Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

Beilstein Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: 21, P. 412 - 420

Published: Feb. 21, 2025

A new series of o -carborane-fused pyrazoles has been recently successfully synthesized. This fusion was expected to create a hybrid 3D/2D aromatic system, combining the 3D aromaticity -carborane with 2D pyrazole. However, while boron cage retains its character, pyrazole’s is lost. As result, rather than forming pyrazoles, synthesis yielded pyrazolines, which are non-aromatic. The limited overlap between π molecular orbitals (MOs) planar heterocycle and n + 1 MOs carborane prevents significant electronic delocalization two fused components. contrasts pyrazole benzene form indazole, where both rings maintain their aromaticity. Our findings demonstrate that peripheral σ-aromaticity π-aromaticity orthogonal, making true system unachievable. highly aromatic, generating negative NICS values (−25 −30 ppm). We have observed these high extend rings, leading incorrect estimations Therefore, relying solely on can be misleading, other computational indicators, along experimental or structural data, should used accurately assess

Language: Английский

---

Advances in organic semiconductors for photocatalytic hydrogen evolution reaction

EES Catalysis, Journal Year: 2023, Volume and Issue: 1(4), P. 333 - 352

Published: Jan. 1, 2023

This article reviews organic photocatalyst hydrogen evolution reaction (HER), discussing the excitonic behaviour and improvement strategies. It also covers progress in photocatalysts, assesses HER efficiency stability.

Language: Английский

---

Photoinduced Selective B–H Activation of nido-Carboranes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(11), P. 7791 - 7802

Published: March 10, 2024

The development of new synthetic methods for B–H bond activation has been an important research area in boron cluster chemistry, which may provide opportunities to broaden the application scope clusters. Herein, we present a reaction strategy direct site-selective functionalization nido-carboranes initiated by photoinduced cage via noncovalent cage···π interaction. As result, nido-carborane radical is generated through single electron transfer from 3D 2D photocatalyst upon irradiation with green light. resulting transient could be directly probed advanced time-resolved EPR technique. In air, subsequent transformations active have led efficient and selective B–N, B–S, B–Se couplings presence N-heterocycles, imines, thioethers, thioamides, selenium ethers. This protocol also facilitates both late-stage modification drugs synthesis nido-carborane-based drug candidates neutron capture therapy (BNCT).

Language: Английский

---

A variable bidentate traceless directing group for nickel-catalyzed regioselective B–H poly-chalcogenation of o-carboranes

Inorganic Chemistry Frontiers, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

A nickel-catalyzed direct cage B–H poly-chalcogenation of icosahedral carborane clusters, enabled by a variable bidentate 8-aminoquinoline traceless directing group, has been developed under oxidant-free and weakly basic conditions.

Language: Английский

---

Triazine-Modified Color-Responsive Triarylboron/Acridine Fluorescent Probe with Multi-Channel Charge Transfer for Highly Sensitive Fluoride Ion Detection

Molecules, Journal Year: 2025, Volume and Issue: 30(4), P. 879 - 879

Published: Feb. 14, 2025

A novel fluoride ion fluorescent probe is designed by introducing the strong electron-withdrawing triazine groups into triarylboron/acridine conjugation system. The A-D-A' molecular configuration endows this molecule with multiple charge-transfer channels; upon reaction F-, act as primary acceptors within molecule, facilitating charge transfer between acridine units and groups. During detection, changes in triarylboron moiety lead to a significant bathochromic-shift fluorescence emission from green yellow. Theoretical calculations attribute phenomenon reduction S1 state energy level fluorination, resulting pronounced visible color change chromogenic response during detection. Based on intensity varying degrees of F- coordination, detection limit low 10-7 M was determined for TB-1DMAc-2TRZ, demonstrating high sensitivity probe.

