Synthesis and Spectroscopic Characterization of Selected Phenothiazines and Phenazines Rationalized Based on DFT Calculation.

Two unique structures were isolated from the phosphorylation reaction of 10 H -phenothiazine. The 5,5-dimethyl-2-(10 H -phenothiazin-10-yl)-1,3,2-dioxaphosphinane 2-oxide ( 2a ) illustrates the product of N -phosphorylation of phenothiazine. Moreover, a potential product of 2a instability, a thiophosphoric acid 2b , was successfully isolated and structurally characterized. Molecule 2a , similarly to sulfoxide derivative 3 , possesses interesting phosphorescence properties due to the presence of d-pπ bonds. The X-ray, NMR, and DFT computational studies indicate that compound 2a exhibits an anomeric effect. Additionally, the syntheses of selected symmetrical and unsymmetrical pyridine-embedded phenazines were elaborated. To compare the influence of phosphorus and sulfur atoms on the structural characteristics of 10 H -phenothiazine derivatives, the high-quality crystals of (4a,12a-dihydro-12 H -benzo[5,6][1,4]thiazino[2,3- b ]quinoxalin-12-yl)(phenyl)methanone ( 1 ) and selected phenazines 5,12-diisopropyl-3,10-dimethyldipyrido[3,2- a :3',2'- h ]phenazine ( 5 ) and 5-isopropyl- N,N ,3-trimethylpyrido[3,2- a ]phenazin-10-amine ( 6a ) were obtained. The structures of molecules 1 , 2a , 2-mercapto-5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide ( 2b ), 3,7-dinitro-10 H -phenothiazine 5-oxide ( 3 ), 5 and 6a were determined by single-crystal X-ray diffraction measurements.