Ethynyl Derivatives Research Articles

Deciphering ethynyl single crystal for NLO applications: Synergistic studies on the structural, Hirshfeld surface, photophysical and DFT assessment

In this contribution, we have integrated multiple approaches in investigating the profiles and behaviour of simple ethynyl derivative, 1-[4-(4-(dimethylaminophenyl)ethynyl)phenyl]ethanone (4DME) tolane which is known to be integrated widely in molecular electronics as conjugated building block in functional molecules. Prepared via simplified aerobic Sonogashira cross-couping reaction, symmetrical chromophore of 4DME crystallizes in monoclinic with complex framework containing the space group of P21/n and includes four molecules within a unit cell. The fingerprint plots and Hirshfeld surface analyses demonstrate the presence of synergism between molecules supporting nonlinear optical response of the compound. It was shown that C⋯H contact (44.5 %) is the major contribution of intermolecular interaction executed by Hirshfeld surface area. The investigation on their spectroscopic, thermal analysis and density functional theory (DFT) analysis operating under B3LYP/6-31G (d,p) were conducted to determine the energies of the LUMO and HOMO level, NLO behaviour, intermolecular charge transport facilitated by global chemical reactivity descriptors, molecular electrostatic potentials (MEP) and hyperpolarizability analyses. From the simulated DFT calculation, it shows that 4DME has good polarizability properties with HOMO-LUMO energy gap of 3.89 eV. Calculated total first hyperpolarizability βtot of 4DME were 1261.40 × 10−30 esu which can be potentially applied as good nonlinear optical materials. The preliminary outcomes prove that this simple ethynyl derivative is capable of being used in optoelectronic industry as NLO-based products. A CW diode laser operating at 532 nm wavelength was used to perform the Z-scan measurements and 4DME showed an effective value of χ(3) in order of 10−6, indicating good nonlinear properties.

CN and CCH azirine derivatives, possible precursors of prebiotic molecules: formation and spectroscopic parameters

ABSTRACT N-heterocycles are of special relevance in astrobiology but at present no nitrogen-containing heterocycles have been detected in the interstellar medium (ISM). Thus far, the simplest N-heterocyclic compound, 2H-Azirine (c-C2H3N), has not been conclusively identified, despite being searched for. Recently, several cyano and ethynyl derivatives of unsaturated hydrocarbons have been discovered in the cold prestellar core Taurus Molecular Cloud 1 (TMC-1). The purpose of this work is to assess the feasibility of the possible formation of cyano and ethynyl derivatives of azirine (c-C2H2N-CN, c-C2H2N-CCH) under interstellar conditions and provide high-level theoretical spectroscopic parameters of the most relevant cyano- and ethynyl-azirine isomers to facilitate their experimental identification. Six isomers are located for each, cyano- and ethynyl-azirine derivatives, and their interconversion processes are studied. The reactions of 2H-azirine with the CN or CCH radicals in the gas phase are explored as possible formation routes of cyano and ethynyl azirine. We found that the formation processes of the most stable isomers, namely 3-cyano-2H-azirine, 2-cyano-2H-azirine, 3-ethynyl-2H-azirine, and 2-ethynyl-2H-azirine, are exothermic and barrier free. Thus, these compounds stand out as potential targets to be searched for in space. Based on the newly determined rotational spectroscopic parameters, which also account for 14N hyperfine splittings, we compile a line catalogue for each system up to 50 GHz as a preliminary and required step to characterize these molecules experimentally, whether in the laboratory or directly in the ISM.

Rotational spectra and astronomical search of five ethynyl derivatives of propene

ABSTRACT The interstellar discovery of the five cyano derivatives of propene brings interest in analogous molecules that could be detected in similar astronomical environments. In this context, ethynyl-propene derivatives are good candidates to be observed in the Taurus Molecular Cloud (TMC-1), where other cyano and ethynyl derivatives of hydrocarbons such as ethane, allene, propene, and cyclopentadiene, among others, have been detected. We have investigated the pure rotational spectra of the five ethynyl-propene derivatives to enable their interstellar detections. These molecular species have been produced by an electric discharge and their rotational spectra were characterized using a Balle–Flygare narrow band-type Fourier-transform microwave spectrometer operating in the frequency region of 4-40 GHz. The spectral analysis allowed us to derive accurate spectroscopic parameters to obtain reliable frequency predictions for astronomical searches. We do not detect any of these species in TMC-1 but we derive upper limits for the abundances for the five isomers.

