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Five fluorescent ONO donor-based organotin(IV) complexes

The preparation, optical resolution, and structural investigations of a series of axially chiral biaryl dicarboxylic acids bearing oxygen, sulfur, and selenium atoms were carried out. The crystal structures of sulfur- and selenium-containing derivatives revealed that the carboxy groups of these compounds are located in a co-planar geometry with the fused aromatic rings including the chalcogen atoms. These conformational controls were found to be achieved by chalcogen-bonding interactions between chalcogen atoms in the aromatic rings and oxygen atoms in the carboxy groups. Even in the case of a binaphthofuran derivative, in which the formation of chalcogen-bonding interactions was expected to be negligible, the carboxy groups were also found to be located in a co-planar geometry toward its fused cyclic rings. Natural bond orbital (NBO) analyses of these dicarboxylic acids indicated the formation not only for the chalcogen-bonding interactions for S and Se derivatives, but also the tetrel-bonding interactions between the oxygen atoms in the carboxy groups and the carbon atoms in the fused cyclic rings for all biaryl dicarboxylic acids. These tetrel-bonding interactions were thought to contribute to conformational control in the binaphthofuran derivative. Physical and chiroptical properties such as the racemization barriers and circular dichroism (CD) spectra of these biaryl dicarboxylic acids were also revealed.

Dual chalcogen-bonding interactions is proposed as a novel means for the conformational control of urea derivatives. The formation of a chalcogen-bonding interaction at both sides of the urea carbonyl group was unambiguously confirmed by X-ray diffraction and natural bond orbital (NBO) analysis via DFT calculations. By virtue of this dual interaction, urea derivatives that bear chalcogen atoms (X = S and Se) adopt a planar structure via the carbonyl oxygen (O) with an X•••O•••X arrangement on the same side of the molecule. The rigidity of the conformational lock was evaluated using the molecular arrangement in the crystal and the rotational barrier of benzochalcogenophene ring, which indicated a stronger conformational lock in benzoselenophene than in benzothiophene urea derivatives. Furthermore, the acidity of the urea derivatives increases according to the Lewis-acidic properties of the chalcogen-bonding interactions, whereby benzoselenophene urea is more acidic than benzothiophene urea. Tweezer-shaped urea derivatives were prepared, and their stereostructure proved the viability of the conformational control for defining the location of the substituents on the urea framework.

We present the experimental visualization of the valence-electron-density distribution in benzene and its kinetically stabilized heavier-element analogues, i.e., 1,2-disilabenzene and 1,2-digermabenzene.

The enantioselective Mannich-type reaction between N-cyano imines with malonic acid half thioesters (MAHTs) was accomplished by using a quinidine-derived chiral squaramide catalyst.

Bridged indigos were synthesized by bridging the two nitrogen atoms in the indigo structure with a carbon chain, and their properties were carefully examined. These bridged indigos have intrinsic planar chirality, and the enantiomers were separated using chiral high-performance liquid chromatography. When the chiral bridged indigos were subjected to thermo- and photoisomerization, the corresponding (Z)-indigo was not observed at all, and racemization was observed. This phenomenon is caused by the low activation energy of inversion due to the 1.5 bond order of the double bond of the indigo skeleton and the large energy difference between the ground states of (E)-indigo and (Z)-indigo.

A dual chalcogen-bonding interaction was proposed as a novel means for the conformational control of urea derivatives. The formation of a chalcogen-bonding interaction at both sides of the urea carbonyl group was unambiguously revealed by X-ray diffraction, as well as by natural bond orbital (NBO) analysis via DFT calculations. By virtue of this dual interaction, urea derivatives bearing chalcogen atoms (X = S and Se) were made to adopt a planar structure via the carbonyl oxygen (O) with an X•••O•••X arrangement on the same side of the molecule. Tweezer-shaped urea derivatives were also developed based on conformational control using the dual chalcogen-bonding interaction.

