Iminocoumarin Derivatives Research Articles

Microwave-assisted Synthesis and Reactivity of Some Novel Chromenopyridine Derivatives Bearing 2,4-Diamino-3-Carbonitrile Moieties

Abstract: In the current study, we reported a cost-effective, simple strategy for the synthesis and reactivity of a novel series of chromenopyridine derivatives involving 2,4-diamino-3-carbonitrile moieties. These new compounds were synthesized in good yields from malononitrile and various chromene derivatives as a precursor, which was prepared by the reduction of iminocoumarin derivatives. The formed iminocoumarin was obtained by Knoevenagel condensation from malononitrile and different aromatic aldehydes. These novel chromenopyridine derivatives were further reacted with triethyl orthoformate under microwave irradiation to afford the final compounds, namely "chromenopyridine formimidate." The structures of all molecules were characterized by FT-IR, 1H NMR, 13C NMR, and elemental analysis.

Novel palladium (II) complexes with iminocoumarin ligands: Synthesis, characterisation, electrochemical behaviour, DFT calculations and biological activities, ADMET study and molecular docking

New Palladium (II) complexes with a series of iminocoumarin derivatives have been synthesized and characterized by analytical analysis, spectral methods, magnetic measurements and thermal studies. The experimental results indicated that the Pd(II) complexes are coordinated to the bidentate iminocoumarin derivatives with a distorted square planar geometry. The DFT calculations were performed in order to optimize the geometric structures, to calculate structural parameters and to explain the chemical reactivity of the synthesized compounds. Electrochemical behaviour of the synthesized compounds was studied by cyclic voltammetry. The antioxidant activity of free ligands and their Pd(II) complexes have been evaluated using the DPPH method. The antimicrobial activity was also evaluated in Vitro against two Gram-negative (E. coli, Klebsiella pneumonia), two gram-positive (Staphylococcus aureus, Enterococcus faecalis) and three fungal strains (Candida albicans, Candida tropicalis and Aspergillus niger) using the agar-diffusion method. The ADMET study was also accomplished in order to predict pharmacokinetic and toxicity of the synthesized compounds. Finaly, and in order to study the molecular interaction of the ligand L3 and its corresponding Pd(II) complex with the microbial enzymes; Docking studies were employed.

Synthesis, characterisation, estimation of ground-and excited-state dipole moments using solvatochromic shift and theoretical studies of new iminocoumarin derivatives

The study on the fluorescence and UV–Vis absorption of some iminocoumarins at ambient temperature in several solvents showed a bathochromic shift with the increase of the solvent polarity. The use of the solvathochromic method allowed us to determine the dipole moment in both ground and excited states. The studied molecules exhibit much higher dipole moments in the excited state than in the ground state, which can be due to the redistribution of π-electron densities in the excited state making molecules more polar with higher dipole moments. Furthermore, HOMO–LUMO gap were also estimated theoretically using B3LYP/6–311 + G (d,p) level of theory; the low energy gap indicated the eventual charge transfer interaction occurring in the molecules, and responsible for their light emitting properties.

A simple approach for the synthesis of coumarin fluorescent dyes under microwave irradiation and their application in textile printing

Purpose The purpose of this study is to successfully implement microwave irradiation for the rapid synthesis of novel fluorescent dyes. The prepared dyes are then applied for printing of polyester and polyamide by silk screen printing process. Design/methodology/approach A series of new N′-(methylene)-2-imino-2H-chromene-3-carbohydrazide derivatives 3a–r were synthesised in excellent yield and high atom economy by the Knoevenagel condensation of salicylaldehyde derivatives 1 and cyano-N′-methyleneaceto-hydrazide derivatives 2 in the presence of piperidine catalyst. The optical properties of the synthesised compounds were recorded; all of the compounds were found to be fluorescent in 1, 4-dioxane solution; they all emitted blue light (440-460 nm). This work shows that the optical properties strongly depend on the nature of the substituent, and indicate which type of substituent is favourable for a given application. It confirms that iminocoumarin derivatives could lead to a new generation of fluorescent probes, prone to easy modification of their chemical structure. These synthesised dyes are used to print polyester and polyamide fabrics using synthetic thickener in the printing paste for silk screen technique. Findings The structures of synthesised dyes were established and confirmed for the reaction products on the basis of their elemental analysis and spectral data (MS, IR and 1H-NMR). The suitability of the prepared dyestuffs for traditional printing on polyester and polyamide fabrics has been investigated. The prints obtained using the synthesised dyes were found to possess high colour strength and excellent overall fastness properties but relatively low light fastness. Research limitations/implications The synthesised fluorescent dyes were prepared by a simple reaction process in microwave. The optical properties for obtained dyes show include the fact that it will have various important applications. In addition, they were used for printing synthetic fabrics and were found to have good results. Practical implications The new fluorescent dyes’ system has excellent printing properties. Also they are superior in terms of yield, purity, colour strength and fastness properties which may lend them valuable commercial production. Originality/value The result of this work aimed to define the scope and limitation of the procedures for the synthesis of novel iminocoumarin dyes via a simple and economic way.

