As-synthesized Coordination Polymers Research Articles

Tunability in dimension, metal and ligand coordination modes and emission properties in Cd(II) and Zn(II) coordination networks based on 4,4’-(hydrazine-1,2-diyilidenebis(methanylylidene)) dibenzoic acid linker

Cd(II) and Zn(II) coordination polymers based on dicarboxylic azine chromophore, 4,4'-(hydrazine-1,2-diylidenebis(methanylylidene)) dibenzoic acid (H2(4-dbahz)), were obtained and include 1D coordination polymer {[Cd(4-dbahz)(dmso)2(H2O)]·(dmso)2}n (1, 2) in the forms of monoclinic and orthorhombic polymorphs, 2D coordination grid {[Zn(4-dbahz)(dmso)]·0.5(dmso·dmf)}n (3), and 3D MOF {[Cd2(4-dbahz)2(dmso)2]·dmso}n (4). The coordination compounds and H2(4-dbahz) chromophore were studied using spectroscopic (FTIR, NMR, PL) and X-ray diffraction methods of analysis. The organic chromophore H2(4-dbahz) reveals dual emission indicated by the emission bands in the high and low energy regions of spectrum. The tuning of emission properties was followed for the as-synthesized coordination polymers 1, 3, 4 and their desolvated products and showed excellent sensing of solvated dmso. The significant enhancement of photoluminescence in the blue region in 1 is associated with elimination of π-π stacking interactions due to accommodation of dmso solvent.

Synthesis and characterization of luminescent metal–organic frameworks for the selective recognition of Cu2+ cation and Tryptophan

Three metal-organic frameworks (MOFs), namely, [Mn(CPP)2(H2O)]n (I), [Cd(CPP)2(H2O)]n (II) and {[Zn2(CPP)2(CO3)]·(ClO4)·(H2O)2}n (III) (HCPP = 4'-(4-(4-carboxylphenoxy)-2,2':6′,2′-terpyridine), were successfully achieved under hydrothermal conditions. The as-synthesized coordination polymers have been characterized by IR spectroscopy, elemental analyses and single crystal X-ray diffraction. Single-crystal X-ray diffraction analyses indicate that compounds Ⅰ and Ⅱ display isomorphous and isostructural, in which the central metal ions present distorted octahedral configurations. Ⅰ and Ⅱ feature fascinating 3D frameworks based on π⋯π and CH⋯π interactions between the pyridine rings appertaining CPP− ligands, while compound Ⅲ possesses a 3D net interlinked via C-H⋯π interactions between the phenyl rings belonging to the CPP− ligands. In their 3D frameworks, the {MnN3O3}, {CdN3O3} and {ZnO2N3}–{ZnO2N3} building units are observed, respectively. Luminescent properties of coordination polymer Ⅱ and Ⅲ demonstrate that they may be acted as fluorescent sensors toward Cu2+ cation and Tryptophan, respectively. Furthermore, investigations on magnetic property reveal that coordination polymer Ⅰ presents antiferromagnetic coupling.

Synthesis and characterization of lanthanide-based coordination polymers for highly selective and sensitive luminescent sensor for Pb2+ over mixed metal ions

Three novel coordination polymers, namely, {[Pr(TTTPC)·(H2O)2]·2Cl·NO3·4H2O}n (I), {[Gd(TTTPC)·(H2O)2]·2Cl·NO3·4H2O}n (II) and {[Yb(TTTPC)·(H2O)2]·3Cl·NO3·0.5DMA·6H2O}n (III) were synthesized in conventional aqueous solutions with H3TTTPC ligands (H3TTTPC = 1,1′,1″-(2,4,6-trimethylbenzene-1,3,5-triyl(methylene))-tris(pyridine-4-carboxylic acid), DMA = N,N-dimethylacetamide) and characterized by infrared spectrometry and single crystal X-ray diffraction. Experimental results show that these MOFs are isomorphous and isostructural, containing the unit of cavate 14-membered cages (Pr2(OCO)4), based on which to generate a one-dimensional (1D) infinite linear metallic chain through the linkage of two COO− groups that are further interlinked reciprocally to polymerize into three-dimensional (3D) porous frameworks. Coordination polymer III shows remarkable selectivity toward Pb2+ and it can be considered as potential selective luminescent probes for Pb2+ ion. Additionally, magnetic analysis indicates coordination polymer I presents antiferromagnetism. Besides, lanthanide contraction effect exists in as-synthesized coordination polymers.

