A facile strategy to adjust the density of planar triangle units in lead borate-nitrates

摘要

Three novel lead(II) borate-nitrates were obtained through a facile hydrothermal reaction by adjusting the concentrations of the starting materials, namely, [Pb-6(mu(4)-O)(4)(BO3)](NO3) (1), H[Pb-6(mu(3)-O)(2)(BO3)(2)](NO3)(3) (2) and H[Pb-8(mu(4)-O)(3)(mu(3)-O)(BO3)(2)](NO3)(3) (3). All three compounds feature lead(II) oxo borate layers that are separated by nitrate anions. The 2D [Pb-6(mu(4)-O)(4)(BO3)](+) layer parallel to the ab plane in 1 is built from 1D [Pb-6(mu(4)-O)(4)](4+) chains along the a axis and bridging borate anions. The 2D H[Pb-6(mu(3)-O)(2)(BO3)(2)](3+) layer in 2 which is perpendicular to the b axis is composed of "isolated" Pb2+ and tetranuclear [Pb-4(mu(3)-O)(2)](4+) clusters interconnected by bridging BO3 groups. The [Pb-8(mu(4)-O)(3)(mu(3)-O)(BO3)(2)](2+) (011) layer in 3 is composed of two types of lead (II) oxo chains, namely, 1D chains of [Pb-4(mu(4)-O)(2)](4+) and 1D chains of [Pb-4(mu(4)-O)(mu(3)-O)](4+), both elongated along the a axis, which are further interconnected by bridging borate anions. This study also demonstrates that a small change in the concentration of the starting materials could result in a product with a different density of the pi-conjugated planar units.