Abstract:
Growth of transition metal malonate (mal) based solids from aqueous solution is investigated in the presence of piperazine (pip). Reaction under ambient conditions favored the growth of [{M(mal) 2 (H 2 O) 2 } {H 2 pip}] (M: Ni, 1; M: Co, 2), [{Gi(mal) 2(H 2 O) 2 }{H 2 pip}].2H 2 O (3), and, [Zn(mal)(pip)(H 2 O)] (4). While 1-3 are molecular solids, 4 is a'2-D coordination polymer. In the case of cobalt, higher acidic condition favored the formation of a molecular organic-inorganic salt, [(H 2 pip){CoCl 4 }] (5). The same reaction under a different crystallization condition, i.e., lesser polar solvent and slightly higher temperature (solvothermal) led to a 2-D coordination polymer [{Co(mal)(H 2 O)(Hpip)}]Cl (6). A retrosynthesis approach has been employed to interpret the crystallization reaction and compare the supramolecular reactivity of aggregating metal tectons in engineering the molecules to form either a molecular solid or coordination polymer.
