A convenient green protocol for oxidative esterification of arylaldehydes over Pd NPs decorated polyplex encapsulated Fe3O4 microspheres.

A mild, competent and eco-friendly protocol has been developed for oxidative esterification of various aldehydes over a post-synthetically modified and Pd fabricated chitosan-starch dual functionalized Fe3O4 microspheres as a magnetically isolable heterogeneous and biocompatible nanocatalyst. Molecular O2 was used as an oxidant in the reaction. A series of aldehydes was directly esterified with MeOH in excellent yields without any pre-activation and involvement of harsh chemicals/conditions. Structural features of the catalyst were assessed through FT-IR, FE-SEM, TEM, EDX, molecular mapping, XRD, VSM and ICP-OES techniques. Due to magnetic core, the catalyst was easily isolated using an external magnet and reused for 8 times in succession, retaining its morphology and catalytic activity.

Chitosan-starch biopolymer modified kaolin supported Pd nanoparticles for the oxidative esterification of aryl aldehydes.

A mild and efficient green protocol has been disclosed for selective oxidative esterification of various aldehydes over a novel Pd fabricated chitosan-starch polyplex encapsulated Kaolin (Kaolin@CS-starch-Pd) as a heterogeneous and reusable biocompatible nanocatalyst. Molecular oxygen was used as an oxidizing agent to generate water as the sole by-product. A wide variety of aldehydes was converted to their methyl esters in high yields. The process involved gentle reaction conditions to avoid any type of pre-activation. Structural features of the catalyst were determined through FT-IR, FE-SEM, TEM, EDX, elemental mapping, XRD and ICP-OES analyses. The material was found to be stable enough toward Pd leaching. Durability of Kaolin@CS-starch-Pd was further justified by retaining its catalytic activity through successful reusability for several times.

Recent developments in the synthesis of regioregular thiophene-based conjugated polymers for electronic and optoelectronic applications using nickel and palladium-based catalytic systems.

Thiophene-based conjugated polymers hold an irreplaceable position among the continuously growing plethora of conjugated polymers due to their exceptional optical and conductive properties, which has made them a centre of attention for the past few decades and many researchers have contributed tremendously by designing novel strategies to reach more efficient materials for electronic applications. This review aims to highlight the recent (2012-2019) findings in design and synthesis of novel thiophene-based conjugated polymers for optical and electronic devices using organometallic polycondensation strategies. Nickel- and palladium-based protocols are the main focus of this account. Among them nickel-catalyzed Kumada catalyst-transfer polycondensation, nickel-catalyzed deprotonative cross-coupling polycondensation, palladium-catalyzed Suzuki-Miyaura and Migita-Kosugi-Stille couplings are the most popular strategies known so far for the synthesis of functionalized regioregular polythiophenes exhibiting fascinating properties such as electronic, optoelectronic, chemosensitivity, liquid crystallinity and high conductivity. This account also presents a brief overview of direct arylation polymerization (DArP) protocol that has shown a great potential to lessen the drawbacks of conventional polymerization techniques. DArP is a cost-effective and green method as it circumvents the need for the synthesis of arylene diboronic acid/diboronic ester and distannyl arylenes using toxic precursors. DArP also puts off the need to preactivate the C-H bonds, hence, presenting a facile route to synthesize polymers with controlled molecular weight, low polydispersity index, high regioregularity and tunable optoelectronic properties using palladium-based catalytic systems.

Recent Advances on 3-Hydroxyflavone Derivatives: Structures and Properties.

Flavonoids are naturally occurring phenolic compounds named as 2-phenyl-1-benzopyran- 4-one and classified into several subclasses according to their basic chemical structures such as flavones, flavonols, flavanones, flavanonols, and flavanols. Among them, flavonols (3-hydroxyflavone), containing a 3-hydroxyl group in association with its 4-keto group and double bond between 2- and 3- carbon atoms, have the best electron conjugated skeleton in flavonoid family, providing several resonance structures and chelating ability, through which various pharmacological activities such as antiviral, antitumour, anti-inflammatory, anticholinesterase, cytotoxicity and particularly high antioxidant activity are demonstrated. They prevent generation of free radicals and are used as food preservatives. Their strong electron conjugation provides them with fluorescent property, which make them used as imaging agents for therapeutic purpose.

Screening of Hallucinogenic Compounds and Genomic Characterisation of 40 Anatolian Salvia Species.

INTRODUCTION: Salvia, an important and widely available member of Lamiaceae family. Although comparative analysis on secondary metabolites in several Salvia species from Turkey has been reported, their hallucinogenic chemicals have not been screened thoroughly. OBJECTIVE: This study provides LC-MS/MS analysis of 40 Salvia species for screening their psychoactive constituents of salvinorin A and salvinorin B. 5S-rRNA gene non-coding region of Salvia plants was sequenced, aligned and compared with that sequence of Salvia divinorum plant. METHODOLOGY: Targeted molecules of salvinorin A and salvinorin B were quantified, using LC-MS/MS, from all aerial parts of 40 Salvia species, collected from different parts of Turkey. Regions of 5S-rRNA gene from different species were amplified by polymerase chain reaction and DNA sequences were aligned with Salvia divinorum DNA sequences. RESULTS: Very few of the Salvia species (S. recognita, S. cryptantha and S. glutinosa) contained relatively high levels of salvinorin A (212.86 ± 20.46 µg/g, 51.50 ± 4.95 µg/g and 38.92 ± 3.74 µg/g, respectively). Salvinorin B was also found in Salvia species of S. potentillifolia, S. adenocaulon and S. cryptantha as 2351.99 ± 232.22 µg/g, 768.78 ± 75.90 µg/g and 402.24 ± 39.71 µg/g, respectively. The sequences of 5S-rRNA gene of 40 different Salvia species were presented and it was found that none of the Salvia species in Turkey had similar DNA sequence to Salvia divinorum plant. CONCLUSION: This is the first report of screening 40 Salvia species in Turkey according to their psychoactive constituents, salvinorin A and salvinorin B and their genomic structures. It is possible that some of these Salvia species may exhibit some psycho activity. Thus, they need to be screened further. Copyright © 2017 John Wiley & Sons, Ltd.

Antioxidant and Anticholinesterase Activities of Some Dialkylamino Substituted 3-Hydroxyflavone Derivatives.

BACKGROUND: Flavones, are a class of naturally occuring polyphenolic compounds which have 2-phenylchromen-4-one structure. Various studies showed that flavones have several pharmacological activities such as antioxidant, anti-inflammatory, antimicrobial, cytotoxic, antitumour and antiallergic. In the present study, 3-hydroxyflavones also called flavonols, posessing 4'-dialkylamino moiety were synthesized, and their antioxidant and anticholinesterase activities were investigated by comparison with unmodified 3-hydroxflavone. METHOD: For investigation of antioxidant potential, radical scavenging assays (DPPH•, ABTS+_, O2.-) were used along with CUPRAC and lipid peroxidation inhibitory assays, as well as anticholinesterase activity by Ellman method. RESULTS: The best results were obtained for 4'-N,N-dimethyl flavonol (1) in both antioxidant and anticholinesterase activity tests, possibly due to its least steric hinderance effect. It exhibited remarkable DPPH free radical scavenging activity (2.43±0,09 µg/mL) competing with a standard compound quercetin (2.10±0,10 µg/mL). Moreover, the other tested flavonols also showed high antioxidant activities. Compounds 5 and 6 exhibited close IC50 values to those of compound 1. CONCLUSION: Antioxidant activity test results were found to be well correlated with anticholinesterase activity test results indicating possible role of antioxidant compounds in the treatment of Alzheimer's disease.