Metal-organic frameworks (MOFs) are promising functional compounds;however, they are known to be moisture sensitive. Here, we investigate the hydration and dehydration processes of the carboxylate-containing MOFs [Ni2...Metal-organic frameworks (MOFs) are promising functional compounds;however, they are known to be moisture sensitive. Here, we investigate the hydration and dehydration processes of the carboxylate-containing MOFs [Ni2(nic)4(H2O)]n (nic = nicotinic acid) and the mononuclear complex [Ni(nic)2(H2O)4], respectively. X-ray single crystal diffraction reveals that the hydrogen bonds between water and carboxylic oxygen play a key role in these processes. Molecular-level mechanisms of reversible hydration and dehydration are proposed, based on the competition between water and carboxylic oxygen for coordination with Ni. This study provides important information for future studies on the hydrolytic stability of MOFs in moisture.展开更多
A new heterobimetallic nitrilotriacetatoperoxotitanate complex with the formula of [Mn（H2O）5]2[Ti（O2）2O（nta）2]·7H2O （1, C6H6O6N = H3nta） has been isolated in pure crystals. It was characterized by element...A new heterobimetallic nitrilotriacetatoperoxotitanate complex with the formula of [Mn（H2O）5]2[Ti（O2）2O（nta）2]·7H2O （1, C6H6O6N = H3nta） has been isolated in pure crystals. It was characterized by elemental analyses, IR, thermal analysis （TGA） and single-crystal X-ray diffraction. Complex 1 crystallizes in monoclinic, space group C2/c with a = 15.088（3）, b = 13.311（3）, c = 17.741（4） , β = 100.92（3）°, Z = 4, V = 3498.6（12） 3, Mr = 968.19, Dc = 1.838 g/cm3, μ = 1.266 mm-1, F（000） = 1992, R = 0.0337 and wR = 0.0819. Single-crystal X-ray analysis reveals that the titanium atom is N,O,O＇,O＇＇-chelated by the nitrilotriacetate and O,O＇-chelated by the peroxo group, and is coordinated to the bridging O atom in an overall pentagonal-bipyramidal geometry. The manganese ions in the compound are both 6-coordinated by five water molecules and one bridged carboxylato oxygen atom. A decameric water cluster consisting of a cyclic water hexamer in a boat fashion is also found in complex 1. The TGA and XRD results prove that 1 undergoes facile thermal decomposition to form the mixture of Mn2O3 and TiO2 at 600～800 ℃, and pure MnTiO3 at 900 ℃.展开更多
文摘Metal-organic frameworks (MOFs) are promising functional compounds;however, they are known to be moisture sensitive. Here, we investigate the hydration and dehydration processes of the carboxylate-containing MOFs [Ni2(nic)4(H2O)]n (nic = nicotinic acid) and the mononuclear complex [Ni(nic)2(H2O)4], respectively. X-ray single crystal diffraction reveals that the hydrogen bonds between water and carboxylic oxygen play a key role in these processes. Molecular-level mechanisms of reversible hydration and dehydration are proposed, based on the competition between water and carboxylic oxygen for coordination with Ni. This study provides important information for future studies on the hydrolytic stability of MOFs in moisture.
基金supported by the Fundamental Research Funds for the Central Universities, SCUT (No. 2009ZM0313) the National Natural Science Foundation of China (B5080320)
文摘A new heterobimetallic nitrilotriacetatoperoxotitanate complex with the formula of [Mn（H2O）5]2[Ti（O2）2O（nta）2]·7H2O （1, C6H6O6N = H3nta） has been isolated in pure crystals. It was characterized by elemental analyses, IR, thermal analysis （TGA） and single-crystal X-ray diffraction. Complex 1 crystallizes in monoclinic, space group C2/c with a = 15.088（3）, b = 13.311（3）, c = 17.741（4） , β = 100.92（3）°, Z = 4, V = 3498.6（12） 3, Mr = 968.19, Dc = 1.838 g/cm3, μ = 1.266 mm-1, F（000） = 1992, R = 0.0337 and wR = 0.0819. Single-crystal X-ray analysis reveals that the titanium atom is N,O,O＇,O＇＇-chelated by the nitrilotriacetate and O,O＇-chelated by the peroxo group, and is coordinated to the bridging O atom in an overall pentagonal-bipyramidal geometry. The manganese ions in the compound are both 6-coordinated by five water molecules and one bridged carboxylato oxygen atom. A decameric water cluster consisting of a cyclic water hexamer in a boat fashion is also found in complex 1. The TGA and XRD results prove that 1 undergoes facile thermal decomposition to form the mixture of Mn2O3 and TiO2 at 600～800 ℃, and pure MnTiO3 at 900 ℃.
