The intercalation of n-alkyldiamines into crystalline layered titanate

The synthesis, characterization, and intercalation of n-alkyldiamines H2N(CH2)(n)NH2 (n = 2, 3, 4, 6, 7, and 8) into layered hydrous tetratitanic acid H2Ti4O9. nH(2)O are reported. From the elemental analysis, the following formula were proposed for the intercalated compounds: (C2H8N2)(0.3)-H2Ti4O9.0.40H(2)O, (C3H10N2)(0.6)H2Ti4O9.0.89H(2)O, (C4H12N2)(0.3)H2Ti4O9.0.40H(2)O, (C6H16N2)(0.6)-H2Ti4O9.0.92H(2)O, (C7H18N2)(0.5)H2Ti4O9.0.50H(2)O and (C8H20N2)(0.6)H2Ti4O9.0.60H(2)O. X-ray diffraction patterns for these matrices showed that the 920 pm interlayer space of the original matrix has the d-spacing values increased to 1118, 1318, 1549, 1662, 1720, and 1766 pm, respectively, for the C-2-C-8 sequence of intercalated n-alkyldiamine. The infrared data are in agreement with the protonated nitrogen atoms of the diamines located in the cavity space. The hydrous matrix showed two mass loss steps in the thermogravimetric curve, corresponding to the release of physisorbed and lattice water molecules. A third mass loss was observed for the intercalated matrices due to the release of organic moiety. From these values, the intercalated matrices represented by the number of carbons in the organic chains can be ordered in the following sequence of thermal stability: C-4 > C-2 > C-3 congruent to C-6 > C-7 congruent to C-8. The lowest amount of intercalated n-alkyldiamines gave the largest thermal stability of the hybrid. (C) 2001 Elsevier Science Ltd. All rights reserved.