114434427400_cit17","doi-asserted-by":"publisher","first-page":"22049","DOI":"10.1039\/C7CP03840B","article-title":"Triplet-triplet annihilation upconversion\nkinetics of C60-Bodipy dyads as organic triplet photosensitizers","volume":"19","author":"Wei","year":"2017","journal-title":"Phys. Chem. Chem. 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Chem."},{"issue":"36","key":"2026090114434427400_cit21","doi-asserted-by":"publisher","first-page":"10601","DOI":"10.1021\/jp062517o","article-title":"Solvent and pressure\neffects on quenching by oxygen\nof 9, 10-dimethylanthracene fluorescence in liquid n-alkanes: A study\non solvent cage effects","volume":"110","author":"Okamoto","year":"2006","journal-title":"J. Phys. Chem. A"},{"issue":"7","key":"2026090114434427400_cit22","doi-asserted-by":"publisher","first-page":"3153","DOI":"10.1021\/acs.jctc.5c02114","article-title":"Reaction-Diffusion Dynamics Simulations\nof Bimolecular Quenching in Solution","volume":"22","author":"Liedtke","year":"2026","journal-title":"J. Chem.\nTheory Comput."},{"issue":"7","key":"2026090114434427400_cit23","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202420070","article-title":"Efficient Near-Infrared to Blue Photon\nUpconversion by Ultrafast Spin Flip and Triplet Energy Transfer at\nOrganic\/2D Semiconductor Interface","volume":"64","author":"Zhao","year":"2025","journal-title":"Angew. Chem.,\nInt. Ed."},{"issue":"22","key":"2026090114434427400_cit24","doi-asserted-by":"publisher","DOI":"10.1002\/adom.202500876","article-title":"Highly Efficient Upconverted Fluorescence\nfrom Coulombically Assembled Ion Pair","volume":"13","author":"Baek","year":"2025","journal-title":"Adv.\nOpt. Mater."},{"issue":"13","key":"2026090114434427400_cit25","doi-asserted-by":"publisher","first-page":"5291","DOI":"10.1021\/acs.nanolett.5c00117","article-title":"Highly Effective Near-Infrared to\nBlue Triplet\u2013Triplet Annihilation Upconversion Nanoparticles\nfor Reversible Photobiocatalysis","volume":"25","author":"Peng","year":"2025","journal-title":"Nano Lett."},{"key":"2026090114434427400_cit26","doi-asserted-by":"publisher","DOI":"10.1016\/j.dyepig.2021.110049","article-title":"Deciphering the Ligand\u2019s geometric effect on\nthe photophysical properties of osmium complex and its application\nin triplet-triplet annihilation upconversion","volume":"199","author":"Yuan","year":"2022","journal-title":"Dyes Pigm."},{"issue":"1","key":"2026090114434427400_cit27","doi-asserted-by":"publisher","first-page":"2157","DOI":"10.1038\/s41467-024-46541-z","article-title":"Molecular near-infrared triplet-triplet annihilation\nupconversion with eigen oxygen immunity","volume":"15","author":"Wang","year":"2024","journal-title":"Nat.\nCommun."},{"key":"2026090114434427400_cit28","doi-asserted-by":"publisher","first-page":"3852","DOI":"10.31635\/ccschem.022.202101507","article-title":"Multiple Resonance\nThermally Activated Delayed Fluorescence Sensitizers Enable Green-to-Ultraviolet\nPhoton Upconversion: Application in Photochemical Transformations","volume":"4","author":"Wei","year":"2022","journal-title":"CCS Chem."},{"issue":"6","key":"2026090114434427400_cit29","doi-asserted-by":"publisher","first-page":"4923","DOI":"10.1039\/D2CP05047A","article-title":"Photosensitive\ndamage of dipeptides: mechanism and influence of structure","volume":"25","author":"Yang","year":"2023","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026090114434427400_cit30","unstructured":"Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Petersson, G. A.; Nakatsuji, H.; Li, X.; Caricato, M.; Marenich, A. V.; Bloino, J.; Janesko, B. G.; Gomperts, R.; Mennucci, B.; Hratchian, H. P.; Ortiz, J. V.; Izmaylov, A. F.; Sonnenberg, J. L.; Williams-Young, D.; Ding, F.; Lipparini, F.; Egidi, F.; Goings, J.; Peng, B.; Petrone, A.; Henderson, T.; Ranasinghe, D.; Zakrzewski, V. G.; Gao, J.; Rega, N.; Zheng, G.; Liang, W.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Throssell, K.; Montgomery, J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J. J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Keith, T. A.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Millam, J. M.; Klene, M.; Adamo, C.; Cammi, R.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Farkas, O.; Foresman, J. B.; Fox, D. J.\n          Gaussian; Gaussian\nInc.: 2009."