An unusual mono-substituted Keggin anion-chain based 3D framework with 24-membered macrocycles as linker units

► The first example of -A-B-A-B- array mono-substituted Keggin chain is observed. ► An unusual three dimensional structure based mono-substituted Keggin anion-chains. ► The photocatalysis and electrochemical properties of the title compound were studied.