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Molbank

Molbank is an international, peer-reviewed, open access journal comprised of a unique collection of one-compound-per-paper short notes on synthetic compounds and natural products published bimonthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), Reaxys, CAPlus / SciFinder, and other databases.
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.7 days after submission; acceptance to publication is undertaken in 3.7 days (median values for papers published in this journal in the first half of 2026).
Recognition of Reviewers: Reviewers whose reports are timely and of high quality receive an APC discount voucher for a future publication in an MDPI journal. Become a reviewer.
Journal Cluster of Chemical Reactions and Catalysis: Catalysts, Chemistry, Electrochem, Inorganics, Molecules, Organics, Oxygen, Photochem, Reactions, Sustainable Chemistry and Molbank.

Impact Factor: 0.3 (2025)

Imprint Information Journal Flyer Open Access ISSN: 1422-8599

Latest Articles

10 pages, 1184 KB

Open AccessCommunication

Synthesis, Spectroscopic Characterization, and Thermal Analysis of (E)-1-(2-Hydroxy-4-methoxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one

by Julián A. Contreras-Pérez, Karen D. Rojas-Ramírez, Paola Acosta-Guzmán, Hugo Rojas, Diana Becerra and Juan-Carlos Castillo

Molbank 2026, 2026(5), M2232; https://doi.org/10.3390/M2232 - 17 Sep 2026

Herein, the previously unreported (E)-1-(2-hydroxy-4-methoxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one 3 was synthesized by Claisen–Schmidt condensation of 1-(2-hydroxy-4-methoxyphenyl)ethan-1-one 1 and 5-methylfuran-2-carbaldehyde 2 using potassium hydroxide in an ethanol/water mixture at 50 °C. The protocol afforded 3 in 85% yield with high atom economy (93.5%), an EcoScale [...] Read more.

Herein, the previously unreported (E)-1-(2-hydroxy-4-methoxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one 3 was synthesized by Claisen–Schmidt condensation of 1-(2-hydroxy-4-methoxyphenyl)ethan-1-one 1 and 5-methylfuran-2-carbaldehyde 2 using potassium hydroxide in an ethanol/water mixture at 50 °C. The protocol afforded 3 in 85% yield with high atom economy (93.5%), an EcoScale score of 61.5, and partial material recovery (MRP = 0.65). The product was comprehensively characterized by FT–IR, NMR, UV–Vis, EI–MS, HRMS, TG, and DSC analyses. UV–Vis and solvatochromic studies revealed a bathochromic shift in the lowest-energy absorption band with increasing solvent polarity, indicating a solvent-dependent electronic response consistent with the extended conjugation of the chalcone framework. Full article

(This article belongs to the Collection Heterocycle Reactions)

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9 pages, 2070 KB

Open AccessCommunication

Crystal Structure of 1,1-Dimethyl-3-(quinolin-2-yl)urea and 3-(Isoquinolin-1-yl)-1,1-dimethylurea

by Svetlana O. Baykova, Sergey V. Baykov, Vadim P. Boyarskiy and Nadezhda A. Bokach

Molbank 2026, 2026(5), M2231; https://doi.org/10.3390/M2231 - 16 Sep 2026

The crystal structures of two isomeric urea derivatives—1,1-dimethyl-3-(quinolin-2-yl)urea (1) and 3-(isoquinolin-1-yl)-1,1-dimethylurea (2)—have been investigated by single-crystal X-ray diffraction. These compounds differ in the relative position of the heterocyclic nitrogen atom and the urea substituent. A structural study revealed that [...] Read more.

The crystal structures of two isomeric urea derivatives—1,1-dimethyl-3-(quinolin-2-yl)urea (1) and 3-(isoquinolin-1-yl)-1,1-dimethylurea (2)—have been investigated by single-crystal X-ray diffraction. These compounds differ in the relative position of the heterocyclic nitrogen atom and the urea substituent. A structural study revealed that the compounds exhibit distinct molecular conformations. In 1, the molecule exists predominantly in a ureide form with a single C–N bond between the quinoline fragment and urea moiety. The ureide group is out of the plane of the quinoline ring, forming an anti-conformation. In contrast, 2 adopts an exocyclic C=N configuration with an intramolecular hydrogen bond between the heterocyclic NH group and ureide oxygen, resulting in a syn-conformation. The supramolecular organization of the compounds also differs: 1 forms one-dimensional chains through N–H···O hydrogen bonds, which further assemble into two-dimensional layers via C–H···O interactions; in 2, the molecules form dimers through intermolecular C–H···O hydrogen bonds. Thus, subtle structural differences between isomeric urea derivatives can lead to distinct molecular conformations, tautomeric forms, and supramolecular organizations. Full article

