The progression from synthetically achiral ligand and metal ion, to isolated chiral metal complex, to homochiral two-dimensional (2D) assembly layer, and finally to conglomerate is presented. The cobalt(III) complexes of achiral tripod-type ligands involving three imidazole groups with the chemical formulas [Co(H3L6)](ClO4)3*H2O (6) and [Co(H3L7)](ClO4)3*0.5H2O (7) were synthesized, where H3L6 = tris[2-(((imidazol-4-yl)methylidene)amino)ethyl]amine and H3L7 = tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine. Each complex induces the chirality of clockwise (C) and anticlockwise (A) enantiomers due to the screw coordination arrangement of the achiral tripod-type ligand around the Co(III) ion. The fully protonated (6, 7), the formally hemi-deprotonated (6', 7'), and the fully deprotonated (6' ', 7' ') complexes were obtained as good quality crystals by adjusting the pH of the solutions. The crystal structures were determined by single-crystal X-ray analyses. There is no intermolecular network structure in the fully protonated complexes (6, 7). The fully deprotonated complexes (6' ', 7' ') form a hydrogen-bonded network structure, in which the C and A enantiomers coexist and are connected through a water molecule. The formally hemi-deprotonated species [Co(H1.5L6 or 7)]1.5+, which functions as a self-complementary chiral building block, generates equal numbers of protonated and deprotonated molecules by an acid-base reaction to form an extended 2D homochiral layer structure consisting of a hexanuclear structure with a trigonal void as a unit. The 2D structure arises from the intermolecular imidazole-imidazolate hydrogen bonds between [Co(H3L6 or 7)]3+ and [Co(L6 or 7)]0, in which adjacent molecules with the same chirality are arrayed in an up-and-down fashion. In the crystal lattices of the perchlorate salts (6', 7'), the perchlorate ions are located in the cavity, and the homochiral layer consisting of C enantiomers and the adjacent layer consisting of A enantiomers are stacked alternately to give an achiral crystal. The chloride salt of the hemi-deprotonated complex [Co(H1.5L6)]Cl1.5*H2O (6a') is found to be a conglomerate, in which the chloride ions are positioned in the intermediate region of the double layer, and layers with the same chirality are well stacked by adopting the up-and-down layer's shape to generate channels, and so form a chiral crystal. The circular dichroism (CD) spectrum of 6a' showed a positive peak and a negative peak at 480 and 350 nm, respectively, and the spectrum of another crystal showed an enantiomeric CD pattern, providing further evidence of spontaneous resolution on crystallization.

The monomer <--> oligomer interconversion of the reported metal complexes is generated by proton abstraction/supply as a common external information input. The mononuclear copper(II) complexes 1 and 2 with [CuCl(2)(HL(n)())] chemical formula have been prepared (HL(1) = N-(2-methylimidazol-4-ylmethylidene)-2-aminoethylpyridine; HL(2) = N-(2-phenylimidazol-4-ylmethylidene)-2-aminoethylpyridine). The crystal structures were determined. 1.H(2)O, C(12)H(16)N(4)OCl(2)Cu: a = 13.773(2) Å, b = 8.245(2) Å, c = 13.861(2) Å, beta = 110.10(1) degrees, monoclinic, P2(1)/n, and Z = 4. 2, C(17)H(16)N(4)Cl(2)Cu: a = 7.6659(7) Å, b = 16.287(1) Å, c = 14.103(1) Å, beta = 95.058(7) degrees, monoclinic, P2(1)/c, and Z = 4. Complexes 1.H(2)O and 2 assume a pentacoordinated square pyramidal geometry with a N(3)Cl(2) donor set consisting of the nitrogen atoms of the protonated tridentate ligand and two chloride ions in the solid state, while in aqueous solution the Cu(II) ion is tetracoordinated (N(3)Ow donor set). When 1 and 2 are treated with an equimolar amount of sodium hydroxide or triethylamine, the deprotonation of the imidazole moiety promotes a self-assembly process, arising from coordination of the imidazolate nitrogen atom to a Cu(II) ion of an adjacent unit, to yield compounds 1'.4H(2)O as the perchlorate salt, and 2'a.6H(2)O as the perchlorate salt and( )()2'b as the hexafluorophosphate salt, respectively. 1'.4H(2)O, C(12)H(15)N(4)O(5)ClCu: a = b = 13.966(2) Å, c = 33.689(3) Å, tetragonal, I4(1)/a, and Z = 16. 2'a.6H(2)O, C(51)H(51)N(12)O(15)Cl(3)Cu(3): a = 15.177(3) Å, b = 15.747(3) Å, c = 14.128(3) Å, alpha = 100.06(2) degrees, beta = 110.37(2) degrees, gamma = 63.54(1) degrees, triclinic, P&onemacr;, and Z = 2. 2'b, C(17)H(15)N(9)F(6)PCu: a = b = 29.812(5) Å, c = 11.484(3) Å, trigonal, R&thremacr;, and Z = 18. The nuclearity of the self-assembled molecules and their detailed structure were confirmed to be cyclic imidazolate-bridged tetranuclear for 1'.4H(2)O and hexanuclear for 2'a.6H(2)O and 2'b, respectively, through single-crystal X-ray analyses and FAB-MS spectra. Variable-temperature experimental magnetic susceptibility data were well reproduced by using the Heisenberg model based on a cyclic tetranuclear structure for 1' and a cyclic hexanuclear structure for 2'a and 2'b. The reversible interconversion between the protonated monomeric and deprotonated oligomeric species were confirmed by pH-dependent potentiometric and electronic spectral titrations in aqueous solution, whereas the Pd(II) complex did not show a perfect disassembly process.