Multidentate N,O-containing ligands, such as N,N¡¯-bis(2-hydroxybenzyl)-ethylenediamine(BHED), N,N¡¯-bis(2-hydroxybenzyl)-propylenediamine(BHPD), N,N¡¯-bis(2-hydroxybenzyl)-diethylenetriamine(BHDT), N,N¡¯-bis(2-hydroxybenzyl)-triethylenetriamine(BHTIF) and N,N¡¯-bis(2-hydroxybenzyl)-tetraethylenepentaamine (BHTP) were synthesized by reduction of the imine group of Bis(salicylidene)-ethylendiamine(BSED), Bis (salicylidene)-propylenediamine(BSPD), Bis(salicylidene)-diethylentriamine(BSDT), Bis(salicylidene)-triethylenetetraamine(BSTT) and Bis(salicylidene)-tetraethylenepentaamine(BSTP). Proton dissociation constants of the ligands and stability constants of transition metal(¥±) ion complexes with BHED, BHPD, BHDT, BHTT, and BHTP were determined by potentiometic titration. The sequence of stability constants (logKML) of complex increases as BHED Zn(¥±) which follows the Irving-Williams series.
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