Search

Bispidines are a family of ligands that plays a pivotal role in various areas of coordination chemistry, with applications in medicinal chemistry, molecular catalysis, coordination polymers synthesis, and molecular magnetism. In the present work, triazole moieties were introduced using the CuAAC click-reaction, with the aim of expanding the number of coordination sites on the bispidine core. The 1,2,3-triazole rings were thus synthesized on propargyl-derived bispidines after reaction with different alkyl azides. The new class of triazole-bispidines was characterized, and their chelation capabilities were evaluated with different metals through NMR titration, ESI-MS spectrometry, and single-crystal X-ray diffraction (SC-XRD). Finally, the suitability of these molecules as metal ligands for the catalytic Henry reaction was demonstrated with copper and zinc. [ABSTRACT FROM AUTHOR]

The current study aims to explain recent developments in the synthesis of Pb(II)-azido metal-organic coordination polymers. Coordination polymers are defined as hybrid materials encompassing metal-ion-based, organic linkers, vertices, and ligands, serving to link the vertices to 1D, 2D, or 3D periodic configurations. The coordination polymers have many applications and potential properties in many research fields, primarily dependent on particular host–guest interactions. Metal coordination polymers (CPs) and complexes have fascinating structural topologies. Therefore, they have found numerous applications in different areas over the past two decades. Azido-bridged complexes are inorganic coordination ligands with higher fascination that have been the subject of intense research because of their coordination adaptability and magnetic diversity. Several sonochemical methods have been developed to synthesize nanostructures. Researchers have recently been interested in using ultrasound in organic chemistry synthetics, since ultrasonic waves in liquids accelerate chemical reactions in heterogeneous and homogeneous systems. The sonochemical synthesis of lead–azide coordination compounds resulted from very fantastic morphologies, and some of these compounds are used as precursors for preparing nano lead oxide. The ultrasonic sonochemistry approach has been extensively applied in different research fields, such as medical imaging, biological cell disruption, thermoplastic welding, food processing, and waste treatment. CPs serve as appropriate precursors for preparing favorable materials at the nanoscale. Using these polymers as precursors is beneficial for preparing inorganic nanomaterials such as metal oxides. [ABSTRACT FROM AUTHOR]

In order to synthesize new coordination polymers with original architectures and interesting magnetic properties, we used the nitranilate ligand (C6O4(NO2)22- = C6N2O82-), derived from the dianionic ligand dhbq2- (2,5-dihydroxy-1,4-benzoquinone = H2C6O42-). The use of this bis-bidentate bridging ligand led to [(DAMS)2{FeNa(C6N2O8)3}·CH3CN]n (1) (DAMS+ = C16H17N2 + = 4-[4-(dimethylamino)-α-styryl]-1-methylpyridinium), a 2D heterometallic coordination polymer presenting an unprecedented structure for any anilato-based compound. This structural type is a 3,6-connected 2D coordination polymer derived from the well-known honeycomb hexagonal structure, where Fe(III) ions alternate with Na+ dimers (as Na2O12 units) in the vertices of the hexagons and with an additional [Fe(C6N2O8)3]3- anion located in the center of the hexagons connecting the three Na+ dimers. The magnetic properties of compound 1 show the presence of paramagnetic isolated high spin Fe(III) complexes with a zero field splitting, |D| = 8.5 cm-1. [ABSTRACT FROM AUTHOR]

The processing of an originally non-porous 1D coordination polymer as monolithic gel, xerogel and aerogel is reported as an alternative method to obtain novel metal-organic porous materials, conceptually different to conventional crystalline porous coordination polymer (PCPs) or metal-organic frameworks (MOFs). Although the work herein reported is focused upon a particular kind of coordination polymer ([M(μ-ox)(4-apy)2]n, M: Co(II), Ni(II)), the results are of interest in the field of porous materials and of MOFs, as the employed synthetic approach implies that any coordination polymer could be processable as a mesoporous material. The polymerization conditions were fixed to obtain stiff gels at the synthesis stage. Gels were dried at ambient pressure and at supercritical conditions to render well shaped monolithic xerogels and aerogels, respectively. The monolithic shape of the synthesis product is another remarkable result, as it does not require a post-processing or the use of additives or binders. The aerogels of the 1D coordination polymers are featured by exhibiting high pore volumes and diameters ranging in the mesoporous/macroporous regions which endow to these materials the ability to deal with large-sized molecules. The aerogel monoliths present markedly low densities (0.082-0.311 g ⋅ cm-3), an aspect of interest for applications that persecute light materials. [ABSTRACT FROM AUTHOR]