(This article belongs to the Section Structure Determination)

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9 pages, 1486 KB

Open AccessCommunication

Bis(triphenylphosphine)iminium Salts of the Low-Valent Carbonyltechnetates [Tc₂(CO)₉Cl]⁻ and [Tc(CO)₃Cl₃]²⁻

by Jonas Genz, Maximilian Roca Jungfer and Ulrich Abram

Molbank 2026, 2026(5), M2230; https://doi.org/10.3390/M2230 - 15 Sep 2026

Reduction of [Tc(CO)₅Br] with sodium amalgam, sodium naphthalenide, or potassium graphite in THF and subsequent addition of bis(triphenylphosphine)iminium chloride, (PPN)Cl, gave mixtures of the orange-yellow Tc(0) compound (PPN)[Tc(CO)₉Cl], (PPN)[1], and the colorless Tc(I) complex (PPN)₂[Tc(CO) [...] Read more.

Reduction of [Tc(CO)₅Br] with sodium amalgam, sodium naphthalenide, or potassium graphite in THF and subsequent addition of bis(triphenylphosphine)iminium chloride, (PPN)Cl, gave mixtures of the orange-yellow Tc(0) compound (PPN)[Tc(CO)₉Cl], (PPN)[1], and the colorless Tc(I) complex (PPN)₂[Tc(CO)₃Cl₃], (PPN)₂[2]. The products have been studied by X-ray diffraction and NMR spectroscopy. The dimeric compound [1]⁻ represents the first example of an anionic technetium(0) complex with only one halide ligand in its coordination sphere. The equatorial carbonyl (and chlorido) ligands at the two technetium atoms show the expected staggered conformation around the (CO)Tc–Tc(CO) axis. The Tc–Tc bond is 3.0269(7) Å. The different nature of the two technetium atoms in compound [1]⁻ is reflected by the appearance of two different ⁹⁹Tc NMR signals in CD₂Cl₂ at −1770 and −2487 ppm, while the corresponding signal of the technetium(I) anion [2]²⁻ appears at −953 ppm in the same solvent. Anion [2]²⁻ shows the expected facial arrangement of the carbonyl and chlorido ligands. The use of the bulky PPN⁺ cation allowed the first determination of the [Tc(CO)₃Cl₃]²⁻ structure by X-ray diffraction without significant interference due to disorder effects in the coordination sphere of the transition metal. Full article

(This article belongs to the Section Structure Determination)

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Graphical abstract

5 pages, 324 KB

Open AccessCommunication

Synthesis and Characterization of Acylhydrazone Derivative from Strictic Acid

by Tianqiong Lang, Min Lu, Huihong Chen and Linlin Song

Molbank 2026, 2026(5), M2229; https://doi.org/10.3390/M2229 - 7 Sep 2026

Under the application of a semi-synthesis strategy, an acylhydrazone derivative from strictic acid (SA), a natural neo-clerodane diterpenoid with a unique 5,10-seco skeleton isolated from Schnabelia terniflora, has been synthesized via a two-step synthetic pathway including hydrazide formation from the carboxylic [...] Read more.

Under the application of a semi-synthesis strategy, an acylhydrazone derivative from strictic acid (SA), a natural neo-clerodane diterpenoid with a unique 5,10-seco skeleton isolated from Schnabelia terniflora, has been synthesized via a two-step synthetic pathway including hydrazide formation from the carboxylic acid moiety of SA and further hydrazonation with p-methylcinnamaldehyde. The target structure was confirmed by ¹H NMR, ¹³C NMR and HRMS data. Full article

(This article belongs to the Section Natural Product Chemistry)

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Scheme 1

8 pages, 5897 KB

Open AccessCommunication

Novel Fluorinated Derivatives of 2-Phenyl-1H-Indole

by Larisa Politanskaya and Irina Bagryanskaya

Molbank 2026, 2026(5), M2228; https://doi.org/10.3390/M2228 - 4 Sep 2026

The indole core is a structural component of a huge number of biologically active natural and synthesized compounds and pharmaceuticals, and their efficient synthesis is an important challenge. Fluorinated indoles have attracted considerable attention, since it was established that fluorine introduction can influence [...] Read more.

