Non-Enzymatic Impedimetric Sensor Based on 3-Aminophenylboronic Acid Functionalized Screen-Printed Carbon Electrode for Highly Sensitive Glucose Detection.

A highly sensitive glucose sensor was prepared by a one-step method using 3-aminophenyl boronic acid as a unit of recognition and a screen-printed carbon electrode (SPCE) as an electrochemical transducer. Scanning Electron Microscopy confirmed the success of the functionalization of the SPCE due to the presence of clusters of boronic acid distributed on the carbon surface. In agreement with the Electrochemical Impedance Spectroscopy (EIS) tests performed before and after the functionalization, Cyclic Voltammetry results indicated that the electroactivity of the electrode decreased 37.9% owing to the presence of the poly phenylboronic acid on the electrode surface. EIS revealed that the sensor was capable to selectively detect glucose at a broad range of concentrations (limit of detection of 8.53 × 10-9 M), not recognizing fructose and sucrose. The device presented a stable impedimetric response when immediately prepared but suffered the influence of the storage time and some interfering species (dopamine, NaCl and animal serum). The response time at optimized conditions was estimated to be equal to 4.0 ± 0.6 s.

Zirconium(IV) metallocavitands as blue-emitting materials.

A series of zirconium-carboxylate metallocavitands with the general formula [(CpZr)3(µ-κ2,O',O″CR)3(µ3-O)(µ2-OH)3]Cl (Cp = cyclopentadienyl; R = C5H4N (5), C6H7N (6), C18H14N (7), and C18H12N (8)) were synthesized in moderate to high yields (40-83%) by reacting the corresponding carboxylic acids 1-4 with Cp2ZrCl2 in a self-assembly procedure at room temperature. The metallocavitands were characterized using (1)H and (13)C NMR spectroscopy and by single-crystal X-ray diffraction. Complexes 7 and 8 exhibit efficient photoluminescence properties in solution. The photoluminescence peak of 7 was observed at 464 nm and that of 8 at 422 nm with respective quantum yields in solution of 87 and 65%.

Synthesis and complexation study of new ExTTF-based hosts for fullerenes.

A new series of exTTF hosts has been synthesized for supramolecular binding study of fullerenes C60 and C70. Binding constants for C60 in chlorobenzene, toluene, toluene-CH2Cl2 and CS2 have been calculated for different hosts and a direct structure-affinity relationship has been established. As predicted, receptors with two exTTF moieties (1, 3 and 4) have demonstrated higher binding abilities toward C70 than C60. Depending on the linker used to attach the exTTF unit to the core of the host, different binding modes (1 : 1 and 2 : 1) have been obtained.

On the interaction of acetone with electrophilic metallocavitands having extended cavities.

We report the synthesis and characterization of tantalum-boronate trimetallic clusters of general formula {[Cp*Ta](3)(µ(2)-RB(O)(2))(3)(µ(2)-OH)(µ(2)-O)(2)(µ(3)-OH)} (R= 4-(C(6)H(5))(C(6)H(4)) (Ta(3)-4Ph), 4-(C(6)H(5)O)(C(6)H(4)) (Ta(3)-4OPh), 4-(C(7)H(7)O)(C(6)H(4)) (Ta(3)-4OBn), 4-(C(8)H(5))(C(6)H(4)) (Ta(3)-4PhEt), and 4-(C(12)H(7))(C(6)H(4)) (Ta(3)-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ΔH° and ΔS° values for association of acetone with the complexes vary between -2.0 and -4.1 kcal·mol(-1) and -3 and 2 cal·mol(-1)·K(-1), respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ΔH(‡) values vary between 8.2 and 11.4 kcal·mol(-1).

1,3,5-Tri- and 1,3,4,5-tetra-substituted 1,4-diazepin-2-one solid-phase synthesis.

Solid-phase syntheses of 1,3,5-tri-substituted and 1,3,4,5-tetra-substituted 1,4-diazepin-2-ones 15-18 have been accomplished by employing inexpensive commercially available alpha- and beta-amino acids on Wang resin. Reductive amination of the imine formed by condensation of Wang aldehyde resin respectively with beta-alaninate 2 and beta-homophenylalaninate 3, followed by aminoacylation with a set of alpha-N-Boc amino acids (Phe epsilon-( Z)-Lys, and Leu) gave tertiary amide resins 7 and 8. Exposure of resins 7 and 8 to an excess of vinyl magnesium bromide in the presence of copper cyanide gave the corresponding gamma,delta-unsaturated ketone resins 9 and 10 by way of a cascade addition. Diazepinones were made by Boc deprotection and intramolecular reductive amination. To diversify the heterocycle, N-alkylation was performed using a series of alkyl halides. Alternatively, diazepinones 15e-g were obtained from treatment of methyl beta-alaninate resins 4 and 20 under similar copper-catalyzed cascade conditions to afford the gamma,delta-unsaturated ketone 21, which was acylated using alpha-N-Fmoc-amino acids (Phe, Trp, gamma-(t-Bu)-Glu). Formation of diazepinones 15 followed a similar protocol, after Fmoc removal with piperidine. Cleavage of the heterocycles with TFA/TES 95:5 gave the N1-p-hydroxybenzyl diazepinones 15-18 in overall isolated yields from 6 to 24% after purification in purities ranging from 81 to 100% according to LCMS analysis.

1,4-Diazepinone and pyrrolodiazepinone syntheses via homoallylic ketones from cascade addition of vinyl Grignard reagent to alpha-aminoacyl-beta-amino esters.

[reaction: see text] 1,4-Diazepinones 5 and pyrrolodiazepinones 8 and 9 were synthesized from common homoallylic ketone precursors 4 prepared by copper-catalyzed cascade addition of a vinyl Grignard reagent to alpha-aminoacyl beta-amino esters 3. Nitrogen deprotection and intramolecular reductive amination yielded 1,4-diazepinones 5. Olefin oxidation, Boc removal, and intramolecular Paal-Knorr condensation gave pyrrolodiazepinones 8 and 9. X-ray structures of diazepinones 5c and 5d depicted dihedral angles about the alpha-amino acid moiety similar to those of the central residue in an ideal reverse gamma-turn.

1,3,5-trisubstituted 1,4-diazepin-2-ones.

Six 1,3,5-trisubstituted 1,4-diazepin-2-ones were synthesized by a sequence featuring the cascade addition of vinyl Grignard to N-[Boc-aminoacyl]-N-alkyl-beta-amino esters, followed by Boc group removal and annulation by a reductive amination. Relative to the parent sequence employing N-Boc-aminoacyl beta-amino esters to make 3,5-disubstituted heterocycle, the additional N-alkyl substituent caused a noticeable acceleration and gave relatively higher yield in the 1,4-diazepin-2-one annulation.