Greener route for microwave enhanced syntheses of bioactive 1,5-benzodiazepines using heterogeneous calcium ferrite/graphene oxide nanocomposite as a novel and sustainable catalyst

In the present paper, a novel and benign protocol for microwave enhanced one pot syntheses of 2,3-dihydro-1,5 benzodiazepine derivatives from substituted acetophenones, aryl-aldehydes and o-phenylene diamine using heterogeneous calcium ferrite/graphene oxide (CF/GO) nanocomposite has been reported. The catalyst was prepared by ultrasonication method and characterized by spectral and analytical techniques. The CF/GO nanocomposite was employed for environmentally benign synthesis of 2,3-dihydro-1,5 benzodiazepines. The synthesized benzodiazepine derivatives were screened for their antimicrobial activities against various bacteria and fungi. The present synthetic strategy offered several advantages such as excellent yields in short span of time, simple modus operandi, ease of isolation and purification of products, simple recovery and reusability of the catalyst. A tentative mechanism for synthesis of 2,3-dihydro-1,5 benzodiazepine using CF/GO nanocatalyst has also been proposed.     

Groebke-Blackburn-Bienaymé multicomponent reaction in scaffold-modification of adenine, guanine, and cytosine: synthesis of aminoimidazole-condensed nucleobases

A multicomponent method for scaffold-modification of nucleobases (adenine, guanine, and cytosine) was developed. This modification approach, as an alternative to usual synthetic routes involving protection-deprotection or S_NAr of halo (or leaving group-equivalent)-purines, affords in one step therapeutically-relevant substituted aminoimidazole-[i]-condensed adenine, [b]-condensed guanine, [c]-condensed cytosine. These derived nucleobases possess enhanced lipophilicity and solubility and contain the functionalities useful for further chemical manipulations.     

Combined experimental and computational study of W(II), Ru(II), Pt(IV) and Cu(I) amine and amido complexes using 15N NMR spectroscopy

Using 2D proton-coupled gHSQC pulse sequences in addition to 1D ¹⁵N NMR experiments of ¹⁵N labeled systems, ¹⁵N NMR chemical shifts of a range of transition metal amido and amine complexes were determined. Tungsten(II), ruthenium(II), platinum(IV) and copper(I) complexes with aniline and their anilido variants were studied and compared to free aniline, lithium anilido and anilinium tetrafluoroborate. Upon coordination of aniline to transition metals, upfield chemical shifts of 20–60 ppm were observed. Deprotonation of the amine complexes to form amido complexes resulted in downfield chemical shifts of 40–60 ppm for all of the complexes except for the tungsten d⁴ system. For the tungsten(II) complexes, the cationic aniline complex displayed a downfield shift of approximately 56 ppm relative to the neutral anilido complex. The change in chemical shift for amine to amido conversion is proposed to depend on the ability of the amido ligand to π-bond with the metal center, which influences the magnitude of the paramagnetic screening term.     

Polyaniline nanotubes for impedimetric triglyceride detection

Polyaniline nanotubes (PANI-NT) based film electrophoretically deposited onto indium–tin–oxide (ITO) coated glass plate has been utilized for covalent immobilization of lipase (LIP), via glutaraldehyde (Glu), for triglyceride detection using impedimetric technique. It is shown that fatty acid molecules produced during triglyceride hydrolysis result in change in charge transfer resistance (R_CT) of PANI-NT film with varying triglyceride concentration. LIP/Glu/PANI-NT/ITO bioelectrode has linearity as 25–300 mg dL^?1, sensitivity as 2.59 × 10^?3 KΩ^?1 mg^?1 dL, response time as 20 s and regression coefficient as 0.99. A low value of apparent Michaelis–Menten constant (～0.62 mM) indicates high enzyme affinity to tributyrin. The LIP/Glu/PANI-NT/ITO bioelectrode has been utilized to estimate triglyceride in serum samples.     

