Klaus Jurkschat

We report a new concept to lower the melting temperature (T _m ) of inorganic‐organic hybrid adamantane‐based cluster compounds by forming unprecedented eutectic cluster mixtures with organic adamantane derivatives. Blending of clusters of the type [( p ‐MeC ₆ H ₄ Si(CH ₂ SnPhE) ₃ ] (E = S, Se, Te) with (3‐F‐4‐Me‐C ₆ H ₃ ) ₃ Ad, (3‐F‐4‐Me‐Ph) ₄ Ad, and (4‐MeO‐C ₆ H ₄ ) ₄ Ad was achieved by mechanical mixing and led to decreased T _m while retaining the components’ chemical identity. Such adamantane‐type compounds are known to exhibit strongly non‐linear optical properties: upon irradiation with a continuous wave (CW) laser diode, they respond either by second‐harmonic generation (SHG), if being crystalline, or by white‐light generation (WLG) with corresponding broadband emission, if being intrinsically amorphous or transformed into a glassy state. Herein, we show that this feature is preserved in the eutectic mixtures, hence, we can report superior properties of these cluster‐based materials that combine favorable nonlinear optical behavior with lowered T _m , which facilitates their processing for future use.

The reaction of the aryllithium derivative 2,6‐[P(O)(O‐ i ‐Pr) ₂ ] ₂ ‐4‐ t ‐Bu‐C ₆ H ₂ Li with iodine chloride, ICl, and elemental bromine, Br ₂ , respectively, gave the aryl halides 2,6‐[P(O)(O‐ i ‐Pr) ₂ ] ₂ ‐4‐ t ‐Bu‐C ₆ H ₂ X ( 1 , X = I; 2 , X = Br, respectively). The aryl iodide 1 was characterized by ¹ H, ¹³ C, ³¹ P NMR, and IR spectroscopy, and both 1 and the water solvate 2 ·H ₂ O by single‐crystal X‐ray diffraction analysis. The structure of 1 in the solid state revealed weak inter‐ and intramolecular P =O···I–Ar electrostatic halogen bonding (HaB) interactions, resulting in 1 being a dimer in the solid state. In solution, however, it is a monomer. For the sake of comparison, the solid‐state structure of the aryl bromide derivative 2,6[P(O)(O‐ i ‐Pr) ₂ ] ₂ ‐4‐ t ‐Bu‐C ₆ H ₂ Br·H ₂ O ( 2 ·H ₂ O) is also reported, revealing a polymeric 2D structure as a result of P O···HOH···OP hydrogen bonds (HBs) and weak intermolecular P( i ‐Pr)O···BrAr HaB interactions. Natural bonding orbital (NBO) and quantum theory of atoms in molecule (QTAIM)/density functional theory (DFT) calculations helped elucidating the nature of the interactions.

Silylium ions, three‐coordinated as well as donor‐stabilized, have attracted the interest of chemists for many years, have paved its way into practical application as catalysts for organic reactions, and have contributed to the understanding of fundamental chemistry problems. Since the first carbenes have been isolated and characterized, they had and still have an ongoing enormous impact on organic as well as on inorganic and organometallic chemistry. Herein, the synthesis and complete characterization of silatranyl cations as their acetonitrile‐ respectively propionitrile‐coordinated hexachlorido antimonates is reported. Upon interaction of the former with 4‐dimethylaminopyridine (DMAP) conversion to an unprecedented carbene–type complex of antimony pentachloride occurred, nicely combining silylium and carbene chemistry.

A series of organotin(IV) complexes featuring the pro‐ligand 2,6‐diacetylpyridine bis(2‐methylbenzoylhydrazone) (H₂L^Me) and various axial ligands have been synthesized. The reactions of H₂L^Me with R₂SnO (where R = Me, n‐Bu, n‐Oct, or t‐Bu) and n‐BuSnCl₃ in anhydrous toluene yielded the seven‐coordinate complexes [Me₂Sn(L^Me)] (1), [n‐Bu₂Sn(L^Me)] (2), [n‐Oct₂Sn(L^Me)] (3), [t‐Bu₂Sn(L^Me)] (4), and [n‐BuSn(L^Me)Cl] (5), respectively. Subsequent treatment of complex 5 with NaN₃ and NH₄SCN afforded the corresponding isothiocyanate and azide derivatives, [n‐BuSn(L^Me)N₃] (6), and [n‐BuSn(L^Me)NCS] (7), respectively. Single crystal X‐ray diffraction studies confirmed that the tin centers in complexes 1, 2, 4, 6, and 7 adopt a seven‐coordinate geometry with a pentagonal bipyramidal configuration. The κ‐N³O² donor set of the ligand occupies the equatorial plane, while the axial positions are occupied by either two R groups, or one R group and one Cl, N₃, or NCS ligand, depending on the specific complex. In addition to X‐ray diffraction analysis, all complexes 1−7 are characterized using Fourier transform infrared spectroscopy, high‐resolution mass spectrometry , and solution‐state Fourier transform nuclear magnetic resonance spectroscopy. The structural distortion within the SnN₃O₂ equatorial plane, attributed to positional shifts of the Sn(IV) center, are also discussed.

