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Two Co(II)-based coordination polymers: [Co 2 (L) 2 (bib) 2 ] n (1) and {[Co 2 (L) 2 (bimb) 2 ]·2H 2 O·DMA)} n (DMA = N,N-dimethylacetamide) (2) using 4,4′-bis(thiomethylene) dibenzoic acid (H 2 L) as the first ligand, 1,4-bis(imidazol)-butane (bib) and 1,4-bis(imidazol-1-ylmethyl)benzene) (bimb) as the second ligands, were synthesized under the condition of solvothermal and characterized by X-ray single-crystal diffraction, elemental analysis, IR spectra and thermogravimetric analysis (TGA). X-ray single-crystal diffraction analysis exhibits that 1 and 2 belong to the triclinic crystal system, space group P -1. The central Co(II) ions exhibit a regular spatial tetrahedral structure which are coordinated by two O atoms from two L2− ligands and two N atoms from two N-donor ligands. Furthermore, the photocatalytic degradation properties and mechanism of 1 and 2 for methylene blue (MB) were investigated. The results show that the band gap (E g) of 1 and 2 is 3.78 eV and 3.82 eV, and the equipotential point (pH pzc) of 1 is 4.25. Both 1 and 2 show excellent photocatalytic degradation for MB. •OH is the main active substance causing MB degradation. The photocatalytic degradation for MB of 1 and 2 is in line with the first order kinetics equation. The pH pzc of complex 1 is 4.25. When pH < 4.25, 1 has a positive charge on the surface, and will generate electrostatic repulsion with MBH2+, inhibiting the adsorption of 1 to MB, so the degradation rate of MB is greatly reduced. When pH > 4.25, complex 1 has a negative charge on the surface and generates electrostatic attraction with MBH2+, which promotes the adsorption of 1 to MB, so the degradation rate of MB is greatly increased. Image 1 [ABSTRACT FROM AUTHOR]

• Two substituted benzyl triphenylphosphinium picrate salts were synthesized and characterized. • The FT-IR and Raman spectra have been discussed and assigned. • The HOMO-LUMO energy gap explains the charge transfer interactions in the molecules. • The nonlinear optical properties were studies using DFT calculations. • The title crystals exhibit violet and green fluorescence emissions in solid state at room temperature. Two new organic hybrid materials, namely, 4-chlorobenzyl triphenylphosphinium picrate and 4-iodobenzyl triphenylphosphinium picrate [4ClBzTPP][PIC](1) and [4IBzTPP][PIC](2), have been grown by slow evaporation solution growth technique and characterized by elemental analysis, spectroscopy, thermal analysis, powder and single crystal XRD. Two new picrates crystallize in triclinic space group P −1 and consist of a pair of [4ClBzTPP]+/[4IBzTPP]+ cations and picrate anions. The one-dimensional anionic chain are constructed by the non-bonded O···O and N···O interactions. Experimental vibrational bands (IR and Raman) have been discussed and assigned. The HOMO-LUMO energy gap explains the charge transfer interactions in the molecules. TG-TDA technique reveals that two materials were stable up to 215 °C and 253 °C, respectively. Excited by 250 nm ultraviolet light, two materials emit main luminescent emissions bands at about 374 nm and 524 nm in solid state at room temperature. In addition, two picrates show good antibacterial activities against Escherichia coli and Staphylococcus aureus. The results of DFT calculations based on the structures of 1 and 2 indicate that the first hyperpolarizability value (β tot) of two crystals are 5.8 and 32.3 times that of KDP, respectively, which show good nonlinear optical properties. [Display omitted] [ABSTRACT FROM AUTHOR]