A novel approach for the synthesis of 1,3,4-oxa(thia)diazole aryl thioethers through a biocatalytic strategy has been introduced. By leveraging Myceliophthora thermophila laccase (Novozym 51003) as a catalyst, catechol undergoes oxidation to ortho-quinone, facilitating subsequent 1,4-thia-Michael addition reactions. The method offers efficiency and mild reaction conditions, demonstrating promise for sustainable synthesis pathways in organic chemistry. Using this approach, 13 new derivatives of 2,5-disubstituted-1,3,4-oxa(thia)diazole aryl thioethers, with a yield of 46–94%, were synthesized.

Triple Bond Species in the Synthesis of Oxa(thia)diazoles and Triazoles (A Review)

Electron-transfer induced photo-oxidation of 4,5-dihydro-1,2,4-oxadiazoles: Experimental and computational studies

Abstract One of the most important issues of the organic light‐emitting diode (OLED) is the highly efficient blue‐emissive material, which demands both excellent photoluminescent quantum yield (PLQY) and balanced carrier mobilities. Herein, a series of blue‐emissive donor–π–acceptor (D–π–A) materials with fluorene π‐bridge and their D–A analogues are synthesized and discovered with a theoretical combined experimental method. Based on the excellent electron mobility of the oxadiazole (OXZ) acceptor, it is further proven that the insertion of the fluorene π‐bridge can not only contribute to the formation of hybrid local and charge‐transfer excited state with high PLQY, but also give rise to the hole mobilities by enhanced intermolecular face‐to‐face stacking. As a result, the non‐doped OLED of TPACFOXZ exhibits a high maximum external quantum efficiency approaching 10% with boosted and balanced hole and electron mobilities of 5.60 × 10−5 and 6.60 × 10−5 cm2 V−1 s−1, respectively, which are among the best results of the non‐doped blue fluorescent OLEDs.

Oxadiazoles: moiety to synthesis and utilize

A novel bipolar NIR iridium(iii) complex (CH3OTPA-BTz-Iq)2Ir(pic-OXD) with both a hole transporting (HT) triphenylamine (TPA) group and an electron transporting (ET) oxadiazole (OXD) group was designed and synthesized. It was observed that the incorporation of OXD and TPA into the ligand (CH3OTPA-BTz-Iq)2Ir(pic-OXD) improved the optophysical and electroluminescence performance in comparison with the parent iridium(iii) complex (CH3OTPA-BTz-Iq)2Irpic. In (CH3OTPA-BTz-Iq)2Ir(pic-OXD)-based OLEDs, a maximum external quantum efficiency (EQEmax) of 1.15% at 716 nm was obtained, which is much superior than that of the (CH3OTPA-BTz-Iq)2Irpic-based OLEDs (0.41% at 723 nm).

1,3,4-Thiadiazole and oxadiazole hetetocycles are well-known pharmacophore scaffolds, which possess wide possibility for chemical modification and identified diverse pharmacological potential. Such essential and many-sided activities let to consider the mentioned heterocycles as ones of the crucial for expression of pharmacological activity, which confirm their importance for medicinal chemistry. Moreover, 1,3,4-oxadiazole cycle is a bioisostere for carboxylic, amide and ester groups, which mostly contribute to enhancement the pharmacological activity by participating in hydrogen bonding interactions with different enzymes and receptors.
 The aim of the work was analysis of literature data about biological activity of non-condensed heterocyclic systems based on 1,3,4-thia(oxa)diazole rings as promising objects for modern bioorganic and medicinal chemistry.
 In this study are presented the analysis of actual literature data about pharmacological activity of heterocyclic systems based on 1,3,4-thiadiazole. It has been established that mentioned scaffolds were identified as the main structural component of biological agents with antimicrobial, anti-inflammatory, analgetic, antitumor antitubercular and antiviral activity. Moreover, the combination of 1,3,4-thiadiazole or 1,3,4-oxadiazole core with various heterocycles led to synergistic effect in many cases. Thus, mentioned scaffolds are important heterocyclic fragments that are considered as promising structural matrices for the construction of new drug-likes molecules.
 An analysis of the biological activity of 1,3,4-thia(oxa)diazole derivatives was carried out, which allowed to confirm their versatile pharmacological potential. Obtained data can be considered as background for further in-depth studies of chemical and pharmacological properties such heterocyclic systems with possible application in medicine.