The indole core is a structural component of a huge number of biologically active natural and synthesized compounds and pharmaceuticals, and their efficient synthesis is an important challenge. Fluorinated indoles have attracted considerable attention, since it was established that fluorine introduction can influence the biological activity of organic molecules. The initial PdCl₂-catalyzed intramolecular cyclization of 4,5-difluoro-2-(phenylethynyl)aniline led to the formation of the corresponding indole in high yield. The result of its subsequent treatment with Selectfluor was the introduction of one or two fluorine atoms onto position 3. The reaction products were isolated individually by preparative thin-layer chromatography and characterized by spectroscopic methods, including IR, ¹H NMR, ¹⁹F NMR, ¹³C NMR and HRMS. The structure of indole, exhaustively fluorinated at position 3—3,3,5,6-tetrafluoro-2-phenyl-3H-indole—was confirmed through single-crystal X-ray diffraction analysis. Full article

(This article belongs to the Collection Heterocycle Reactions)

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7 pages, 2604 KB

Open AccessCommunication

Synthesis and Structure of Macrocyclic Tetraimidazolium Salt Containing Propylene and m-Phenylene Linkers

by Jun-Ichi Ito and Makoto Yamashita

Molbank 2026, 2026(5), M2227; https://doi.org/10.3390/M2227 - 2 Sep 2026

Macrocyclic tetraimidazolium salts 2 and 3 containing propylene and m-phenylene linkers were synthesized from diimidazole derivative 1 and 1,3-diiodopropane. The molecular structure of 3 was determined by single-crystal X-ray diffraction analysis, revealing an almost planar macrocyclic framework. DFT calculations identified three low-energy [...] Read more.

Macrocyclic tetraimidazolium salts 2 and 3 containing propylene and m-phenylene linkers were synthesized from diimidazole derivative 1 and 1,3-diiodopropane. The molecular structure of 3 was determined by single-crystal X-ray diffraction analysis, revealing an almost planar macrocyclic framework. DFT calculations identified three low-energy conformers of the tetracation in 3, suggesting conformational flexibility in solution. Full article

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Graphical abstract

6 pages, 474 KB

Open AccessShort Note

N-[3-(N-tert-Butoxycarbonylaminooxy)propyl]-2-[2-(3-butynylcarbonylamino)ethylthio]-1,3-benzothiazole-6-carboxamide

by Gabriella G. Meisner, Nora N. Veigas and Christopher R. Shugrue

Molbank 2026, 2026(5), M2226; https://doi.org/10.3390/M2226 - 1 Sep 2026

We report the synthesis of a modified benzothiazole sulfide. This compound contains a heterocyclic core, a Boc-protected hydroxylamine, and an appended alkyne. This benzothiazole was accessed through three total steps, including an amidation reaction and two nucleophilic aromatic substitutions. The identity of the [...] Read more.

We report the synthesis of a modified benzothiazole sulfide. This compound contains a heterocyclic core, a Boc-protected hydroxylamine, and an appended alkyne. This benzothiazole was accessed through three total steps, including an amidation reaction and two nucleophilic aromatic substitutions. The identity of the title compound was confirmed through ¹H, ¹³C, ¹H–¹H COSY, HSQC, and HMBC NMR, in addition to IR, MALDI-MS, HRMS, and HPLC. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Graphical abstract

8 pages, 1940 KB

Open AccessCommunication

Synthesis and Structural Characterization of a New One-Dimensional Zinc(II) Coordination Polymer Based on a Fluorinated Thiosemicarbazone Schiff Base Ligand

by Jinhua Wang, Guan Wang and Chengwen Li

Molbank 2026, 2026(5), M2224; https://doi.org/10.3390/M2224 - 1 Sep 2026

This study reports the synthesis and characterization of a dinuclear zinc(II) complex, [Zn₂(L1)₂(L2)]·DMF·Et₃N (C₄₅H₅₄F₂N₁₀O₅S₂Zn₂), constructed from a fluoro-substituted thiosemicarbazone [...] Read more.

