Sonochemical synthesis of two novel Pb(II) 2D metal coordination polymer complexes: New precursor for facile fabrication of lead(II) oxide/bromide micro-nanostructures

Ψ-Polyhedral symbols for coordination geometries of lead(II) with a stereochemically active lone pair

Because an IUCr/IUPAC-designated set of letters/numbers identifies the configuration of the atoms linked to the Pb^II atom in its coordination compounds, a Ψ prefix before such as a polyhedral symbol provides useful information when its lone pair is stereochemically active. Such notation is especially relevant when the metal atom is connected to eight or more atoms regardless of whether the lone pair is active or inert. The polyhedral symbols for the crystal structures in some 50 articles published after 2000 are reported here as the original studies did not expressly identify coordination geometries.

Solvent-tuned ultrasonic synthesis of 2D coordination polymer nanostructures and flakes

Herein, a new 2-dimensional coordination polymer based on copper (II), {Cu2(L)(DMF)2}n, where L stands for 1,2,4,5-benzenetetracarboxylate (complex 1) is synthesized. Interestingly, we demonstrate that both solvent and sonication are relevant in the top-down fabrication of nanostructures. Water molecules are intercalated in suspended crystals of complex 1 modifying not only the coordination sphere of Cu(II) ions but also the final chemical formula and crystalline structure obtaining {[Cu(L)(H2O)3]·H2O}n (complex 2). On the other hand, ultrasound is required to induce the nanostructuration. Remarkably, different morphologies are obtained using different solvents and interconversion from one morphology to another seems to occur upon solvent exchange. Both complexes 1 and 2, as well as the corresponding nanostructures, have been fully characterized by different means such as infrared spectroscopy, x-ray diffraction and microscopy.

Ultrasound-assisted exfoliation of a layered 2D coordination polymer with HER electrocatalytic activity

Large blue rectangular crystals of the 2D layered coordination polymer 1 have been obtained. The interest for this complex is two-fold. First, complex 1 is made of 2D layers packing along the (0-11) direction favored by the presence of lattice and coordinated water molecules. And second, nanostructures that could be derived by delamination are potentially suitable for catalytic purposes. Therefore it represents an excellent example to study the role of interlayer solvent molecules on the ultrasound-assisted delamination of functionally-active 2D metal-organic frameworks in water, a field of growing interest. With this aim, ultrasound-assisted delamination of the crystals was optimized with time, leading to stable nanosheet colloidal water suspensions with very homogeneous dimensions. Alternative bottom-up synthesis of related nanocrystals under ultrasound sonication yielded similar shaped crystals with much higher size dispersions. Finally, experimental results evidence that the nanostructures have higher catalytic activities in comparison to their bulk counterparts, due to larger metallic center exposition. These outcomes confirm that the combination of liquid phase exfoliation and a suitable synthetic design of 2D coordination polymers represents a very fruitful approach for the synthesis of functional nanosheets with an enhancement of catalytic active sites, and in general, with boosted functional properties.

Selective ultrasonic assisted synthesis of iron oxide mesoporous structures based on sulfonated melamine formaldehyde and survey of nanorod/sphere, sphere and core/shell on their catalysts properties for the Biginelli reaction

Sulfonated melamine-formaldehyde including iron oxide nanoparticles were synthesized by sulfonation of melamine-formaldehyde and then Fe₃O₄ nanoparticles were bounded onto the surface of sulfonated melamine-formaldehyde (SMF). Two different iron oxide nanostructures including nanorods/spheres and nanospheres on sulfonated melamine-formaldehyde (SMF/Fe₃O₄) were obtained only by modifying the time of radiation from 4 to 8 h in our synthetic method. Furthermore core/shell (Fe₃O₄@SMF) was prepared by entrapping Fe₃O₄ magnetic nanoparticles as the core and sulfonated melamine-formaldehyde as the outer shell. The prepared components were characterized via, Fourier transform infrared spectroscopy (FT-IR), titration, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Barret-Joyner-Halenda (BJH) analysis, vibrating sample magnetometer (VSM), energy-dispersive X-ray (EDX) spectroscopy, and thermal gravimetric analysis (TGA). According to obtained results, the synthesized products had a thermal stability near 180 °C, particle-size distribution around of 20-140 nm and surface area between 6 and 10 m²/g. In this study, vapor was used as a heat source. These effective and magnetically recoverable catalysts were employed for the synthesis of numerous 3,4-dihydropyrimidin-2(1H)-ones by utilizing aldehydes, ethylacetoacetate and urea. Functional easiness, excellent yields, short reaction time, the simplicity of work-up or filter, and thermal stability of these catalysts created them as appropriate heterogeneous systems and acceptable alternative to different heterogeneous catalysts.