Phenanthridines spectra

The position of the 1La transition in the phenanthridine spectrum is in good agreement with the LCAO transition energy (as in other monoazaaromatics). The agreement between calculated and observed intensities is less satisfactory.236... 

Like acridine, phenanthridine and dimethyl acetylenedicarboxylate in methanol give a high yield of 1 1 1 molar adduct. Ultraviolet absorption spectrum comparisons show that this is best formulated as 9,10-dihydro-9-methoxy-10- (tran.s-l,2-dimethoxycarbonylvinyl) phenanthridine (142) rather than the corresponding phenanthridinium methoxide (143) under neutral conditions acidification changes the spectrum to that characteristic of the phenanthridinium cation. Crystallization of the adduct (142) from methanol containing 5-15% of water gave the betaine [(144) the positions of the ester and carboxylate groups have not been established], while in the presence... 

Quinapyramine (74) has a broader spectrum of trypanocidal activity than the phenanthridine drugs and is less toxic. A dose of 4.4 mg kg-1 is curative in cattle infected with T. vivax and T. congolense. 

Studies on benzo-fused analogs of 78 have also been reported. Solutions of unstable dibenzo[b,e]phosphabenzene (phosphaanthracene) (80, R = H)286 and dibenzo[6,d]phosphabenzene (phosphaphenanthrene) (81)287 have been prepared and examined by UV spectroscopy. The overall shape of the spectrum due to 80 (R = H) resembles that of anthracene rather than acridine, whereas that of 81 resembles the phenanthridine more closely than the phenanthrene spectrum. The absorptions of both 80 (R = H) and 81 show the typical strong bathochromic shifts relative to their nitrogen and carbocyclic analogs. 10-Phenyldibenzo[6, e]phospha-benzene (80, R = Ph)288 is more stable than its parent and shows similar UV absorption. 

Occasionally, the chemical shifts obtained directly from the H-decoupled NMR spectrum of a [G- H] labeled compound can be assigned without recourse to analysis of the complex spectrum. This was possible (53) for phenanthridine (XIV). 

---