Crystal transformation synthesis of a highly stable fluorescent 3D indium-tetranuclear {In4(µ2-OH)3} building block based metal organic framework through a dinuclear complex.

A rare 3D tetranuclear {In4(µ2-OH)3} building block based MOF {[In4/3(µ2-OH)(2,6-pydc)(1,4-bda)0.5(H2O)]·2H2O}n (2) was obtained through a crystal transformation from a dimeric complex In3(2,6-pydc)3(1,4-bda)1.5(H2O)6 (1). With a 2D + 3D → 3D compact structure, 2 retains crystallinity in boiling water and organic solvents, exhibiting exceptional fluorescence quenching behaviour for the DMSO molecule.