The preparation and characterization of a novel hybrid material based on the combination of a 2D-layered double hydroxide (LDH) nanosheets and a 1D-coordination polymer (1D-CP) has been achieved through a simple mixture of suspensions of both building blocks via an exfoliation/restacking approach. The hybrid material has been thoroughly characterized demonstrating that the 1D-CP moieties are intercalated as well as adsorbed on the surface of the LDH, giving rise to a layered assembly with the coexistence of the functionalities of their initial constituents. This hybrid represents the first example of the assembly of 1D/2D nanomaterials combining LDH with CP and opens the door for a plethora of different functional hybrid systems. [ABSTRACT FROM AUTHOR]

Herein, we present the syntheses of a novel coordination polymer (CP) based on the perylene-3,4,9,10-tetracarboxylate (pery) linkers and sodium metal ions. We have chosen sodium metal center with the aim of surmising the effect that the modification of the metal ion may have on the relative humidity (RH) experimental measurements of the material. We confirm the role of the ions in the functionalization of the deposited layer by modifying their selectivity towards moisture content, paving the way to the generation of sensitive and selective chemical sensors. [ABSTRACT FROM AUTHOR]

The selective preparation, structural and spectroscopic study of two new rhenium cluster complexes trans-[Re6S8(bpy)4(CN)2] and trans-[Re6S8(bpy)2(CN)4]2− (bpy = 4,4′-bipyridine) obtained by reactions of corresponding hexarhenium cyanohalides with molten bpy are reported. The complexes were crystallized as solvates, displaying supramolecular structures based on cluster units linked by numerous weak interactions with bpy molecules. The molecular compound trans-[Re6S8(bpy)4(CN)2] (1) is insoluble in water and common organic solvents, while the ionic compound trans-Cs1.7K0.3[Re6S8(bpy)2(CN)4] (2) is somewhat soluble in DMSO, DMF and N-methylpyrrolidone. The presence of the redox-active ligand bpy leads to the occurrence of multi-electron reduction transitions in a solution of 2 at moderate potential values. The ambidentate CN− ligand is the secondary functional group, which has potential for the synthesis of coordination polymers based on the new cluster complexes. In addition, both new compounds show a weak red luminescence, which is characteristic of complexes with a {Re6S8}2+ cluster core. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of coordination polymers and metal–organic frameworks (MOFs) has attracted a significant interest over the last decades due to their fascinating physical properties, as well as their use in a wide range of technological, environmental, and biomedical applications. The initial use of 2-pyridyl oximic ligands such as pyridine-2 amidoxime (H2pyaox) and 2-methyl pyridyl ketoxime (Hmpko) in combination with 1,2,4,5-benzene tetracarboxylic acid (pyromellitic acid), H4pma, provided access to nine new compounds whose structures and properties are discussed in detail. Among them, [Zn2(pma)(H2pyaox)2(H2O)2]n (3) and [Cu4(OH)2(pma)(mpko)2]n (9) are the first MOFs based on a 2-pyridyl oxime with 9 possessing a novel 3,4,5,8-c net topology. [Zn2(pma)(H2pyaox)2]n (2), [Cu2(pma)(H2pyaox)2(DMF)2]n (6), and [Cu2(pma)(Hmpko)2(DMF)2]n (8) join a small family of coordination polymers containing an oximic ligand. 9 exhibits selectivity for FeIII ions adsorption, as was demonstrated by a variety of techniques including UV-vis, EDX, and magnetism. DC magnetic susceptibility studies in 9 revealed the presence of strong antiferromagnetic interactions between the metal centers, which lead to a diamagnetic ground state; it was also found that the magnetic properties of 9 are affected by the amount of the encapsulated Fe3+ ions, which is a very desirable property for the development of magnetism-based sensors. [ABSTRACT FROM AUTHOR]

A relatively unexplored synthetic route in redox-active Mn(II/III) coordination chemistry has been employed toward the preparation of a new mixed-valence MnII/III 1-D linear chain from the reaction of [MnIII(sacb)2]− precursor with a MnII source, where sacbH2 is the Schiff base ligand N-salicylidene-2-amino-5-chlorobenzoic acid. The mononuclear (Pr2NH2)[MnIII(sacb)2] (1) compound was obtained in excellent yields (>85%) from the 1:2:3 reaction of Mn(O2CMe)2∙4H2O, sacbH2 and Pr2NH, respectively. In 1, the two doubly deprotonated sacb2− ligands act as Ocarboxylate,Nimine,Ophenoxide-tridentate chelates, while the second carboxylate O atom of sacb2− is dangling and H-bonded to the Pr2NH2+ countercation. Complex 1 was subsequently used as a 'ligand' to react stoichiometrically with the 'metal' Mn(NO3)2∙4H2O, thus leading to the 1-D coordination polymer {[MnIIMnIII(sacb)2(H2O)2(MeOH)2](NO3)}n (2) in good yields (~50%). The removal of Pr2NH2+ from the vicinity of the [MnIII(sacb)2]− metalloligand has rendered possible (vide infra) the coordination of the second Ocarboxylate of sacb2− to neighboring {MnII(H2O)2(MeOH)2}2+ units, and consequently the formation of the 1-D polymer 2. Direct-current (dc) magnetic susceptibility studies revealed the presence of very weak antiferromagnetic exchange interactions between alternating MnIII and MnII atoms with a coupling constant of J = −0.08 cm−1 for g = 2.00. The combined results demonstrate the potential of the 'metal complexes as ligands' approach to yield new mixed-valence Mn(II/III) coordination polymers with interesting structural motifs and physicochemical properties. [ABSTRACT FROM AUTHOR]

