Synlett 2016; 27(11): 1613-1617
DOI: 10.1055/s-0035-1561447
synpacts
© Georg Thieme Verlag Stuttgart · New York

Biradicaloid with a Twist: Lowering the Singlet–Triplet Gap

Prince Ravat
,
Tomáš Šolomek
,
Peter Ribar
,
Michal Juríček*
Weitere Informationen

Publikationsverlauf

Received: 25. Februar 2016

Accepted after revision: 21. März 2016

Publikationsdatum:
27. April 2016 (online)


Dedicated to Miroslav Kozák

Abstract

Fusing two phenalenyl units such that a Kekulé structure is obtained leads to ‘biradicaloid’ systems, which typically display low ­singlet–triplet (S–T) energy gaps. The value of the S–T gap in biradicaloids can be lowered by extending the conjugated system for an additional fused ring(s). Recently, we have described an alternative approach to decrease the S–T gap with the aid of through-space interactions that arise in helically twisted biradicaloids. Using [5]helicene-based biradicaloid ‘cethrene’ as an illustrative example, we have shown that the value of its S–T gap is substantially decreased when compared to that of its planar isomer heptazethrene, on account of the helical twist, inducing crucial intramolecular interactions.

 
  • References

  • 1 New address: T. Šolomek, Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113, USA.
  • 2 Gomberg M. J. Am. Chem. Soc. 1900; 22: 757
  • 3 Sogo PB, Nakazaki M, Calvin M. J. Chem. Phys. 1957; 26: 1343
  • 4 Kubo T. Chem. Rec. 2015; 15: 218
  • 5 Morita Y, Suzuki S, Sato K, Takui T. Nat. Chem. 2011; 3: 197
  • 6 Morita Y, Nishida S In Stable Radicals: Fundamentals and Applied Aspects of Odd-Electron Compounds . Hicks RG. John Wiley and Sons; Chichester: 2010: 81-145
  • 7 Reid DH. Q. Rev. Chem. Soc. 1965; 19: 274
  • 8 Goto K, Kubo T, Yamamoto K, Nakasuji K, Sato K, Shiomi D, Takui T, Kubota M, Kobayashi T, Yakusi K, Ouyang JY. J. Am. Chem. Soc. 1999; 121: 1619
  • 9 Mandal SK, Samanta S, Itkis ME, Jensen DW, Reed RW, Oakley RT, Tham FS, Donnadieu B, Haddon RC. J. Am. Chem. Soc. 2006; 128: 1982
  • 10 Pal SK, Itkis ME, Tham FS, Reed RW, Oakley RT, Haddon RC. Science 2005; 309: 281
  • 11 Hicks RG. Nat. Chem. 2011; 3: 189
  • 12 Morita Y, Nishida S, Murata T, Moriguchi M, Ueda A, Satoh M, Arifuku K, Sato K, Takui T. Nat. Mater. 2011; 10: 947
  • 13 Morita Y, Suzuki S, Fukui K, Nakazawa S, Kitagawa H, Kishida H, Okamoto H, Naito A, Sekine A, Ohashi Y, Shiro M, Sasaki K, Shiomi D, Sato K, Takui T, Nakasuji K. Nat. Mater. 2008; 7: 48
  • 14 Itkis ME, Chi X, Cordes AW, Haddon RC. Science 2002; 296: 1443
  • 15 Sun Z, Zeng Z, Wu J. Acc. Chem. Res. 2014; 47: 2582
