Novel charge transfer supramolecular assemblies with Keggin anions and 2-amino-5-nitropyridine

摘要

Several novel compounds with the non-linear optical chromophore 2-amino-5-nitropyridine (2A5NP) and Keggin polyoxoanions (alpha-isomers),having the general formula (2A5NP)_mH_n[XM_(12)O_(40))]centre dot xH_2O,M = Mo,W,were synthesised.Compounds were obtained with X = P,n = 3,m = 3 and 4 and X = Si,n = m = 4 (x = 2-6).Thus,for each of the anions [PMO_(12)O_(40)]~(3-) and [PW_(12)O_(40)]~(3-) two different compounds were obtained,with the same anion and organic counterpart but with a different stoichiometric ratio.These presented different charge transfer properties and thermal stability.All compounds were characterised by spectroscopic and analytical techniques.The single crystal X-ray diffraction structure of (2A5NP)_4H_3[PMO_(12)O_(40)]centre dot 2.5H_2O centre dot 0.5C_2H_5OH showed that the water solvent molecules and the organic chromophores are assembled via infinite one-dimensional chains of hydrogen bonds with formation of open channels,which accommodate [PMO_(12)O_(40)]~(3-) and ethanol solvent molecules.