A new macrocyclic dipyrazolate salt of diazatetraester structure able to efficiently and selectively interact with psychotropic phenethylammonium salts: influence of the amine substituents on the stability of the ammonium dipyrazolate complexes

Abstract

The equilibrium stability constants ( K s) of a series of ammonium pyrazolate complexes [L 2 2−]2RN(R′)H 2 + ( 7, R′=H and 8, R′=Me) formed from a new macrocyclic disodium dipyrazolate salt of diazatetraester structure 6[L 2 2−] 2Na + and ammonium salts [RNH 3 +X − or RN(Me)H 2 +X −] of psychotropic drugs and neurotransmitter catecholamines has been evaluated by electrochemical methods in DMSO solution. The resulting K s values demonstrate that in general, the diazatetraester crown-derived dipyrazolate salt 6 exerts a stronger complexing effect over phenethylammonium ions than that of the dioxatetraester crown-derived disodium dipyrazolate salt 2 previously reported. Interestingly, complexes formed by secondary ammonium salts of psychotropic amines [(±)-methamphetamine, (+)-methamphetamine and (±)-3,4-methylenedioxymethamphetamine (MDMA ‘ecstasy’)] are much more stable than those formed by primary ammonium salts of dopamine and norepinephrine. A study of the stability constants of ammonium pyrazolate complexes in terms of the contributions of substituent groups on the common phenethylamine unit is reported.