The gallabenzene-type yttrium complex [(1-Me-3,5-tBu₂−C₅H₃Ga)(μ-Me)Y(2,4-dtbp)] (A) is readily formed from one-pot-reactions using mixtures [YMe₃] _n /GaMe₃/K(2,4-dtbp) (2,4-dtbp=2,4-di-tert-butyl-pentadienyl), while the remaining pentadienyl ligand gets easily displaced by pentamethylcyclopentadienyl affording B, showcasing the strong interaction of the heterobenzene ligand with the rare-earth-metal center. Distinct ligand bonding is revealed by ⁸⁹Y NMR chemical shifts.

Abstract

The yttrium gallabenzene complex [(1-Me-3,5-tBu₂−C₅H₃Ga)(μ-Me)Y(2,4-dtbp)] is accessible from Y(GaMe₄)₃ and K(2,4-dtbp) via a tandem salt metathesis/methane elimination (2,4-dtbp=2,4-di-tert-butyl-pentadienyl). The pentadienyl ligand in [(1-Me-3,5-tBu₂−C₅H₃E)(μ-Me)Y(2,4-dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC₅Me₅ and KTp^Me,Me (Tp^Me,Me=tris(pyrazolyl-Me₂-3,5)borato) affording [(1-Me-3,5-tBu₂−C₅H₃E)(μ-Me)Y(Tp^Me,Me)] and [(1-Me-3,5-tBu₂−C₅H₃E)(μ-Me)Y(C₅Me₅)]. The yttrium center in [(1-Me-3,5-tBu₂−C₅H₃E)(μ-Me)Y(2,4-dtbp)] readily forms adducts with neutral Lewis bases like 4-DMAP (4-dimethylaminopyridine), PMe₃, DMPE (1,2-bis(dimethylphosphino)ethane), and DME (1,2-dimethoxyethane). In stark contrast, addition of TMEDA (N,N,N’,N’-tetramethylethylenediamine) results in methyl/pentadienyl exchange between aluminum and yttrium resulting in [(1-(2,4-dtbp)-1-Me-3,5-tBu₂−C₅H₃Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single-crystal X-ray diffraction (SCXRD) and heteronuclear (⁸⁹Y, ³¹P) NMR spectroscopy.

The solid-state [4+4] cycloaddition of a commercially available anthracene derivative affords facile synthesis of a cycloadduct. The cycloaddition is reversible in the solid-state using heat or mechanical force. The cycloadduct is highly solvatomorphic due to presence of unused, strong hydrogen-bond donors and is applied to the thermal stabilization of monomers.

Abstract

The crystal structure of a commercially available anthracene derivative, anthracene-9-thiocarboxamide, is reported here for the first time. The compound undergoes a [4+4] cycloaddition in the solid state to afford facile synthesis of the cycloadduct (CA). The cycloaddition is also reversible in the solid state using heat or mechanical force. Due to the presence of unpaired, strong hydrogen-bond donor atoms on the CA, significant solvatomorphism is achieved, and components of the solvatomorphs self-assemble into four different classes of supramolecular structures. The CA readily crystallizes with a variety of structurally-diverse solvents including those containing oxygen-, nitrogen-, or pi-acceptors. Some of the solvents the CA crystallized with include thiophene, benzene, and the three xylene isomers; thus, the CA was employed in industrially-relevant solvent separation. However, in competition studies, the CA did not exhibit selectivity. Lastly, it is demonstrated that the CA crystallizes with vinyl-containing monomers and is currently the only compound that crystallizes with both widely used monomers 4-vinylpyridine and styrene. Solid-state complexation of the CA with the monomers affords over a 50 °C increase in the monomer's thermal stabilities. The strategy of designing molecules with unused donors can be applied to achieve separations or volatile liquid stabilization.

B/N-codoped polycyclic aromatic hydrocarbons (PAHs) were constructed via combining the B- and N-doped π-systems. Two B/N-codoped PAHs were synthesized through the Mallory photoreaction, and their electronic structures and optical properties could be effectively modulated via static and dynamic control of intramolecular charge transfer states.