Self-assembly of π-conjugated molecules in solution generally occurs owing to either an enthalpic or an entropic gain; however, designing π-conjugated systems that simultaneously exhibit enthalpically and entropically favorable self-assembly behavior is challenging. Herein, the self-assembly behavior of tetraazatetrathia[8]circulenes is disclosed, which is driven by both enthalpy and entropy. Single-crystal X-ray diffraction analysis demonstrated that molecules of these tetraazatetrathia[8]circulenes form face-to-face stacked dimers with a 1D columnar structure owing to the circularly arranged dipole moments. Importantly, concentration- and temperature-dependent 1 H NMR spectra revealed that the formation of self-assemblies of tetraazatetrathia[8]circulenes in chloroform and methanol is favored by both enthalpic and entropic factors. The unique association behavior is due to the presence of sp2 -hybridized nitrogen atoms, which weakly coordinate to the hydrogen atoms of these solvents and reduce the π-electron density of the circulene cores.

Here we report an anionic meso-tetrakis(4-carboxymethylthio-2,3,5,6-tetrafluorophenyl) zinc porphyrin (ZnTF4PPTC4–) to form a supramolecular complex with a cationic lithium endohedral [60]fullerene...

Reactions of isolable disilynes and digermynes with alkynes can result in the formation of the corresponding disila- (DSBs) and digermabenzenes (DGBs), wherein two carbon atoms of the benzene ring are replaced by silicon or germanium atoms. Detailed structural and spectroscopic analyses of these DSBs and DGBs have revealed that they exhibit considerable aromaticity, comparable to that of benzene. However, in contrast to the all-carbon system benzene, these DSBs and DGBs are highly reactive toward small molecules such as oxygen, hydrogen, 1,3-dienes, and water. During the investigation of their reactivity, we discovered that a 1,2-DGB works as a catalyst for the cyclotrimerization of arylalkynes, which provides access to the corresponding 1,2,4-triarylbenzenes. In this perspective article, our recent progress in the area of DSB and DGB chemistry is summarized., Reactions of isolable disilynes and digermynes with alkynes can result in the formation of the corresponding disila- (DSBs) and digermabenzenes (DGBs), wherein two carbon atoms of the benzene ring are replaced by silicon or germanium atoms.

A one-pot transformation of biaryl dicarboxylic acids to (

D2-symmetric dirhodium(II) carboxylate catalysts that bear axially chiral binaphthothiophene δ-amino acid derivatives have been developed. Conformational control is supported through chalcogen-bond...

We designed and synthesized a novel Si-rhodamine derivative, NORD-1, as a red-light-controllable nitric oxide (NO) releaser, on the basis of photoredox parameter analysis. Red-light-responsive NO release from NORD-1 was confirmed by ESR spin trapping and quantified with an NO electrode and by means of Griess assay. The NO release cross section (e656 nm·ΦNO) of NORD-1 was calculated to be 3.65 × 102, which is larger than that of a previously reported yellowish-green-light-controllable NO releaser, NO-Rosa5. The photoresponsiveness of NO release from NORD-1 was precise and efficient enough to induce vasodilation ex vivo under Magnus test conditions. Finally, we showed that intracavernous pressure (ICP) could be controlled in rats in vivo with the combination of NORD-1 and a red-light source without increasing systemic blood pressure, which is a serious side effect of usual NO releasers, such as nitroglycerin and isopentyl nitrite. NORD-1 is expected to be a useful chemical tool for NO research, as well as a candidate agent to control the circulatory system.

The toxicity of lead perovskite hampers the commercialization of perovskite-based photovoltaics. While tin perovskite is a promising alternative, the facile oxidation of tin(II) to tin(IV) causes a high density of defects, resulting in lower solar cell efficiencies. Here, we show that tin(0) nanoparticles in the precursor solution can scavenge tin(IV) impurities, and demonstrate that this treatment leads to effectively tin(IV)-free perovskite films with strong photoluminescence and prolonged decay lifetimes. These nanoparticles are generated by the selective reaction of a dihydropyrazine derivative with the tin(II) fluoride additive already present in the precursor solution. Using this nanoparticle treatment, the power conversion efficiency of tin-based solar cells reaches 11.5%, with an open-circuit voltage of 0.76 V. Our nanoparticle treatment is a simple and broadly effective method that improves the purity and electrical performance of tin perovskite films., Tin based perovskites are easily oxidized, which generates large density of defects and compromised the solar cell efficiency. Here Nakamura et al. add metallic tin nanoparticles in the precursor solution to suppress tin (IV) impurities and enable high efficiency tin based perovskite solar cells.