Difluoroboron (BF2)-containing dyes have attracted great interest owing to their exceptionally high luminescence efficiency and good electron-withdrawing properties. However, only a few reports on difluoroboron-based thermally activated delayed fluorescence (TADF) have been addressed. In this contribution, a novel BF2-containing TADF molecule of BFOXD, which contains two acceptor fragments of oxadiazole (OXD) and BF2 and one donor unit of 9,9-dimethylacridine, was synthesized and characterized. For comparison, the precursor of OHOXD bearing one acceptor unit was also investigated. Both molecules clearly show TADF characteristics with sky-blue emission in solution and film state. Additionally, OHOXD undergoes excited-state intramolecular proton transfer-coupled intramolecular charge transfer processes. Using 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi) as the host, the organic light-emitting diodes fabricated via a solution process show maximum external quantum efficiency (EQE) of 2.98 and 13.8% for OHOXD- and BFOXD-based devices, respectively. While the bipolar TADF host of 10-(4-((4-(9H-carbazol-9-yl)phenyl)sulfonyl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (CzAcSF) is utilized instead of CzSi, the OHOXD- and BFOXD-based devices exhibit better performances with the maximum EQEs of 12.1 and 20.1%, respectively, which render the most efficient and the bluest emission ever reported for the BF2-based TADF molecules. This research demonstrates that introduction of one more acceptor unit into the TADF molecule could have a positive effect on emission efficiency, which opens a new way to design high-efficiency TADF molecules.

In the present study, five-membered heterocyclic ring systems containing oxygen with one, two, three, and four nitrogen atoms in the ring along with their isomeric forms and their corresponding 1:1 water complexes have been fully optimized at the ab initio molecular orbital theory and Density Functional Theory (DFT) using aug-cc-pVDZ basis set. The optimized geometric parameters and stabilization energies of the complexes are reported. The study suggests that nitrogen of heterocyclic ring is a stronger hydrogen bond acceptor in comparison to oxygen and ability of nitrogen to act as hydrogen bond acceptor increases in the order oxazole (OZ) > oxadiazole (ODZ) > oxatriazole (OTZ) > oxatetrazole (OTTZ). The results are corroborated by Natural Bond Orbital (NBO) analysis, Quantum Theory of Atoms in Molecules (QTAIM), Symmetry Adapted Perturbation Theory (SAPT), and Molecular Electrostatic Potential (MEP) studies. The blue- and red-shifts in the hydrogen bond donors X-H (X = O, C) stretching frequencies have also been analyzed. Hydrogen bond ability has also been governed in the presence of reactivity descriptors including chemical potential (μ), global hardness (η), and electrophilicity index (ω).

This research assessed the effects of various chemical structures and molecular sizes on the simulated geometric parameters, electron structures, and spectroscopic properties of single-chain complex alternating donor–acceptor (D–A) monomers and copolymers that are intended for use as photoactive layer in a polymer solar cell by using Kohn–Sham density functional theory with B3LYP exchange-correlation functional. The 3-hexylthiophene (3HT) was selected for electron donor, while eight chemicals, namely thiazole (Z), thiadiazole (D), thienopyrazine (TP), thienothiadiazole (TD), benzothiadiazole (BT), thiadiazolothieno-pyrazine (TPD), oxadiazole (OXD) and 5-diphenyl-1,2,4-triazole (TAZ), were employed as electron acceptor functional groups. The torsional angle, bridge bond length, intramolecular charge transfer, energy levels, and molecular orbitals were analyzed. The simulation results reveal that the geometry and electron structure of donor–acceptor monomer and copolymer are significantly impacted by heterocyclic rings, heteroatoms, fused rings, degree of steric hindrance and coplanarity of the acceptor molecular structure. Planar conformation was obtained from the D copolymer, and a pseudo-planar structure with the TD copolymer. The TAZ acceptor exhibited strong steric hindrance due to its bulky structure and non-planarity of its structure. An analysis of the electron structures indicated that the degree of intramolecular electron-withdrawing capability had the rank order TAZ < Z < D < TPD < OXD < TP < BT < TD. The TD is indicated as the most effective acceptor among those that were simulated. However, the small energy gaps of TD as well as TPD copolymer indicate that these two copolymers can be used in transparent conducting materials. The copolymer based on BT acceptor exhibited good intramolecular charge transfer and absorbed at 656 nm wavelength which is close to the maximum flux of solar spectrum. Hence, the BT acceptor functional group provides a compromise in the characteristics of a donor–acceptor copolymer, useful in a polymeric candidate material for the photoactive layer in a polymer solar cell.

A simple and convenient syntheses and characterization of selected amino acid esters, 1,2,4-triazaoles, thiadiazoles and oxadiazoles in good yields using simple conditions are described. The antimicrobial activities of these new benzimidazole-acetamido conjugates are described.