Language: Английский

---

Synthesis and Stability of o-Carborane-Fused Phospholes

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: March 20, 2025

Herein, we report that ArLi, formed in situ through the Li/Br exchange between aryl bromide and n-butyllithium, can undergo rapid intramolecular Li/H(Ccage–H) to functionalize o-carboranes. Based on this observation, a dual C–H lithiation reaction of 2- or 3-o-carboryl benzothiophenes was developed, series o-carborane-fused phospholes were synthesized by dilithio compounds with chlorophosphine. This is simple high chemical selectivity medium yields. It also be applied furan derivative. Stability studies demonstrated these phosphole derivatives are stable both trivalent coordination states for phosphorus. In contrast, their oxides sensitive moisture air susceptible attack nucleophiles, leading breakage Ccage-P bond. Computational results indicate newly generated rings have weak aromaticity.

Language: Английский

---

Visible‐Light‐Induced Photoreduction of Carborane Phosphonium Salts: Efficient Synthesis of Carborane‐Oxindole‐Pharmaceutical Hybrids

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(31)

Published: April 29, 2023

Visible-light-induced photoreaction of carboranes is an effective approach to prepare carborane-containing compounds. While several methods involving boron-centered carboranyl radicals have been established, those for carbon-centered are underdeveloped, except the UV-light-promoted photohomolysis. Herein, we describe a simple but access by photoreduction carborane phosphonium salts under blue light irradiation without using transition metals and photocatalysts. The utility method was demonstrated successfully preparing range carborane-oxindole-pharmaceutical hybrids radical cascade reactions. Computational experimental studies suggest that generated single-electron transfer photoactive charge-transfer complexes between additive potassium acetate.

Language: Английский

---

Redox-active carborane clusters in bond activation chemistry and ligand design

Chemical Communications, Journal Year: 2023, Volume and Issue: 59(66), P. 9918 - 9928

Published: Jan. 1, 2023

The icosahedral carborane cluster can accept two electrons and change from a closed closo -form to an open nido -form. This transformation unlocks the potential for bond activation chemistry, uranyl capture, stabilization of low-valent centers.

Language: Английский

---

Boosting 2000‐Fold Hypergolic Ignition Rate of Carborane by Substitutes Migration in Metal Clusters

Advanced Science, Journal Year: 2024, Volume and Issue: 11(23)

Published: April 3, 2024

Abstract Hypergolic propellants rely on fuel and oxidizer that spontaneously ignite upon contact, which fulfill a wide variety of mission roles in launch vehicles spacecraft. Energy‐rich carboranes are promising hypergolic fuels, but triggering their energy release is quite difficult because ultrastable aromatic cage structure. To steer the development carborane‐based high‐performance material, carboranylthiolated compounds integrated with atomically precise copper clusters presented, yielding two distinct isomers, Cu 14B‐S 14C‐S , both possessing similar ligands core structures. With migration thiolate groups from carbon atoms to boron atoms, ignition delay (ID) time shortened 6870 3 ms when contacted environmentally benign high‐test peroxide (HTP, H 2 O concentration 90%). The extraordinarily short ID ranking among best HTP‐active materials. experimental theoretical findings reveal benefitting groups, characterized by an electron‐rich metal kernel, displays enhanced reducibility superior charge transfer efficiency. This results exceptional activation rates HTP, consequently inducing carborane combustion simultaneous energy. fundamental investigation shed light advanced green propulsion systems.

Language: Английский

---

The Possible Aromatic Conjugation via the Different Edges of (Car)Borane Clusters: Can the Relationship Between 3D and 2D Aromatic Systems Be Reconciled?

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(61)

Published: Aug. 29, 2024

Abstract The possible aromatic conjugation between 3D and 2D units is in the focus since synthesis of benzocarborane. It has been showed that icosahedral 1,2‐dicarba‐ closo ‐dodecaborane systems fused with rings a global 3D/2D aromaticity does not exist. Despite this fact during last years several studies proposed interactions moieties. Herein, while tuning size effective charge (car)borane systems, we demonstrate character can be excluded any investigated cases, detectable conjugative properties explained effect well‐known negative hyperconjugation.

Language: Английский

---