Enantioselective recognition of 1,2-aminoalcohols by the binol receptor dangled with pyrrole-2-carboxamide and its analogues

Novel binol receptor with pyrrole-2-carboxamide moiety and its analogues have been designed, synthesized, and used to enantioselectively recognize 1,2-aminoalcohols via multiple hydrogen bonding. The pyrrole-based binol receptor showed the highest enantioselectivity among the four receptors as determined by the ¹H NMR. The DFT calculation strongly supports complementary hydrogen bonding between alcoholic -OH and pyrrolyl groups.     

Surfactant-mediated electrodeposition of bismuth telluride films and its effect on microstructural properties

We report the synthesis of highly crystallographically textured films of stoichiometric bismuth telluride (Bi(2)Te(3)) in the presence of a surfactant, sodium lignosulfonate (SL), that resulted in the improved alignment of films in the (110) plane and offered good control over the morphology and roughness of the electrodeposited films. SL concentrations in the range 60-80 mg dm(-3) at a deposition potential of -0.1 V vs SCE (saturated calomel electrode) were found to yield the most improved crystallinity and similar or superior thermoelectric properties compared with results reported in the literature.     

Metal Nanozyme with Ester Hydrolysis Activity in the Presence of Ammonia-Borane and Its Use in a Sensitive Immunosensor

Metal nanoparticle surfaces are used for peroxidase- and oxidase-like nanozymes but not for esterase-like nanozymes. It is challenging to obtain rapid catalytic hydrolysis on a metal surface and even more so without a catalytically labile substrate. Here, we report that metal nanoparticle surfaces rapidly catalyze non-redox ester hydrolysis in the presence of redox H₃N−BH₃ (AB). Metal hydrides are readily generated on a Pt nanoparticle (PtNP) from AB, and as a result the PtNP becomes electron-rich, which might assist nucleophilic attack of H₂O on the carbonyl group of an ester. The nanozyme system based on PtNP, AB, and 4-aminonaphthalene-1-yl acetate provides an electrochemical signal-to-background ratio much higher than natural enzymes, due to the rapid ester hydrolysis and redox cycling involving the hydrolysis product. The nanozyme system is applied in a sensitive electrochemical immunosensor for thyroid-stimulating hormone detection. The calculated detection limit is approximately 0.3 pg mL⁻¹, which indicates the high sensitivity of the immunosensor using the PtNP nanozyme.     

Single sensor for two metal ions: colorimetric recognition of Cu2+ and fluorescent recognition of Hg2+

The first novel rhodamine B based sensor, rhodamine B hydrazide methyl 5-formyl-1H-pyrrole-2-carboxylate Schiff base (2) capable of detecting both Cu(2+) and Hg(2+) using two different detection modes has been designed and synthesized. The metal ion induced optical changes of 2 were investigated in MeOH:H(2)O (3:1) HEPES buffered solution at pH 7.4. Sensor 2 exhibits selective colorimetric recognition of Cu(2+) and fluorogenic recognition of Hg(2+) with UV-vis and fluorescence spectroscopy, respectively. Moreover, both of the Cu(2+) and Hg(2+) recognition processes are proven to be hardly influenced by other coexisting metal ions.     

Odor Provocation Test for Laryngeal Hypersensitivity

This study was to present an odor provocation/challenge test for laryngeal hypersensitivity in a suspected odor induced dysphonic patient. The second aim was to rule out secondary gain from organic laryngeal hypersensitivity. Two steps were taken for this purpose. First, because the evaluation of hypersensitivity may be affected by the perception of odor, the study investigated laryngeal hypersensitivity during nasal and oral breathing separately to disentangle possible cognitive reactions to odors. Second, a healthy control (HC) participant was used with the identical testing protocol for nasal breathing to minimize unbiased results. The HC's response to nasal breathing of the odors showed no response to all the stimuli. The participant with possible secondary gain issues responded differently to the odors when presented nasally versus orally. Oral breathing showed less severe and less frequent laryngeal hypersensitive reactions. This suggests that laryngeal hypersensitivity was either due to the odor, cognitive information, sensory changes in olfaction leading to psychological conditioning, or for any possible secondary gain. Hence, it is difficult to indicate the precise reason (cause and effect) for the participant's laryngeal hypersensitivity; however, this study describes the first structured, controlled, repeatable, and randomized design to investigate odor induced laryngeal hypersensitivity and decipher possible secondary gain from true laryngeal hypersensitivity.     

