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4-Pyrrolidinopyridyl)bis(acetylacetonato)zinc(II) forms perfectly polar as well as centrosymmetric crystal structures depending sensitively on the solvent and the rate of crystallization. Semiempirical computational modeling of molecular clusters, incorporating solvation effects, highlights the delicate balance of energetics involved in the solvent polarity preference of the extreme structures. A suitable choice of solvents provides crystals exhibiting an unusual cogrowth of polar/centric as well as polar/polar domains. This material provides a vivid illustration of the subtle nature of supramolecular assembly leading to extreme organizational motifs and opens up possibilities of realizing novel multidomain architectures in crystals.Organization of molecules in crystals results from a complex, often subtle interplay of intermolecular interactions, making accurate ab initio prediction of crystal structures a very difficult proposition. 1 The problem is considerably compounded in the case of polymorphic structures where, even under apparently identical conditions as in concomitant polymorphs, 2 the same molecule organizes in different crystalline assemblies. Particularly intriguing would be the case of polymorphs that manifest grossly different packing motifs. Such a situation could, in principle, be encountered in the context of centrosymmetric and noncentrosymmetric polymorphic structures of dipolar molecules, the latter being of potential interest in quadratic nonlinear optical applications. 3 Although several instances of such polymorphism are known, 4 noncentrosymmetric lattices often involve small deviations from a centrosymmetric organization, 5 leading to descriptions such as "approximately centrosymmetric". 4 Optimal molecular orientations for applications such as phase-matched second harmonic generation (SHG) or electrooptic effect call for specific design strategies. 6,7 A case that merits special attention is the formation of perfectly polar molecular assemblies 8 wherein every molecular dipole makes exactly 0°angle with respect to a specific crystallographic direction. This would be the opposite extreme of the commonly encountered centrosymmetric formation, 9 which by analogy can be described as constituted of "perfectly antiparallel" molecular dipoles with equal numbers making 0 and 180°a ngles with respect to specific crystallographic directions. Perfectly polar crystals are ideal candidates for molecular ferroelectric, piezoelectric, or pyroelectric materials as well as for electrooptic applications. Strategies such as cocrystallization, 7 salt formation, 10 and host-guest complexation 11 have been developed for achieving polar molecular assemblies. We have reported "self-poling" in a single component metal-organic system leading to perfectly polar molecular organization. 12 In the general context of supramolecular assembly and polymorphism in particular, it would be of considerable interest if a molecule was to form centrosymmetric as well as perfectly polar lattices. We report here such a scenario...