Current Organic Chemistry - Volume 21, Issue 16, 2017

Background: Although the synthesis of α-hydroxymethylenebisphosphonic acids (dronic acids) and derivatives by reaction of the corresponding carboxylic acids (or its derivatives) with P-reagents, such as phosphorus trichloride, phosphorous acid and phosphoryl chloride formed the subject of many studies, in most cases, the selection of the P-reagents, their ratio, and the conditions (solvent and temperature) were not optimized. Method: Selection of the appropriate P-reagents and their ratios, along with the conditions is possible, only if the reaction protocol (sequence of the steps) or the mechanism is known. For this purpose, the relevant information was extracted from the literature, critically discussed and the conclusions were drawn. Our own experiences are also summarized on the possible mechanisms, and on the related optimum set of the reaction parameters depending mainly on the nature of the solvent used. Conclusion: This review gives a better understanding of the dronate chemistry, and promotes “greener” and more practical syntheses.

Background: Polymer-peptide/protein conjugates immobilized on surface have gained considerable attention, mostly due to their broad scope of applications in biomedical fields. To optimize their properties, the combined knowledge of polymer chemistry and biochemistry has to be applied. Method: The main methods to obtain such surfaces involve “grafting to” or “grafting from” of polymeric linkers with subsequent attachment of a peptide/protein. Alternatively, a “ready-made” conjugate may be grafted to the surface. Result: The structure of the polymer linker significantly influences the properties of the active surface, and a variety of physicochemical methods and tools have been successfully applied to study the structure-property relationship of these surfaces. Conclusion: This review outlines the applied synthetic strategies leading to covalently attached bioconjugates on the surface and the characterization techniques used to study those materials. The relevance of different linear polymeric linkers and their influence on the properties of the obtained materials is discussed.

Background & Objective: Fullerene-containing liquid crystals have attracted considerable attention in a wide variety of fields including materials science, supramolecular chemistry, bioscience, nanoscience and nanotechnology based on the outstanding photophysical and electrochemical properties of fullerenes. This review describes the recent and significant developments of fullerene-containing liquid crystals which displayed thermotropic liquid crystalline phases. Method: Different strategies, such as fullerenes dispersed in liquid crystals, liquid crystals as precursors to prepare fullerene-containing liquid crystals and self-assemble of fullerene derivatives, have been used to obtain such liquid crystalline materials with the enhancement of properties. Conclusion: Liquid crystalline phase behavior of nanomaterials themselves, self-assembly and alignment of nanomaterials in liquid-crystalline media have been discussed in this review. It should be certain that this kind of materials will play an important role in nanoscience and nanotechnology in the near future.

Background: Rearrangements as an important class of organic reactions could provide structural isomers of the original molecules. They can transform precursors into favorable difficult-to-make products. One of the important synthetic tools in modern organic chemistry is the Smiles rearrangement and its different variants, which have diverse applications in organic chemistry. Objective: The Smiles rearrangement is one of the intramolecular nucleophilic aromatic substitution reactions wherein incorporate a heteroatom as a nucleophile and an activated electrophilic arene. Regarding the importance of nucleophiles' role in the development of different variants of the Smiles rearrangement herein, we have surveyed several examples of Smiles rearrangement with the emphasis on their nucleophiles’ types. Accordingly, three classes of Smiles rearrangement, employing carbanion, oxygen and nitrogen as different nucleophiles have been investigated which are accompanied with their detailed mechanisms. Conclusion: Categorization of Smiles rearrangements according to their nucleophiles’ species provides the better understanding about these rearrangements that could enhance the synthesis of useful chemical compounds such as medicinal compounds, functional materials and so on. Representation of different aspects of Smiles rearrangement such as their mechanisms and synthetic utility helps researchers understand and take advantage of Smiles rearrangement to make a greater attempt to further development in this important class of reactions.

Background: Nitrogen containing heterocycle is one kind of the most important heterocycle. Among them, 1,2,4-triazolo[3,4-α]pyridine is a classic five member heterocycle fused six member heterocycle. 1,2,4-Triazolo-[3,4-α ]pyridine scaffold has been widely used in building blocks for drugs, pesticides and other fields. Method & Objective: This review will highlight the early and recent work on the synthesis methods of diversity 1,2,4-triazolo[3,4-α]pyridines. In order to promote the development of more efficient and environment friendly reaction, this paper detailed that the synthetic procedure has been listed using many condensation agents, such as HOAc, orthoformate, Ph3PCl2, Lawesson reagent, PS-PPh3, HCOOH, POCl3, Mitsunobu reagent, Burgess reagent, IBD, metal catalyst, chloramine-T, trivalent Iodine reagent and so on. Also the 1,2,4- triazolo[3,4-α]pyridines were synthesized under microwave irradiation or conventional heat directly. This review also covers different biological activities towards various 1,2,4-triazolo-[3,4-α]pyridines including antiinflammatory activity, anti-convulsant activity, antibiotics activity, antifungal activity, herbicidal activity, fungicidal activity, anticancer activity, antivirus activity, anti- type 2 diabetes activity, etc.

Background: Dye-sensitized solar cells have received attention recently for efficient converting sunlight to electricity. Organic dyes provide a feasible alternative due to the practical advantages, such as facile structure tuning, easy synthesis process, and low cost. Organic sensitizers are generally designed to link the electron donor and the electron acceptor. When light irradiated on the dyes, these dipolar molecules induce intramolecular charge transfer from the donor to the acceptor, and the electron is then injected into TiO2 via the anchoring groups (carboxylic acids). Objective and Method: This work systematically synthesized the dyes containing triphenylamine as the electron donor, a series of donor-π-acceptor as the conjugation segment, and 2-cyanoacetic acid as the electron acceptor, where donor-π-acceptor structures are expected to enable efficiently photoinduced charge separation. The photovoltaic performance of the dyes is significantly related to the linker type. Results: The charge transfer from the excited dye molecules to the conduction band of TiO2 is improved in the styrene-π -linked dye, showing highly effective improvement in the efficiency of the corresponding devices as compared dye-based devices with N-methylpyrrole, 3,4-ethylenedioxythiophene linkers and no linker. The device with N-methylpyrrole-linker-based dye bearing positions of C3 and C4 on N-methylpyrrole linker has the lowest conjugation effect and efficiency. Styrene-linker-based dye shows a broad incident-photon-tocurrent conversion efficiency response with a signal of up to 670 nm, covering most of the ultrviolet-visible light region. Conclusion: Device efficiencies of 5.18% and 7.56% for dye-sensitized devices using Styrene-linker-based dye and N3 dye, respectively, assembled using the same method and measured under AM 1.5 irradiation.