The Effect of Auxiliary Nitrogenated Linkers on the Design of New Cadmium-Based Coordination Polymers as Sensors for the Detection of Explosive Materials

Three new cadmium-based coordination polymers, denoted [Cd(hfipbb)(4,4’-bipy)] ( CdPF-1 ), [Cd(hfipbb)(2,2’-bipy)] ( CdPF-2 ), and [Cd(hfipbb)(1,10-phen)] ( CdPF-3 ), have been hydrothermally synthesized by using the well-known V-shaped organic linker 4,4’-(hexafluoroisopropylidene)bis(benzoic acid) (H₂hfipbb), together with different nitrogenated auxiliary linkers. Considering the d¹⁰ configuration of the transition metal selected, the luminescent properties for these CdPF-n materials were explored, finding that materials CdPF-2 and CdPF-3 act as excellent sensors in the detection of explosive nitro aromatic compounds. The photoluminescence properties of CdPF-2 and CdPF-3 revealed that significant and sensitive fluorescence quenching was observed toward NP (nitrophenol) for CdPF-2 and PA (picric acid) for CdPF-3 in MeOH suspensions.     

Use of capillary electrophoresis for characterisation of vinyl‐terminated Au nanoprisms and nanooctahedra

It is described a simple, rapid and efficient methodology to characterise and separate gold nanoprisms and nanooctahedra by capillary electrophoresis. This technique is suitable to distinguish between morphologies and it can be used as a powerful separation tool after a customised synthesis of both structures. This synthesis was carried out by amending two parameters, temperature and pH, and a sharp decrease was found in nanotriangles when temperature was increased from 70 up to 95°C. However, when the synthesis was performed at a given temperature, an increase in pH did not promote an important change in isolation of any structure until pH = 9.5, critical in the final morphology of the nanoparticle. Gold nanoprisms and nanooctahedra were successfully separated by capillary electrophoresis according to differences in charge‐to‐mass ratio of the morphologies. Final particle morphology was confirmed by transmission electron microscopy analysis. Under optimal working conditions, a mixture containing both shapes of gold nanoparticles was initially injected and two major peaks were obtained for each structure. Capillary electrophoresis allowed to study pH and temperature influence on both morphologies. It was inferred that the ratio between triangles and octahedra decreased to a great extent when increasing both temperature and pH.     

Contribution of thermal imaging to fertigation in soilless culture

Thermography is a tool used in many scientific disciplines, including agriculture. This paper describes the application of thermography as a rapid diagnostic method of adequate watering. Two experiments were conducted. In experiment 1, Philodendron erubescens and Anthurium andraeum were transplanted to pots in a greenhouse in Almeria (Spain). The vegetative growth parameters of these plants were measured. In experiment 2, two areas of vegetative cover were established on green walls: one with a combination of aromatic plants and another with ornamental indoor plants. The thermographic images were recorded using a compact infrared camera, which had a spectral infrared range of 7.3–13 μm, microbolometer of 320 × 240 pixels, and the resolution was 0.01 °C at 30 °C. Three irrigation treatments were applied in both experiments, consisting of a control treatment (CT), a deficit irrigation [1/3 less volume, deficient irrigation (DI)] treatment, and an excess irrigation [1/3 greater volume, excess irrigation (EI)] treatment. In both experiments, the sample temperatures were recorded by thermography for each irrigation treatment. In experiment 1, the vegetative growth parameters were greater under CT than under DI or EI. The data of the reference thermographs over the leaves of the potted plants were significantly correlated with the superior growth parameters under the optimal irrigation treatment. A continuous vegetative canopy was formed on both of the green walls in experiment 2, and the average temperatures were correlated with the irrigation treatments in this experiment. The temperatures reflected in the reference thermographs allowed for the determination of the most appropriate irrigation treatment. These results suggest that thermography can be a useful method to provide an early diagnosis of water stress in potted plants and green walls.     

An Adjustable Cleft Based on an 8-Sulfonamide-2-Naphthoic Acid with Oxyanion Hole Geometry

Cleft type receptors showing the oxyanion hole motif have been prepared in a straightforward synthesis starting from the commercial 3,7-dihidroxy-2-naphthoic acid. The double H-bond donor pattern is achieved by the introduction of a sulfonamide group in the C-8 position of naphthalene and a carboxamide at the C-2 position. This cleft, for which the geometry resembles that of an oxyanion hole, is able to adjust to different guests, as shown by the analysis of the X-ray crystal structures of associates with methanol or acetic acid. Combination of hydrogen bonds and charge-transfer interactions led to further stabilization of the complexes, in which the electron-rich aromatic ring of the receptor was close in space to the electron-deficient dinitroaromatic guests. Modelling studies and bidimensional NMR experiments have been carried out to provide additional information.     

Synthesis of 1-aryl-3H-[1,2,5]triazepino[5,4-a]benzimidazol-4(5H)-ones and quantum chemical investigation of the rotamers of the Boc-protected hydrazide key intermediate

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Design and Sensing Properties of a Self‐Assembled Supramolecular Oligomer

Supramolecular polymers are a class of macromolecules stabilized by weak non‐covalent interactions. These self‐assembled aggregates typically undergo stimuli‐induced reversible assembly and disassembly. They thus hold great promise as so‐called functional materials. In this work, we present the design, synthesis, and responsive behavior of a short supramolecular oligomeric system based on two hetero‐complementary subunits. These “monomers” consist of a tetrathiafulvalene‐functionalized calix[4]pyrrole (TTF‐C[4]P) and a glycol diester‐linked bis‐2,5,7‐trinitrodicyanomethylenefluorene‐4‐carboxylate (TNDCF), respectively. We show that when mixed in organic solvents, such as CHCl₃, CH₂ClCH₂Cl, and methylcyclohexane, supramolecular aggregation takes place to produce short oligomers stabilized by hydrogen bonding and donor–acceptor charge‐transfer (CT) interactions. The self‐associated materials were characterized by ¹H NMR and UV/Vis/NIR absorption spectroscopy, as well as by concentration‐ and temperature‐dependent absorption spectroscopy and dynamic light scattering (DLS) analyses of both the monomeric and oligomerized species. The self‐associated system produced from TTF‐C[4]P and TNDCF exhibits a concentration‐dependent aggregation behavior typical of supramolecular polymers. Further support for the proposed self‐assembly came from theoretical calculations. The fluorescence emitting properties of TNDCF are quenched under conditions that promote the formation of supramolecular aggregates containing TTF‐C[4]P and TNDCF. This quenching effect has been utilized as a probe for the detection of substrates in the form of anions (i.e., chloride) and nitroaromatic explosives (i.e., 1,3,5‐trinitrobenzene). Specifically, the addition of these substrates to mixtures of TTF‐C[4]P and TNDCF produced a fluorescence “turn‐on” response.