Abstract

Doping heteroatoms into polycyclic aromatic hydrocarbons (PAHs) may alter their structures and thereby physical properties. This study reports the construction of B/N-codoped PAHs via combining the B- and N-doped π-systems. Two π-extended B/N-codoped PAHs were synthesized through the Mallory photoreaction. Both feature a C₄₈BN₂ π-skeleton, which is assembled by linearly fusing three substructures including B-doped and sp²-hybridized N-doped π-moieties and one pyrene unit. In comparison to the pristine B-doped analog, their intramolecular charge transfer (ICT) states are distinctly modulated by the fused N-doped π-system and the further incorporated cyano group, leading to their tunable optical properties, as revealed by detailed theoretical and experimental analysis. Furthermore, these three molecules have sufficient Lewis acidity and can coordinate with Lewis base to form Lewis acid-base adducts, and notably, such intermolecular complexation can further dynamically modulate their ICT transitions and thereby photophysical properties, such as producing blue, green and red fluorescence.

Podophyllotoxin is an aryltetralin lignan lactone derived from different plants of Podophyllum. It consists of five rings with four chiral centers, one trans-lactone and one aryl tetrahydronaphthalene skeleton with multiple modification sites. Moreover, podophyllotoxin and its derivatives showed lots of bioactivities, including anticancer, anti-inflammatory, antiviral, and insecticidal properties. The demand for podophyllotoxin and its derivatives is rising as a result of their high efficacy. As a continuation of our previous review (Chem. Eur. J., 2017, 23, 4467-4526), herein we summarized total synthesis, biotransformation, structural modifications, bioactivities, and structure-activity relationships of podophyllotoxin and its derivatives from 2017 to 2022. Meanwhile, we compiled an update information on the origin of new podophyllotoxin analogues from plants from 2014 to 2022. We hope that this review will provide a reference for future high value–added applications of podophyllotoxin and its analogues in the pharmaceutical and agricultural fields

The dehydrogenation of glycerol to lactic acid (LA) under both acceptorless and transfer dehydrogenation conditions using readily available, inexpensive, environmentally benign and earth-abundant base metal salt CoCl2 is reported here. The CoCl2 (0.5 mol%) catalyzed acceptorless dehydrogenation of glycerol at 160 °C in the presence of 0.75 equiv of KOH, gave up to 33% yield of LA in 44% selectivity apart from hydrogen. Alternatively, with acetone as a sacrificial hydrogen acceptor, the CoCl2 (0.5 mol%) catalyzed dehydrogenation of glycerol at 160 °C in the presence of 1.1 equiv of NaOtBu resulted in up to 93% LA with 96% selectivity along with another value-added product isopropanol. Labelling studies revealed a modest secondary KIE of 1.68 which points to the involvement of C-H bond activation as a part of the catalytic cycle but not as a part of the rate-determining step. Catalyst poisoning experiments with PPh3 and CS2 are indicative of the homogeneous nature of the reaction mixture involving molecular species that are likely to be in-situ formed octahedral Co(II) as inferred from EPR, HRMS and Evans magnetic moment studies. The net transfer dehydrogenation activity is attributed to exclusive contribution from the alcoholysis step.

Diradicals: Simple, modular and convergent access to diradicals with controllable S−T gap demonstrated with two examples.

Abstract

Reactions of a benzo[e][1,2,4]triazine with dilithiobenzenes lead to di-Blatter diradicals connected at the N(1) positions via a spin coupling unit, 1,4-phenylene or 1,3-phenylene. Electrochemical analysis in MeCN revealed four one-electron redox processes separated by 0.1–0.3 V in both diradicals. Variable temperature EPR measurements in polystyrene (PS) solid solutions gave the singlet-triplet energy gaps ΔE _S-T=2 J of −3.02(11) and −0.16(1) kcal mol⁻¹ for 1,4-phenylene and 1,3-phenylene derivatives, respectively. The latter negative value was attributed to conformational properties of the diradical in the PS solid solution. Results suggest a simple and efficient access to a family of stable Blatter diradicals with a controllable S−T gap through a judicious choice of the arylene coupling unit. DFT calculations indicate that the triplet state is stabilized by (het)arylenes with low LUMO.

The amorphous titanium dioxide is used to coat eGaSn nanodroplets (eGaSn NDs) to construct the core-shell structure of eGaSn@TiO₂ nanodroplets (eGaSn@TiO₂ NDs). The amorphous TiO₂ shell forms a stable SEI film, alleviates volume expansion, and provides electron/ion transport channels. The resulting eGaSn@TiO₂ NDs exhibit high capacities of 580, 540, 515, 485, 456 and 426 mAh g⁻¹ at 0.1, 0.2, 0.5, 1, 2 and 5 C, respectively. No obvious decay is observed in more than 500 cycles with a capacity of 455 mAh g⁻¹ at 1 C.