A pentadentate Schiff base pro‐ligand, suitable for the generation of metal complexes containing two chiral centers, is synthesized. The pro‐ligand H ₂ L ^Me is reacted with diorganotin precursors to yield the tin compounds [Me ₂ Sn(L ^Me )] ( 1 ), [ n‐ Bu ₂ Sn(L ^Me )] ( 2 ), [ t‐ Bu ₂ Sn(L ^Me )] ( 3 ), [Bn ₂ Sn(L ^Me )] ( 4 ), and [ n‐ Oct ₂ Sn(L ^Me )] ( 5 ), where L ^Me = N ‐[( E )‐1‐[6‐[( E )‐ N ‐( p ‐tolylsulfonamido)‐ C ‐methylcarbonimidoyl]pyridin‐2‐yl]ethylideneamino]‐ p ‐tolylsulfonamide. Characterization in solution (NMR spectroscopy and high‐resolution mass spectrometry) and solid state (Fourier transform infrared spectroscopy and single crystal X‐ray diffraction analysis) confirms for each compound a seven‐coordinate C ₂ SnN ₃ O ₂ environment with pentagonal‐bipyramidal geometry. The ¹¹⁹ Sn NMR spectra exhibit high field‐shifted signals, consistent with seven coordinated diorganotin Schiff base derivatives. In the solid state, the S(O)C ₆ H ₄ Me moieties in 1 – 4 are mutually anti ‐oriented, resulting in molecular topologies similar to those found in Jacobsen's catalyst. In addition to van der Waals interactions, the molecular arrangements in the 3D solid‐state structures are primarily controlled by CH⋯O hydrogen bonds, along with CH⋯N, CH⋯π, and π⋯π interactions giving macrocyclic or cage‐type assemblies.

A series of spiroisatin‐based hydrazide conjugates IV(a–t) was synthesized and structurally characterized using spectral data, with compound IV‐a further confirmed by x‐ray diffraction analysis. All the synthesized compounds were evaluated for their biological potential in a cell painting assay. Among the synthesized spiroisatin derivatives, compound IV‐p exhibited significant activity in inducing cellular morphological changes, with an induction value of 30.6%. In addition, some compounds showed high biosimilarities with marketed drugs. Specifically, the compounds IV‐n and IV‐p showed a high biosimilarity with the orally active iron chelator deferasirox, and IV‐m showed a high biosimilarity with the kinase inhibitor alisertib. Furthermore, compounds IV‐p showed significant inhibition against human breast cancer (MDA‐MB‐231 = 82.37%) and colorectal carcinoma cell lines (HCT‐116 = 86.25%) during preliminary investigations. Moreover, it was revealed through molecular docking analysis that IV‐p possesses a good binding score against ferroportin and Aurora A kinase (−9.3 and −9.2 kcal/mol), which are quite comparable with the deferasirox (−9.2 kcal/mol) and alisertib (−9.8 kcal/mol). Pharmacokinetic studies revealed that the synthesized conjugates have good oral bioavailability, balanced hydrophilicity, and minimal toxicity. The results of this study clearly highlight the potential of these conjugates as promising small bioactive molecules.

We report the syntheses of tin(II) salts of the types [L¹SnX]SnX₃ [L¹=2,6‐{(i‐PrO)₂(O)P}₂C₅H₃N: 1, X=Cl; 2, X=Br], [L²SnCl]SnCl₃ [L²=2‐{(i‐PrO)Ph(O)P}‐6‐{(i‐PrO)₂(O)P}C₅H₃N: 3], [L³SnX]SnX₃ [L³=2,6‐{MeO(O)C}₂C₅H₃N: 4, X=Cl; 5, X=Br], [L⁴SnX]SnX₃ [L⁴=2,6‐{Et₂N(O)C}₂C₅H₃N: 6, X=Cl; 7, X=Br]. These compounds were obtained by addition of SnX₂ to the corresponding ligand inducing autoionization of the respective tin(II) halide. The thermal stability of 1, 3, and 4 was elucidated, giving, under ester cleavage and cyclisation, the tin(II) derivatives 8–12. The reaction of [L¹SnCl]SnCl₃ (1) with W(CO)₄(thf)₂ afforded the tungsten tetracarbonyl complex [{L¹SnCl}{SnCl₃}W(CO)₄] (13), representing the first example in which a tin(II) stannate anion and a tin(II) stannylium cation simultaneously coordinate to a transition metal centre. The compounds were characterized by single crystal X‐ray diffraction analyses and in part by elemental analyses, IR and NMR spectroscopy, electrospray ionization mass spectrometry. DFT calculations accompany the experimental work.

Die ringöffnende Si‐Fluorierung einer Vielzahl von Azasilolderivaten Cyclo‐1‐(iPr₂Si)−4‐X−C₆H₃−2‐CH₂NR (4: R=2,6‐iPr₂C₆H₃, X=H; 4 a: R=2,4,6‐Me₃C₆H₂, X=H; 9: R=2,6‐iPr₂C₆H₃, X=tBuMe₂SiO; 10: R=2,6‐iPr₂C₆H₃, X=OH; 13: R=2,6‐iPr₂C₆H₃, X=HCCCH₂O; 22: R=2,6‐iPr₂C₆H₃, X=tBuMe₂SiCH₂O) mit verschiedenen ¹⁹F‐Fluoridquellen untersucht, optimiert und die gewonnenen Erfahrungen in einem translationalen Ansatz genutzt, um ein einfaches ¹⁸F‐Markierungsprotokoll für die Azasilolderivate [¹⁸F]6 und [¹⁸F]14 zu erstellen. Letzteres stellt eine potenziell klickbare CycloSiFA‐prothetische Gruppe dar, die bei der Entwicklung von PET‐Tracern unter Verwendung der Cu‐katalysierten Triazolbildung eingesetzt werden könnte. Auf der Grundlage unserer Ergebnisse hat CycloSiFA das Potenzial, ein neuer Einstieg in nicht‐kanonische Markierungsmethoden für die Entwicklung radioaktiver PET‐Tracer zu werden.