Studies on Preparation and Hydrogen Storage Properties of Dual-Metal Ferrocenyl Coordination Polymer Microspheres

A series of dual-metal ferrocenyl coordination polymer microspheres (M1M2-CPMs, M1M2 = CoMn, CoCu, MnCu) were synthesized by the reaction of 1,1′-ferrocene dicarboxylic acid with mixed metal salts via solvothermal method. From SEM and TEM images, it was found that all the as-synthesized coordination polymers showed microspheres structures. The products were also characterized by X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The M1M2-CPMs showed good thermostability and remained stable up to 250 °C. These M1M2-CPMs exhibited hydrogen uptake capacity. More interestingly, through the comparison among three microspheres we found that the M1M2-CPMs with hollow structures showed better hydrogen uptake.

Zero-, one-, two- and three-dimensional coordination polymers based on tetracarboxylic acid: Syntheses, structures, magnetic and luminescent properties

A series of coordination polymers, namely, {[Co(H2ttac)(phen)2]4H2O}n (1), {[Zn(H2ttac)(phen)2]4H2O}n (2), [Cu(H2ttac)(phen)]n (3), [Zn2(ttac)(DMZ)H2O]n (4), and [Cd(ttac)(phen)H2O]n (5)(H4ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, phen = 1,10-phenanthroline, DMZ = Dimidazole) have been prepared under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction. Structural analysis reveals that the as-synthesized coordination polymers have different structures, ranging from zero-(1 and 2), one-(3), two-(4) to three-(5) dimensions, which are mainly due to the different metal ions, the degree of deprotonation and coordination modes of the H4ttac ligands. It is worth mentioning that, based on the diversified π–π stacking and/or C–H···π interactions between H4ttac ligands and/or nitrogen-containing auxiliary ligands, 1–4 are assembled form low-dimensional structures into three-dimensional (3D) frameworks. Especially, Jahn-Teller effect occurs in 3 and its magnetic study confirms that it presents antiferromagnetic coupling through the (O2C-Ar-Ar-CO2)2 bridges. Significantly, luminescent emission of 3 displays selective recognition towards L-Arginin. Thermogravimetric (TG) analyses of the coordination polymers have also been investigated.

Three novel transition metal coordination polymers based on (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid sodium salt: Hydrothermal syntheses, structures, and properties

Three novel transition metal coordination polymers including [Cd2(Na2PPDA)2Cl4]n (I), [Zn(Na2PPDA)(ClO4)2·4H2O]n (II) and [Ni(Na2PPDA)(ClO4)2·4H2O]n (III) were prepared under hydrothermal conditions based on (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid sodium salt (Na2PPDA) and characterized by elemental analysis, infrared spectrometry and single crystal X-ray diffraction. The outstanding structural feature of I is that four cadmium atoms are linked into a zigzag-shaped polymeric chain in the sequence of Cd–(Cl)2–Cd–(Cl)2–Cd–(Cl)2–Cd by three μ2-Cl bridges. Findings indicate that I displays a three-dimensional (3D) network constructed via hydrogen bonds and C–H⋯π interactions. Both coordination polymers of II and III present isomorphous and isostructural characters, in which the adjacent metal centers in the same chain connected up and down through hydrogen bonds (generated through μ2-ClO4− anions) to construct the left- and right-handed helical chains which are further interconnected by hydrogen bonds, thereby affording a two-dimensional (2D) layer. Moreover, thermogravimetric (TG) analyses, the magnetic and luminescent properties of as-synthesized coordination polymers were also investigated.

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.

Synthesis, characterization and thermal decomposition kinetics as well as evaluation of luminescent properties of several 3D lanthanide coordination polymers as selective luminescent probes of metal ions

A series of 3D isomorphous and isostructural coordination polymers, namely, {[Ln4(PDA)6(H2O)6]·H2O}∞ (Ln=La, Nd, Sm and Gd; corresponding as-synthesized products are denoted as 1, 2, 3, and 4, respectively; PDA2−=pyridine-2,6-dicarboxylate anion), were synthesized under hydrothermal conditions and characterized by means of elemental analyses, infrared spectrometry, thermal analysis and single crystal X-ray diffraction. In the meantime, the thermal decomposition kinetics of the as-synthesized complexes was investigated under non-isothermal conditions using the Achar differential method and the Coats–Redfern integral method. The room-temperature luminescent properties of the metal-organic frameworks (MOFs) of the lanthanide coordination polymers were measured. It has been found that Ln(III) centers in the complexes adopt eight-coordinated and nine-coordinated modes with N1O7 and N2O7 donors to construct distorted triangular dodecahedral and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic La4C4O8 unit (16-membered ring), lanthanide coordination polymers 1–4 are connected into highly ordered two-dimensional corrugated layers via O—C—O linkers and further assembled into 3D architectures through hydrogen bonds. Besides, lanthanide contraction effect exists in as-synthesized coordination polymers; and the lanthanide coordination polymers possess good selectivity toward metal ions such as Mg2+, Cu2+ and Pb2+, showing promising potential as selective luminescent probes of those metal ions.