This study reports the synthesis and characterization of a dinuclear zinc(II) complex, [Zn₂(L1)₂(L2)]·DMF·Et₃N (C₄₅H₅₄F₂N₁₀O₅S₂Zn₂), constructed from a fluoro-substituted thiosemicarbazone Schiff base ligand (2-(3-fluoro-5-hydroxybenzylidene)-N-methylhydrazine-1-carbothioamide, L1) and a rigid bipyridine auxiliary ligand (1,4-di(pyridin-4-yl)-2,5-dimethoxybenzene, L2) under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the monoclinic space group C2/c, featuring discrete dinuclear [Zn₂] units in which each Zn(II) center adopts a distorted square pyramidal geometry. These dinuclear units are extended into one-dimensional zigzag chains along the crystallographic c-axis via bridging L2 ligands, and further assembled into a two-dimensional supramolecular layer through hydrogen-bonding interactions involving lattice triethylamine and DMF molecules, ultimately forming a three-dimensional network. Both DMF and triethylamine molecules are disordered about a twofold rotation axis. This work highlights the structural directing roles of the fluoro-substituted multidentate Schiff base ligand and the rigid auxiliary ligand in the assembly of zinc(II) coordination polymers. Full article

(This article belongs to the Section Structure Determination)

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5 pages, 1329 KB

Open AccessShort Note

(5aS,8R,9aR)-5,5,8-Trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one

by Nikolai S. Li-Zhulanov, Dmitrii D. Golovchenko, Tatyana V. Rybalova, Maria E. Modelskaya, Artem D. Rogachev, Konstantin P. Volcho and Nariman F. Salakhutdinov

Molbank 2026, 2026(5), M2225; https://doi.org/10.3390/M2225 - 1 Sep 2026

The monoterpene-derived 1,4-oxazepan-3-one, (5aS,8R,9aR)-5,5,8-trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one, was synthesized from the corresponding (−)-isopulegol-based chloroacetamide by intramolecular cyclization in acetonitrile. The product was isolated in 70% yield as colorless crystals. Its structure was established by one- and [...] Read more.

The monoterpene-derived 1,4-oxazepan-3-one, (5aS,8R,9aR)-5,5,8-trimethyloctahydrobenzo[f][1,4]oxazepin-3(2H)-one, was synthesized from the corresponding (−)-isopulegol-based chloroacetamide by intramolecular cyclization in acetonitrile. The product was isolated in 70% yield as colorless crystals. Its structure was established by one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry and was confirmed by single-crystal X-ray diffraction analysis. The transformation provides concise access to a fused bicyclic 1,4-oxazepan-3-one bearing a stereochemically defined para-menthane scaffold. Full article

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Graphical abstract

8 pages, 1498 KB

Open AccessShort Note

5-Cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium Chloride Hydrate

by Andreas S. Kalogirou, Andreas Kourtellaris and Panayiotis A. Koutentis

Molbank 2026, 2026(4), M2222; https://doi.org/10.3390/M2222 - 18 Aug 2026

Reaction of 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile with sodium 2-aminophenolate (1.5 equiv.) in anhydrous THF at ca. 0–20 °C afforded the known 4-chlorobenzo[5,6][1,4]oxazino[2,3-c][1,2,6]thiadiazine in 76% yield. In contrast, treatment of the same substrate with 2-aminophenol (3 equiv.) in acetonitrile at ca. [...] Read more.

Reaction of 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile with sodium 2-aminophenolate (1.5 equiv.) in anhydrous THF at ca. 0–20 °C afforded the known 4-chlorobenzo[5,6][1,4]oxazino[2,3-c][1,2,6]thiadiazine in 76% yield. In contrast, treatment of the same substrate with 2-aminophenol (3 equiv.) in acetonitrile at ca. 20 °C gave 5-cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium chloride hydrate in 93% yield. This compound was characterized by ¹H and ¹³C NMR, IR and UV-vis and mass spectrometry, together with melting point and elemental analysis, and its structure was supported by single-crystal X-ray crystallography. Full article

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8 pages, 922 KB

Open AccessShort Note

2-([1,1′-Biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one

by Yuki Sawatari, Kazunobu Igawa, Eiji Tsurumaki and Gen-ichi Konishi

Molbank 2026, 2026(4), M2223; https://doi.org/10.3390/M2223 - 18 Aug 2026

The previously unreported seven-membered-ring benzanilide derivative, 2-([1,1′-biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one (1), was synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The crystal structures of 1 and the known six-membered-ring analogue (2) were compared with [...] Read more.