Acyclic enediynes fused to triazole and benzothiophene containing propargylamine moieties

Synthesis of 3-(5-triazolyl)- and 3-(3-benzothienyl)-propargylamines includes the Mannich reaction of the corresponding ethynyl derivatives with diaminomethanes. The MTT test of the synthesized compounds toward the viability of NCI-H460 lung carcinoma cells and WI-26 VA4 normal lung fibroblast cells reveals one of them possessing a notable cytotoxic activity.

Laboratory rotational spectroscopy and astronomical search of ethynyl substituted naphthalene

ABSTRACT The recent interstellar detection of cyanonaphthalenes brings interest in related aromatic molecular species that could be present in similar astronomical environments. In this context, ethynyl derivatives of naphthalene are promising candidates to be observed in the Taurus Molecular Cloud (TMC-1), where cyanonaphthalenes together with cyano- and ethynyl-derivatives of cyclopentadiene and benzene have been detected. To enable the interstellar searches for ethynyl derivatives of naphthalene, their pure rotational spectra need to be investigated in the laboratory. We have observed for the first time the rotational spectra of 1- and 2-ethynylnaphthalene species using a broad-band Fourier-transform microwave spectrometer operating in the 2–8 GHz frequency region. Accurate spectroscopic parameters are derived from the analysis of the experimental spectra, allowing for reliable predictions for astronomical searches. Our searches in TMC-1 for both isomers provide upper limits for the abundances of these species.

Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey

We report the detection of fulvenallene (c-C5H4CCH2) in the direction of TMC-1 with the QUIJOTE1line survey. Thirty rotational transitions withKa = 0,1,2,3 andJ = 9−15 were detected. The best rotational temperature fitting of the data is 9 K and a derived column density is (2.7 ± 0.3) × 1012cm−2, which is only a factor of 4.4 below that of its potential precursor cyclopentadiene (c-C5H6), and 1.4–1.9 times higher than that of the ethynyl derivatives of cyclopentadiene. We searched for fulvene (c-C5H4CH2), a CH2derivative of cyclopentadiene, for which we derive a 3σupper limit to its column density of (3.5 ± 0.5) × 1012cm−2. Upper limits were also obtained for toluene (C6H5CH3) and styrene (C6H5C2H3), the methyl and vinyl derivatives of benzene. Fulvenallene and ethynyl cyclopentadiene are likely formed in the reaction between cyclopentadiene (c-C5H6) and the ehtynyl radical (CCH). However, the bottom-up gas-phase synthesis of cycles in TMC-1 underestimates the abundance of cyclopentadiene by two orders of magnitude, which strengthens the need to study all possible chemical pathways to cyclisation in cold dark cloud environments, such as TMC-1. However, the inclusion of the reaction between C3H3+and C2H4produces a good agreement between model and observed abundances.

Discovery of five cyano derivatives of propene with the QUIJOTE line survey

We report the discovery of five cyano derivatives of propene towards TMC-1 with the QUIJOTE line survey: trans and cis-crotononitrile (t-CH3CHCHCN, c-CH3CHCHCN), methacrylonitrile (CH2C(CH3)CN), and gauche and cis-allyl cyanide (g-CH2CHCH2CN and c-CH2CHCH2CN). The observed transitions allowed us to derive a common rotational temperature of 7 ± 1 K for all them. The derived column densities are N(t-CH3CHCHCN) = (5 ± 0.5) × 1010 cm−2, N(c-CH3CHCHCN) = (1.3 ± 0.2) × 1011 cm−2, N(CH2C(CH3)CN) = (1.0±0.1) × 1011 cm−2, N(g-CH2CHCH2CN) = (8.0 ± 0.8) × 1010 cm−2, and N(c-CH2CHCH2CN) = (7.0 ± 0.7) × 1010 cm−2, respectively. The abundance of cyano-propene relative to that of propene is thus ∼10−2, which is considerably lower than those of other cyano derivatives of abundant hydrocarbons. Upper limits are obtained for two ethynyl derivatives of propene (E and Z-CH3CHCHCCH).

Ultrastable Conjugated Microporous Polymers Containing Benzobisthiadiazole and Pyrene Building Blocks for Energy Storage Applications.