Organoruthenium(II) compounds with pyridyl benzoxazole/benzthiazole moiety: studies on DNA/protein binding and enzyme mimetic activities

We report herein synthesis and characterization of four new organoruthenium(II) complexes of the type [RuH(CO)(PPh₃)₂(L_1,2)]Cl (1, 3) and [Ru(CO)(Cl)₂(AsPh₃)(L_1,2)] (2, 4) derived from the reaction of [RuHCl(CO)(EPh₃)₃] (E = P or As) with 2-(pyridine-2yl)benzoxazole (L₁) and 2-(pyridine-2yl)benzthiazole (L₂). Single-crystal X-ray diffraction data of 2 proved octahedral geometry of the complexes with a 1?:?1 ratio between the metal and the coordinated ligands. The binding affinities of 1–4 toward calf-thymus DNA (CT-DNA) and BSA were thoroughly studied by various spectroscopic techniques. Furthermore, the coordination compounds exhibit catecholase-like activities in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone and phosphatase-like activities in the hydrolysis of 4-nitrophenyl phosphate to 4-nitrophenolate ion. The kinetic parameters have been determined using Michaelis–Menten approach. The highest k_cat values suggested that coordination compounds exhibit higher rates of catalytic efficacy.     

Performance of 2-Hydroxy-1-Naphthaldehyde-2-Amino Thiazole as a Highly Selective Turn-on Fluorescent Chemosensor for Al(III) Ions Detection and Biological Applications

Journal of Fluorescence - The thiazole based Schiff base 2-hydroxy-1-naphthaldehyde-2-amino thiazole (receptor1) was synthesized through a single step process and characterized by spectroscopic and...     

A chiral ketone for enantioselective recognition of 1,2-amino alcohols

A novel auxillary chiral ketone has been designed, synthesized, and used to enantioselectively recognize 1,2-amino alcohols. This work proves that the keto group can serve as a chiral recognition center by imine formation supported by resonance assisted hydrogen bonding (RAHB).     

Effects of ring substituents on enantioselective recognition of amino alcohols and acids in uryl-based binol receptors

The uryl-based binol aldehyde, (S)-2-hydroxy-2′-(3-phenyluryl-benzyl)-1,1′-binaphthyl-3-carboxaldehyde (1), binds 1,2-amino alcohols and amino acids stereoselectively by reversible formation of imine bond. Hydrogen bond (between uryl group and alcohol -OH moiety) plays an important role in the stereoselectivity of amino alcohols. Hence, any substituents on phenyl group in 1 are expected to affect H-bond ability of uryl group. To study the effects of ring substituents on the stereoselective recognition of amino alcohols, (substituted phenyl)uryl-based chiral binol receptors have been prepared. The receptors with electron-donating X substituents have been synthesized from (S)-2-methoxymethoxy-2′-hydroxy-1,1′-binaphthyl-3-carboxaldehyde and X-phenyluryl-benzyl bromide. The receptors with electron-withdrawing Y substituents, however, required a different synthetic strategy including transformation of an aldehyde to alcohol. The incorporation of the electron withdrawing groups slightly accelerated the stereoselective recognition property of the receptor. Though the acceleration is not so remarkable, this work demonstrates the versatile derivatization of 1 in achieving higher stereoselective recognition of 1,2-amino alcohols and stereoconversion of l-amino acids to d-amino acids.