Synthesis and properties of biobased epoxy resins. part 1. Glycidylation of flavonoids by epichlorohydrin

Biobased epoxy resins were synthesized from a catechin molecule, one of the repetitive units in natural flavonoid biopolymers also named condensed tannins. The reactivity of catechin toward epichlorohydrin to form glycidyl ether derivatives was studied using two model compounds, resorcinol and 4‐methylcatechol, which represent the A and B rings of catechin, respectively. These model molecules clearly showed differences in reactivity upon glycidylation, explaining the results found with catechin monomer. The reaction products were characterized by both FTIR and NMR spectroscopy and chemical assay. The glycidyl ether of catechin (GEC) was successfully cured in various epoxy resin formulations. The GECs thermal properties showed that these new synthesized epoxy resins displayed interesting properties compared to the commercial diglycidyl ether of bisphenol A (DGEBA). For instance, when incorporated up to 50% into the DGEBA resin, GEC did not modify the glass‐transition temperature. Epoxy resins formulated with GEC had slightly lower storage moduli but induced a decrease of the swelling percentage, suggesting that GEC‐enhanced crosslinking in the epoxy resin networks. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Biostimulant Formulations and Moringa oleifera Extracts to Improve Yield,Quality, and Storability of Hydroponic Lettuce

The urgent need to increase the sustainability of crop production has pushed the agricultural sector towards the use of biostimulants based on natural products. The current work aimed to determine whether the preharvest application of two commercial formulations, based on a Fabaceae enzymatic hydrolysate or a blend of nitrogen sources including fulvic acids, and two lab-made aqueous extracts from Moringa oleifera leaves (MLEs), could improve yield, quality, and storability of lettuce grown in a hydroponic system, as compared to an untreated control. Lettuce plants treated with the MLEs showed significantly improved quality parameters (leaf number, area, and color), total phenolic content and antioxidant activity, and resistance against the fungal pathogen Botrytis cinerea, comparable to that obtained with commercial formulates, particularly those based on the protein hydrolysate. A difference between the M. oleifera extracts was observed, probably due to the different compositions. Although further large-scale trials are needed, the tested MLEs seem a promising safe and effective preharvest means to improve lettuce agronomic and quality parameters and decrease susceptibility to rots.     

Rethinking Uncaging: A New Antiaromatic Photocage Driven by a Gain of Resonance Energy

Photoactivatable compounds for example photoswitches or photolabile protecting groups (PPGs, photocages) for spatiotemporal light control, play a crucial role in different areas of research. For each application, parameters such as the absorption spectrum, solubility in the respective media and/or photochemical quantum yields for several competing processes need to be optimized. The design of new photochemical tools therefore remains an important task. In this study, we exploited the concept of excited-state-aromaticity, first described by N. Colin Baird in 1971, to investigate a new class of photocages, based on cyclic, ground-state-antiaromatic systems. Several thio- and nitrogen-functionalized compounds were synthesized, photochemically characterized and further optimized, supported by quantum chemical calculations. After choosing the optimal scaffold, which shows an excellent uncaging quantum yield of 28 %, we achieved a bathochromic shift of over 100 nm, resulting in a robust, well accessible, visible light absorbing, compact new photocage with a clean photoreaction and a high quantum product (ϵ⋅Φ) of 893 M⁻¹ cm⁻¹ at 405 nm.     

Differential sandwich theorems for analytic functions defined by Sălăgean operator

In this paper we obtain some subordination and superordination results by using the Sălăgean operator acting on the Hadamard product of certain analytic functions in the open unit disk.     

Argument estimates of certain meromorphically p-valent functions associated with a family of linear operator

Making use of linear operator we investigate some inclusion relationships and some argument properties of certain meromorphically p-valent functions.     

Subordination and superordination properties of p-valent functions defined by a generalized fractional differintegral operator

For a generalized fractional differintegral operator associated with p- valent functions, we study different properties of differential subordination and superordination related to this operator.     

Some applications of differential subordination of <Emphasis Type="Italic">p</Emphasis>-valent functions associated with Cho-Kwon-Srivastava operator

Making use of the principle of differential subordination, we investigate some inclusion relationships of certain subclasses of p-valent analytic functions which are defined by Cho-Kwon Srivast ava Operator.     

Generalization of certain subclasses of multivalent functions with negative coefficients defined by using a differential operator

Making use of a differential operator, we introduce and study a certain class SC_n(j,p,q,α,λ) of p-valently analytic functions with negative coefficients. In this paper, we obtain numerous sharp results including (for example ) coefficient estimates, distortion theorem, radii of close-to convexity, starlikeness and convexity and modified Hadamard products of functions belonging to the class SC_n(j,p,q,α,λ). Finally, several applications investigate an integral operator, and certain fractional calculus operators are also considered.     

Synthesis and structural study of new substituted chiral sulfamoyl oxazolidin-2-ones

The synthesis of new series of oxazolidinones having sulfonamide moieties is described. These compounds are synthesized in good yield starting prochiral 1,3-dichloro-2-propanol and chlorosulfonyl isocyanate. This strategy involves the formation of carboxylsulfamide by carbamoylation–sulfamoylation reaction followed by intermolecular cyclization. In order to determine the enantioselectivity during the cyclization step, X-ray studies of products are performed.     

Ring-closing metathesis towards functionalised pentacyclic steroids

A new synthetic pathway towards pentacyclic steroids was described via a ring-closing metathesis reaction as the key step.