The unusual physicochemical properties of azulene and azulene-based compounds

This review shows the unusual physicochemical properties and wide application of azulene and its derivatives. The recent synthesis strategies of kinds of substituted azulene are also listed.     

Trifluoromethoxylation/trifluoromethylthiolation/trifluoro- methylselenolation strategy for the construction of heterocycles

The XCF₃ groups (X=O, S, Se) play an increasingly important role in modern organic chemistry due to their unique electronegativity, lipophilic nature, metabolic stability, and bioavailability. Heterocyclic compounds are important scaffolds in many bioactive compounds and drugs. The incorporation of XCF₃ groups into heterocyclic compounds can change their physicochemical and biological properties, which injects new vitality into the application of heterocyclic compounds in many fields such as organic chemistry, the pharmaceutical chemistry, and life sciences. In this paper, the recent progress in the synthesis of F₃CX-containing heterocycles is reviewed, and the application scope and mechanism of some reactions are discussed.     

Aza-Heterocyclic Building Blocks with In-Ring CF2-Fragment

Modern organic chemistry is a titan supporting and reinforcing pharmaceutical, agricultural, food and material science products. Over the past decades, the organic compounds market has been evolving to meet all the research demands. In this regard, medicinal chemistry is especially dependent on available chemical space as subtle tuning of the molecule structure is required to create a drug with relevant physicochemical properties and a remarkable activity profile. The recent rapid evolution of synthetic methodology to deploy fluorine has brought fluorinated compounds to the spotlight of MedChem community. And now unique properties of fluorine still keep fascinating more and more as its justified installation into a molecular framework has a beneficial impact on membrane permeability, lipophilicity, metabolic stability, pharmacokinetic properties, conformation, pK_a, etc. The backward influence of medicinal chemistry on organic synthesis has also changed the landscape of the latter towards new fluorinated topologies as well. Such complex relationships create a flexible and ever-changing ecosystem. Given that MedChem investigations strongly lean on the ability to reach suitable building blocks and the existence of reliable synthetic methods in this review we collected advances in the chemistry of respectful, but still enigmatic gem-difluorinated aza-heterocyclic building blocks.     

Azulene-based organic functional molecules for optoelectronics

Design and synthesis of new organic functional materials with improved performance or novel properties are of great importance in the field of optoelectronics. Azulene, as a non-alternant aromatic hydrocarbon, has attracted rising attention in the last few years. Different from most common aromatic hydrocarbons, azulene has unique characteristics, including large dipole moment, small gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). However, the design and synthesis of azulene-based functional materials are still facing several challenges. This review focuses on the recent development of organic functional materials employing azulene unit. The synthesis of various functionalized azulene derivatives is summarized and their applications in optoelectronics are discussed, with particular attention to the fields including nonlinear optics (NLO), organic field-effect transistors (OFETs), solar cells, and molecular devices.     

Recurrent relations for the approximation of the physicochemical constants of homologues

In addition to the earlier revealed physicochemical constants of homologues whose changes in arbitrary series obey the simplest linear recurrent relations A (n + k) = aA(n) + b, such equations are shown to be applicable to the approximation of the solubility of organic compounds in water (k = 1), temperature dependences of the solubility of organic and inorganic compounds in water (k = ΔT), and nematic-isotropic phase transition temperatures for liquid crystals (k = 2). The a and b coefficients of linear recurrent relations are only determined by the nature of the homologous difference, and, if the homologous difference is the same, they are close for different series. This enables various properties of virtually arbitrary organic compounds to be described by unified recurrent equations, which is equivalent to the existence of a general method for their calculation. For continuous properties (for the example of the temperature dependence of solubility), a method for solving recurrent equations with nonintegral or nonequidistant argument values is suggested.     

