Handedness geometrical chirality

The condition of handedness or lack of superimposabil-ity of molecules differing only with respect to the stereochemical arrangement of identical substituents around a tetrahedral center. In 1893, Lord Kelvin succinctly defined chirality I call any geometrical figure, or any group of points, chiral, and say that it has chirality, if its image in a plane mirror, ideally realized, cannot be brought to coincide with itself. ... 

In its geometrically most regular form, shown in Figure 21, the (10,3)-a net has cubic symmetry and angles at nodes are all 120°. 4-Fold helices run parallel to the axes. All the helices have the same handedness, making the net as a whole chiral. Wells foresaw, before real examples were known, that the (10,3)-a net is in principle capable of participating in interpenetration not only with an identical net... 

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