The new fluorescent chromophore BOPHY can be readily synthesized in two steps from commercially available reagents via the coupling of pyrrole-2-carboxaldehyde with hydrazine followed by reaction with BF3. The resultant symmetric and dimeric tetracycle is composed of two BF2 units in six-membered chelate rings appended with pyrrole units on the periphery. The quantum yields of fluorescence for the unmodified compound and the tetramethyl variant are near unity, with values of 95 and 92%, respectively, in CH2Cl2. We have probed the electronic structure of this compound via cyclic voltammetry and density functional theory analysis.
A series of dimeric ReI(CO)3 compounds have been prepared by means of a one‐pot reaction of [Re(CO)5X] (X = Cl, Br), pyridine‐2‐carboxyaldehyde, and o‐, m‐, or p‐phenylenediamine. For the m‐ and p‐substituted phenylenediamine reactions, phenyl‐bridged bis(pyridine‐2‐carbaldimine) compounds of the formula [Re(CO)3X]2(μ‐PPC) [3–7; X = Cl, Br; μ‐PPC = m‐ or p‐phenylene bis(pyridine‐2‐carbaldimine)] were produced, with m‐phenylenediamine forming a mixture of isomers. For reactions with o‐phenylenediamine, multiple products formed (compounds 8–11), which ranged from the desired o‐phenylene bis(pyridine‐2‐carbaldimine) adduct to 2‐pyridylbenzimidazole and bridging dipyridinylquinoxaline complexes. An example of each complex was structurally elucidated by single‐crystal X‐ray methods. The dimeric m‐ and p‐phenylene‐bridged Re(CO)3X compounds, including a sulfonate derivative designed to improve solubility, were investigated for possible photophysical applications through the use of UV/Vis spectroscopy and cyclic voltammetry; the study revealed coupling between the rhenium centers.
A new dipyridyl-functionalized silica gel (DPSG) was synthesized. The potentiometric response of silver ion was investigated at a carbon paste electrode chemically modified with functionalized nanoporous silica gel. The electrodes with a DPSG proportions of 10.1% (w/w), showed very stable potential. Calibration plots with Nernstian slopes for Ag þ were observed, 58.7 (AE 0.9) mV decade
À1, over a wide linear range of concentration (5.0 Â 10 À7 to 1.0 Â 10 À1 M). The electrode has a detection limit of 1.0 Â 10 À7 M. The selectivity coefficients measured by the match potential method in acetate buffer, pH 5.5, were investigated. The electrode has fast response time, high performance, high sensitivity in wide cation activity ranges, and good long term stability (more than 6 months). The method was satisfactory and used to determine the concentration of silver ion in waste waters contaminated by this metal.
Half-hemiporphyrazine macrocycles, which can be called "semihemiporphyrazines", were synthesized using the Re(CO) unit as a templating agent. The products of these template reactions are six-coordinate rhenium complexes, with a facial arrangement of carbonyls, a halide, and a bidentate semihemiporphyrazine chelate that tilts out of the plane of coordination. Three types of semihemiporphyrazines can be produced from these reactions, depending on the alternate heterocycle to the isoindoline unit; structures including pyridine, thiazole, and benzimidazole were formed. The electronic structures of these compounds were probed using spectroscopy as well as density functional theory methods.
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