Photochromism in oxalatoniobates

摘要

Addition of 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen) or 2-aminopyridine (2-NH2-py) to aqueous solutions of (NH4)[NbO(C2O4)(2)(H2O)(2)]center dot 3H(2)O (Nb-Ox) yields tris-oxalate complexes (bpyH(2))(bpyH)[NbO (C2O4)(3)]center dot 2H(2)O (1), (phenH)(3)[NbO(C2O4)(3)]center dot 3H(2)O (2), and (2-NH2-pyH)(3)[NbO(C2O4)(3)]center dot 2H(2)O (3), which were characterised by XRD, IR and EA. Bipyridinium salt 1 demonstrates remarkable photoactivity even under irradiation by daylight. The nature of the photoactivity was studied by diffuse reflectance (DR) spectroscopy, ESR and quantum-chemical calculations.