A series of end-functionalized poly(3-hexylthiophene)s (P3HTs) were synthesized by end-capping with electron-deficient moieties (EDMs, oxadiazole (OXD) and triazole (TAZ)) to prevent the negative influence of bromine chain ends in the common uncapped P3HT in polymer solar cell (PSC) applications. On the basis of the electron-withdrawing capability of the planar OXD end groups, P3HT-end-OXD relative to the uncapped P3HT exhibits a raised absorption coefficient, extended exciton lifetime, and increased crystalline order in the blend with PCBM, leading to an effectual improvement in photovoltaic parameters. However, P3HT-end-TAZ has an opposite result even worse than that of the uncapped P3HT, arising from bulky TAZ end groups. As a consequence, P3HT-end-OXD gives a power conversion efficiency (PCE) of 4.24%, which is higher than those of the uncapped P3HT (3.28%) and P3HT-end-TAZ (0.50%). The result demonstrates that the EDM modification is a valuable method to tailor the structural defect of polymer chain ends. However, the efficacy is dependent on the structure of EDM.

Abstract A series of novel pyridylethenyl oxadiazoles (III) (9 examples) are efficiently synthesized by cyclocondensation of pyridylacryloyl hydrazides with orthoesters.

The discovery of Oxadiazoles leads to the development of some medicinally important compounds with wide range of biological activities. Oxadiazoles can be synthesized by several methods using carboxylic acid as a starting material. Since Oxadiazoles had been widely investigated, this review is focused on defining the place of oxadiazoles derivatives in biomedical research, highlighting their versatile biological properties, the mode of action and Structure Activity Relationship (SAR) studies for a variety of antimicrobial, anti-tubercular, anti-cancer activity along with some enzyme inhibitory activities.

The synthesis, structure and biological activity of Oxadiazole derivatives have long been the focus of research interests in the field of Medicinal Chemistry. A number of Oxadiazole derivatives have been reported to possess interesting biological activities such as Antimicrobial, Anti-inflammatory and Antifungal activities etc. Around 09 new derivatives were synthesized, with the standard chemicals and well established procedures. The synthesized compounds were tested for their preliminary tests, physical constants, TLC etc. IR, 1H-NMR Spectra and CHN analysis confirmed the structures of the final compounds. The proposed compounds were screened for their antimicrobial and anti-inflammatory activities with the standard drugs in the well-equipped microbiology and pharmacology lab by using standard methods.

Abstract Review: [66 refs.

In the view of extensive literature survey which revealed the anticonvulsant profile of 1,4-dihydropyridines and 1,3,4-oxadiazoles, we have coupled these two moieties with the aim of achieving enhanced anticonvulsant effect. The synthesis of novel compounds comprised of four steps; firstly the Hantzsch dihydropyridines were prepared, then their esters were prepared and then their corresponding hydrazides were prepared from which the final compounds were synthesized. A greener approach is employed by using chloramine-T as an efficient and safer oxidative catalyst for the synthesis of oxadiazole, and the use of microwave technique for accelerating the chemical reactions. The structures of the newly synthesized compounds were confirmed on the basis of IR, 1 H-NMR and Mass analyses. Acute toxicity study was done to determine LD 50 of the newly synthesized compounds. Some of the synthesized compounds were evaluated for their anticonvulsant effect by PTZ induced convulsions method. Statistical testing was done by one way ANOVA followed by Dunnett’s test. The compounds AN1242 and CA7212 showed highest percentage of protection against convulsions at the dose of 15 mg/kg among the evaluated compounds compared to control.

A series of Oxadiazole derivatives ( 4 a - d ) have been synthesized from (2 , 4, 5 - triphenyl - imidazole - 1 - yl) - acetic acid hydrazide under various reaction condition s . Elemental analysis, IR, 1 H NMR and mass spectral data confirmed the structure of the newly synthesized compounds. All the s ynthesized Oxa diazole derivatives have been investigated for their anti - inflammatory activity show ing moderate to good activity .

Improved electroluminescence efficiency of polyfluorenes by simultaneously incorporating dibenzothiophene-S,S-dioxide unit in main chain and oxadiazole moiety in side chain

A set of new hyaluronic acid (HA) derivatives was obtained by binding fluorinated oxadiazole (OXA) moieties to an amino derivative of the polysaccharide (HA-EDA). The obtained HA-EDA-OXA biomaterials are potentially able to improve oxygenation into a scaffold for tissue engineering purposes. The oxygen solubility in aqueous dispersions of the obtained derivatives showed that polymers were able to improve oxygen uptake and maintenance in the medium. The HA-EDA-OXA was employed to form a hydrogel in situ by reaction with a vinyl sulphone derivative of inulin, under physiological conditions. The influence of the presence of OXA moieties on the mechanical properties of the obtained hydrogels as well as on the metabolic activity of incorporated primary fibroblasts was investigated. The produced HA-EDA-OXA biomaterials were able to promote cell growth under hypoxic conditions.