The previously unreported seven-membered-ring benzanilide derivative, 2-([1,1′-biphenyl]-4-yl)-2,3,4,5-tetrahydro-1H-benzo[c]azepin-1-one (1), was synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The crystal structures of 1 and the known six-membered-ring analogue (2) were compared with that of the corresponding five-membered-ring analogue (3). Increasing ring size was found to induce steric distortions around the amide moiety, resulting in systematic changes in the π-conjugation with the adjacent phenyl groups. This study establishes a structural basis for controlling the electronic properties of ring-fixed benzanilides through ring-size engineering. Full article

(This article belongs to the Section Structure Determination)

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10 pages, 2430 KB

Open AccessCommunication

Synthesis and Structure of Palladium(II) Complex with (2E)-2-[1-(4-Aminophenyl)ethylidene]hydrazine-1-carbothioamide

by Daria S. Levchenko, Artem S. Igonin, Ekaterina I. Isaeva, Ruslan I. Baichurin, Oleg P. Demidov and Sergey V. Makarenko

Molbank 2026, 2026(4), M2221; https://doi.org/10.3390/M2221 - 17 Aug 2026

This work presents the synthesis and structural characterization of a previously unknown palladium(II) complex with (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide, which in the solid state forms a highly symmetric tetrametallic metallamacrocycle. The structure of the synthesized (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide and corresponding palladium(II) complex was established [...] Read more.

This work presents the synthesis and structural characterization of a previously unknown palladium(II) complex with (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide, which in the solid state forms a highly symmetric tetrametallic metallamacrocycle. The structure of the synthesized (2E)-2-[1-(4-aminophenyl)ethylidene]hydrazine-1-carbothioamide and corresponding palladium(II) complex was established by ¹H, ¹³C–{¹H}, ¹H–¹³C HMQC, and ¹H–¹³C HMBC NMR spectroscopy; IR and UV spectroscopy; mass spectrometry; TGA/DSC analyses; and single-crystal X-ray diffraction. Full article

(This article belongs to the Section Structure Determination)

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6 pages, 901 KB

Open AccessShort Note

4-Methyl-N-(2-methylbenzyl)-N′-(2-methylbenzylidene)benzenesulfonohydrazide

by Lei Gao, Yue Zhang and Xiaoxu Tan

Molbank 2026, 2026(4), M2219; https://doi.org/10.3390/M2219 - 17 Aug 2026

This work describes the synthesis of 4-methyl-N-(2-methylbenzyl)-N′-(2-methylbenzylidene)benzenesulfonohydrazide. Full characterization of the target compound is achieved through melting point measurement, ¹H NMR, ¹³C NMR spectroscopy and mass spectrometry, with unambiguous structural confirmation provided by single-crystal X-ray diffraction. Aggregated [...] Read more.

This work describes the synthesis of 4-methyl-N-(2-methylbenzyl)-N′-(2-methylbenzylidene)benzenesulfonohydrazide. Full characterization of the target compound is achieved through melting point measurement, ¹H NMR, ¹³C NMR spectroscopy and mass spectrometry, with unambiguous structural confirmation provided by single-crystal X-ray diffraction. Aggregated analytical data from multiple characterization techniques confirms successful preparation of the newly synthesized molecule and validates its structural integrity. Full article

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6 pages, 320 KB

Open AccessShort Note

1-[(4S)-4-Benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium Tetrafluoroborate

by Jakub Adamek, Natalia Sępek and Agnieszka Październiok-Holewa

Molbank 2026, 2026(4), M2220; https://doi.org/10.3390/M2220 - 17 Aug 2026

1-[(4S)-4-benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium tetrafluoroborate was synthesized in a two-step procedure starting from (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one. In the first step, (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one was treated with DIBAL-H at −78 °C in DCM and then converted to (4S)-4-benzyl-3-(1-trimethylsilyloxy)propyl-1,3-oxazolidin-2-one with TMSOTf at −78 °C [...] Read more.

