Related Experiment Video
Updated: Jan 30, 2026

Making, Testing, and Using Potassium Ion Selective Microelectrodes in Tissue Slices of Adult Brain
Published on: May 7, 2018
Isoselective Ring-Opening Polymerization of rac-Lactide Catalyzed by Sodium/potassium Tetradentate Aminobisphenolate
Xinlei Li1, Zhaowei Jia1, Xiaobo Pan1
1State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou, 730000, P. R. China.
Abstract:
Two sodium/potassium tetradentate aminobisphenolate ion-paired complexes were synthesized and structurally characterized. These ion-paired complexes are efficient catalysts for the ring-opening polymerization of rac-lactide (rac-LA) in the presence of 5 equivalents BnOH as an initiator and the side reaction of epimerization can be suppressed well at low temperatures. The polymerizations are controllable, affording polylactides with desirable molecular weights and narrow molecular weight distributions; the highest molecular weight can reach 50.1 kg mol-1 in this system, and a best isoselectivity of Pm =0.82 was achieved. Such polymerizations have rarely been reported for isoselective sodium/potassium complexes without crown ether as an auxiliary ligand. The solid structures suggest that BnOH can be activated by an interaction with the anion of sodium/potassium complex via a hydrogen bond and that the monomer is activated by coordination to sodium/potassium ion.
Related Concept Videos
Regulation of Sodium and Potassium
Sodium Regulation
Sodium ions make up approximately 90% of extracellular cations, with a normal blood plasma concentration of 136–148 mEq/L. A decrease in blood volume and pressure triggers the release of renin from granular cells in the juxtaglomerular complex (JGC), primarily...
Formation of Complex Ions
Roles of Electrolytes: Sodium and Potassium
Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct...
Common Ion Effect
Precipitation of Ions
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:

