Stacked-Ring Aromaticity Rewires Quantum Interference and Through-Space Transport

Stacking antiaromatic rings does more than switch aromaticity: it rewires how electrons interfere and flow through space. Here, we show that stacked-ring aromaticity (SRA), generated by cofacial coupling of 4nπ antiaromatic molecules, transforms their quantum-transport landscape. Vertical compression converts paratropic monomers into cylindrically delocalized aromatic dimers with continuous interlayer current-density flux and strong through-space electronic coupling. Remarkably, this antiaromatic-to-SRA transition systematically inverts the preferred electrode connectivity: the anchoring topology that favors transport in the monomer becomes the less efficient interlayer pathway in the dimeric configuration, while the alternative connectivity becomes dominant. This behavior arises from the reorganization of destructive quantum-interference features through interlayer orbital coupling. The effect is maximized near d = 2.70 Å, where magnetic reversal, energetic stabilization, and high interlayer transmission converge. This connectivity inversion is rationalized by a minimal Green's function analysis as a layer-parity effect that changes the phase condition governing quantum interference in opposite-layer transport. Interestingly, the odd-layered stacking remains globally antiaromatic yet preserves efficient transport across the full three-layer stack, showing that the stacking-induced transport network survives the even-odd magnetic reversal. SRA therefore provides a mechanically accessible strategy for reshaping quantum interference and through-space conductance in molecular junctions.