Three novel Zn-based coordination polymers (CPs), [Zn(MIPA)]n (1), {[Zn(MIPA)(4,4′-bipy)0.5(H2O)]·1.5H2O}n (2), and {[Zn(MIPA)(bpe)]·H2O}n (3) (MIPA = 4-methoxyisophthalic acid, 4,4′-bipy = 4,4′-bipyridine, bpe = (E)-1,2-di(pyridine-4-yl)ethane), were constructed by ligand 4-methoxyisophthalic acid under solvothermal conditions. Compound 1 features a beaded 2D-layer architecture, while compound 2 presents a 2-fold interpenetrating structure with a uninodal three-connected hcb topology. Compound 3 has a 3-fold interpenetrated four-connected dmp topology. Photoluminescence investigations of compound 2 were explored in detail, by which ions were detected, and it was observed to have the highest quenching efficiency toward Al3+ and S2− ions. The possible fluorescence quenching mechanisms of 2 toward Al3+ and S2− ions were also explored. To the best of our knowledge, this is the first potential dual-responsive luminescent probe based on a Zn(II) coordination polymer for detecting Al3+ and S2− ions via a luminescence quenching effect in ethanol. [ABSTRACT FROM AUTHOR]

Ionothermal synthesis is a little used method for the preparation of coordination polymers. By this method, two cadmium compounds were synthesized, 1, with formula Cd3(ox)F2(Ina)2 (Ina = isonicotinate) and 2, Cd(NO3)2(4,4′-Bpy) (4,4′-Bpy = 4,4′-Bipyridine). The modification of the reaction conditions has allowed to obtain 2 as a pure phase. The structure of both compounds was determined by a single-crystal X-ray diffraction. Compound 1 is isostructural to the previously reported Cd2Zn(ox)(OH)2(Ina)2. It crystallizes in the monoclinic space group P21/n and present a three-dimensional (3D) network, built-up from [Cd3(ox)F2]n2n+ layers, linked by isonicotinate ligands. Crystals of 2 are formed by twins of two components which are rotated ca. 180° to each other. This compound crystallizes in the triclinic P-1 space group and its structure can be describe as a two-dimensional (2D) 4 connected 'sql' net. The layers are composed by [Cd(NO3)2]n chains linked through 4,4′-Bpy ligands, and are pillared along the [011] direction. The thermal decomposition of 2 was studied by thermogravimetric and thermodiffractiometric techniques. The compound decomposes gradually starting from 160 °C, and due to heating, the structure suffers slight reversible changes in the bond distances and angles. [ABSTRACT FROM AUTHOR]

Solvent can play a crucial role in the synthesis of coordination polymers (CPs). Here, this study reports how the coordinating solvent approach (CSA) can be used as an effective tool to control the nature of the final CP. This study exploited the system Cu(II)-4,4′-bipyridine coupled to different coordinating solvents, such as DMA, DMF and DMSO. This allowed the isolation and structurally characterization of four new CPs: three 2D layered networks and one 1D chain. Moreover, it was evidenced that even adventitious water can play the role of the coordinating solvent in the final CP. [ABSTRACT FROM AUTHOR]

Platooning strategy is an important component of autonomous driving technology. Autonomous vehicles in platoons are often equipped with a variety of on-board sensors to detect the surrounding environment. The abundant data collected by autonomous vehicles in platoons can be transmitted to the infrastructure through vehicle-to-infrastructure (V2I) communications using the IEEE 802.11 distributed coordination function (DCF) mechanism and then uploaded to the cloud platform through the Internet. The cloud platform extracts useful information and then sends it back to the autonomous vehicles respectively. In this way, autonomous vehicles in platoons can detect emergency conditions and make a decision in time. The characteristics of platoons would cause a fair-access problem in the V2I communications, i.e., vehicles in the platoons moving on different lanes with different velocities would have different resident time within the infrastructure's coverage and thus successfully send different amounts of data to the infrastructure. In this case, the vehicles with different velocities will receive different amounts of useful information from the cloud. As a result, vehicles with a higher velocity are more likely to suffer from a traffic accident as compared to the vehicles with a lower velocity. Hence, this paper considers the fair-access problem and proposes a fair-access scheme to ensure that vehicles with different velocities successfully transmit the same amount of data by adaptively adjusting the minimum contention window of each vehicle according to its velocity. Moreover, the normalized throughput of the proposed scheme is derived. The validity of the fair-access scheme is demonstrated by simulation. [ABSTRACT FROM AUTHOR]