AN ANALYSIS OF SUBSTITUENT EFFECTS ON THE PROTON AND C-13 CHEMICAL-SHIFTS OF 2-SUBSTITUTED 9-ISOTHIOCYANATOACRIDINES

Proton and C-13 NMR chemical shifts and coupling constants J(H,H) of a series of 2-substituted 9-isothiocyanatoacridines and their 4-methyl and 4-methoxy analogs were determined. The obtained values were utiliz ed in analysis of substituent effects using empirical equations based on two- and three-parameter linear correlations. It was found that sho rt-range interactions (positions ipso, ortho and meta) are well descri bed by the three-parameter model of Reynolds whereas long-range effect s are satisfactorily compatible with the two-parameter model. The domi nant direction of conjugation in the acridine skeleton was derived fro m changes in chemical shifts due to substitution (SCS).