1-[(4S)-4-benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium tetrafluoroborate was synthesized in a two-step procedure starting from (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one. In the first step, (4S)-4-benzyl-3-propionyl-1,3-oxazolidin-2-one was treated with DIBAL-H at −78 °C in DCM and then converted to (4S)-4-benzyl-3-(1-trimethylsilyloxy)propyl-1,3-oxazolidin-2-one with TMSOTf at −78 °C in DCM in the presence of pyridine. Next, the silylated intermediate was transformed to the expected 1-[(4S)-4-benzyl-1,3-oxazolidin-2-one-3-yl]propyltriphenylphosphonium tetrafluoroborate by reaction with Ph₃P·HBF₄ at −40 °C in DCM. The structures of the compounds obtained were confirmed by spectroscopic methods (¹H-, ¹³C{¹H}-, ³¹P{¹H}-NMR, IR) and HRMS analysis. Full article

(This article belongs to the Section Organic Synthesis and Biosynthesis)

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Scheme 1

4 pages, 607 KB

Open AccessShort Note

2-(4H-Indeno[2,1-d][1,2,3]thiadiazol-4-ylidene)-1H-indene-1,3(2H)-dione

by Sofia D. Usova, Ekaterina A. Knyazeva, Ludmila V. Mikhalchenko and Oleg A. Rakitin

Molbank 2026, 2026(4), M2218; https://doi.org/10.3390/M2218 - 14 Aug 2026

The design of solar cells with a bulk heterojunction is one of the most promising areas in renewable energy sources. Acceptor dopants with suitable physical characteristics are desirable components for ternary organic solar cells with cascade charge transfer. In this Short Note, 2-(4 [...] Read more.

The design of solar cells with a bulk heterojunction is one of the most promising areas in renewable energy sources. Acceptor dopants with suitable physical characteristics are desirable components for ternary organic solar cells with cascade charge transfer. In this Short Note, 2-(4H-indeno[2,1-d][1,2,3]thiadiazol-4-ylidene)-1H-indene-1,3(2H)-dione was prepared by thionation of [1,2′-biindenylidene]-1′,3,3′(2H)-trione with Lawesson’s reagent in refluxing benzene. The structure of newly synthesized compound was strictly confirmed by spectral methods. The obtained optical and electrochemical properties make this compound a promising candidate for use in ternary organic solar cells. Full article

(This article belongs to the Collection Heterocycle Reactions)

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Figure 1

6 pages, 613 KB

Open AccessShort Note

(±)-2-Chloro-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenylacetamide

by Diyana Dimitrova, Stanimir Manolov, Iliyan Ivanov, Dimitar Bojilov and Paraskev Nedialkov

Molbank 2026, 2026(4), M2216; https://doi.org/10.3390/M2216 - 12 Aug 2026

Herein, we report the rapid mechanochemical synthesis of a novel hybrid amide, (±)-2-chloro-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenylacetamide. The target compound was obtained via direct acylation of 1,4-benzodioxan-6-amine with (±)-2-chloro-2-phenylacetyl chloride under ball-milling conditions in only 1 min. Its structure was confirmed by ¹ [...] Read more.

Herein, we report the rapid mechanochemical synthesis of a novel hybrid amide, (±)-2-chloro-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenylacetamide. The target compound was obtained via direct acylation of 1,4-benzodioxan-6-amine with (±)-2-chloro-2-phenylacetyl chloride under ball-milling conditions in only 1 min. Its structure was confirmed by ¹H and ¹³C NMR, IR spectroscopy, and HRMS. Full article

(This article belongs to the Section Structure Determination)

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Figure 1

4 pages, 285 KB

Open AccessShort Note

2,3-Dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one

by Nataliia Slyvka, Lesya Saliyeva, Dmytro Khylyuk, Serhii Holota and Mykhailo Vovk

Molbank 2026, 2026(4), M2217; https://doi.org/10.3390/M2217 - 12 Aug 2026

Imidazo [2,1-b][1,3]thiazines and their fused analogues are an important class of nitrogen- and sulfur-containing heterocycles that exhibit a wide range of biological activities. Herein, a straightforward synthetic protocol for 2,3-dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one under catalyst-free, mild conditions is reported. [...] Read more.