Perovskite-related oxynitrides – Recent developments in synthesis,characterisation and investigations of physical properties

Since the first investigations of perovskite type oxynitrides with the generalised composition ABO_3?xN_x about twenty years ago, these compounds have become of growing interest. The incorporation of nitride ions in the perovskite lattice results in distinct changes in the electronic structure leading to unusual physical properties. In this article we report on new synthesis techniques, different analytical methods, progress in the structural characterisation by comprehensive diffraction techniques and local spectroscopic methods like XAS and NMR as well as state of the art theoretical investigations. Various physical characteristics like electrical and thermal transport parameters and dielectric properties are described. The thermal and chemical stability of oxynitride perovskites are investigated and their applications in different photocatalytic reactions are discussed.     

Synthesis and properties of fluorosilicon compounds for protection of cultural monuments from harmful environmental exposure

Methods for the synthesis of perfluorocarboxylic acid derivatives with reactive trialkoxysilyl groups soluble in organic and organofluorine (1,1,2-trichlorotrif1uoroethane, etc.) solvents have been developed. The contact angles of water and decalin, water absorption, resistance to freezing, and salt-resistance of limestone and plaster samples treated with these compounds were determined. Fluorosilicon organic compounds impart more hydro- and oleophobic properties to the protected surfaces than known organosilicon agents and reliably protect sculptures and architectural monuments from mold and algae deposition.     

Natural products dereplication by diffusion ordered NMR spectroscopy (DOSY)

Diffusion-ordered NMR spectroscopy (DOSY) can be used to analyze mixtures of compounds since resonances deriving from different compounds are distinguished by their diffusion coefficients (D). Previously, DOSY has mostly been used for organometallic and polymer analysis, we have now applied DOSY to investigate diffusion coefficients of structurally diverse organic compounds such as natural products (NP). The experimental Ds derived from 55 diverse NPs has allowed us to establish a power law relationship between D and molecular weight (MW) and therefore predict MW from experimental D. We have shown that D is also affected by factors such as hydrogen bonding, molar density and molecular shape of the compound and we have generated new models that incorporate experimentally derived variables for these factors so that more accurate predictions of MW can be calculated from experimental D. The recognition that multiple physicochemical properties affect D has allowed us to generate a polynomial equation based on multiple linear regression analysis of eight calculated physicochemical properties from 63 compounds to accurately correlate predicted D with experimental D for any known organic compound. This equation has been used to calculate predicted D for 217 043 compounds present in a publicly available natural product database (DEREP-NP) and to dereplicate known NPs in a mixture based on matching of experimental D and structural features derived from NMR analysis with predicted D and calculated structural features in the database. These models have been validated by the dereplication of a mixture of two known sesquiterpenes obtained from Tasmannia xerophila and the identification of new alkaloids from the bryozoan Amathia lamourouxi. These new methodologies allow the MW of compounds in mixtures to be predicted without the need for MS analysis, the dereplication of known compounds and identification of new compounds based solely on parameters derived by DOSY NMR.

We report accurate DOSY NMR based molecular weight and diffusion coefficient prediction tools. These tools can be used to dereplicate known natural products from databases using structurally rich NMR data as a surrogate for mass spectrometric data.     

Transformations based on ring-opening of gem-difluorocyclopropanes

gem-Difluorocyclopropanes are an important fluorinated class of compounds with applications in medicinal chemistry, material sciences and organic synthesis. The transformations based on their ring-opening reactions have been recognized to be useful methods for rapidly synthesizing various fluorinated organic molecules. In this digest paper, we describe these efforts and highlight their powerfully potential and applications as fluorine-containing synthons in organic chemistry.     

Structural and electronic properties of organophosphorus-based systems as sensitizers in solar cells

Considerable attention has been paid to modulating these organic π-conjugates to realize effective and efficient organic photovoltaic by the means of theoretical methods. In respect to this, six commonly used heterocyclic compounds: thiophine (Th), thienopyrazine (TP), benzothiadiazole (BD), quinoxahine (BP), benzobisthiadiazole (BBD), and thenothiadiazole (TD) were co-oligomerized with bisazaphosphole (BAP) and theoretically examined for use in solar cells using density functional theory and time-dependent density functional theory to evaluate their optical, electronic, and light harvesting efficiency, as well as voltaic properties. The results showed that TP, TD, BD, BP, and BDD were preferable for optimization of the bandgaps and molecular energy levels of these organophosphorus-based compounds over Th. heterocyclic compounds. The calculated electron transfer process to the conduction band of [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) and the subsequent regeneration in BAP–BBD and PBAP (polybisazaphosphole)–TD were possible in organic voltaic cells, making these modeled compounds more proficient solar cell sensitizers. The method used can be explored in understanding the relationship between electronic properties and molecular structure of other materials for electronic devices.     