In recent years, conjugated microporous polymers (CMPs) have become important precursors for environmental and energy applications, compared with inorganic electrode materials, due to their ease of preparation, facile charge storage process, π-conjugated structures, relatively high thermal and chemical stability, abundance in nature, and high surface areas. Therefore, in this study, we designed and prepared new benzobisthiadiazole (BBT)-linked CMPs (BBT–CMPs) using a simple Sonogashira couplings reaction by reaction of 4,8-dibromobenzo(1,2-c;4,5-c′)bis(1,2,5)thiadiazole (BBT–Br2) with ethynyl derivatives of triphenylamine (TPA-T), pyrene (Py-T), and tetraphenylethene (TPE-T), respectively, to afford TPA–BBT–CMP, Py–BBT–CMP, and TPE–BBT–CMP. The chemical structure and properties of BBT–CMPs such as surface areas, pore size, surface morphologies, and thermal stability using different measurements were discussed in detail. Among the studied BBT–CMPs, we revealed that TPE–BBT–CMP displayed high degradation temperature, up to 340 °C, with high char yield and regular, aggregated sphere based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. Furthermore, the Py–BBT–CMP as organic electrode showed an outstanding specific capacitance of 228 F g−1 and superior capacitance stability of 93.2% (over 2000 cycles). Based on theoretical results, an important role of BBT–CMPs, due to their electronic structure, was revealed to be enhancing the charge storage. Furthermore, all three CMP polymers featured a high conjugation system, leading to improved electron conduction and small bandgaps.

A Dual Approach on Experimental, Theoretical Insight of Structural Elucidation, Hirshfeld Surface Analysis, Optical and Electrochemical Properties of Acyl Thiourea-Ethynyl Hybrid Derivatives.

Hybrid moieties of ethynylated-thiourea, Th1 and Th2 have been synthesised via the addition reaction between ethynyl derivatives and 4-tert-butylbenzoyl isothiocyanate in acetone, and were characterised by selected spectroscopic methods (i.e., 1H and 13C NMR, UV–visible, FT-IR) and elemental analysis. Thermogravimetric analysis indicated that Th1 and Th2 were relatively stable up to ca. 210 °C. Single-crystal X-ray diffraction was used to identify the crystal structure of Th2 in which the centre of 1-acyl thiourea moiety (-C(O)NHC(S)NH) exhibits S conformation. The Hirshfeld surface analysis has allowed visualizing the crystal packing, which is characterised by the prolonged intermolecular N–H⋯O = C and N–H⋯S = C hydrogen-bonding interactions within Th2 molecule. Electrochemical data of both compounds correspondingly exhibit irreversible redox potential processes. Besides, frontier molecular orbitals and Natural Bond Orbital population analysis were computed at the B3LYP/6-31G (d, p) level of approximation, suggesting strong delocalization of the electronic density through a conjugated π-system involving the ethynyl-phenyl and thiourea groups.Graphical Figure of molecular structure for acyl thiourea-ethynyl derivative. Two derivatives of acyl thiourea-ethynyl were synthesised and characterised by selected spectroscopic methods such as 1H and 13C NMR, UV-visible, FT-IR, elemental, thermal, electrochemical, X-ray diffraction, and density functional theory (DFT) calculation for molecular orbitals and natural bond orbital population analysis.

The QUIJOTE line survey of TMC-1

We present the recent results obtained with the QUIJOTE line survey of the cold dark core TMC-1. The observations have been carried out with the YEBES 40m radio telescope (see Figure 1) in the Q-band (31-50 GHz). A new set of receivers have been installed in the telescope within the frame of the ERC synergy Nanocosmos project that allows to cover the whole 31-50 GHz band in dual polarization [1]. The spectral resolution is 38.15 kHz. The sensitivity achieved so far varies between 0.12 and 0.25 mK, and allows to search for new molecules in a line by line (no stacking) detection procedure. These new data have permitted to detect the many relatively small protonated species of abundant molecules and eight sulfur-bearing species. The most exciting result is the detection of hydrocarbon chains and cycles with low permanent dipole moment, such as CH2CHCCH, CH2CCHCCH, the propargyl radical (C3H3), cyclopentadiene, indene (the first PAH detected in space), ortho-benzyne and two ethynyl derivatives of cyclopentadiene (c-C5H5CCH) ([2–7]). We have found that the gas-phase chemistry of hydrocarbons in TMC-1 has to be revisited in depth.

Sonogashira cross-coupling reactions of 5-(benzothiazol-2-yl)-1-(4-iodophenyl)-3-phenyl-6-vinyl(phenyl)verdazyls: synthetic and theoretical aspects

New ethynyl derivatives were synthesized from 5-(benzothiazol-2-yl)-1-(4-iodophenyl)-3-phenyl-6-vinyl(phenyl)verdazyls using Sonogashira cross-coupling reactions carried out in two stages. The resulted radicals were characterized using EPR, IR, UV/Vis spectroscopy, mass spectrometry, and cyclic voltammetry. Electronic structure calculations using quantum chemistry methods were performed to analyze some experimental results.

