ASSEMBLY AND POLYMERIZATION OF SOME AROMATIC-AMINES IN ALPHA-VOPO4-CENTER-DOT-2H(2)O

Under soft conditions (dry ROH, 25 degrees C), pyrazole, pyrazine and phenazine intercalate into alpha-VOPO4 . 2H(2)O as protonated, non-coordinated amines. Intermediates during pyrazine uptake include a metastable phase with d(001)=13.3 Angstrom, ascribed to bilayer formation. Benzidine (bz) instead gives two bz(+) charge transfer (CT) bronzes: VOPO4(bz)(0.5). 2H(2)O (dry EtOH) and VOPO4(bz)(0.7). 3.5H(2)O (95% EtOH) with interlayer distances lower (7.05 Angstrom and 6.65 Angstrom, respectively) than in alpha-VOPO4 . 2H(2)O itself. Interlayer 'pocket' orientation with layer shifting and turbostraticity to accommodate bz(+) cations is suggested, which differs from the assembly of bz(+) in smectites and V2O5. VOPO4(bz)(0.5). 2H(2)O shows 'moving solid' behaviour, probably due to changes in specific H-bonding between intercalate and sheet with water content. It is concluded that surface ruffling and specific H-bonding influence composite formation and assembly. Pyrrole (pyrr) almost completely polymerises on intercalation into alpha-VOPO4 . 2H(2)O, giving 'nestled' polymer composites with differing polypyrrole (Ppyrr) oxidation levels, whereas aniline uptake is governed by base protonation and proton-induced reassembly. Both give differently loaded nanocomposites (with interlayer distances in the range 6.4-17.9 Angstrom) depending on amine delivery (vapour, liquid, solution) and intercalant state (powder dispersion, film). Pyrrole loadings are higher with dispersions and lower with firms, but the opposite is the case for aniline (An). For example, neat An gives VOPO4(An)(1.3) . 13.5H(2)O (interlayer distance 17.9 Angstrom), An-EtOH gives VOPO4(An)(0.4) (14.8 Angstrom), and gaseous An gives VOPO4(An)(0.66). 2.2H(2)O (6.65 Angstrom). As prepared, the Ppyrr shows mixed-polaron states, and both series give EPR spectra characteristic of highly anisotropic V-IV-containing clusters and do not conduct. All become amorphous on calcination (160 degrees C), the An-containing composites polymerising to completion. Calcined VOPO4(Ppyrr)(0.66). 1.4H(2)O (from neat pyrrole) is a semiconductor, the EPR spectra (cationic amine and separated V-IV ions) further supporting strong polymer-sheet electronic interactions with the formation of V-IV island clusters. Assemblies of the two amines in VOPO, are suggested.