Chemistry Reference
In-Depth Information
BTCA Dihydrate
(Single Crystal)
“Pure” BTCA
(Polycrystalline Powder)
Heat
100 °C, 3.5 hours
Solid State
Dehydration Process
Fig. 13 Optical micrographs showing that a single crystal of BTCA dihydrate leads to a
polycrystalline product (“pure” phase of BTCA) upon dehydration
Fig. 14 Crystal structure of BTCA, with the three crystallographically independent molecules
displayed in different colours (A,
green
;B,
blue
;C,
red
): (a) a hydrogen-bonded chain of A and C
molecules viewed approximately along the
c
-axis, and (b) the complete crystal structure viewed
along the
b
-axis (the AC chains run into the page, with adjacent AC chains cross-linked by
hydrogen bonding to B molecules)
case, the structure of “pure” TTCA has again been determined [
118
] directly from
powder XRD data, using the direct-space genetic algorithm technique for structure
solution followed by Rietveld refinement. The structure of “pure” TTCA, shown in
Fig.
15
, presents interesting contrasts in comparison with the structure of the “pure”
phase of the oxygen analogue cyanuric acid.
