Topological Evolution in Mercury(II) Schiff Base Complexes Tuned through Alkyl Substitution – Synthesis, Solid‐State Structures, and Aggregation‐Induced Emission Properties

From two series of Schiff base ligands, ( E )‐ N ‐(pyridine‐2‐yl)(CMe=NPhR) and ( E )‐ N ‐(pyridine‐2‐yl)(CH=NPhR) [R = H, L1a , L1b ; 2‐CH 3 , L2a , L2b ; 4‐CH 3 , L3a , L3b ; 2,6‐(CH 3 ) 2 , L4a , L4b ; 2,6‐(C 2 H 5 ) 2 , L5a , L5b ; 2,6‐( i ‐C 3 H 7 ) 2 , L6a , L6b ; 2,4,6‐(CH 3 ) 3 , L7a , L7b ], fourteen mercury(II) complexes, namely, Hg 1a –Hg 7a and Hg 1b –Hg 7b were synthesized. Their structures were established by single‐crystal X‐ray diffraction, and they were physically characterized by 1 H and 13 C NMR spectroscopy, ESI‐MS, FTIR spectroscopy, elemental analysis (EA), and powder XRD (PXRD). The crystal structures indicate that the position and type of substituent can directly influence the formation of 1D → 3D supramolecular metal–organic frameworks through C–H ··· Cl and π–π interactions. Complexes Hg 1a –Hg 7a and Hg 1b –Hg 7b display deep blue emissions at λ = 401–428 nm in acetonitrile solution and light blue emissions at λ = 443–494 nm in the solid state. It is worth noting that Hg 1a , Hg 3a , Hg 1b , and Hg 3b exhibit good aggregation‐induced emission (AIE) properties in CH 3 CN/H 2 O solutions.