Solid-state fluorescence properties of small iminocoumarin derivatives and their analogues in the coumarin series

Considering the many potential applications of fluorescent materials, dyes that exhibit emission in the solid state are in high demand, especially if they are easy to prepare and inexpensive. In this respect, exploring the behaviour of basic iminocoumarins seemed relevant. The spectroscopic properties of 3-cyano-7-diethylamino-2-iminocoumarin and a derivative bearing an ethoxycarbonyl group were therefore studied in the solid state, and a comparison was made with the corresponding coumarin. The three compounds had very close fluorescence properties in solution. In contrast, the coumarin derivative was much more emissive in the solid state than the iminocoumarins. This discrepancy was tentatively related to the crystal packing modes. A comparison was made with 7-diethylaminocoumarin to clarify the role of the cyano group, which may not be advantageous from a spectroscopic viewpoint. Using a solvent-exchange method, the three cyano compounds generated elongated microparticles, the substituted iminocoumarin derivative even led to flat microfibers. This work shows that small coumarins are valuable solid-state fluorescent dyes while small iminocoumarins should be used as building blocks to access more elaborated compounds if solid-state applications are envisaged.

Novel Iminocoumarin Derivatives: Synthesis, Spectroscopic and Computational Studies.

Three novel iminocoumarin derivatives with high quantum yield are synthesized from 3-benzimidazole substituted coumarin and different aromatic aldehydes. The photophysical behavior of the synthesized compounds was studied using UV-visible and fluorescence spectroscopy in polar and non-polar solvents. The compounds show absorption maxima at around 450nm and emission maxima at around 500nm. The quantum yields of compounds in dichloromethane and chloroform are more than 0.90. The absorption, emission and quantum yield of compounds are dependent on the polarity of solvents. Along with an intense absorption, these compounds show shoulder absorption peak in the studied solvents. The solvent polarity plots revealed the charge transfer process in the synthesized molecules from donor to acceptor. Density Functional Theory and Time Dependent Density Functional Theory computations have been used to have more understanding of the structural, molecular, electronic and photophysical parameters of the dyes. The dyes were characterized by FT-IR, (1)H NMR, (13)C NMR and mass spectral analysis.

Small Iminocoumarin Derivatives as Red Emitters: From Biological Imaging to Highly Photoluminescent Non-doped Micro- and Nanofibres.

The fluorescence properties of four derivatives of 3-thienyl-2-(N-dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7-position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state. The 7-diethylamino derivative was strongly fluorescent in various solvents, with marked solvatochromism. Its fluorescence was quenched by aggregation. In contrast, the methoxy derivatives were only moderately or weakly fluorescent in solution, but two of them were strongly photoluminescent in the crystalline state, owing to favourable molecular packing. The 6-methoxy derivative even exhibited spectacular crystallization-enhanced emission, examples of which are particularly rare for this type of dyes. Dyes were tested for biological use. The 7-diethylamino derivative led to particularly strong fluorescence staining of the cytoplasm of HCT-116 colon cancer cells. No fading was observed over prolonged illumination by the microscope light beam, but a phototoxic effect was detected. The use of the dyes as red-emitting materials was also investigated. Using easy-to-implement preparation methods, the compounds self- assembled to give one-dimensional nano- and microsized particles, including millimeter-long microfibres that exhibited clear wave-guiding properties. This study shows the value of these low molecular-weight molecules for the preparation of new orange and red-emitting fluorescent materials based on totally pure dye.

ChemInform Abstract: Synthesis and Characterization of Azo‐3‐cyano‐iminocoumarin Dyes.

AbstractA three‐step procedure based on the formation of azo aldehydes, Knoevenagel condensation and reaction with isocyanate or thioisocyanate derivatives paves the way towards the synthesis of new N‐substituted iminocoumarin derivatives (VII) and (IX).