Photo-fenton degradation of phenol red catalyzed by inorganic additives: A technique for wastewater treatment

Oxidation by photo-Fenton like reaction is an economically feasible process for degradation of a variety of hazardous pollutants in wastewater from dyeing and printing industries. In present study, the progress of the reaction has been monitored spectrophotometrically. An effort has been made to observe the effect of various inorganic additives like sodium thiosulfate and potassium bromate. The effect of variation of different parameters such as pH, concentrations of dye, Fe³⁺ ion and additives, amount of H₂O₂, and light intensity on the rate of photodegradation was also observed. A tentative mechanism for the reaction has been proposed.     

Molecularly imprinted polyaniline-polyvinyl sulphonic acid composite based sensor for para-nitrophenol detection

We report results of the studies relating to the fabrication and characterization of a conducting polymer based molecularly imprinted para-nitrophenol (PNP) sensor. A water pollutant, para-nitrophenol is electrochemically imprinted with polyvinyl sulphonic acid (PVSA) doped polyaniline onto indium tin oxide (ITO) glass substrate. This PNP imprinted electrode (PNPI-PANI-PVSA/ITO) prepared via chronopotentiometric polymerization and over-oxidation is characterized by Fourier transform infra-red spectroscopy (FT-IR), UV–visible (UV–vis) spectroscopy, contact angle (CA), scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. The response studies of PNPI-PANI-PVSA/ITO electrode carried out using DPV reveal a lower detection limit of 1 × 10⁻³ mM, improved sensitivity as 1.5 × 10⁻³ A mM⁻¹ and stability of 45 days. The PNPI-PANI-PVSA/ITO electrode shows good precision with relative standard deviation of 2.1% and good reproducibility with standard deviation of 3.78%.     

Kinetics and mechanism of oxidation of 1,4-butanediol by chromium(VI) in acid perchlorate medium

Summary The kinetics of oxidation of 1,4-butanediol by chromium(VI) was studied in acid perchlorate medium and the oxidation product of the diol was identified as 4-hydroxybutanal. The kinetic rate law observed accounted for the complex dependence of the hydrogen ion k=(k₂K₁[H+]+k₃K₁K₂[H+]²)/(1+K₁[H]+) where k is the observed second-order rate constant.     

Electrophoretically deposited polyaniline nanotubes based film for cholesterol detection

Polyaniline nanotube (PANI-NT) based films have been fabricated onto indium-tin-oxide (ITO) coated glass plates via electrophoretic technique. These PANI-NT/ITO electrodes have been utilized for covalent immobilization of cholesterol oxidase (ChOx) using glutaraldehyde (Glu) as cross-linker. Structural, morphological and electrochemical characterization of PANI-NT/ITO electrode and ChOx/Glu/PANI-NT/ITO bioelectrode have been done using FT-IR spectroscopy, SEM, electrochemical impedance spectroscopy and cyclic voltammetry techniques. Response studies of the ChOx/Glu/PANI-NT/ITO bioelectrode have been carried out using both linear sweep voltammetry and UV-Visible spectrophotometry. The results of the biosensing studies reveal that this bioelectrode can be used to detect cholesterol in wide detection range of 25-500 mg/dL with high sensitivity of 3.36 mA mg(-1) dL and fast response time of 30 s at pH 7.4. This bioelectrode exhibits very low value of Michaelis-Menten constant of 1.18 mM indicating enhanced interactions between cholesterol and ChOx immobilized onto this nanostructured PANI matrix.     

Polyaniline/Single‐Walled Carbon Nanotubes Composite Based Triglyceride Biosensor

Nanocomposite film comprising of polyaniline (PANI) and single walled carbon nanotubes (SWCNT) has been fabricated onto indium‐tin‐oxide (ITO) coated glass plate using electrophoretic technique. Co‐immobilization of glycerol dehydrogenase (GDH) and lipase (LIP) has been done via N‐ethyl‐N′‐(3‐dimethylaminopropyl) carbodiimide and N‐hydroxysuccinimide chemistry to explore its application for triglyceride (tributyrin) sensing. Response studies have been done using linear sweep voltammetry revealing that LIP‐GDH/PANI‐SWCNT‐TB/ITO bioelectrode can detect tributyrin in the range of 50 to 400 mg dL^?1 with low Michaelis–Menten constant of 1.138 mM, improved response time of 12 s, high sensitivity as 4.28×10^?4 mA mg^?1 dL and storage stability of about 13 weeks.