A general method for alkali-metal-promoted reductive difunctionalization of alkenes has been developed by means of reduction-resistant alkoxy-substituted electrophiles. A series of 1,2-diboration and 1,2-dicarbofunctionalization products can be synthesized by employing trimethoxyborane and strained cyclic ethers such as oxirane and oxetane. In addition, unsymmetrical carbo- or thioborations have been accomplished via sequential treatment with trimethoxyborane and carbon or sulfur electrophiles.

Several examples of stable low-coordinated species of heavier group 14 elements (Si, Ge, Sb, Pb) such as divalent species and multiple-bond compounds have been reported. With the goal in mind to create unprecedented low-coordinated species of heavier group 14 elements that exhibit considerably increased redox stability, ferrocenyl (Fc)-substituted low-coordinated species of heavier group 14 elements were designed. In this short account article, recent progress on the synthesis of Fc-based low-coordinated species of heavier group 14 elements is summarized.

Three new mixed-ligand oxidovanadium(IV) complexes [VIVOL1–2(LN–N)] (1–3) have been synthesized using two tridentate bi-negative –ONS chelating dithiocarbazate ligands, H2L1-2, where H2L1 = S-methyl 3-(2-hydroxynaphthyl)methylenedithiocarbazate, and H2L2 = 4-chloro-S-benzyl 3-(2-hydroxy-4-diethylaminophenyl)methylenedithiocarbazate and neutral N,N-donor bases (LN–N) like 1,10-phenanthroline (phen) (1 and 2) and 2,2′-bipyridine (bipy) (3) as a co-ligand. All the ligands and their corresponding metal complexes have been successfully characterized using several physicochemical (elemental analysis), spectroscopic (UV-vis, IR and EPR), spectrometric (ESI-MS) and electrochemical (cyclic voltammetry) methods. The geometry of the complexes was determined by X-ray diffraction analysis and also optimized using density functional theory (DFT) calculations, which revealed that the compounds possess a distorted octahedral geometry with tridentate dianionic L1-2 in the meridional arrangement and bidentate co-ligand LN–N with an equatorial–axial coordination. To evaluate the biological activity of the oxidovanadium(IV) species, their interactions with calf thymus-DNA (CT-DNA) and human serum albumin (HSA) were studied through UV-vis absorption titration and fluorescence spectral methods. The results indicated that all the complexes have moderate binding affinity towards both DNA and HSA. Finally, the in vitro antiproliferative activity of all the complexes was evaluated against human cervical cancer (HeLa) and mouse embryonic fibroblast (NIH-3T3) cell lines by MTT assay and the results suggested that the complexes were significantly active compared to various clinically reported drugs.

The enantioselective reaction of imines bearing a cyano group as an activating group with malonic acid half thioesters gave chiral cyanamide derivatives with high enantioselectivity. The density functional theory (DFT) calculation clarified the stereochemical outcome and importance of the

The reduction of fullerene (C60) with sodium dispersion in the presence of an excess amount of dipropyl sulfate was found to yield highly propylated fullerene, C60(nC3H7)n (max. n = 24), and C60(nC3H7)20 was predominantly generated as determined by mass spectroscopy.

A one-pot transformation of biaryl dicarboxylic acids to (NH)-phenanthridinone derivatives based on a Curtius rearrangement and subsequent basic hydrolysis was developed. This method is also applicable for the preparation of optically active amide-functionalized [7]helicene-like molecules. Furthermore, aza[5]helicene derivatives with a phosphate moiety were isolated as a product of the Curtius rearrangement step in the case of substrates that bear chalcogen atoms. The stereostructures of these products, revealed by X-ray diffraction analysis, suggested that chalcogen-bonding and pnictogen-bonding interactions might contribute to their stabilization. The configurational stability of the helicene-like molecules and their chiroptical properties were further investigated.