Synthesis and Characterization of Azo-3-Cyano-Iminocoumarin Dyes

A three-step procedure based on the formation of azo aldehydes, Knoevenagel condensation and reaction with isocyanate or thioisocyanate derivatives paves the way towards the synthesis of new N-substituted iminocoumarin derivatives (VII) and (IX).

A one-pot, pseudo four-component synthesis of novel benzopyrano[2,3-b]pyridines under solvent-free conditions

A facile, one-pot, pseudo four-component catalyst- and solvent-free synthesis of novel benzopyrano[2,3-b]pyridines is achieved by Michael addition of various naphthols to iminocoumarin derivatives obtained from Knoevenagel condensation of salicylaldehydes with malononitrile, which can be attacked by another molecule of malononitrile to afford the title products. The advantages of this procedure are mild reaction conditions, high yields of products, generality, short reaction times and operational simplicity.

Fluorescent boron(iii) iminocoumarins (Boricos)

Complexation of iminocoumarin derivatives with BF3·OEt2 provides novel N^N boron(III) dyes exhibiting high absorption coefficients and quantum yields as great as 81%. The excellent chemical stability of these dyes enables the grafting of Boranil or Bodipy units to give derivatives in which the Borico subunit can act either as an energy acceptor or as an antenna for a red emitting fluorophore.

ChemInform Abstract: Michael Addition of α‐Azido Ketones on Iminocoumarin Derivatives: An Efficient Access to New Functionalized Azido Chromenes.

AbstractThe azides (IVb‐d) can be further converted to the corresponding triazolyl chromenes.

Michael addition of α-azido ketones on iminocoumarin derivatives: an efficient access to new functionalized azido chromenes

A facile one-pot synthesis of functionalized azido chromenes was achieved by Michael addition of α-azido ketones on iminocoumarin derivatives obtained from salicylaldehydes and malononitrile. Synthesized azido chromenes were successfully transformed into triazolyl chromenes by the [3+2] cycloaddition reaction.

A Simple Method for the Synthesis of Functionalised Chromenes via Vinylogous Michael Addition of α,α-Dicyanoalkenes on Iminocoumarin Derivatives

A one-pot synthesis of 2-amino-4 H-chromeneswas achieved in good yields from three-component reaction of salicyl-aldehyde,malononitrile, and α,α-dicyanoalkenes catalysedby triethylamine.

The synthesis and optical characterization of novel iminocoumarin derivatives

A series of novel long-wavelength, fluorescent, novel iminocoumarin derived dyes were synthesized by extending the π-conjugation and spatial location of the benzimidazolic and iminochromene rings in a planar structure. Several dyes display a fluorescent maxima ≥600 nm whilst others showed fluorescent maxima in the NIR region.

Preparation and optical properties of new fluorescent iminocoumarins: Study of N-acyl-derivatives

Six new iminocoumarin dyes, bearing a cyano group at the 3-position and a diethylamino group at the 7-position, were synthesized. These compounds differ by the nature of the acyl substituent borne by the imino group. They were studied in CH 2Cl 2 and ethanol by UV/vis absorption and fluorescence spectroscopy. This work shows that the optical properties strongly depend on the nature of the substituent borne by the imino group, and indicates which type of substituent is favourable for a given application. It confirms that iminocoumarin derivatives could lead to a new generation of fluorescent probes, prone to easy modification of their chemical structure.

Optical properties of new fluorescent iminocoumarins. Part 2. Solvatochromic study and comparison with the corresponding coumarin

The optical properties of two new iminocoumarin dyes, bearing a cyano group at the 3-position and an N-diethylamino group at the 7-position, were studied by UV–vis absorption and fluorescence spectroscopy in a large number of solvents. Dye 1 bears a free imino group, while dye 2 is substituted by an ethoxycarbonyl group on the imino function. The properties of these dyes were compared with those of 3-cyano-7-diethylaminocoumarin (3). The study shows that the three compounds display close spectroscopic behaviour in a large range of solvents, but the iminocoumarins exhibit much better fluorescence efficiency than the coumarin in polar and moderately protic solvents. This shows that iminocoumarin derivatives can advantageously replace coumarins in this type of solvents, and confirms that substitution on the imino group is a convenient way to obtain good fluorescent probes designed for various purposes. To cite this article: H. Turki et al., C. R. Chimie 9 (2006).