Studies On The Synthesis,Structure And Properties Of Metal Complexes Of 3,5-dicarboxybenzeneboronic Acid And Metal Complexes Induced By The Deboronated Reaction Of 3,5-Dicarboxybenzeneboronic Acid

The metal-organic framework compounds constructed from carboxylate ligands aroused great interest for their novel structures and unique properties.Although a lot of related complexes have been reported,similar complexes containing boron are rarely studied.3,5-dicarboxybenzenboronic acid,which contains electron-deficient group of-B(OH)₂,can endow the targeted complexes with electron-deficient groups,as well as special properties.3,5-dicarboxybenzenboronic acid is easy to deboronate,which can change the chemical environment of chemical reaction and induce the formation of the MOFs with special structures.We managed to prepare several compounds with novel structures and properties in this work by using a 3,5-dicarboxybenzenboronic acid as ligand or the inducing effect of its deboronated reaction.H₂L¹,H₂L² and H₂L³ in this work represent 3,5-dicarboxybenzenboronic acid,5-Hydroxyisophthalic acid and Isophthalic acid,respectively.The main work is listed below.1.A compound of[Co₄NaO₂(L¹)₃(HL¹)(H₂O)₁₁]n·12nH₂O(1)with ribbon-like structure was prepared by using the ligand of 3,5-dicarboxybenzenboronate.It features planar butterfly Co₄ cluster as secondary building units,which are further linked by 3,5-dicarboxybenzeneboronate ligands to build the ribbon-like structure.The 3,5-dicarboxybenzeneboronate ligands in this compound present two kindes coordination modes.The carboxylate groups of one kind of(L₁)^2-ligunu coordinate to the Co(?)ions in ?₃-?¹,?² bridging modes.The carboxylate groups from the other kind of 3,5-dicarboxybenzeneboronate ligand afford just one carboxylic oxygen atom to coordinate to the disordered Na⁺ ion.Each Na⁺ ion is linked to the Co(?)ion on the body position of the butterfly structure by two carboxylic oxygen atoms and one water molecule.Compound(1)is characterized by elemental analysis,IR,thermogravimetric analysis,XRD-powder diffraction,magnetic properties,fluorescence and so on.The magnetic measurement of compound(1)revealed the presence of dominant antiferromagnetic interactions between Co(?)ions.Its fluorescence emission peak is attributed to internal electron transition of the ligand perturbated by metal ions.Some post-modification studies on the group of-B(OH)₂ in this compound were also investigated.2.The reaction of 3,5-dicarboxybenzenboronic acid(H₂L¹)with Cu(?)salts gave two complexes[Cu₂₄(L²)₂₄(CH₃OH)₁₆(H₂O)₈]·19THF·3CH₃OH(2)and {[Cu₂₄(L²)₂₄(HOCH₃)s(H₂O)₁₂(diox)₂]·32CH₃OH·56H₂O}n(3),which were formed from the deboronated product(5-hydroxyisophthalic acid,H₂L²)of H₂L¹.Two adjacent Cu²⁺ ions in 2 are bridged by four carboxylate ligands in syn-syn bridging modes,forming a dinuclear nit[Cu₂(COO)₄]₂-.Each L^2- ligand bridges four Cu(?)ions from two dinuclear units,behaving as ?₄:?^4- bridge.Each dinuclear node is connected to another four dinuclear units by four(L²)^2- ligands,forming an isolated 24-nuclear nanoscale cage.Complex(3)is a two-dimensional metal-organic framework based on the secondary building units of[Cu₂₄(L²)₂₄(H₂O)₁₂(CH₃OH)₈]which are similar to those cages in complex(2).The pore volume per unit cel of complexes(2)and(3)are 58.9%and 56.6%,respectively.The magnetic studies of complexs(2)and(3)indicate the presence of antiferromagnetic interactions between their metal ions.The adsorption results show that the two compounds have nitrogen adsorption capacity of 71.2 and 141.28 cm³·g^-1,and CO2 adsorption capacity of 18.12 and 22.92 cm³·g^-1,respectively.3.Five new compounds[Cu(L²)_0.14(L³)_0.86(H₂O)]n·3H₂O(4),{[Er₂(H₂O)₁₀(L²)₂](L²)·3H₂O}n(5),[Co(N₃)₂(4,4'-bpy)]n(6),[Cu₂(4,4'-bpy)(OAc)₄]n·2nH₂O(7),and K[Fe^?₃(OH)₆(SO₄)₂](8)were solvothermally synthesized using the resulted ligand from the deboronated reaction of 3,5-dicarboxybenzenboronic acid or its its inducing effect.In the complex(4),the disordered hydroxyl group and hydrogen atoms occupy the original position of -B(OH)₂.The adjacent Cu(?)ions in 4 are bridged by four carboxylate groups of four (L²)2-ligands to form a[Cu₂(COO)₄]unit,which is connected with another four ones by four(L²)^2- ligands to construct a two-dimensional skeleton.In 5,(L¹)^2- decomposed into(L2)2-.The adjacent Er^3- ions in complex 5 are bridged by(L²)^2-,forming an 5-type one-dimensional chain.There is one(L²)^2- ligand per formular unit in 5,balancing the charge.Complex(6)is a chiral compound induced by H₂L¹ or its deboronated reaction.It shows a three-dimensional structure formed by the connection of Co(?)ions through N₃-and 4,4'-bpy molecules with neither H₂L¹ nor its deboronated products in the structure.A characteristic feature is that there are three kinds of helical chains of single helix,double spiral,and triple helix.Every adjacent Cu(?)ions in complex(7)are linked by four acetate ions to form a paddlewheel dinuclear units,which are further connected by 4,4'-pyridine molecules to form a one-dimensional chain.Three Fe(?)ions in compound(8)are cosolidated by one SO₄^2- ion and three hydroxide ions to form a triangular Fe₃ unit,which is further linked to another three Fe₃ units around it by sharing the Fe(?)vertexes leading to the construction of a two-dimensional network.The K+ions connect the neighboring two-dimensional sheets into a three-dimensional structure by the coordination of hydroxide groups to K⁺ ions.