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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π*) and (n,π*) versus (σ*,π*) States. Substituent-Induced State Switching in Triplet Ketones

Götz Bucher
+ Author Affiliations
- Author Affiliations

WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK. Email: goebu@chem.gla.ac.uk

Australian Journal of Chemistry 70(4) 387-396 https://doi.org/10.1071/CH16621
Submitted: 2 November 2016  Accepted: 23 November 2016   Published: 21 December 2016

Abstract

The intramolecular interaction of ketone triplet excited states with nucleophilic substituents is investigated by studying the electronic properties of phenalenone and a range of phenalenones functionalized in position 9 as a model system. In accordance with the literature, a (π,π*) triplet excited state is predicted for phenalenone. Similarly, 9-fluoro-, 9-chloro-, and 9-methoxyphenalenone are calculated to have (π,π*) lowest triplet excited states, whereas the lowest triplet states of 9-bromo-, 9-iodo, 9-methylthio, and 9-dimethylaminophenalenone are predicted to have (σ*,π*) character. As a result of the interaction between halogen and oxygen lone pairs increasing with increasing orbital size, the antibonding linear combination of substituent lone pairs with oxygen lone pairs sufficiently rises in energy to change the character of the lowest triplet excited state of the 9-substituted phenalenones from (π,π*) to (σ*,π*). These unusual triplet excited states or exciplexes should essentially behave like (n,π*) triplets states, but will differ from pure (n,π*) states by showing significant spin densities at the substituent heteroatoms, predicted to reach values of 0.25 for 9-iodophenalenone, and ~0.5 for 9-dimethylaminophenalenone. Vertical T1–T2 excitation energies calculated indicate that the stabilization of the (σ*,π*) relative to the (π,π*) state can reach 1 eV. Preliminary calculations on the triplet excited states of 2-iodobenzophenone, 4-iodo-2-butanone, and iodoacetone indicate that intramolecular triplet exciplex formation should be a general phenomenon, as long as the ring being formed is at least a five-membered ring.


References

[1]  N. J. Turro, Modern Molecular Photochemistry 1991 (University Science Books: Sausalito, CA).

[2]  J. K. Bell, H. Linschitz, J. Am. Chem. Soc. 1963, 85, 528.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3sXksVantQ%3D%3D&md5=f6d12a7d8b83958a7195353db6ea3343CAS |

[3]  H. Lutz, M.-C. Duval, E. Bréhéret, L. Lindqvist, J. Phys. Chem. 1972, 76, 821.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE38XhtFagtb4%3D&md5=0a26914e3c6952b37ea7491f772df929CAS |

[4]  M. N. R. Ashfold, G. A. King, D. Murdock, M. G. D. Nix, T. A. A. Oliver, A. G. Sage, Phys. Chem. Chem. Phys. 2010, 12, 1218.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXht1Wms7Y%3D&md5=d9432034c95065344ab17979f611337cCAS |

[5]  G. Bucher, C. Lu, W. Sander, ChemPhysChem 2005, 6, 2607.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtleqtL7E&md5=6b0d56c63f7cbb3b1acad5fedd2378b4CAS |

[6]  S. Ginagunta, G. Bucher, J. Phys. Chem. A 2011, 115, 540.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXosl2iug%3D%3D&md5=0e6b65cfaa8b0df3981cdd55c4fa9c10CAS |

[7]  D. Zhang, Monatsh. Chem. 2010, 141, 1279.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhsVWqt73M&md5=360a47474d071c32fb8106d52f78bd45CAS |

[8]  J. G. Hill, G. Bucher, J. Phys. Chem. A 2014, 118, 2332.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXjsFOlsL0%3D&md5=5eb7806f66364d49663f0c1d7759f390CAS |

[9]  D. Klapstein, U. Pischel, W. M. Nau, J. Am. Chem. Soc. 2002, 124, 11349.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38Xms1CnsL4%3D&md5=d1fb0f71c05992e64e377182864dc4e9CAS |

[10]  S.-C. Chen, T.-S. Fang, Chem. Phys. Lett. 2007, 450, 65.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXhsVSgurbN&md5=1042f894001a4b96fa5bdaae95dc5686CAS |

[11]  U. Pischel, W. M. Nau, J. Am. Chem. Soc. 2001, 123, 9727.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXmslOhurY%3D&md5=7c591b54eb1e766d1f59753cc6842c42CAS |

[12]  E. Oliveros, P. Suardi-Murasecco, T. Aminian-Saghafi, A. M. Braun, Helv. Chim. Acta 1991, 74, 79.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXhvVCltb0%3D&md5=71d188b6b20af552cf0f7098a7ba56e0CAS |

[13]  M. C. Daza, M. Doerr, S. Salzmann, C. M. Marian, W. Thiel, Phys. Chem. Chem. Phys. 2009, 11, 1688.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXisFeqtrk%3D&md5=2427b870630e5c945770fd15367333f6CAS |

[14]  C. Flors, P. R. Ogilby, J. G. Luis, T. A. Grillo, L. R. Izquierdo, P.-L. Gentilli, L. Bussoti, S. Nonell, Photochem. Photobiol. 2006, 82, 95.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XitFCisb8%3D&md5=e10a07a70766f199244a6fdc763edebcCAS |

[15]  O. Anamimoghadam, M. D. Symes, C. Busche, D. Long, S. T. Caldwell, C. Flors, S. Nonell, L. Cronin, G. Bucher, Org. Lett. 2013, 15, 2970.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXoslSqt7s%3D&md5=c0d349062c58e23798aab37ac3fa45e5CAS |