Styryl quinazolinones and its ethynyl derivatives induce myeloid differentiation.

The tumor suppressor transcription factor CCAAT enhancer-binding protein α (C/EBPα) expression is downregulated in myeloid leukemias and enhancement of C/EBPα expression induces granulocytic differentiation in leukemic cells. Previously we reported that Styryl quinazolinones induce myeloid differentiation in HL-60 cells by upregulating C/EBPα expression. To identify more potent molecule that can induce leukemic cell differentiation we synthesized and evaluated new series of styryl quinazolinones, ethynyl styryl quinazolinones, styryl quinolinones and thienopyrimidinones. Thienopyrimidinones were found toxic and styryl quinolinones were found inactive. Ethynyl styryl quinazolinone 39 and styryl quinazolinone 5 were found active on par with the earlier reported analogues 1 and 2 suggesting that the 5-nitro furan-2-yl styryl quinazolinones find a real promise in leukemic cell differentiation. The improved potency of 5 suggested that further modifications in the 5-nitro furan-2-yl styryl quinazolinones can be at the phenyl substitution at the 3-position of the quinazolinone ring apart from the 5-position of the heteroaryl ring.

Practical Gram-Scale Synthesis of Either α- or β-Anomer of C-Vinyl Glycosides

The synthesis C-vinyl glycosides, useful intermediates for the synthesis of C-glycoconjugates, was carried out on gram-scale by controlled reduction of the corresponding ethynyl derivatives in good to excellent yields in different carbohydrate series.

Ultrafast Singlet Exciton Fission Dynamics in 9,10-Bis(phenylethynyl)anthracene Nanoaggregates and Thin Films

The possibility of overcoming the Shockley–Queisser limit of organic solar cell (OSC) efficiency by multiexciton generation through singlet exciton fission has recently attracted significant research interest. Herein we show that 9,10-bis(phenylethynyl)anthracene (BPEA), an ethynyl derivative of anthracene and a widely used fluorescence molecular probe, exhibits an efficient singlet exciton fission process in the solid state. Steady state and time-resolved emission experiments carried out on a nanoaggregate and thin film of BPEA reveals an orders-of-magnitude reduction in emission yields and the singlet lifetime as compared to the near-unity emission yield and long emission lifetime in solution. Femtosecond and nanosecond resolved transient absorption studies unraveled exciton–exciton annihilation (at high excitation fluence) and singlet exciton fission to be the dominant relaxation processes with a fission yield of about 74 ± 6%. A high singlet fission yield with a long triplet lifetime (of about 30 μs) ...

Verdazyl Radical Building Blocks: Synthesis, Structure, and Sonogashira Cross‐Coupling Reactions

A general and effective method for the synthesis of 3‐phenylveradzyl radicals bearing a variety of iodophenyl substituents has been developed. The synthesized radicals have been characterized by ESR, UV/Vis spectroscopy, and cyclic voltammetry. Structures of biphenyl‐substituted radicals have been solved by X‐ray crystal structure analysis. The synthesized iodoverdazyls are applicable in the Sonogashira coupling reaction for the preparation of a wide range of ethynyl derivatives. Both N‐2 and C‐6 substituents were functionalized through Sonogashira coupling.

Acceptor and donor substituted alkoxy(phenyleneethynylenes) (Alkoxy-PEs): Synthesis, thermal, linear and nonlinear optical properties

A series of acceptor and donor substituted bis(alkoxy)phenyl ethynyl oligomers 4,4′-((2,5-alkyoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(nitrobenzene) (alkyl=C4H93a; C8H173b and C12H253c) and 4,4′-((2,5-alkyoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(methylbenzene) (alkyl=C4H94a; C8H174b and C12H254c) has been synthesized by the palladium catalyzed cross coupling reaction of 1,4-dialkoxy-2,5-diiodobenzene with appropriate alkynes. The newly synthesized products were characterized by UV–Vis, IR and multinuclear NMR spectroscopic techniques as well as elemental analyses. All the synthesized bis-(alkoxy)phenyl ethynyl derivatives exhibit good thermal stability (T5=329–347°C) as evident by thermo gravimetric analysis. In nitrophenyl substituted 3a-c, emission is observed in the green region, while in tolyl substituted 4a-c, emission is observed in the blue region of the electromagnetic radiation. Continuous wave (CW) closed aperture Z-scan technique reveals the signature of third-order nonlinearity in the materials that are thermal in nature.

