Counter-complementarity

According to the HTH model this gives a reduction of the antiferromagnetic contribution to the magnetic coupling (see Eq.4.21) and illustrates the anti-synergistic effect or counter-complementarity of the two ligands. 

Fig. 4 Self-assembly of branched DNA molecules to form larger arrangements. Left Four-arm branched junction made from four differently colored strands. Its double helical domains are tailed in 5 sticky ends labeled (counter-clockwise from the left) X, Y, X, and F the sticky ends are indicated by small extensions from the main strand (our convention is to represent 3 ends by arrowheads). The primed sticky ends complement the unprimed ones. Right Four of these Junctions can self-assemble through this complementarity to yield a quadrilateral. The sticky ends have come together in a complementary fashion. Note that this assembly does not use up all the available sticky ends, so that those that are left over could be used to generate a lattice in 2D, and, indeed, in 3D...

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