},{"issue":"11","key":"2026090114434427400_cit31","doi-asserted-by":"publisher","DOI":"10.1063\/5.0021253","article-title":"Photon upconversion in multicomponent\nsystems: Role of back energy transfer","volume":"153","author":"Meroni","year":"2020","journal-title":"J. Chem.\nPhys."},{"issue":"6","key":"2026090114434427400_cit32","doi-asserted-by":"publisher","DOI":"10.1063\/5.0277862","article-title":"Thermally modulated triplet\u2013triplet\nannihilation: Deciphering the temperature dependence of upconversion\ndynamics","volume":"163","author":"Shao","year":"2025","journal-title":"J. Chem. Phys."},{"issue":"26","key":"2026090114434427400_cit33","doi-asserted-by":"publisher","first-page":"7968","DOI":"10.1021\/ja00260a006","article-title":"Properties of atoms\nin molecules: atomic volumes","volume":"109","author":"Bader","year":"1987","journal-title":"J. Am. Chem. Soc."},{"issue":"5","key":"2026090114434427400_cit34","doi-asserted-by":"publisher","first-page":"580","DOI":"10.1002\/jcc.22885","article-title":"Multiwfn:\nA multifunctional wavefunction analyzer","volume":"33","author":"Lu","year":"2012","journal-title":"J.\nComput. Chem."},{"issue":"8","key":"2026090114434427400_cit35","doi-asserted-by":"publisher","DOI":"10.1063\/5.0216272","article-title":"A comprehensive\nelectron wavefunction analysis toolbox for chemists, Multiwfn","volume":"161","author":"Lu","year":"2024","journal-title":"J. Chem. Phys."},{"issue":"40","key":"2026090114434427400_cit36","doi-asserted-by":"publisher","first-page":"22168","DOI":"10.1021\/jacs.3c08115","article-title":"Bulky Substituents\nPromote Triplet\u2013Triplet Annihilation Over Triplet Excimer Formation\nin Naphthalene Derivatives","volume":"145","author":"Olesund","year":"2023","journal-title":"J. Am. Chem. Soc."},{"issue":"50","key":"2026090114434427400_cit37","doi-asserted-by":"publisher","first-page":"22976","DOI":"10.1021\/jacs.2c09543","article-title":"Manipulating Exciton Dynamics toward\nSimultaneous High-Efficiency Narrowband Electroluminescence and Photon\nUpconversion by a Selenium-Incorporated Multiresonance Delayed Fluorescence\nEmitter","volume":"144","author":"Cao","year":"2022","journal-title":"J. Am. Chem. Soc."},{"issue":"15","key":"2026090114434427400_cit38","doi-asserted-by":"publisher","first-page":"5745","DOI":"10.1021\/jacs.1c00331","article-title":"Diphenylanthracene\nDimers for Triplet-Triplet Annihilation Photon Upconversion: Mechanistic\nInsights for Intramolecular Pathways and the Importance of Molecular\nGeometry","volume":"143","author":"Olesund","year":"2021","journal-title":"J. Am. Chem. Soc."},{"issue":"24","key":"2026090114434427400_cit39","doi-asserted-by":"publisher","first-page":"19001","DOI":"10.1021\/acs.inorgchem.1c02846","article-title":"Efficient Triplet\u2013Triplet\nAnnihilation Upconversion in Solution\nand Hydrogel Enabled by an S-T Absorption Os(II) Complex Dyad with\nan Elongated Triplet Lifetime","volume":"60","author":"Wei","year":"2021","journal-title":"Inorg. Chem."},{"issue":"8","key":"2026090114434427400_cit40","doi-asserted-by":"publisher","first-page":"2435","DOI":"10.1021\/acsenergylett.2c01224","article-title":"Diffusion-Free Intramolecular Triplet\u2013Triplet\nAnnihilation in Engineered Conjugated Chromophores for Sensitized\nPhoton Upconversion","volume":"7","author":"Mattiello","year":"2022","journal-title":"ACS Energy Lett."}],"container-title":["The Journal of Physical\nChemistry Letters"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acs.jpclett.6c01840","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/jpclcd\/article-pdf\/17\/34\/9777\/66608611\/acs.jpclett.6c01840.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/jpclcd\/article-pdf\/17\/34\/9777\/66608611\/acs.jpclett.6c01840.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T18:43:50Z","timestamp":1788288230000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/jpclcd\/article\/17\/34\/9777\/5259557\/The-Effect-of-Steric-Hindrance-on-Triplet-Triplet"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,17]]},"references-count":40,"journal-issue":{"issue":"34","published-online":{"date-parts":[[2026,8,17]]},"published-print":{"date-parts":[[2026,8,27]]}},"URL":"https:\/\/doi.org\/10.1021\/acs.jpclett.6c01840","relation":{},"ISSN":["1948-7185"],"issn-type":[{"value":"1948-7185","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,17]]}}}