Syntheses,Structures And Properties Of The Complexes Based On 2-(hydroxymethyl)-1H-benzo-[d]imidazole-5-carboxylic Acid Ligand

Multifunctional coordination polymers?CPs?materials have excellent gas adsorption and separation,ion exchange,conductivity,luminescence,catalysis and other unique properties,have become one of the hotspots in coordination chemical research.Rational design of functional organic ligands is an important means of increasing the flexibility and diversity of the coordination polymer chemical structure.In recent years,the use of N-atom and O-atom multi-tooth ligands to build a new network structure and unique properties of multifunctional coordination polymers have been a lot of reported.In order to further explore the self-assembly,coordination chemical properties and structure of nitrogen heterocyclic carboxylic acid ligands and metal ions.In this paper,2-?hydroxymethyl?-1H-benzo[d]imidazole-5-carboxylic acid?H₂L?was synthesized and reacted with different metal salts to get fourteen novel structure coordination polymers.Complexes structurally were characterized by IR,X-ray single crystal diffraction,PXRD and TGA.Moreover,the solid-state fluorescence properties of Zn?II?/Cd?II?/Co?II?/La?III?complexes were studied in detail.The solid UV diffuse reflectances of complexes 1-14 were investigated.The catalytic performance of complexes 1-7 for Knoevenagel condensation reaction and 10-14 for homocoupling reaction of iodine benzene derivatives were investigated.The main contents and conclusions are as follows:1.2-?hydroxymethyl?-1H-benzo[d]imidazole-5-carboxylic acid?H₂L?ligand was synthesis and characterized by IR and 1H NMR.H₂ L as ligand reacted with different salts to synthesize nine Zn?II?/Cd?II?/La?III?coordination polymers: [Zn₃?L?₂??₂-OH?₂]_n?1?,{[Zn₂?HL?₂?H₂O?₂]·SiF₆}_n?₂?,[Zn?HL??SCN?]_n?3?,{[Zn₂?HL?₂?SO₄?]·?4,4?-bpy?}_n?4?[4,4?-bpy = 4,4?-bipyridine],{[Zn?HL?₂]·2H₂O}_n?5?,{[Cd?HL?₂]·2H₂O}_n?6?,[Cd₂?HL?₂?H₂O?₂?SO4?]_n?7?[Cd?L??4,4?-bpy?_0.5]_n?8?and [La0.18?HL?_0.18?CH₃COO?_0.36?H₂O?_0.54]_n?9?.The above complexes were tested by X-ray single crystal diffraction,the results showed that the complexes 1 and 8 have 3D network structures,3-6,9 showed infinite 1D chain structures,2 and 7 showed two-dimensional network structures.The solid-state fluorescence properties and solid UV diffuse reflectance of ligand and complexes 1-9 tests were performed.The complexes 1-7 are activated to give activated complexes 1a-7a,the catalytic performance of 1a-7a for Knoevenagel condensation reaction were studied.The results show that ₂a-7a can not catalyze the Knoevenagel condensation reaction,complex 1a can be used as the selective heterogeneous catalyst for the condensation reaction of benzaldehyde and malononitrile.The structure of the complex 1a indicated that the channel of 1a is favorable for catalyzing the Knoevenagel condensation reaction.2.The ligand H₂ L was reacted with different metal salts Co?II?/Ni?II?/Cu?II?to synthesize five coordination polymers: {[Co₂?HL?₂?H₂O?3?SO₄?]·H₂O}_n?10?,{[Co₂?HL?₂?H₂O?₂]·SiF₆}_n?11?,{[Ni₂?HL?₂?H₂O?₃?SO₄?]·2H₂O}_n?1₂?,{[Ni₂?HL?₂?H₂O?4]·H₂O·SiF₆}_n?13?,{[Cu₂?HL?₂?H₂O?₂]·SiF₆}_n?14?.The complexes were tested by X-ray single crystal diffraction,the results showed that the complexes 10-14 have two-dimensional network structures.The solid-state fluorescence properties of ligand and 10?11 tests were performed.The catalytic performance of complexes 10-14 for homocoupling reaction of iodine benzene derivatives was investigated,the experimental results show that complexes 10-14 can catalyze this coupling reaction.Calculated the band gap values?Eg?of these complexes by UV diffuse reflectance.The results show that combined with the catalytic properties of different complexes,found that the catalytic activity of the complex sequence with the band gap energy?Eg?the size of a certain correlation.