Recent advances in the synthesis and CF functionalization of gem-difluoroalkenes

The gem-difluoroalkenes and related compounds have gained much attention from the organic synthetic community due to their widespread applications as versatile fluorinated building blocks for the synthesis of pharmaceuticals, agrochemicals and functional materials. In the past two decades, significant progress has been made to the development of efficient methods for the construction of gem-difluoroalkenes and useful reactions involving the cleavage of CF bond in gem-difluoroalkenes. In this Digest review, these advances in the synthesis and reaction chemistry of gem-difluoroalkenes are summarized, with special emphasis placed on novel synthetic applications of them in recent ten years.     

Investigation of novel compounds via in silico approaches of EGFR inhibitors as anticancer agents

Before the experimental studies of a compound to be synthesized from in vitro to in vivo, it is possible to save both time and money with in silico approaches only with Computer Aided Drug Design (CADD) methods. In other words, compounds that can be new drug candidates can be suggested by drug design using computational drug discovery strategies. In this study, all molecules in the ChEMBL Database were virtual screened based on drugs with inhibitory properties on the Epidermal Growth Factor Receptor (EGFR), one of the receptor tyrosine kinases, which is effective in cancer cells. During this High-Throughput Screening (HTS), the number of compounds was minimized according to the parameters of the reference drugs, physicochemical properties such as logP, M.W., HBA, HDB, RosLip. As a result of in silico approaches and molecular docking analysis, ten compounds with the highest docking scores were determined and a model compound that could be a new drug candidate was proposed.     

Advancements in the Synthesis and Applications of Cationic N‐Heterocycles through Transition Metal‐Catalyzed C−H Activation

Cationic N‐heterocycles are an important class of organic compounds largely present in natural and bioactive molecules. They are widely used as fluorescent dyes for biological studies, as well as in spectroscopic and microscopic methods. These compounds are key intermediates in many natural and pharmaceutical syntheses. They are also a potential candidate for organic light‐emitting diodes (OLEDs). Because of these useful applications, the development of new methods for the synthesis of cationic N‐heterocycles has received a lot of attention. In particular, many C?H activation methodologies that realize high step‐ and atom‐economies toward these compounds have been developed. In this review, recent advancements in the synthesis and applications of cationic N‐heterocycles through C?H activation reactions are summarized. The new C?H activation reactions described in this review are preferred over their classical analogs.     

Selective Formal Carbene Insertion into Carbon-Boron Bonds of Diboronates by N-Trisylhydrazones

Bisborylalkanes play important roles in organic synthesis as versatile bifunctional reagents. The two boron moieties in these compounds can be selectively converted into other functional groups through cross-coupling, oxidation or radical reactions. Thus, the development of efficient methods for synthesizing bisborylalkanes is highly demanded. Herein we report a new strategy to access bisborylalkanes through the reaction of N-trisylhydrazones with diboronate, in which the bis(boryl) methane is transformed into 1,2-bis(boronates) via formal carbene insertion. Since the N-trisylhydrazones can be readily derived from the corresponding aldehydes, this strategy represents a practical synthesis of 1,2-diboronates with broad substrate scope. Mechanistic studies reveal an unusual neighboring group effect of 1,1-bis(boronates), which accounts for the observed regioselectivity when unsymmetric 1,1-diboronates are applied.     

