A series of temperature-dependent CdII-complexes containing an important family of N-rich heterocycles from in situ conversion of pyridine-type Schiff base

An efficient method for the synthesis of a wide variety of N-rich heterocycles has been systematically explored. The synthetic protocol involves a solvothermal in situ metal–ligand reaction of pyridine-type Schiff base N-(2-pyridylmethyl)-pyridine-2-carbaldimine (L) with Cd2+ ions, resulting in the efficient formation of nine temperature-dependent CdII-complexes 1–9 supported by six types of N-rich heterocycles L1–6. To the best of our knowledge, both the synthetic strategy with solvothermal in situ CdII-mediated Schiff base-conversion and N-rich heterocycle rings L1–2 as well as cis-L6 are reported for the first time. Meanwhile, plausible in situ formation mechanisms of L1–6 are also proposed.