[16]  G. Bucher, R. Bresolí-Obach, C. Brosa, C. Flors, J. G. Luis, T. A. Grillo, S. Nonell, Phys. Chem. Chem. Phys. 2014, 16, 18813.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXht1aitbbL&md5=eb451d68416380bf970f6ad11632cf44CAS |

[17]  O. Anamimoghadam, M. Symes, S. Sproules, D. Long, L. Cronin, G. Bucher, J. Am. Chem. Soc. 2015, 137, 14944.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2MXhslGmsrnP&md5=c464ccd436ee7c40d927c0e3cbd902a0CAS |

[18]  O. Anamimoghadam, D. Long, G. Bucher, RSC Adv. 2014, 4, 56654.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhvVGhs77M&md5=8593488e3592671159fd8d115b4a2de1CAS |

[19]  M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr, J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, Revision A.02 2009 (Gaussian, Inc.: Wallingford, CT).

[20]  Y. Zhao, N. E. Schultz, D. G. Truhlar, J. Chem. Theory Comput. 2006, 2, 364.
         | Crossref | GoogleScholarGoogle Scholar |

[21]  Y. Zhao, D. G. Truhlar, Theor. Chem. Acc. 2008, 120, 215.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXltFyltbY%3D&md5=cc861ed842819ae5ac3119d096252f86CAS |

[22]  J. Tomasi, B. Mennucci, R. Cammi, Chem. Rev. 2005, 105, 2999.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXmsVynurc%3D&md5=0247156fd47936bac149482703a173acCAS |

[23]  S. Miertuš, E. Scrocco, J. Tomasi, Chem. Phys. 1981, 55, 117.
         | Crossref | GoogleScholarGoogle Scholar |

[24]  T. H. Dunning, Jr, P. J. Hay, in Modern Theoretical Chemistry (Ed. H. F. Schaefer III) 1977, Vol. 3, pp. 1–28 (Plenum: New York, NY).

[25]  G. Igel-Mann, H. Stoll, H. Preuss, Mol. Phys. 1988, 65, 1321.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL1MXmtVaitL8%3D&md5=62cef174278fcb6d3fc162d17f9e827bCAS |

[26]  T. H. Dunning, J. Chem. Phys. 1989, 90, 1007.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL1MXksVGmtrk%3D&md5=592af84e00c432902e231e287168b4baCAS |

[27]  R. A. Kendall, T. H. Dunning, R. J. Harrison, J. Chem. Phys. 1992, 96, 6796.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XktFClurw%3D&md5=b57c3f730b3b0012d0bea11fc1bf39c1CAS |

[28]  D. E. Woon, T. H. Dunning, J. Chem. Phys. 1993, 98, 1358.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3sXhtlans7Y%3D&md5=7f7af57059a1dc4afec61549847e952bCAS |

[29]  G. C. Pimentel, J. Chem. Phys. 1951, 19, 446.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaG3MXlsVGktw%3D%3D&md5=a499b74d2149a98e9ce7078705b0d1b2CAS |

[30]  E. Magnusson, J. Am. Chem. Soc. 1990, 112, 7940.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3cXlslynsbs%3D&md5=7f551066ce8590834dd1c8616006bd88CAS |

[31]  For the relevant orbitals, please see the Supplementary Material.

[32]  V. P. Novikov, S. Samdal, L. V. Vilkov, Russ. J. Gen. Chem. 2004, 74, 1247.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXpvFOlsrk%3D&md5=fa67266e0a1b93ae97dd4dd9462667a7CAS |

[33]  S. Sasaki, G. P. C. Drummen, G. Konishi, J. Mater. Chem. C 2016, 4, 2731.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XitlGitLk%3D&md5=9ef7241e8487526919cf491190bd3c03CAS |

[34]  P. Jacques, X. Allonas, M. Von Raumer, P. Suppan, E. Haselbach, J. Photochem. Photobiol. Chem. 1997, 111, 41.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2sXnvFSnu78%3D&md5=70ee1d5664a1fb5778f32649e895877dCAS |

[35]  C. Devadoss, R. W. Fessenden, J. Phys. Chem. 1990, 94, 4540.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3cXisVartro%3D&md5=032758cd37586c7a23ec868f6301a3adCAS |

[36]  Preliminary ns time-resolved laser flash photolysis experiments with 5 (355 nm excitation wavelength, 8 ns pulse duration, 80 mJ pulse–1, CH3CN, 1 atm. Ar) did not show any transient species decaying on the ns or longer timescales. While this negative evidence is not conclusive, it would be consistent with the T1 lifetime of 5 being very short. It may also point to C–I cleavage being inefficient, as the phenyl-type radical and/or an iodine atom complex would have had to be observed otherwise. O. Anamimoghadam, G. Bucher, unpublished work.

[37]  The observation that the C–I bond length does not vary between S0 and T1 of 5 would support this. However, upon extremely rapid radiationless deactivation of the excited state, cleavage of the relatively weak C–I bond in a hot ground state ketone might nevertheless occur.

[38]  P. J. Wagner, J. H. Sedon, A. Gudmundsdottir, J. Am. Chem. Soc. 1996, 118, 746.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28XjtVWqug%3D%3D&md5=200d4da4fe9ae54b6c6dbd55f3a8354cCAS |

[39]  Excited states of o-thiyl ketones have been reported to be deactivated efficiently via a charge transfer interaction; see ref. [38] and Q. Cao, Part I, Photoinduced Sulfur Carbon Bond Cleavage : Part II, Photocyclization of ortho-Benzoyl-N-alkylanilinium Ions, Ph.D. thesis, Michigan State University, 1990.