Lirong Yang

Synthesis, spectroscopic properties and theoretical studies of bis-Schiff bases derived from polyamine and pyrazolones

A series of novel bis-Schiff base were synthesized from 1-aryl-3-methyl-4-benzoyl-5-pyrazolones and diethylenetriamine (or triethylenetetramine) as the starting materials. All of these bis-Schiff bases were characterized by means of NMR, IR, and MS. The UV-vis absorption spectra and fluorescent spectra of these bis-Schiff bases were also measured. Moreover, the B3LYP/6-31G(d) method was used to optimize the ground state geometry of the bis-Schiff bases; and the UV-vis spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVDZ basis set of TD-B3LYP method. It has been found that all of these bis-Schiff bases show a remarkable absorption peak in a wavelength range of 270-340 nm; and their maximum emission peaks are around 348 nm.

Coordination polymers based on 3,3′,4,4′-benzophenone-tetracarboxylate and N-containing pillars: syntheses, structure, characterization and properties

Three novel coordination polymers including {[Mn2(bptc)2(phen)4]·2H2O}∞ (I), [Zn2(bptc)4·(bpy)2·H2O]∞ (II), and {[Zn2(bptc)4·(bpy)2·H2O] ⊃ bpy}∞ (III) (bptc = 3,3′,4,4′-benzophenone-tetracarboxylate, bpy = 4,4′-bipyridine, phen = 1,10-phenanthroline) were prepared under hydrothermal conditions and characterized by elemental analysis, infrared spectrometry, and single crystal X-ray diffraction. Moreover, the thermal stability of as-synthesized coordination polymers was evaluated by thermogravimetric analysis; and their magnetic and luminescent properties were also investigated. Findings indicate that coordination polymer I displays a three-dimensional (3D) network constructed via π–π interactions of the building block {[Mn2(bptc)2(phen)4]·2H2O}. Besides, Zn(1) and Zn(2) centers in coordination polymer II are four-coordinated and six-coordinated, respectively, thereby affording two-dimensional (2D) planar sheet and 3D porous frameworks that are interlinked through identical linkers of four-coordinated motif (COO–Zn–COO). As-synthesized coordination polymer III contains a 3D framework similar to that of II, but the cavities in III are occupied by uncoordinated bpy guest molecules. Moreover, as-synthesized coordination polymer I presents antiferromagnetic coupling through the (O2C–C–C–CO2)2 bridges, and II displays selectivity towards Hg+ ion in terms of the luminescent emission.

Crystal structure characterization as well as theoretical study of spectroscopic properties of novel Schiff bases containing pyrazole group

A series of novel Schiff bases containing pyrazole group were synthesized using 1-aryl-3-methyl-4-benzoyl-5-pyrazolone and phenylenediamine as the starting materials. All as-synthesized Schiff bases were characterized by means of NMR, FT-IR, and MS; and the molecular geometries of two Schiff bases as typical examples were determined by means of single crystal X-ray diffraction. In the meantime, the ultraviolet-visible light absorption spectra and fluorescent spectra of various as-synthesized products were also measured. Moreover, the B3LYP/6-1G(d,p) method was used for the optimization of the ground state geometry of the Schiff bases; and the spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVTZ basis set of TD-B3LYP method. It has been found that all as-synthesized Schiff bases show a remarkable absorption peak in a wavelength range of 270-370 nm; and their maximum emission peaks are around 344 nm and 332 nm, respectively.

Construction of 0D to 3D Copper(II) MOFs based on heterocyclic carboxylic acid: Synthesis, structures, cyclic voltammograms, and luminescent properties

The crystal structures of MOFs [Cu(PDA)(Phen)(H2O)]2 · 5H2O (I) and [Cu(PZCA)2(H2O)2] · 2H2O (II) (H2PDA = pyridine-2,6-dicarboxylic acid, Phen = 1,10-phenanthroline, HPZCA = pyrazine-2-carboxylic acid, H2PZDA = pyrazine-2,3-carboxylic acid) have been prepared under hydrothermal conditions. These MOFs have been characterized by element analysis, single-crystal X-ray diffraction, thermogravimetric analyses and IR spectroscopy. 3D frameworks of MOFs I and II are fabricated from zero-dimensional (0D) motifs through hydrogen bonds and π-π interactions. In MOF II, the PZCA ligand comes from in situ decarboxylation of the part of pyrazine-2,3-dicarboxylic acid (H2PZDA). Luminescent emissions bands of MOF I in methanol have been measured at room temperature and it displays selectivity to Zn2+, Cu2+, Pb2+, and Cd2+ ions. Cyclic voltammetry of MOFs I and II showed that the Cu(II/I) couple is irreversible.

A 2D Hydrogen-Bonded 1D Coordination Network of Pr(III) with Pyridine-2,6-Dicarboxylic Acid: Hydrothermal Synthesis, Structure, and Luminescent Properties

A coordination polymer {[Pr(PDA)2(H2O)2]·4H2O}n was synthesized through the reaction between pyridine-2,6-dicarboxylic acid (H2PDA) and Pr(NO3)3·6H2O under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single-crystal X-ray diffraction studies. The compound crystallizes in monoclinic system, space group P(2)/c1. Hydrogen bonds exist between adjacent 1D chains to form planes that are further arranged as highly corrugated 2D sheet structure. Luminescence of the complex has been measured in the solution of DMF at room temperature. In addition, the luminescent emissions of the complex showed certain selectivity toward some metal ions.

Synthesis, structure, and luminescent properties of a novel binuclear Gd(III) compound

The compound [Gd2(PZDA)3(H2O)]n (I), where H2PZDA = 2,3-pyrazinedicarboxylic acid, was synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectrometry, thermogravimetric analysis and single crystal X-ray diffraction (CIF file CCDC no. 848802). In I, Gd(III) centers adopt eight-coordinated and nine-coordinated modes to construct distorted triangular dodecahedral and tricapped trigonal prism configurations, respectively. Three-dimensional (3D) structure of the compound is formed through C-H⋯π interactions and π-π stacking. Measurement of the luminescent property at room temperature shows that the as-synthesized compound presents good selectivity towards Pb2+ ion, suggesting that it may be promising potential as selective luminescent probes of Pb2+ ion.

Antimicrobial activity and density functional calculations of a supramolecular manganese complex

The density functional theory calculations on the manganese complex ([Mn(8-OHQ)3] · CH3OH, 8-OHQ = 8-hydroxyquinoline) is made and its stabilization, molecular orbital composition, orbital energies, and NBO charge distribution have been investigated. The crystal structure of the complex closely resembles the optimized structure. In vitro activities against some antimicrobials (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis) are determined. The antimicrobial activities present a positive correlation between the concentrations and bioactivities of the complex. The relationship between bioactivities and molecular orbitals (HOMO and LUMO orbitals) of the complex is also discussed.

[CoCl(TPPyP)], a novel bifunctional catalyst for the coupling reaction of carbon dioxide and propylene oxide

A novel bifunctional catalyst chloro[meso-tetrakis(1-phenylpyrazol-4-yl)porphyrin] cobalt(III), [CoCl(TPPyP)], has been prepared and used to catalyse the synthesis of propylene carbonate from carbon dioxide and propylene oxide under mild conditions. Propylene carbonate was obtained with a yield of 25.2% at 100 °C in the absence of co-catalyst. A reaction mechanism is proposed.