Thermal behaviors and adsorption properties of two Europium(III) complexes based on 2-(4-carboxyphenyl)imidazo[4,5-f]-1,10-phenanthroline

4-(1H-Imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzaldehyde as a probe in pure solvents: Solvatochromism, electric dipole moment and pH influence

The spectral properties of 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzaldehyde (1) in eleven organic solvents of different polarity have been studied. In order to determine the contributions of specific and non-specific interactions between the considered compound and the solvents, the solvatochromic Lippert-Mataga, McRae, Bakhshiev methods have been applied. The compound demonstrates positive solvatochromism. The dipole moment of the excited state of 1 obtained using the Reichardt method is equal to 10.56/7.08 D for trans- and cis-conformers, respectively, and agrees well with the theoretically calculated value. The influence of the polarizability of 1 on changes in the dipole moments has been analyzed using the Bilot-Kawski method. The multiple linear regression analysis in the framework of the Kamlet-Abboud-Taft and Catalán models has highlighted that the main properties which determine the Stokes shift of 1 are the acidity and dipolarity of the solvent. The variation of pH by additions of acid or base to solution 1 leads to significant changes in absorption and fluorescence spectra, therefore, 1 can be of interest as a solvatochromic probe, being sensitive to acidic/base properties of the environment. It has also been found out that the anion form of 1 is present in the DMSO solution. An addition of N,N-dimethylcyclohexylamine intensifies the dissociation of the considered compound in the DMSO solution and suppresses the fluorescence at a large amine excess.

Three new cadmium(II) coordination compounds based on 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline: syntheses, structures and luminescence

Three cadmium(II) coordination compounds, [Cd(pyip)2(CH3COO)2] (1), [Cd(pyip)2(cis-OH)2]·H2O (2) and [Cd(pyip)2(trans-OH)2]·3H2O (3), based on 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (pyip) have been synthesized by a hydrothermal method and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1, 2 and 3 all appear as monomeric entities, which are further assembled into supramolecular networks by hydrogen bonding interactions. The Cd(II) centers in compounds 2 and 3 lie in distinct octahedral environments with the hydroxyl groups in cis- and trans-positions, respectively, leading to the generation of different structures . Photoluminescence studies of compounds 1–3 were also carried out.

Dual Emission in a Ligand and Metal Co-Doped Lanthanide-Organic Framework: Color Tuning and Temperature Dependent Luminescence

In this study, we report the luminescence color tuning in the lanthanide metal-organic framework (LnMOF) ([La(bpdc)Cl(DMF)] (1); bpdc^2- = [1,1'-biphenyl]-4,4'-dicarboxylate, DMF = N,N-dimethylformamide) by introducing dual emission properties in a La³⁺ MOF scaffold through doping with the blue fluorescent 2,2'-diamino-[1,1'-biphenyl]-4,4'-dicarboxylate (dabpdc^2-) and the red emissive Eu³⁺. With a careful adjustment of the relative doping levels of the lanthanide ions and bridging ligands, the color of the luminescence was modulated, while at the same time the photophysical characteristics of the two chromophores were retained. In addition, the photophysical properties of the parent MOF (1) and its doped counterparts with various dabpdc^2-/bpdc^2- and Eu³⁺/La³⁺ ratios and the photoinduced energy transfer pathways that are possible within these materials are discussed. Finally, the temperature dependence study on the emission profile of a doped analogue containing 10% dabpdc^2- and 2.5% Eu³⁺ (7) is presented, highlighting the potential of this family of materials to behave as temperature sensors.

Synthesis, structures and properties of six lanthanide complexes based on a 2-(2-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline ligand

Six lanthanide complexes [Tb(2-NCP)₂(NO₃)]_n (1), [Eu(2-NCP)₂(3-PYC)]_n (2), [Sm(2-NCP)₂(3-PYC)]_n (3), [Eu(2-NCP)(SA)]_n (4), [Tb(2-NCP)(SA)]_n (5) and [Tb(2-NCP)(AA)]_n (6) (2-HNCP = 2-(2-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline, 3-HPYC = pyridine-3-carboxylic acid, H₂SA = succinic acid, H₂AA = adipic acid) have been synthesized by hydrothermal route, and the crystal structures were analyzed through elemental analysis, infrared spectroscopy, single crystal X-ray diffraction. Complexes 1 and 6 present two-dimensional (2D) layers, which are further connected to three-dimensional (3D) supramolecular architectures through C–H⋯π interactions. Complexes 2 and 3 exhibit infinite one-dimensional chains. Finally, the neighboring chains are packed by C–H⋯π interactions, giving rise to 3D supramolecular network. Complexes 4 and 5 display 2D layers, which are further extend to 3D supramolecular structures via C–H⋯O intermolecular hydrogen bonding. Six complexes possess good thermal stabilities, characteristic photoluminescence properties, and photocatalytic activities for the degradation of organic dyes under visible light irradiation. In addition, the complex 6 exhibits significantly enhanced photocatalytic activity for methylene blue, and the degradation rate could reach 81.2% in 370 min. Meanwhile trapping experiments indicated that the hole, ·O₂⁻ and ·OH are the main activated species. Furthermore, by comparing the photoluminescent and photocatalytic mutation results of same metal complexes induced by interconversion of coligands, we confirm that the properties mutation induced by coligands is much obvious and controllable.

Six lanthanide complexes based on 2-HNCP possess good thermal stabilities, characteristic photoluminescence properties, and photocatalytic activities for organic dyes degradation under visible light irradiation.

Syntheses, crystal structures, adsorption properties and visible photocatalytic activities of highly stable Pb-based coordination polymers constructed by 2-(2-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline and bridging linkers

Five lead(ii) complexes have been hydrothermally synthesized and characterized.

A series of metal–organic frameworks constructed by a rigid-flexible 5-(bis(4-carboxybenzyl)amino)isophthalic acid: syntheses, crystal structures and physical properties

Four new MOFs have been hydrothermally synthesized and characterized.