Ni-pyridine Alcohol Complexes: Synthesis, Structure, And Properties

The nonlinear optical effect(NLO)refers to an optical phenomenon in which the environment of the medium differs depending on the electromagnetic field of light(including the direction and magnitude of the vibration).Nonlinear optical effects are generated by electromagnetic radiation.The important nonlinear optical effects include harmonic generation,laser,and Raman shift.So far,various materials including inorganic materials,organic materials,conjugated polymers,and organometallic compounds have been used to investigate third-order NLO properties.The coordination compounds have the advantages of easy assembly,wide range of metals,ligand diversity,and structure tunability.In the last few decades,single-ion complexes,discrete transition metal clusters,coordination polymers and metal-organic frameworks,have been intensely reported as NLO active materials.In this thesis,we studied the contribution of heavy atoms at different spatial positions to nonlinear properties for a class of stable [Ni4O4] clusters.Eight compounds were synthesized by solvothermal method using different Ni(II)and pyridinol ligands LNH2,LCl,and LBr(LNH2 = 2-(hydroxymethyl)-4-aminopyridine,LCl = 4-chloro-2-pyridinemethanol,LBr = 5-bromo-2-pyridinemethanol),and five of them have been compared for their third-order NLO properties.The effects of different substituents,heavy atoms,and spatial position for the third-order NLO properties were studied comparatively by changing the ligand substituents.These compounds are [Ni4(LNH2)4(Me OH)4Cl4](1),[Ni4(LCl)4(Et OH)4Cl4](2),[Ni4(LBr)4(H2O)4Cl4](3),[Ni4(LCl)4(Et OH)4Br4](4),[Ni4(LBr)4(Me OH)4(Br)4](5).The five compounds share the same cubic [Ni4O4] skeleton.Preliminary results suggest that the NLO property is largely defined by the cluster core skeleton and the directly coordinated atoms,but with limited contribution from the heavy atoms peripherally attached to the aromatic ligands.In addition,we synthesized three additional tetranuclear cubane crystals based on the LNH2 pyridyl alcohol ligand [Ni4(LNH2)4(?-CH3COO)2(CH3COO)2(Me OH)2](6),[Ni4(LNH2)4(Et OH)4Cl4](7)and [Ni4(LNH2)4(DMF)4(?-CH3COO)2](8),and the above compounds were characterized.Finally,we also explored the reactivity of pyridinol with polycarboxylic acids such as terephthalic acid,2,6-naphthalene dicarboxylic acid,pyromellitic acid,trimesic acid and 5,5-dimethyl-1,3-phenylsilicic acid.Five zero-dimensional and one-dimensional chain compounds [Ni(pdm)2(BDC)]n(9),[Ni(pdm)2(NDA)]n?n DMF(10),[Ni(pdm)2(PMA)]n(11),[Ni2(pdm)4(BTC)2]?2DMF(12)and Ni(pdm)2(DMBS)2(13)(pdm = 2-pyridinemethanol,H2 BDC = terephthalic acid,H2 NDA = 2,6-Naphthalene dicarboxylic acid,PMA = Pyromellitic acid,H3 BTC = Trimesic acid and DMBS = 5,5-Dimethyl-1,3-phenylsilicic acid)have been synthesized.The magnetic properties of compounds [Ni(pdm)2(BDC)]n(9),[Ni(pdm)2(NDA)]n?n DMF(10),[Ni2(pdm)4(BTC)2]?2DMF(12)were studied.