Polyoxometalate/-triazine hybrid heterostructures with ultrafast photochromic properties.

As an emerging class of hybrid complexes, donor-acceptor (D-A) hybrid heterostructures, which combine the advantages of both organic and inorganic photoactive components, provide excellent platforms for the fabrication of photochromic materials with enhanced photo-responsive performances. Herein, four novel hybrid heterostructures, namely HTPT·(PWO)·2NMP (1), (HTPT)·(PWO) (2), (HTPT)·(SiWO)·2Cl·2MeCN (3), and HTPT·(HPMoO)·Cl·3NMP (4) (TPT is tri(4-pyridyl)--triazine, NMP is -methylpyrrolidone), have been synthesized and characterized. Benefitting from the strong interactions (anion-π interactions) and matching electron energy levels between the donors and acceptors, some of them exhibited ultrafast photochromic behaviour even up to 1 second. Furthermore, based on experimental and theoretical calculations, the plausible PIET process and structure-activity relationship have been discussed in detail.