Synthesis and Spectroscopic Properties of the Elusive 3a,9a-Diazaperylenium Dication

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 degrees 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. [structure: see text]

Synthesis of Substituted Diazoniapentaphene Salts by an Unexpected Rearrangement‐Cyclodehydration Sequence

“…In contrast, in dimethyl sulfoxide (DMSO) the fluorescence is strongly quenched (Φ F = 0.01-0.03 for unsubstituted and methyl-substituted diazoniapentaphenes), and the emission spectra are structureless. A similar decrease of fluorescence in DMSO was observed for the related 3a,9a-diazaperylenium dication [23] as well as for benzo [b]quinolizinium salts, [24] and it was correlated with the high electronic donor strength of this solvent in combination with the low reduction potential of the chromophore. [24] Notably, compound 10b, where the fused aromatic system is disrupted by two methylene groups, also shows reasonably strong UV absorption and fluorescence properties.…”

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

“… a Reagents and conditions: (a) Na 2 S 2 O 4 , MeOH, 5% NaOH, reflux, 1 h; (b) copper bronze, diethyl phthalate, reflux, 5 min; (c) photochemical; (d) 1-chloronaphthalene, reflux, 5 min; (e) NH 3 (20%), Zn powder, rt, 2 h; (f) 2-chloropyrimidine, K 2 CO 3 , DMF, reflux, 2 h; (g) Raney Ni, cyclohexene, DMF, 110 °C, 1 h; (h) urea, DMF, reflux, 2 h; (i) reflux, Ar, 48 h; (j) HgO, AcOH, reflux, 48 h. …”

“…A uniquely short synthesis of the 3 a ,9 a -diazaperylenium dication 36.16 was reported in 2002 by Sotiriou-Leventis, Leventis, et al The hydrogenated p -phenylenediamine precursor 36.15 , which is extremely easily oxidizable, was first obtained by a one-step quadruple cyclization of p -phenylenediamine with 1-bromo-3-chloropropane . Dehydrogenation of 36.15 using mercury­(II) oxide led to the formation of the dication 36.16 and the monocation 36.17 in an approximately 1:3 molar ratio.…”

Phenanthrene-Extended Phenazine Dication: An Electrochromic Conformational Switch Presenting Dual Reactivity

“…While being challenging, the preparation of positively charged doped PAHs is potentially highly rewarding. In fact, this approach could result not only in semiconducting materials presenting charge transfer states but also in the introduction of highly polar bonds that are useful for self-assembly and sensing. − Moreover, the possibility of introducing the heteroatoms in a neutral state and oxidizing them in a later step can result in materials with a behavior depending on the oxidation state and in molecular switching capabilities due to hybridization change. , While various examples of PAHs presenting a single charged atom in their structure have been reported in different contributions, ,,,, doubly charged ones are less explored, with notable examples presenting O, N, S, or combinations of these heteroatoms, using both surface and solution-based chemistry. − From this point of view, parent and π-extended dihydrophenazines represent valuable precursors toward the generation of 2 + N-doped PAHs. These derivatives are known to be easily oxidized and have been synthesized by various groups, − leading to their use as emitters, redox-active materials, or organocatalysts. − Interestingly, while the radical cations of such derivatives have been extensively explored, ,,, the aromatic dicationic diamagnetic states have been widely neglected and studied almost exclusively in solution, , with some notable exceptions successfully isolating N-alkyl derivatives of the parent phenazinium dication, which, however, were reported as highly reactive (Figure ).…”