Noncentrosymmetric Cu(II) Layered Hydroxide: Synthesis, Crystal Structure, Nonlinear Optical, and Magnetic Properties of Cu2(OH)3(C12H25SO4)

Single crystals of the layered copper hydroxide dodecylsulfate Cu-2(OH)(3)(C12H25SO4) have been obtained for the first time, by controlled hydrolysis of an aqueous copper acetate solution. Interestingly, this compound crystallizes in a noncentrosymmetric space group (P2(1), a = 5.591(10) angstrom, b = 6.108(11) angstrom, c= 26.96(5) angstrom, a = gamma = 90, beta = 92.76), which is further confirmed by nonlinear optical measurements. Within the course of the synthesis, a probable intermediate between Cu(OAc)(2): H2O and the layered Cu-2(OH)(3)(C12H25SO4) was isolated and characterized. X-ray structure analysis showed that this intermediate presents a ribbon-like structure of formula Cu-3(C12H25SO4)(2)(CH3COO)(2)(OH)(2)(H2O)(2). The magnetic properties of the layered Cu-2(OH)(3)(C12H25SO4) have been analyzed in the high-temperature region (T > 20 K) by considering a high-temperature series expansion for a S = 1/2 Heisenberg two-dimensional triangular lattice. At lower temperature, the compound shows a three-dimensional antiferromagnetic ordering (T-N = 10.8 K). The ribbon-like compound Cu-3(C12H25SO4)(2)(CH3COO)(2)(OH)(2)(H2O)(2) presents an overall antiferromagnetic behavior, resulting from a combination of ferro- and antiferromagnetic interactions between nearest neighbors within the chains.