Synthesis and Spectroscopic Properties of the Elusive 3a,9a-Diazaperylenium Dication Chariklia Sotiriou-Leventis,* Abdel-Monem M. Rawashdeh, Woon Su Oh, and Nicholas Leventis* Department of Chemistry, UniVersity of Missouri-Rolla, Rolla, Missouri 65409 leVentis@umr.edu Received September 7, 2002 ABSTRACT The 3a,9a-diazaperylenium dication (1) was synthesized for the first time in two steps from p-phenylene diamine. Ab initio calculations show a twisted ground state with a 6.4° tilt between the two quinolizinium building blocks. Dication 1 is photoluminescent in fluid solutions of H 2 O, CH 3 CN, and CH 3 NO 2 , but not in rigid matrices of the same solvents. This phenomenon has been attributed to a geometric relaxation of the tilted ground state into an emitting planar lowest singlet excited state. Several symmetric diaza analogues of small fused polyaro- matic systems are known. Notable examples include 1,10- phenanthroline, a common chelating agent, 2,6-diazaan- thracene, 1 which has been involved recently in directed self- assembly of chiral macrocyclic tetranuclear Pd and Pt molecular squares, 2 2,7-diazapyrene, 3 whose diquaternized dicationic derivative is water soluble and has been used as a sensitizer for photooxidations, 4 and as a DNA intercalator, 5 and also 2,9-diazaperopyrene, whose N,N′-dimethyl dicat- ionic derivative also interacts and binds nucleic acid com- ponents and catalyzes the photocleavage of single stranded oligonucleotides. 6 The monoquaternized derivative of 2,7- diazapyrene has been used also as a fluorescent dopant of sol-gel type materials for sensing O 2 . 7 Similarly, derivatives of 3,9-diazaperylene have been known since the 1980s. 8 A five-step synthesis and the photophysics of 1,7-diazaperylene were reported in the 1990s, 9 and a two-step synthesis of 1,12-diazaperylene from isoquinoline was described in 2001. 10 The 3a,9a-diazaperyle- nium dication (1), an isomer of the N,N′-diprotonated forms of 3,9-, 1,7-, and 1,12-diazaperylene, has not been known. 11 In contrast, the quinolizinium building block of 1 has been known since 1954, 12 and has been the subject of numerous spectroscopic, 13 crystallographic, 14 chemical, 15 theoretical, 16 * Email address for C.S.-L.: cslevent@umr.edu. (1) (a) Schwan, T. J.; Miles, N. J. J. Heterocycl. Chem. 1982, 19, 1351- 1353. (b) Bolitt, V.; Mioskowski, C.; Ready, S. P.; Falck, T. J. Synthesis 1988, 388-389. (2) (a) Stang, P. J.; Olenyuk, B. Angew. Chem., Int. Ed. Engl. 1996, 35, 732-736. (b) Olenyuk, B.; Whiteford J.; Stang, P. J. J. Am. Chem. Soc. 1996, 118, 8221-8230. (3) (a) Sotiriou-Leventis, C.; Mao, Z. J. Heterocycl. Chem. 2000, 37, 1665-1667. (b) Sotiriou-Leventis, C.; Mao, Z.; Rawashdeh, A.-M. M. J. Org. Chem. 2000, 65, 6017-6023. (4) Blacker, A. J.; Jazwinski, J.; Lehn, J.-M. HelV. Chim. Acta 1987, 70,1-12. (5) (a) Blacker, A. J.; Jazwinski, J.; Lehn, J.-M.; Wilhelm, F. X. J. Chem. Soc., Chem. Commun. 1986, 1035-1037. (b) Brun, A. M.; Harriman, A. J. Am. Chem. Soc. 1992, 114, 3656-3660. (c) Becker, H.-C.; Norden, B. J. Am. Chem. Soc. 1997, 119, 5798-5803. (6) Slama-Schwok, A.; Jazwinski, J.; Be ´re ´, A.; Montenay-Garestier, T.; Rouge ´e, M.; He ´le `ne, C.; Lehn, J.-M. Biochemistry 1989, 28, 3227-3234. (7) Leventis, N.; Elder, I. A.; Rolison, D. R.; Anderson, M. L.; Merzbacher, C. I. Chem. Mater. 1999, 11, 2837-2845. (8) (a) Tatke, D. R.; Seshadri, S. Indian J. Chem., Sect. B 1983, 22B, 1197-1199. (b) Tatke, D. R.; Seshadri, S. Dyes Pigm. 1986, 7, 153-158. ORGANIC LETTERS 2002 Vol. 4, No. 23 4113-4116 10.1021/ol0268687 CCC: $22.00 © 2002 American Chemical Society Published on Web 10/16/2002