Crystallographic scale, acidity

A crystallographic scale of acidity has been developed. Measuring the mean C—H O distances in crystal structures correlated well with conventional P a(DMSO) values. An ab initio study was able to correlate ring strain in strained hydrocarbons with hydrogen-bond acidity. ... 

Many viruses have icosahedral symmetry. Their nucleic-acid component (DNA or RNA) is contained in the hole of a capsid formed by the package of coat proteins. A first question then arises, whether in these vimses the external envelope of the capsid is related according to a crystallographic scaling to the viral hole in a way similar to that in axially symmetric biomacromolecules. 

The density of CusAs is 6-7 to 7-7 the density calculated from crystallographic data 5 is 8-22. The hardness is 3-0 to 3-3 on Mohs scale. The specific heat is 6 0-0919. On heating, sublimation occurs at 345° to 370° C.7 The arsenide decomposes on strong heating.8 It is completely reduced when heated in hydrogen.9 It is stable towards hydrochloric acid, but is attacked by nitric acid.10... 

We define pK according to eq 15. It is roughly corrected for ion-pair effects via the ApKj term of eq 16 that makes use of the estimated inter-ion pair distances a for the two salts MA, and MA2 from crystallographic studies and the Fuoss eq 12. The pK 3 should be approximately equal to absolute pK , in part because of our choice of anchor for the scale, [HPCy3]BPh4, with pK = pKa = 9.7. This is shown for picric acid where the absolute pKa " is 11.6 [62] while pK is determined to be 10 2 (Table 1.3). The agreement will improve as actual values are determined by use of conductivity measurements. 

Figure 3.5 Proposed sequence for the growth of plate-like well-crystallized boehmite crystals in acetic acid solution. Growth starts from gibbsite or pseudoboehmite precursors. Top Micrographs showing the crystal shapes of well-crystallized synthetic boehmite prepared by the method described in Ref. (60) (full size images with scale available in original paper). Bottom proposed growth sequence with crystallographic relationships. Reprinted from Ref. (60).

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