Synthesis and Characterisation of Fused Heterocyclic Molecular Rods: A Combined Experimental and Theoretical Study on Diethynyl Dithienothiophenyl Derivatives

AbstractA structural and electronic diversity of symmetric diethynyl dithienothiophenyl (DTT) molecular rods were synthesised and their properties fully characterised using optical and thermal analysis and complemented with density functional theory (DFT) calculations. It was found that some structures are stable up to 381 °C. Due to the nature of both the derivative and the substituent, physical properties such as electron donating ability and thermal stability can be fine‐tuned to generate rationally designed materials, all of which have excellent solubility in common organic solvents. The single‐crystal x‐ray structures revealed that both bulky silyl and linear alkyl derivatives generate regular lateral close packing between the adjacent molecules, suitable for charge‐transfer in organic thin‐film transistors (OTFTs), whereas the same ethynyl derivative without an alkyl chain gives a non‐planar interlinking structure and thus unsuitable for OTFTs. These air‐stable electron rich DTT‐based molecular rods have strong potential as organic semiconductors for organic electronic applications.

The discovery of half-sandwich iridium complexes containing lidocaine and (pyren-1-yl)ethynyl derivatives of phenylcyanamide ligands for photodynamic therapy.

The successful design, synthesis, characterization, photophysical properties and anticancer mechanistic studies of a series of half-sandwich cyclopentadienyl iridium(iii) complexes of the type [Cp*IrIII(LC)(L1)](PF6), 1, and [Cp*IrIII(LC)(L2)](PF6), 2, in which Cp* = pentamethylcyclopentadienyl, L1 = 4-(pyren-10-yl)ethynyl-phenylcyanamide, L2 = 4'-(pyren-10-yl)ethynyl-4-cyanamidobiphenyl, and LC = lidocaine, are reported for their application as photodynamic therapy (PDT) agents. The DNA binding, DNA photocleavage, cellular uptake, and apoptosis of the complexes have also been studied.

Synthesis, in vivo Anticoagulant Evaluation and Molecular Docking Studies of Bicoumarins Obtained from Furocoumarin Peucedanin.

Synthesis of 7,7.-linked bicoumarins, 3,3.-linked bi(2-isopropyl)psoralens as well as 1H-1,2,3-triazole linked coumarin-2,3-dihydrofurocoumarin and furocoumarin-2,3-dihydrofurocoumarin hybrids was performed by two alternative pathways, either involving a catalyzed transformations of the ethynyl derivatives of plant coumarins - peucedanin or peuruthenicin. The Sonogashira reaction of 7-ethynyl coumarins or 3-ethynyl-2-isopropylpsoralen with the subsequent coumarin triflates led to 7,7´-linked bicoumarins or 3,3´-linked bipsoralens. 1,2,3-Triazole linked coumarin-2,3-dihydrofurocoumarin or furocoumarin-2,3-dihydrofurocoumarin hybrids were synthesized by a regioselective Cu-catalyzed cycloaddition reaction of 2-azidooreoselone with 7-alkynylcoumarins or 3-ethynyl-2-isopropylpsoralen. Pharmacological screening of synthesized bicoumarins for anticoagulant activity in vivo revealed that coumarin-dihydrofurocoumarin hybrids linked with a 1,2,3-triazole ring 20 and 22 were the most active compounds. The presented prothrombin time (PT) values comparable to the reference drug warfarin in a dose 100 mg/kg. Docking studies were undertaken to gain insight into the possible binding mode of these compounds with the coagulation factor Xa (FXa) binding site. The moderate toxicity of compounds 20 and 22 (LD50 valuewas more than 3000 mg/kg) encouraged the further design of therapeutically relevant analogues based on these novel type of coumarin hybrids.

Curious (Old and New) Antiviral Nucleoside Analogues with Intriguing Therapeutic Potential.

In the current context of antiviral drug development, which has been traditionally dominated by herpesviruses, human immunodeficiency virus (HIV) and hepatitis C virus (HCV), a new viral target has been recently gained unforeseen attention, Ebola virus. Ten nucleoside analogues, or categories thereof, are reviewed for their therapeutic potential as antiviral drugs: (i) BCX4430, a C-nucleoside; (ii) 4'-azido-, 4'-cyano-, and 4'-ethynyl derivatives; (iii) 4'-thionucleosides; (iv) cordycepin (3'-deoxyadeosine); (v) pyrazofurin, another C-nucleoside; (vi) neplanocin A analogues; (vii) EICAR, a ribavirin analogue; (viii) GR-92938X, a double carboxamide; (ix) sofosbuvir (Solvaldi(®)), a 2'-C-methylnucleoside; and (x) favipiravir (T-705), a pyrazine analogue.