Abstract

Gallium-based alloy liquid metal batteries currently face limitations such as volume expansion, unstable solid electrolyte interface (SEI) film and substantial capacity decay. In this study, amorphous titanium dioxide is used to coat eutectic GaSn nanodroplets (eGaSn NDs) to construct the core-shell structure of eGaSn@TiO₂ nanodroplets (eGaSn@TiO₂ NDs). The amorphous TiO₂ shell (~6.5 nm) formed a stable SEI film, alleviated the volume expansion, and provided electron/ion transport channels to achieve excellent cycling performance and high specific capacity. The resulting eGaSn@TiO₂ NDs exhibited high capacities of 580, 540, 515, 485, 456 and 426 mAh g⁻¹ at 0.1, 0.2, 0.5, 1, 2 and 5 C, respectively. No significant decay was observed after more than 500 cycles with a capacity of 455 mAh g⁻¹ at 1 C. In situ X-ray diffraction (in situ XRD) was used to explore the lithiation mechanism of the eGaSn negative electrode during discharge. This study elucidates the design of advanced liquid alloy-based negative electrode materials for high-performance liquid metal batteries (LMBs).

In order to achieve a multifunctional compound with potential application in organic photonics and electronics, a multidonor benzothiadiazole derivative was rationally designed and synthesized employing microwave irradiation as energy source, increasing the process efficiency about yields and reaction times in comparison with conventional conditions. This powerful compound displayed solvatochromism and showed efficient behavior as red optical waveguide with low OLC around 10-2 dB μm-1 and with the capacity of light transmission in two directions. In addition, the proposed derivative acted as efficient p-type semiconductor in organic field-effect transistors (OFETs) with hole mobilities up 10-1 cm2V-1s-1. This corroborates its multifunctional character, thus making it a potential candidate to be applied in hybrid organic field-effect optical waveguides (OFEWs).

In the present work, several manganese(I) complexes of chelating heteroditopic ligands Mn1-3, featuring ImNHC (imidazol-2-ylidene) connected to a 1,2,3-triazole-N or tzNHC (1,2,3-triazol-5-ylidene) donors via a methylene spacer, with possible modifications at the triazole backbone have been synthesized and completely characterized. Notably, the CO stretching frequencies, electrochemical analysis, and frontier orbital analysis certainly suggests that the chelating ImNHC-tzNHC ligands have stronger donation capabilities than the related ImNHC-Ntz ligand in the synthesized complexes. Moreover, these well-defined phosphine free Mn(I)-NHC complexes have been found to be effective non-bifunctional catalysts for the α-alkylation of nitriles using alcohols and importantly, the catalyst Mn1 containing ImNHC connected to a weaker triazole-N donor displayed higher activity compared to Mn2/Mn3 containing an unsymmetrical bis-carbene donors (ImNHC and tzNHC). A wide range of aryl nitriles were coupled with diverse (hetero)aromatic as well as aliphatic alcohols to get the corresponding products in good to excellent yields (32 examples, up to 95% yield). The detailed mechanistic studies including deuterium labelling experiments reveal that the reaction follows a Borrowing Hydrogen pathway.

One pair of isomers, IDT-BOF containing S···O/F···H noncovalently configurational locks and IDT-BFO containing F···H/O···H noncovalently configurational locks, were designed and synthesized with an acceptor-π-donor-π-acceptor (A-π-D-π-A) structure by choosing 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (IDT) as the D unit, F/n-hexyloxy substituted phenyl ring as π bridge, and 3-(dicyanomethylidene)indan-1-one as the A unit. Owing to the S···O/F···H or F···H/O···H noncovalently configurational locks, both IDT-BOF and IDT-BFO show completely planar structure. In comparison to IDT-BFO, IDT-BOF exhibits similar LUMO but higher HOMO energy levels, leading to a smaller optical bandgap and red-shifted absorption. However, IDT-BOF-based bulk-heterojunction organic solar cells (BHJ-OSCs) coupled with PBDB-T, and PCE-10 as donor materials both exhibited a lower PCE than that of IDT-BFO (PBDB-T: 5.2% vs. 6.1%; PCE-10: 1.7% vs. 3.2%). Comprehensively comparing and investigating IDT-BOF:PBDB-T and IDT-BFO:PBDB-T OSCs suggested that the large phase separation and serious charge recombination of IDT-BOF based OSCs contributed to its lower PCE. Importantly, ternary solar cells based on PBDB-T:Y5 as control devices by adding 10% IDT-BFO exhibited a 5% enhancement in the PCE compared to the control device (14.3% vs. 13.6%).