A spirogermabifluorene that bears sterically demanding 3,3′,5,5′-tetra(t-butyl)-2,2′-biphenylene groups (1) was obtained from the reaction of in-situ-generated 2,2′-dilithiobiphenylene with GeCl2·(dioxane). The solid-state structure and the redox behavior of 1 were examined by single-crystal X-ray diffraction analysis and electrochemical measurements, respectively. The sterically hindered biphenyl ligands endow 1 with high redox stability and increased electron affinity. The experimental observations were corroborated by theoretical DFT calculations.

CH3NH3PbI3 (MAPbI3) perovskite layers can be obtained by thermal annealing thin films of the intermediate dimethyl sulfoxide (DMSO) intercalated complex, MA2Pb3I8·2DMSO. In the present work, the fo...

Reduction of alkynes with alkali metals in the presence of B2pin2 results in diboration of alkynes. Distinct from conventional dissolving metal hydrogenations, two carbon–boron bonds and also two c...

The first examples of stable, crystalline, and air-sensitive 1,4-digermabenzenes were isolated. These species photochemically isomerize into the corresponding air-stable digerma-Dewar-benzenes. More importantly, alkyl-substituted Dewar-type-1,4-digermabenzenes can be considered as reversible "air-stable activators" for small molecules such as dihydrogen, carbon dioxide, and acetylene at room temperature. The regeneration of these activators can be accomplished via a thermal retro-isomerization that affords the corresponding 1,4-digermabenzenes.

The intrinsic dynamic and static natures of the E⋯E′ interactions at the 1,8-positions of 1-(MeE)–8-(MeE′)C10H6 [1a–1f (E ≠ E′) and 1g–1j (E = E′)] were elucidated with QTAIM-DFA, after structural determination of 1-(PhE)–8-(PhE′)C10H6 (3a–3f), where (E, E′: x) = (O, S: a), (O, Se: b), (O, Te: c), (S, Se: d), (S, Te: e), (Se, Te: f), (O, O: g), (S, S: h), (Se, Se: i) and (Te, Te: j) (χE ≥ χE′). While the AB structures are confirmed for 3a, 3b and 3d–3f, which consist of the np(E)⋯σ*(E′–CPh) interactions, the structure was BB for 3c, where the E–CR/E′–CR (R = Ph) bond is perpendicular to the naphthyl plane in A and it is placed on the plane in B. While the AB structures are determined by the p(E)–π(Ph) conjugations, the BB structure is by the crystal packing effect. The BA structure with np(E′)⋯σ*(E–CPh) was not detected. While the nature of a typical hydrogen bond with covalency was predicted for BB, AA and BA, with the CT-MC (molecular complex formation through charge transfer) nature for AB in 1e and 1f (R = Me for E–CR/E′–CR), the CT-MC nature was predicted for all conformers of 1j, for example. NBO analysis for 1a–1f revealed that the acceptor orbitals contribute much more than the donor orbitals and the order is σ*(O–CMe

Herein we report the synthesis of five new mononuclear mixed ligand oxidovanadium(IV) complexes [V

Quadruply BN-fused tetrathia[8]circulenes were synthesized through four-fold electrophilic borylation. The single-crystal X-ray diffraction analysis revealed that the BN-fused tetrathia[8]circulene with peripheral phenyl groups exhibits crystal polymorphism, in which the circulene core adopts both planar and saddle conformations in the solid state. The experimental and theoretical studies revealed that the weaker aromaticity of azaborine compared with benzene renders the flexibility of the BN-fused tetrathia[8]circulenes.

Self-assembly of π-conjugated molecules in solution generally occurs owing to either an enthalpic or an entropic gain; however, designing π-conjugated systems that simultaneously exhibit enthalpically and entropically favorable self-assembly behavior is challenging. Herein, the self-assembly behavior of tetraazatetrathia[8]circulenes is disclosed, which is driven by both enthalpy and entropy. Single-crystal X-ray diffraction analysis demonstrated that molecules of these tetraazatetrathia[8]circulenes form face-to-face stacked dimers with a 1D columnar structure owing to the circularly arranged dipole moments. Importantly, concentration- and temperature-dependent