Controlled Growth of the Non-centrosymmetric Zn(3-ptz)2 and Zn(Oh)(3-ptz) Metal-organic Frameworks

Non-centrosymmetric single-crystal metal-organic frameworks (MOF) are promising candidates for phase-matched nonlinear optical communication, but typical hydrothermal synthesis produces small crystals with relatively low transmittance and poor phase matching. We study the effect of the metal-to-ligand molar ratio and reaction pH on the hydro-thermal synthesis of the non-centrosymmetric Zn(3-ptz)2 and Zn(OH)(3-ptz) MOFs with in-situ ligand formation. In acidic environments, we find that decreasing the amount of ligand below the stoichiometric molar ratio 1:2 also produces highly transparent single-crystal octahedrons of Zn(3-ptz)2. In alkaline environments, we obtain long rod-like Zn(OH)(3-ptz) crystals whose length exceeds previous reports by up to four orders of magnitude. Potential applications of these results in the development of MOF-based nonlinear optical devices are discussed.