2-Acetyl­pyridinium 3-amino-2-chloro­pyridinium tetra­chloridocobaltate(II)

In the title complex, (C5H6ClN2)(C7H8NO)[CoCl4], the CoII ions are tetra­hedrally coordinated. The crystal structure is built from hydrogen-bonded centrosymmetric tetra­mers of tetra­chloridocobaltate(II) dianions and 3-amino-2-chloro­pyridinium cations, additionally strengthened by significant π–π stacking of pyridinium rings [interplanar distance 3.389 (3) Å]. The tetra­mers are linked by N—H⋯Cl hydrogen bonds into chains; the second kind of cations, viz. 2-acetyl­pyridinium, are connected by N—H⋯Cl hydrogen bonds to both sides of the chain. The Co—Cl bond lengths in the dianion correlate with the number of hydrogen bonds accepted by the Cl atom. An intramolecular C—H⋯Cl interaction is also present

Imine-Based Architectures at Surfaces and Interfaces: From Self-Assembly to Dynamic Covalent Chemistry in 2D

Within the last two decades, dynamic covalent chemistry (DCC) has emerged as an efficient and versatile strategy for the design and synthesis of complex molecular systems in solution. While early examples of supramolecularly assisted covalent synthesis at surfaces relied strongly on kinetically controlled reactions for post-assembly covalent modification, the DCC method takes advantage of the reversible nature of bond formation and allows the generation of the new covalently bonded structures under thermodynamic control. These structurally complex architectures obtained by means of DCC protocols offer a wealth of solutions and opportunities in the generation of new complex materials that possess sophisticated properties. In this focus review we examine the formation of covalently bonded imine-based discrete nanostructures as well as one-dimensional (1D) polymers and two-dimensional (2D) covalent organic frameworks (COFs) physisorbed on solid substrates under various experimental conditions, for example, under ultra-high vacuum (UHV) or at the solid–liquid interface. Scanning tunneling microscopy (STM) was used to gain insight, with a sub-nanometer resolution, into the structure and properties of those complex nanopatterns

Chlorido[2,15-dimethyl-3,7,10,14,20-penta­azabicyclo­[14.3.1]eicosa-1(20),2,14,16,18-penta­ene]manganese(II) perchlorate acetonitrile solvate

The Mn ion in the title complex, [MnCl(C17H27N5)]ClO4·CH3CN, is six-coordinated with a geometry inter­mediate between penta­gonal pyramidal and heavily distorted octa­hedral. In the macrocycle, the pyridinium ring makes a large dihedral angle of 63.70 (9)° with the best plane through the remaining four N atoms. This feature is common for 17-membered N5 rings, in contrast to their 16- and 15-membered analogues which often form planar N5 systems. In the crystal, N—H⋯O and C—H⋯O interactions help to establish the packing. The perchlorate counter-ion is rotationally disordered around the chlorine centre, with occupation factors of 0.74 (1) and 0.26 (1)

Photoisomerisation and light-induced morphological switching of a polyoxometalate–azobenzene hybrid

The functionalization of a spherical Keplerate-type polyoxometalate {Mo72V30} with a cationic azobenzene surfactant has been achieved through ionic self-assembly. The photoisomerisation reaction of this complex, which emerges in a light-triggered aggregation–disaggregation process, has been followed by 1H NMR spectroscopy, dynamic light scattering, absorption spectroscopy and scanning electron microscopy analyses

Graphene oxide-mesoporous SiO2 hybrid composite for fast and efficient removal of organic cationic contaminants

International audienceIn this study, we have developed a novel mesoporous SiO2 - graphene oxide hybrid material (SiO2NH2-GO) as highly efficient adsorbent for removal of cationic organic dyes from water. The fabrication of such a three-dimensional (3D) SiO2NH2-GO composite has been achieved via the condensation reaction between the amine units exposed on 3-aminopropyl-functionalized silica nanoparticles and the epoxy groups on surface of GO. As a proof-of-concept, SiO2NH2-GO was used for the removal of archetypical dyes from water and revealed outstanding maximum adsorption capacity towards methylene blue (MB), rhodamine B (RhB) and methyl violet (MV) at pH 10 reaching 300, 358 and 178 mg g−1 for MB, RhB and MV, respectively, thus outperforming the neat components of composite, i.e. GO and SiO2. Moreover, the adsorption process revealed that ∼99.7% of MB, RhB and MV have been removed in only 3 min thereby highlighting the superior nature of SiO2NH2-GO composite with respect to most of graphene oxide-based adsorbents of organic dyes. Finally, the composite was used in solid phase extraction (SPE) as column packing material, for continuous water purification, thus highlighting the great potential of SiO2NH2-GO for the large-scale removal of cationic dyes from aqueous solutions