Seeds as Potential Sources of Phenolic Compounds and Minerals for the Indian Population

Seeds are major sources of nutrients and bioactive compounds for human beings. In this work, the chemical composition and physicochemical properties of 155 Indian seeds (belonging to 49 families) are reported. Moisture and ash were measured with reference protocols from AOAC; total polyphenols and flavonoids were measured with spectrophotometric methods after extraction with organic solvents, and mineral elements were determined by X-ray fluorescence spectrophotometry. Total phenolic compounds, flavonoids and mineral contents (Al, Ba, Ca, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, P, Rb, S, Sr, Ti, V and Zn) were found to vary in the ranges 182–5000, 110–4465 and 687–7904 mg/100 g (DW), respectively. Noticeably, polyphenol contents higher than 2750 mg/100 g were observed in 18 seeds. In addition, mineral contents >5000 mg/100 g were detected in the seeds from Cuminum cyminum, Foeniculum vulgare, Commiphora wightii, Parkia javanica, Putranjiva roxburghii, Santalum album and Strychnos potatorum. Botanical and taxonomical variations in the proximate characteristics of the examined seeds are also discussed.     

Electrochemistry of Electrode Materials Containing S−Se Bonds for Rechargeable Batteries

Sulfur (S) and selenium (Se) have been considered as promising high capacity cathode materials for rechargeable batteries. They have differences in their physical properties (e.g., electronic conductivity) but the same number of electrons in their outermost shells, which leads to similarity in their electrochemical behavior in batteries. In recent years, some efforts have been taken to combine them in electrodes in the hope of improved battery performance. The S−Se bonds of these electrode materials lead to unusual properties and intriguing electrochemical behavior, which have attracted increasing interest. In this Minireview, electrode materials containing S−Se bonds are summarized, including inorganic S_xSe_y solid solutions, organic compounds, and organic–inorganic hybrid materials. Our understanding in these materials is still premature, but they have shown unique properties to be electrode materials. We hope this Minireview could provide a new insight into the design, synthesis, and understanding of these materials, which could enable high energy density rechargeable batteries.     

3-Carboxylic Acid and Formyl-Derived Coumarins as Photoinitiators in Photo-Oxidation or Photo-Reduction Processes for Photopolymerization upon Visible Light: Photocomposite Synthesis and 3D Printing Applications

In this paper, nine organic compounds based on the coumarin scaffold and different substituents were synthesized and used as high-performance photoinitiators for free radical photopolymerization (FRP) of meth(acrylate) functions under visible light irradiation using LED at 405 nm. In fact, these compounds showed a very high initiation capacity and very good polymerization profiles (both high rate of polymerization (Rp) and final conversion (FC)) using two and three-component photoinitiating systems based on coum/iodonium salt (0.1%/1% w/w) and coum/iodonium salt/amine (0.1%/1%/1% w/w/w), respectively. To demonstrate the efficiency of the initiation of photopolymerization, several techniques were used to study the photophysical and photochemical properties of coumarins, such as: UV-visible absorption spectroscopy, steady-state photolysis, real-time FTIR, and cyclic voltammetry. On the other hand, these compounds were also tested in direct laser write experiments (3D printing). The synthesis of photocomposites based on glass fiber or carbon fiber using an LED conveyor at 385 nm (0.7 W/cm²) was also examined.     

In situ hydrothermal synthesis of tetrazole coordination polymers with interesting physical properties

Tetrazole compounds have been studied for more than one hundred years and applied in various areas. Several years ago Sharpless and his co-workers reported an environmentally friendly process for the preparation of 5-substituted 1H-tetrazoles in water with zinc salt as catalysts. To reveal the exact role of the zinc salt in this reaction, a series of hydrothermal reactions aimed at trapping and characterizing the solid intermediates were investigated. This study allowed us to obtain a myriad interesting metal-organic coordination polymers that not only partially showed the role of the metal species in the synthesis of tetrazole compounds but also provided a class of complexes displaying interesting chemical and physical properties such as second harmonic generation (SHG), fluorescence, ferroelectric and dielectric behaviors. In this tutorial review, we will mainly focus on tetrazole coordination compounds synthesized by in situ hydrothermal methods. First, we will discuss the synthesis and crystal structures of these compounds. Their various properties will be mentioned and we will show the applications of tetrazole coordination compounds in organic synthesis. Finally, we will outline some expectations in this area of chemistry. The direct coordination chemistry of tetrazoles to metal ions and in situ synthesis of tetrazole through cycloaddition between organotin azide and organic cyano group will be not discussed in this review.