  • 16 Clar E, Macpherson IA. Tetrahedron 1962; 18: 1411
  • 17 Li Y, Heng W.-K, Lee BS, Aratani N, Zafra JL, Bao N, Lee R, Sung YM, Sun Z, Huang K.-W, Webster RD, López Navarrete JT, Kim D, Osuka A, Casado J, Ding J, Wu J. J. Am. Chem. Soc. 2012; 134: 14913
  • 18 Bleaney B, Bowers KD. Proc. R. Soc. London, Ser. A 1952; 214: 451
  • 19 Ravat P, Baumgarten M. Phys. Chem. Chem. Phys. 2015; 17: 983
  • 20 Ravat P, Šolomek T, Rickhaus M, Häussinger D, Neuburger M, Baumgarten M, Juríček M. Angew. Chem. Int. Ed. 2016; 55: 1183
  • 21 Ortiz RP, Casado J, Hernández V, López Navarrete JT, Viruela PM, Ortí E, Takimiya K, Otsubo T. Angew. Chem. Int. Ed. 2007; 46: 9057
  • 22 Watanabe M, Chang YJ, Liu S.-W, Chao T.-H, Goto K, Islam MdM, Yuan C.-H, Tao Y.-T, Shinmyozu T, Chow TJ. Nat. Chem. 2012; 4: 574
  • 23 Sun Z, Lee S, Park KH, Zhu X, Zhang W, Zheng B, Hu P, Zeng Z, Das S, Li Y, Chi C, Li R.-W, Huang K.-W, Ding J, Kim D, Wu J. J. Am. Chem. Soc. 2013; 135: 18229
  • 24 Shimizu A, Kubo T, Uruichi M, Yakushi K, Nakano M, Shiomi D, Sato K, Takui T, Hirao Y, Matsumoto K, Kurata H, Morita Y, Nakasuji K. J. Am. Chem. Soc. 2010; 132: 14421
  • 25 Shimizu A, Uruichi M, Yakushi K, Matsuzaki H, Okamoto H, Nakano M, Hirao Y, Matsumoto K, Kurata H, Kubo T. Angew. Chem. Int. Ed. 2009; 48: 5482
  • 26 Huang J, Kertesz M. J. Am. Chem. Soc. 2007; 129: 1634
  • 27 Kubo T, Shimizu A, Sakamoto M, Uruichi M, Yakushi K, Nakano M, Shiomi D, Sato K, Takui T, Morita Y, Nakasuji K. Angew. Chem. Int. Ed. 2005; 44: 6564
  • 28 Cui Z.-H, Lischka H, Beneberu HZ, Kertesz M. J. Am. Chem. Soc. 2014; 136: 5539
  • 29 Mou Z, Uchida K, Kubo T, Kertesz M. J. Am. Chem. Soc. 2014; 136: 18009
  • 30 Cui Z.-H, Lischka H, Beneberu HZ, Kertesz M. J. Am. Chem. Soc. 2014; 136: 12958
  • 31 Suzuki S, Morita Y, Fukui K, Sato K, Shiomi D, Takui T, Nakasuji K. J. Am. Chem. Soc. 2006; 128: 2530
  • 32 Takano Y, Taniguchi T, Isobe H, Kubo T, Morita Y, Yamamoto K, Nakasuji K, Takui T, Yamaguchi K. J. Am. Chem. Soc. 2002; 124: 11122
  • 33 Koike H, Chikamatsu M, Azumi R, Tsutsumi J, Ogawa K, Yamane W, Nishiuchi T, Kubo T, Hasegawa T, Kanai K. Adv. Funct. Mater. 2016; 26: 277
  • 34 Chikamatsu M, Mikami T, Chisaka J, Yoshida Y, Azumi R, Yase K, Shimizu A, Kubo T, Morita Y, Nakasuji K. Appl. Phys. Lett. 2007; 91: 043506
  • 35 HZ: 8.9 kcal mol–1 by DFT, B3LYP/6-31G(d)/cc-pVTZ20 and 8.1 kcal mol–1 by DFT, CAM-B3LYP/6-31G(d,p).17 DBHZ1: 8.9 kcal mol–1 by DFT, CAM-B3LYP/6-31G(d,p).23
  • 36 The calculated (DFT, CAM-B3LYP/6-31G(d,p)) ΔE ST values for OZ 17 and DBHZ2 23 are 3.7 and 3.3 kcal mol–1, respectively.
  • 37 DFT, B3LYP/6-31G(d)/cc-pVTZ.20