Imidazo [2,1-b][1,3]thiazines and their fused analogues are an important class of nitrogen- and sulfur-containing heterocycles that exhibit a wide range of biological activities. Herein, a straightforward synthetic protocol for 2,3-dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one under catalyst-free, mild conditions is reported. The title compound was obtained via the regioselective heterocyclization of 4,5-dihydro-1H-imidazole-2-thiol with alkyl propiolates (methyl or ethyl) by stirring at room temperature for 24 h in ethanol. The structure of the synthesized compound and the regioselectivity of the reaction were confirmed through a combination of ¹H, ¹³C, and 2D NMR experiments (HSQC, HMBC), LC-MS, and elemental analysis. The synthesized title compound is of interest to synthetic organic and medicinal chemistry as a starting building block with potential for further core modification. Full article

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7 pages, 796 KB

Open AccessShort Note

(1E,4E)-1,5-Bis(2,4-dichlorophenyl)penta-1,4-dien-3-one Oxime

by Juan P. Montaño, Andres F. Sánchez and Rodrigo Abonia

Molbank 2026, 2026(4), M2215; https://doi.org/10.3390/M2215 - 6 Aug 2026

The target (1E,4E)-1,5-bis(2,4-dichlorophenyl)penta-1,4-dien-3-one oxime 4 was prepared in good yield, as a key aza-precursor for the Nazarov cyclization, through a two-step sequence in this study. Initially, the starting divinyl ketone 1a was obtained via a Claisen–Schmidt condensation reaction between [...] Read more.

The target (1E,4E)-1,5-bis(2,4-dichlorophenyl)penta-1,4-dien-3-one oxime 4 was prepared in good yield, as a key aza-precursor for the Nazarov cyclization, through a two-step sequence in this study. Initially, the starting divinyl ketone 1a was obtained via a Claisen–Schmidt condensation reaction between 2,4-dichlorobenzaldehyde 3 and acetone in the presence of aqueous 20% NaOH. Subsequently, treating 1a with hydroxylamine hydrochloride under thermal conditions resulted in the expected oxime in excellent yield, and its structure was confirmed by analytic and spectroscopic techniques. Full article

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Open AccessShort Note

Bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile

by Anastasiya S. Yushkova, Ekaterina A. Knyazeva and Oleg A. Rakitin

Molbank 2026, 2026(4), M2214; https://doi.org/10.3390/M2214 - 4 Aug 2026

Compounds containing electron-withdrawing dicyanopyrazine and 1,2,5-chalcogenadiazole fragments are promising for the design of magnetic and optoelectronic materials. In this paper, bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile was prepared via Körner–Hinsberg condensation of benzo[1,2-c:3,4-c′]bis([1,2,5]thiadiazole)-4,5-dione with 2,3-diaminomaleonitrile in the presence of catalytic amounts of TsOH in refluxing ethanol. The structure [...] Read more.

Compounds containing electron-withdrawing dicyanopyrazine and 1,2,5-chalcogenadiazole fragments are promising for the design of magnetic and optoelectronic materials. In this paper, bis([1,2,5]thiadiazolo)[3,4-f:3′,4′-h]quinoxaline-8,9-dicarbonitrile was prepared via Körner–Hinsberg condensation of benzo[1,2-c:3,4-c′]bis([1,2,5]thiadiazole)-4,5-dione with 2,3-diaminomaleonitrile in the presence of catalytic amounts of TsOH in refluxing ethanol. The structure of the newly synthesized compound was established via elemental analysis, mass spectrometry, ¹³C NMR, and IR spectroscopy. Full article

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11 pages, 3119 KB

Open AccessCommunication

N-Demethyl-N-nitrosolevofloxacin

by Claudio Maestri, Mattia Lopresti, Ivana Miletto, Attila Benyei, Marzia Petreti, Luisa Zangirolami, Camilla Cavallotti and Giovanni B. Giovenzana

Molbank 2026, 2026(4), M2211; https://doi.org/10.3390/M2211 - 4 Aug 2026

Levofloxacin is an antibiotic belonging to the fluoroquinolone family. N-Demethyllevofloxacin, a metabolite and an impurity of levofloxacin, features a secondary amine that is susceptible to N-nitrosation, raising concerns about the formation of a potentially toxic nitrosamine. The corresponding N-nitrosamine was [...] Read more.

Levofloxacin is an antibiotic belonging to the fluoroquinolone family. N-Demethyllevofloxacin, a metabolite and an impurity of levofloxacin, features a secondary amine that is susceptible to N-nitrosation, raising concerns about the formation of a potentially toxic nitrosamine. The corresponding N-nitrosamine was synthesized in two steps and characterized using HRMS, NMR spectroscopy, IR spectroscopy, UV absorption and emission spectroscopies and powder X-ray diffraction. This work provides a reliable reference for the quantitation and control of nitrosamine impurities associated with levofloxacin in chemical and pharmaceutical contexts. Full article

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