Mechanochemical Synthesis of Coordination Compounds Based on Carboxylic Acid
|Keywords||Mechanochemistry Metal Organic Frameworks(MOFs) Liquid AssistedGrinding (LAG)|
"Mechanochemistry" refers to reactions, normally of solids, induced by the input of mechanical energy, such as by grinding in mortar or in ball mills, is rapidly developing as an alternative and sometimes preferable approach to synthesis compared to conventional methods(solvent-based methods, ultrasonic method, microwave method) which rely on the use of bulk solvents. It is becoming more intensely studied partly because it can promote reactions between solids quickly and quantitatively, operating with little energy, preparation quantity is large, with either no added solvent or only nominal amounts.Here, we report some MOFs material which obtain under mechanochemical sconditions, and examined by XRPD. We divided them to the following two parts:CHAPTER1Using a small shaking ball mill, liquid-assisted grinding (LAG) of metal salts or oxides (ZnO, CdO, Cu(OAc)2·H2O, Co(OAc)2·4H2O, Mn(OAc)2·4H2O, Ni(OAc)2·4H2O) with two equivalents of isonicotinic acid (HINA) and small amounts of water (up to5.6molar equivalents) gave discrete aquocomplexes trans-[M(INA)2(OH2)4][M=Zn(1), Cd(3), Cu(5), Ni(7), Co(8), Mn(9)] efficiently within30min. For M=Zn, Cd and Cu these complexes readily undergo reversible formal dehydration to the extended network structures [M(INA)2][M=Zn(2), Cu(6)] or [Cd(INA)2(OH2)]·DMF(4) by further LAG with non-aqueous liquids such as methanol or DMF. Overall, the mechanochemical dehydrations are more effective than heating or immersion in bulk solvents. The work demonstrates a two-step mechanochemical synthesis of coordination networks via discrete aquo complexes which may be preferable to single step reactions or grinding-annealing procedures in some cases. For example, the two step method was the only way to prepare [Cd(INA)2(OH2)]· DMF mechanochemically and the porous network [Cu(INA)2] could not be obtained from the aquo complex by heating.In a planetary or a shaking ball mill, when H2O (50μL), DMF (50uL), and methanol (150μL) are utilized as assisting liquids in ball milling, the mechanochemical reactions between nicotinic acid and zinc oxide or basic zinc carbonate have been studied. The results show that ball milling of the starting materials in the presence of H2O or DMF in the planetary (at45Hz) or the shaking (at20Hz) ball mill, a zero-dimensional coordination compound,[Zn(NA)2(H2O)4](10) is obtained successfully. Interestingly, when a mixture: HNA, zinc oxide and water (50μL) is ground in the planetary ball mill at15Hz,30minutes grinding lead to a large amount of unreacted starting materials left. However, if given longer grinding time (60minutes), the large amounts of tetrahydrated zinc (Ⅱ) nicotinate is also prepared. CHAPTER2H2IP, H2AIP, H3IP, and H4BDCPPI were used as organic ligands to react with M(OAc)2(M=Cu, Co, Mn, Ni), ZnO and [ZnCO3]2·[Zn(OH)2]3in a Shaking ball mill with traces of solvent (H2O, CH3OH and DMF),[Zn(IP)(H2O)](11),[Cu(HAIP)2]·H2O (12),[Co(HAIP)2(H2O)2]·2H2O (13),[Co(HIP)(H2O)3](14) and SUN-50(15) were obtained successfully. Moreover, EDTA was used as organic ligands to react with Gd(CO3)2·xH2O in a Planetary ball mill with H2O,[Gd(C10H12N2O8)(H2O)3]·5H2O (16) was obtained.